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Dear Readers! I started this blog when my daughter was in the NICU. She had ventriculitis. Her CSF report grew E.coli. But, she was injected Teicoplanin directly into her brain. The doctors made two errors here:

Teicoplanin is for gram-positive bacteria only. It does not treat E.coli.
Teicoplanin is not for intraventricular use. The manufacturer strongly discourage injecting Teicoplanin into the brain.

My daughter bled into the brain. She lived for another two years and ultimately died.

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Kisqali Femara Co-Pack (Ribociclib and Letrozole) - Dose, MOA

Kisqali Femara Co-Pack (Ribociclib and letrozole) is used in the treatment of advanced or metastatic breast cancer. Ribociclib is a small-molecule cyclin-dependent kinase (CDK) inhibitor that is selective for CDK 4 and 6. Letrozole (Femara) is an aromatase inhibitor (anti-estrogen drug) that catalyzes the conversion of androgens to estrogens.

Ribociclib and letrozole Uses:

Advanced or Metastatic Breast Cancer:
- Ribociclib and letrozole (Kisqali Femara Co-Pack) is indicated as initial endocrine-based therapy in Hormone-Receptor Positive (HR-positive) and HER2-Negative (human epidermal growth factor receptor-negative) premenopausal or postmenopausal women with metastatic or advanced breast cancer.
- Limitations of use: Premenopausal or perimenopausal females who are on ribociclib and letrozole treatment should also receive a luteinizing hormone-releasing hormone agonist.

Kisqali Femara Co-Pack (Ribociclib and letrozole) Dose in Adults:

The recommended dose is 600/2.5 mg once daily for 21 days followed by 7 days off-treatment.

Use in Children:

Not indicated.

Pregnancy Risk Category: X

Refer to individual drugs (letrozole, ribociclib) for more information about its use during pregnancy.
It has not been tested in human or animal pregnancies. Its mechanism of action may lead to adverse fetal outcomes.
Every woman with reproductive potential should have a pregnancy check done prior to treatment.
Women who are pregnant should also be advised to use effective contraception for the duration of treatment as well as for the first three weeks.

Use of letrozole and ribiclib during breastfeeding

It is unknown whether the drug will be excreted into breastmilk.
The manufacturer suggests that you stop breastfeeding for at least three weeks following the last dose.

Dose in Renal Disease:

Refer to individual drug monograph.

Dose in Liver Disease:

Dose reduction is required in severe liver disease. Refer to individual drug monograph.

Also, see individual agents (Ribociclib and letrozole)

Common Side Effects of Kisqali Femara Co-Pack (Ribociclib and letrozole):

Cardiovascular:
- Peripheral Edema
Central Nervous System:
- Fatigue
- Headache
- Insomnia
Dermatologic:
- Alopecia
- Skin Rash
- Pruritus
Endocrine & Metabolic:
- Decreased Serum Potassium
Gastrointestinal:
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Decreased Appetite
- Stomatitis
- Abdominal Pain
Genitourinary:
- Urinary Tract Infection
Hematologic & Oncologic:
- Neutropenia
- Leukopenia
- Decreased Platelet Count
- Anemia
- Decreased Serum Phosphate
- Lymphocytopenia
Hepatic:
- Increased Serum Alanine Aminotransferase
- Increased Serum Aspartate Aminotransferase
- Abnormal Hepatic Function Tests
Neuromuscular & Skeletal:
- Back Pain
Renal:
- Increased Serum Creatinine
Respiratory:
- Dyspnea
Miscellaneous:
- Fever

Less Common Side Effects of Ribociclib and letrozole:

Cardiovascular:
- Syncope
- Prolonged Q-T interval on ECG

Hepatic:
- Hepatotoxicity
- Increased serum bilirubin

Contraindications to Kisqali Femara Co-Pack (Ribociclib and letrozole):

For contraindications and Warnings, refer to individual drugs monograph: Letrozole and ribociclib.

Ribociclib and letrozole (co-packaged): Drug Interaction

Risk Factor C (Monitor therapy)
Abemaciclib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Abemaciclib.
AmLODIPine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of AmLODIPine.
Apixaban	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Apixaban.
ARIPiprazole	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of ARIPiprazole. Management: Monitor for increased aripiprazole pharmacologic effects. Aripiprazole dose adjustments may or may not be required based on concomitant therapy and/or indication. Consult full interaction monograph for specific recommendations.
Benzhydrocodone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Benzhydrocodone. Specifically, the concentration of hydrocodone may be increased.
Blonanserin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Blonanserin.
Bosentan	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Bosentan	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bosentan. Management: Concomitant use of both a CYP2C9 inhibitor and a CYP3A inhibitor or a single agent that inhibits both enzymes with bosentan is likely to cause a large increase in serum concentrations of bosentan and is not recommended. See monograph for details.
Brexpiprazole	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Brexpiprazole. Management: The brexpiprazole dose should be reduced to 25% of usual if used together with both a moderate CYP3A4 inhibitor and a strong or moderate CYP2D6 inhibitor, or if a moderate CYP3A4 inhibitor is used in a CYP2D6 poor metabolizer.
Cannabidiol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cannabidiol.
Cannabis	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be increased.
Ceritinib	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of Ceritinib. Ceritinib may enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Ceritinib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Chloramphenicol (Ophthalmic)	May enhance the adverse/toxic effect of Myelosuppressive Agents.
Citalopram	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Citalopram.
Clofazimine	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Coccidioides immitis Skin Test	Immunosuppressants may diminish the diagnostic effect of Coccidioides immitis Skin Test.
Codeine	CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Codeine.
Crizotinib	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of Crizotinib. QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Crizotinib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
CYP3A4 Inducers (Moderate)	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
CYP3A4 Inhibitors (Moderate)	May decrease the metabolism of CYP3A4 Substrates (High risk with Inhibitors).
CYP3A4 Substrates (High risk with Inhibitors)	CYP3A4 Inhibitors (Moderate) may decrease the metabolism of CYP3A4 Substrates (High risk with Inhibitors). Exceptions: Alitretinoin (Systemic); Praziquantel; Trabectedin; Vinorelbine.
Deferasirox	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Denosumab	May enhance the adverse/toxic effect of Immunosuppressants. Specifically, the risk for serious infections may be increased.
Dronabinol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dronabinol.
Duvelisib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Erdafitinib	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Erdafitinib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Erythromycin (Systemic)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Estrogen Derivatives	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Estrogen Derivatives.
Fluconazole	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Fosnetupitant	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Haloperidol	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of Haloperidol. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
HYDROcodone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of HYDROcodone.
Ifosfamide	CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Ifosfamide.
Imatinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Imatinib.
Larotrectinib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Levomethadone	Aromatase Inhibitors may increase the serum concentration of Levomethadone.
Manidipine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Manidipine.
Mesalamine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
Mirodenafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Mirodenafil.
Naldemedine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Naldemedine.
Nalfurafine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Nalfurafine.
Netupitant	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
NiMODipine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of NiMODipine.
Ocrelizumab	May enhance the immunosuppressive effect of Immunosuppressants.
Ondansetron	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
OxyCODONE	CYP3A4 Inhibitors (Moderate) may enhance the adverse/toxic effect of OxyCODONE. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of OxyCODONE. Serum concentrations of the active metabolite Oxymorphone may also be increased.
Palbociclib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Pentamidine (Systemic)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Pexidartinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pexidartinib.
Pidotimod	Immunosuppressants may diminish the therapeutic effect of Pidotimod.
Promazine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
QT-prolonging Antidepressants (Moderate Risk)	May enhance the QTc-prolonging effect of QTprolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Exceptions: Citalopram.
QT-prolonging Antipsychotics (Moderate Risk)	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Antipsychotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Exceptions: Pimozide; QUEtiapine.
QT-prolonging Class IC Antiarrhythmics (Moderate Risk)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
QT-prolonging Kinase Inhibitors (Moderate Risk)	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Kinase Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QT-prolonging Kinase Inhibitors (Moderate Risk). Exceptions: Encorafenib; Entrectinib.
QT-prolonging Miscellaneous Agents (Moderate Risk)	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Exceptions: Domperidone.
QT-prolonging Quinolone Antibiotics (Moderate Risk)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
QUEtiapine	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of QUEtiapine. QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QUEtiapine. Management: Monitor for increased quetiapine toxicities including QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Rupatadine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Rupatadine.
Ruxolitinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ruxolitinib.
Salmeterol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Salmeterol.
Sarilumab	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
SAXagliptin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of SAXagliptin.
Sildenafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sildenafil.
Silodosin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Silodosin.
Siltuximab	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Siponimod	Immunosuppressants may enhance the immunosuppressive effect of Siponimod.
Tamsulosin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tamsulosin.
Tertomotide	Immunosuppressants may diminish the therapeutic effect of Tertomotide.
Tetrahydrocannabinol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tetrahydrocannabinol.
Ticagrelor	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ticagrelor.
Tocilizumab	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Trabectedin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Trabectedin.
Trastuzumab	May enhance the neutropenic effect of Immunosuppressants.
Udenafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Udenafil.
Vilazodone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vilazodone.
Vindesine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vindesine.
Zuclopenthixol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Zuclopenthixol.
Risk Factor D (Consider therapy modification)
Acalabrutinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Acalabrutinib. Management: Reduce acalabrutinib dose to 100 mg once daily with concurrent use of a moderate CYP3A4 inhibitor. Monitor patient closely for both acalabrutinib response and evidence of adverse effects with any concurrent use.
Avanafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Avanafil. Management: The maximum avanafil adult dose is 50 mg per 24-hour period when used together with a moderate CYP3A4 inhibitor. Patients receiving such a combination should also be monitored more closely for evidence of adverse effects.
Baricitinib	Immunosuppressants may enhance the immunosuppressive effect of Baricitinib. Management: Use of baricitinib in combination with potent immunosuppressants such as azathioprine or cyclosporine is not recommended. Concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted.
Brigatinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with moderate CYP3A4 inhibitors when possible. If such a combination cannot be avoided, reduce the dose of brigatinib by approximately 40% (ie, from 180 mg to 120 mg, from 120 mg to 90 mg, or from 90 mg to 60 mg).
Bromocriptine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bromocriptine. Management: The bromocriptine dose should not exceed 1.6 mg daily with use of a moderate CYP3A4 inhibitor. The Cycloset brand specifically recommends this dose limitation, but other bromocriptine products do not make such specific recommendations.
Budesonide (Topical)	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Topical). Management: Per US prescribing information, avoid this combination. Canadian product labeling does not recommend strict avoidance. If combined, monitor for excessive glucocorticoid effects as budesonide exposure may be increased.
Cilostazol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cilostazol. Management: Consider reducing the cilostazol dose to 50 mg twice daily in adult patients who are also receiving moderate inhibitors of CYP3A4.
Colchicine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Colchicine. Management: Reduce colchicine dose as directed when using with a moderate CYP3A4 inhibitor, and increase monitoring for colchicine-related toxicity. See full monograph for details. Use extra caution in patients with impaired renal and/or hepatic function.
CYP3A4 Inhibitors (Strong)	May increase the serum concentration of Ribociclib. Management: Avoid use of ribociclib with strong CYP3A4 inhibitors when possible; if combined use cannot be avoided, reduce ribociclib dose to 400 mg once daily. Exceptions are discussed in separate monographs. Exceptions: Voriconazole.
Dabrafenib	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects).
Dapoxetine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dapoxetine. Management: The dose of dapoxetine should be limited to 30 mg per day when used together with a moderate inhibitor of CYP3A4.
Deferiprone	Myelosuppressive Agents may enhance the neutropenic effect of Deferiprone. Management: Avoid the concomitant use of deferiprone and myelosuppressive agents whenever possible. If this combination cannot be avoided, monitor the absolute neutrophil count more closely.
Deflazacort	CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Deflazacort. Management: Administer one third of the recommended deflazacort dose when used together with a strong or moderate CYP3A4 inhibitor.
DOXOrubicin (Conventional)	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of DOXOrubicin (Conventional). Management: Seek alternatives to moderate CYP3A4 inhibitors in patients treated with doxorubicin whenever possible. One U.S. manufacturer (Pfizer Inc.) recommends that these combinations be avoided.
Echinacea	May diminish the therapeutic effect of Immunosuppressants.
Eletriptan	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eletriptan. Management: The use of eletriptan within 72 hours of a moderate CYP3A4 inhibitor should be avoided.
Eliglustat	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eliglustat. Management: Use should be avoided under some circumstances. See full drug interaction monograph for details.
Encorafenib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Encorafenib. Management: Avoid concomitant use of encorafenib and moderate CYP3A4 inhibitors whenever possible. If concomitant administration is unavoidable, decrease the encorafenib dose prior to initiation of the CYP3A4 inhibitor. See full monograph for details.
Encorafenib	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Encorafenib. Management: Avoid using moderate CYP3A4 inhibitors together with encorafenib if possible. If the combination must be used, reduce the encorafenib dose prior to initiation of the moderate CYP3A4 inhibitor and monitor QT interval. See full monograph for details.
Eplerenone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eplerenone. Management: When used concomitantly with moderate inhibitors of CYP3A4, eplerenone dosing recommendations vary by indication and international labeling. See full drug interaction monograph for details.
Everolimus	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Everolimus. Management: Everolimus dose reductions are required for most indications. See full monograph or prescribing information for specific dose adjustment and monitoring recommendations.
FentaNYL	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of FentaNYL. Management: Monitor patients closely for several days following initiation of this combination, and adjust fentanyl dose as necessary.
Fingolimod	Immunosuppressants may enhance the immunosuppressive effect of Fingolimod. Management: Avoid the concomitant use of fingolimod and other immunosuppressants when possible. If combined, monitor patients closely for additive immunosuppressant effects (eg, infections).
GuanFACINE	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of GuanFACINE. Management: Reduce the guanfacine dose by 50% when initiating this combination.
Ibrutinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ibrutinib. Management: When treating B-cell malignancies, decrease ibrutinib to 280 mg daily when combined with moderate CYP3A4 inhibitors. When treating graft versus host disease, monitor patients closely and reduce the ibrutinib dose as needed based on adverse reactions.
Ivacaftor	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivacaftor. Management: Ivacaftor dose reductions are required; consult full monograph content for specific age- and weight-based recommendations. No dose adjustment is needed when using ivacaftor/lumacaftor with a moderate CYP3A4 inhibitor.
Leflunomide	Immunosuppressants may enhance the adverse/toxic effect of Leflunomide. Specifically, the risk for hematologic toxicity such as pancytopenia, agranulocytosis, and/or thrombocytopenia may be increased. Management: Consider not using a leflunomide loading dose in patients receiving other immunosuppressants. Patients receiving both leflunomide and another immunosuppressant should be monitored for bone marrow suppression at least monthly.
Lorlatinib	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Avoid concurrent use of lorlatinib with any CYP3A4 substrates for which a minimal decrease in serum concentrations of the CYP3A4 substrate could lead to therapeutic failure and serious clinical consequences.
Lurasidone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lurasidone. Management: Lurasidone US labeling recommends reducing lurasidone dose by half with a moderate CYP3A4 inhibitor. Some non-US labeling recommends initiating lurasidone at 20 mg/day and limiting dose to 40 mg/day; avoid concurrent use of grapefruit products.
Meperidine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Meperidine. Management: Consider reducing meperidine dose if concomitant use with moderate CYP3A4 inhibitors is required. Monitor for signs and symptoms of respiratory depression and sedation when these agents are combined.
MiFEPRIStone	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Management: Minimize doses of CYP3A4 substrates, and monitor for increased concentrations/toxicity, during and 2 weeks following treatment with mifepristone. Avoid cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus.
Nilotinib	May enhance the QTc-prolonging effect of Ribociclib. Management: Consider alternatives to this combination. Patients with other risk factors (eg, older age, female sex, bradycardia, hypokalemia, hypomagnesemia, heart disease, and higher drug concentrations) are likely at greater risk for these toxicities.
Nivolumab	Immunosuppressants may diminish the therapeutic effect of Nivolumab.
Olaparib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Olaparib. Management: Avoid use of moderate CYP3A4 inhibitors in patients being treated with olaparib, if possible. If such concurrent use cannot be avoided, the dose of olaparib should be reduced to 150 mg twice daily.
QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk)	Ribociclib may enhance the QTcprolonging effect of QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Ribociclib. Management: Avoid concomitant use of ribociclib and strong CYP3A4 inhibitors that prolong the QTc interval whenever possible. If combined, decrease the ribociclib dose to 400 mg daily. Monitor for ribociclib toxicities including QTc prolongation and arrhythmias.
Ranolazine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ranolazine. Management: Limit the ranolazine adult dose to a maximum of 500 mg twice daily in patients concurrently receiving moderate CYP3A4 inhibitors (e.g., diltiazem, verapamil, erythromycin, etc.).
Roflumilast	May enhance the immunosuppressive effect of Immunosuppressants.
Sipuleucel-T	Immunosuppressants may diminish the therapeutic effect of Sipuleucel-T. Management: Evaluate patients to see if it is medically appropriate to reduce or discontinue therapy with immunosuppressants prior to initiating sipuleucel-T therapy.
Sirolimus	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sirolimus. Management: Monitor for increased serum concentrations of sirolimus if combined with a moderate CYP3A4 inhibitor. Lower initial sirolimus doses or sirolimus dose reductions will likely be required.
Sonidegib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sonidegib. Management: Avoid concomitant use of sonidegib and moderate CYP3A4 inhibitors when possible. When concomitant use cannot be avoided, limit CYP3A4 inhibitor use to less than 14 days and monitor for sonidegib toxicity (particularly musculoskeletal adverse reactions).
Stiripentol	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Management: Use of stiripentol with CYP3A4 substrates that are considered to have a narrow therapeutic index should be avoided due to the increased risk for adverse effects and toxicity. Any CYP3A4 substrate used with stiripentol requires closer monitoring.
Suvorexant	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Suvorexant. Management: The recommended dose of suvorexant is 5 mg daily in patients receiving a moderate CYP3A4 inhibitor. The dose can be increased to 10 mg daily (maximum dose) if necessary for efficacy.
Tamoxifen	Ribociclib may increase the serum concentration of Tamoxifen. Management: Concurrent use of ribociclib with tamoxifen is not indicated. Use of this combination may increase the effects and toxicities of tamoxifen.
Tezacaftor	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tezacaftor. Management: When combined with moderate CYP3A4 inhibitors, tezacaftor/ivacaftor should be given in the morning, every other day. Ivacaftor alone should be given in the morning, every other day on alternate days from tezacaftor/ivacaftor.
Tofacitinib	Immunosuppressants may enhance the immunosuppressive effect of Tofacitinib. Management: Concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted, and this warning seems particularly focused on more potent immunosuppressants.
Tolvaptan	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tolvaptan. Management: Jynarque dose requires adjustment when used with a moderate CYP3A4 inhibitor. See labeling or full interaction monograph for specific recommendations. Use of Samsca with moderate CYP3A4 ihibitors should generally be avoided.
Vaccines (Inactivated)	Immunosuppressants may diminish the therapeutic effect of Vaccines (Inactivated). Management: Vaccine efficacy may be reduced. Complete all age-appropriate vaccinations at least 2 weeks prior to starting an immunosuppressant. If vaccinated during immunosuppressant therapy, revaccinate at least 3 months after immunosuppressant discontinuation.
Venetoclax	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Venetoclax. Management: Reduce the venetoclax dose by at least 50% in patients requiring these combinations.
Zopiclone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Zopiclone. Management: The starting adult dose of zopiclone should not exceed 3.75 mg if combined with a moderate CYP3A4 inhibitor. Monitor patients for signs and symptoms of zopiclone toxicity if these agents are combined.
Risk Factor X (Avoid combination)
Aprepitant	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Aprepitant.
Asunaprevir	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Asunaprevir.
BCG (Intravesical)	Immunosuppressants may diminish the therapeutic effect of BCG (Intravesical).
BCG (Intravesical)	Myelosuppressive Agents may diminish the therapeutic effect of BCG (Intravesical).
Bosutinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bosutinib.
Budesonide (Systemic)	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Systemic).
Cladribine	May enhance the immunosuppressive effect of Immunosuppressants.
Cladribine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
Cobimetinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cobimetinib. Management: Avoid the concomitant use of cobimetinib and moderate CYP3A4 inhibitors. If concurrent short term (14 days or less) use cannot be avoided, reduce the cobimetinib dose to 20 mg daily.
Conivaptan	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
CYP3A4 Inducers (Strong)	May decrease the serum concentration of Ribociclib.
Dipyrone	May enhance the adverse/toxic effect of Myelosuppressive Agents. Specifically, the risk for agranulocytosis and pancytopenia may be increased
Domperidone	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Domperidone.
Entrectinib	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Entrectinib.
Flibanserin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Flibanserin.
Fosaprepitant	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Fosaprepitant.
Fusidic Acid (Systemic)	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Grapefruit Juice	May increase the serum concentration of Ribociclib.
Idelalisib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Ivabradine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivabradine.
Lefamulin	May enhance the QTc-prolonging effect of QT-prolonging CYP3A4 Substrates. Management: Do not use lefamulin tablets with QT-prolonging CYP3A4 substrates. Lefamulin prescribing information lists this combination as contraindicated.
Lomitapide	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lomitapide.
Naloxegol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Naloxegol.
Natalizumab	Immunosuppressants may enhance the adverse/toxic effect of Natalizumab. Specifically, the risk of concurrent infection may be increased.
Neratinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Neratinib.
Pimecrolimus	May enhance the adverse/toxic effect of Immunosuppressants.
Pimozide	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pimozide.
Pimozide	May enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk).
Pomegranate	May increase the serum concentration of Ribociclib.
Posaconazole	May increase the serum concentration of QT-prolonging CYP3A4 Substrates. Such increases may lead to a greater risk for proarrhythmic effects and other similar toxicities.
QT-prolonging Agents (Highest Risk)	May enhance the QTc-prolonging effect of Ribociclib.
Simeprevir	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Simeprevir.
St John's Wort	May decrease the serum concentration of Ribociclib.
Tacrolimus (Topical	May enhance the adverse/toxic effect of Immunosuppressants.
Ulipristal	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ulipristal. Management: This is specific for when ulipristal is being used for signs/symptoms of uterine fibroids (Canadian indication). When ulipristal is used as an emergency contraceptive, patients receiving this combination should be monitored for ulipristal toxicity.
Vaccines (Live)	Immunosuppressants may enhance the adverse/toxic effect of Vaccines (Live). Immunosuppressants may diminish the therapeutic effect of Vaccines (Live). Management: Avoid use of live organism vaccines with immunosuppressants; live-attenuated vaccines should not be given for at least 3 months after immunosuppressants.

Ribociclib and letrozole (co-packaged): Drug Interaction

Risk Factor C (Monitor therapy)
Abemaciclib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Abemaciclib.
AmLODIPine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of AmLODIPine.
Apixaban	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Apixaban.
ARIPiprazole	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of ARIPiprazole. Management: Monitor for increased aripiprazole pharmacologic effects. Aripiprazole dose adjustments may or may not be required based on concomitant therapy and/or indication. Consult full interaction monograph for specific recommendations.
Benzhydrocodone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Benzhydrocodone. Specifically, the concentration of hydrocodone may be increased.
Blonanserin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Blonanserin.
Bosentan	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Bosentan	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bosentan. Management: Concomitant use of both a CYP2C9 inhibitor and a CYP3A inhibitor or a single agent that inhibits both enzymes with bosentan is likely to cause a large increase in serum concentrations of bosentan and is not recommended. See monograph for details.
Brexpiprazole	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Brexpiprazole. Management: The brexpiprazole dose should be reduced to 25% of usual if used together with both a moderate CYP3A4 inhibitor and a strong or moderate CYP2D6 inhibitor, or if a moderate CYP3A4 inhibitor is used in a CYP2D6 poor metabolizer.
Cannabidiol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cannabidiol.
Cannabis	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be increased.
Ceritinib	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of Ceritinib. Ceritinib may enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Ceritinib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Chloramphenicol (Ophthalmic)	May enhance the adverse/toxic effect of Myelosuppressive Agents.
Citalopram	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Citalopram.
Clofazimine	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Coccidioides immitis Skin Test	Immunosuppressants may diminish the diagnostic effect of Coccidioides immitis Skin Test.
Codeine	CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Codeine.
Crizotinib	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of Crizotinib. QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Crizotinib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
CYP3A4 Inducers (Moderate)	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
CYP3A4 Inhibitors (Moderate)	May decrease the metabolism of CYP3A4 Substrates (High risk with Inhibitors).
CYP3A4 Substrates (High risk with Inhibitors)	CYP3A4 Inhibitors (Moderate) may decrease the metabolism of CYP3A4 Substrates (High risk with Inhibitors). Exceptions: Alitretinoin (Systemic); Praziquantel; Trabectedin; Vinorelbine.
Deferasirox	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Denosumab	May enhance the adverse/toxic effect of Immunosuppressants. Specifically, the risk for serious infections may be increased.
Dronabinol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dronabinol.
Duvelisib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Erdafitinib	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Erdafitinib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Erythromycin (Systemic)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Estrogen Derivatives	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Estrogen Derivatives.
Fluconazole	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Fosnetupitant	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Haloperidol	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of Haloperidol. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
HYDROcodone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of HYDROcodone.
Ifosfamide	CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Ifosfamide.
Imatinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Imatinib.
Larotrectinib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Levomethadone	Aromatase Inhibitors may increase the serum concentration of Levomethadone.
Manidipine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Manidipine.
Mesalamine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
Mirodenafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Mirodenafil.
Naldemedine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Naldemedine.
Nalfurafine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Nalfurafine.
Netupitant	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
NiMODipine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of NiMODipine.
Ocrelizumab	May enhance the immunosuppressive effect of Immunosuppressants.
Ondansetron	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
OxyCODONE	CYP3A4 Inhibitors (Moderate) may enhance the adverse/toxic effect of OxyCODONE. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of OxyCODONE. Serum concentrations of the active metabolite Oxymorphone may also be increased.
Palbociclib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Pentamidine (Systemic)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Pexidartinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pexidartinib.
Pidotimod	Immunosuppressants may diminish the therapeutic effect of Pidotimod.
Promazine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
QT-prolonging Antidepressants (Moderate Risk)	May enhance the QTc-prolonging effect of QTprolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Exceptions: Citalopram.
QT-prolonging Antipsychotics (Moderate Risk)	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Antipsychotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Exceptions: Pimozide; QUEtiapine.
QT-prolonging Class IC Antiarrhythmics (Moderate Risk)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
QT-prolonging Kinase Inhibitors (Moderate Risk)	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Kinase Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QT-prolonging Kinase Inhibitors (Moderate Risk). Exceptions: Encorafenib; Entrectinib.
QT-prolonging Miscellaneous Agents (Moderate Risk)	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Exceptions: Domperidone.
QT-prolonging Quinolone Antibiotics (Moderate Risk)	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
QUEtiapine	QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may enhance the QTcprolonging effect of QUEtiapine. QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QUEtiapine. Management: Monitor for increased quetiapine toxicities including QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk.
Rupatadine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Rupatadine.
Ruxolitinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ruxolitinib.
Salmeterol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Salmeterol.
Sarilumab	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
SAXagliptin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of SAXagliptin.
Sildenafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sildenafil.
Silodosin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Silodosin.
Siltuximab	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Siponimod	Immunosuppressants may enhance the immunosuppressive effect of Siponimod.
Tamsulosin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tamsulosin.
Tertomotide	Immunosuppressants may diminish the therapeutic effect of Tertomotide.
Tetrahydrocannabinol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tetrahydrocannabinol.
Ticagrelor	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ticagrelor.
Tocilizumab	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers).
Trabectedin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Trabectedin.
Trastuzumab	May enhance the neutropenic effect of Immunosuppressants.
Udenafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Udenafil.
Vilazodone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vilazodone.
Vindesine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vindesine.
Zuclopenthixol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Zuclopenthixol.
Risk Factor D (Consider therapy modification)
Acalabrutinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Acalabrutinib. Management: Reduce acalabrutinib dose to 100 mg once daily with concurrent use of a moderate CYP3A4 inhibitor. Monitor patient closely for both acalabrutinib response and evidence of adverse effects with any concurrent use.
Avanafil	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Avanafil. Management: The maximum avanafil adult dose is 50 mg per 24-hour period when used together with a moderate CYP3A4 inhibitor. Patients receiving such a combination should also be monitored more closely for evidence of adverse effects.
Baricitinib	Immunosuppressants may enhance the immunosuppressive effect of Baricitinib. Management: Use of baricitinib in combination with potent immunosuppressants such as azathioprine or cyclosporine is not recommended. Concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted.
Brigatinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with moderate CYP3A4 inhibitors when possible. If such a combination cannot be avoided, reduce the dose of brigatinib by approximately 40% (ie, from 180 mg to 120 mg, from 120 mg to 90 mg, or from 90 mg to 60 mg).
Bromocriptine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bromocriptine. Management: The bromocriptine dose should not exceed 1.6 mg daily with use of a moderate CYP3A4 inhibitor. The Cycloset brand specifically recommends this dose limitation, but other bromocriptine products do not make such specific recommendations.
Budesonide (Topical)	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Topical). Management: Per US prescribing information, avoid this combination. Canadian product labeling does not recommend strict avoidance. If combined, monitor for excessive glucocorticoid effects as budesonide exposure may be increased.
Cilostazol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cilostazol. Management: Consider reducing the cilostazol dose to 50 mg twice daily in adult patients who are also receiving moderate inhibitors of CYP3A4.
Colchicine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Colchicine. Management: Reduce colchicine dose as directed when using with a moderate CYP3A4 inhibitor, and increase monitoring for colchicine-related toxicity. See full monograph for details. Use extra caution in patients with impaired renal and/or hepatic function.
CYP3A4 Inhibitors (Strong)	May increase the serum concentration of Ribociclib. Management: Avoid use of ribociclib with strong CYP3A4 inhibitors when possible; if combined use cannot be avoided, reduce ribociclib dose to 400 mg once daily. Exceptions are discussed in separate monographs. Exceptions: Voriconazole.
Dabrafenib	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects).
Dapoxetine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dapoxetine. Management: The dose of dapoxetine should be limited to 30 mg per day when used together with a moderate inhibitor of CYP3A4.
Deferiprone	Myelosuppressive Agents may enhance the neutropenic effect of Deferiprone. Management: Avoid the concomitant use of deferiprone and myelosuppressive agents whenever possible. If this combination cannot be avoided, monitor the absolute neutrophil count more closely.
Deflazacort	CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Deflazacort. Management: Administer one third of the recommended deflazacort dose when used together with a strong or moderate CYP3A4 inhibitor.
DOXOrubicin (Conventional)	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of DOXOrubicin (Conventional). Management: Seek alternatives to moderate CYP3A4 inhibitors in patients treated with doxorubicin whenever possible. One U.S. manufacturer (Pfizer Inc.) recommends that these combinations be avoided.
Echinacea	May diminish the therapeutic effect of Immunosuppressants.
Eletriptan	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eletriptan. Management: The use of eletriptan within 72 hours of a moderate CYP3A4 inhibitor should be avoided.
Eliglustat	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eliglustat. Management: Use should be avoided under some circumstances. See full drug interaction monograph for details.
Encorafenib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Encorafenib. Management: Avoid concomitant use of encorafenib and moderate CYP3A4 inhibitors whenever possible. If concomitant administration is unavoidable, decrease the encorafenib dose prior to initiation of the CYP3A4 inhibitor. See full monograph for details.
Encorafenib	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Encorafenib. Management: Avoid using moderate CYP3A4 inhibitors together with encorafenib if possible. If the combination must be used, reduce the encorafenib dose prior to initiation of the moderate CYP3A4 inhibitor and monitor QT interval. See full monograph for details.
Eplerenone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eplerenone. Management: When used concomitantly with moderate inhibitors of CYP3A4, eplerenone dosing recommendations vary by indication and international labeling. See full drug interaction monograph for details.
Everolimus	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Everolimus. Management: Everolimus dose reductions are required for most indications. See full monograph or prescribing information for specific dose adjustment and monitoring recommendations.
FentaNYL	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of FentaNYL. Management: Monitor patients closely for several days following initiation of this combination, and adjust fentanyl dose as necessary.
Fingolimod	Immunosuppressants may enhance the immunosuppressive effect of Fingolimod. Management: Avoid the concomitant use of fingolimod and other immunosuppressants when possible. If combined, monitor patients closely for additive immunosuppressant effects (eg, infections).
GuanFACINE	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of GuanFACINE. Management: Reduce the guanfacine dose by 50% when initiating this combination.
Ibrutinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ibrutinib. Management: When treating B-cell malignancies, decrease ibrutinib to 280 mg daily when combined with moderate CYP3A4 inhibitors. When treating graft versus host disease, monitor patients closely and reduce the ibrutinib dose as needed based on adverse reactions.
Ivacaftor	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivacaftor. Management: Ivacaftor dose reductions are required; consult full monograph content for specific age- and weight-based recommendations. No dose adjustment is needed when using ivacaftor/lumacaftor with a moderate CYP3A4 inhibitor.
Leflunomide	Immunosuppressants may enhance the adverse/toxic effect of Leflunomide. Specifically, the risk for hematologic toxicity such as pancytopenia, agranulocytosis, and/or thrombocytopenia may be increased. Management: Consider not using a leflunomide loading dose in patients receiving other immunosuppressants. Patients receiving both leflunomide and another immunosuppressant should be monitored for bone marrow suppression at least monthly.
Lorlatinib	May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Avoid concurrent use of lorlatinib with any CYP3A4 substrates for which a minimal decrease in serum concentrations of the CYP3A4 substrate could lead to therapeutic failure and serious clinical consequences.
Lurasidone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lurasidone. Management: Lurasidone US labeling recommends reducing lurasidone dose by half with a moderate CYP3A4 inhibitor. Some non-US labeling recommends initiating lurasidone at 20 mg/day and limiting dose to 40 mg/day; avoid concurrent use of grapefruit products.
Meperidine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Meperidine. Management: Consider reducing meperidine dose if concomitant use with moderate CYP3A4 inhibitors is required. Monitor for signs and symptoms of respiratory depression and sedation when these agents are combined.
MiFEPRIStone	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Management: Minimize doses of CYP3A4 substrates, and monitor for increased concentrations/toxicity, during and 2 weeks following treatment with mifepristone. Avoid cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus.
Nilotinib	May enhance the QTc-prolonging effect of Ribociclib. Management: Consider alternatives to this combination. Patients with other risk factors (eg, older age, female sex, bradycardia, hypokalemia, hypomagnesemia, heart disease, and higher drug concentrations) are likely at greater risk for these toxicities.
Nivolumab	Immunosuppressants may diminish the therapeutic effect of Nivolumab.
Olaparib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Olaparib. Management: Avoid use of moderate CYP3A4 inhibitors in patients being treated with olaparib, if possible. If such concurrent use cannot be avoided, the dose of olaparib should be reduced to 150 mg twice daily.
QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk)	Ribociclib may enhance the QTcprolonging effect of QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Ribociclib. Management: Avoid concomitant use of ribociclib and strong CYP3A4 inhibitors that prolong the QTc interval whenever possible. If combined, decrease the ribociclib dose to 400 mg daily. Monitor for ribociclib toxicities including QTc prolongation and arrhythmias.
Ranolazine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ranolazine. Management: Limit the ranolazine adult dose to a maximum of 500 mg twice daily in patients concurrently receiving moderate CYP3A4 inhibitors (e.g., diltiazem, verapamil, erythromycin, etc.).
Roflumilast	May enhance the immunosuppressive effect of Immunosuppressants.
Sipuleucel-T	Immunosuppressants may diminish the therapeutic effect of Sipuleucel-T. Management: Evaluate patients to see if it is medically appropriate to reduce or discontinue therapy with immunosuppressants prior to initiating sipuleucel-T therapy.
Sirolimus	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sirolimus. Management: Monitor for increased serum concentrations of sirolimus if combined with a moderate CYP3A4 inhibitor. Lower initial sirolimus doses or sirolimus dose reductions will likely be required.
Sonidegib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sonidegib. Management: Avoid concomitant use of sonidegib and moderate CYP3A4 inhibitors when possible. When concomitant use cannot be avoided, limit CYP3A4 inhibitor use to less than 14 days and monitor for sonidegib toxicity (particularly musculoskeletal adverse reactions).
Stiripentol	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Management: Use of stiripentol with CYP3A4 substrates that are considered to have a narrow therapeutic index should be avoided due to the increased risk for adverse effects and toxicity. Any CYP3A4 substrate used with stiripentol requires closer monitoring.
Suvorexant	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Suvorexant. Management: The recommended dose of suvorexant is 5 mg daily in patients receiving a moderate CYP3A4 inhibitor. The dose can be increased to 10 mg daily (maximum dose) if necessary for efficacy.
Tamoxifen	Ribociclib may increase the serum concentration of Tamoxifen. Management: Concurrent use of ribociclib with tamoxifen is not indicated. Use of this combination may increase the effects and toxicities of tamoxifen.
Tezacaftor	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tezacaftor. Management: When combined with moderate CYP3A4 inhibitors, tezacaftor/ivacaftor should be given in the morning, every other day. Ivacaftor alone should be given in the morning, every other day on alternate days from tezacaftor/ivacaftor.
Tofacitinib	Immunosuppressants may enhance the immunosuppressive effect of Tofacitinib. Management: Concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted, and this warning seems particularly focused on more potent immunosuppressants.
Tolvaptan	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tolvaptan. Management: Jynarque dose requires adjustment when used with a moderate CYP3A4 inhibitor. See labeling or full interaction monograph for specific recommendations. Use of Samsca with moderate CYP3A4 ihibitors should generally be avoided.
Vaccines (Inactivated)	Immunosuppressants may diminish the therapeutic effect of Vaccines (Inactivated). Management: Vaccine efficacy may be reduced. Complete all age-appropriate vaccinations at least 2 weeks prior to starting an immunosuppressant. If vaccinated during immunosuppressant therapy, revaccinate at least 3 months after immunosuppressant discontinuation.
Venetoclax	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Venetoclax. Management: Reduce the venetoclax dose by at least 50% in patients requiring these combinations.
Zopiclone	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Zopiclone. Management: The starting adult dose of zopiclone should not exceed 3.75 mg if combined with a moderate CYP3A4 inhibitor. Monitor patients for signs and symptoms of zopiclone toxicity if these agents are combined.
Risk Factor X (Avoid combination)
Aprepitant	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Aprepitant.
Asunaprevir	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Asunaprevir.
BCG (Intravesical)	Immunosuppressants may diminish the therapeutic effect of BCG (Intravesical).
BCG (Intravesical)	Myelosuppressive Agents may diminish the therapeutic effect of BCG (Intravesical).
Bosutinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bosutinib.
Budesonide (Systemic)	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Systemic).
Cladribine	May enhance the immunosuppressive effect of Immunosuppressants.
Cladribine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
Cobimetinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cobimetinib. Management: Avoid the concomitant use of cobimetinib and moderate CYP3A4 inhibitors. If concurrent short term (14 days or less) use cannot be avoided, reduce the cobimetinib dose to 20 mg daily.
Conivaptan	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
CYP3A4 Inducers (Strong)	May decrease the serum concentration of Ribociclib.
Dipyrone	May enhance the adverse/toxic effect of Myelosuppressive Agents. Specifically, the risk for agranulocytosis and pancytopenia may be increased
Domperidone	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Domperidone.
Entrectinib	May enhance the QTc-prolonging effect of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of Entrectinib.
Flibanserin	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Flibanserin.
Fosaprepitant	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Fosaprepitant.
Fusidic Acid (Systemic)	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Grapefruit Juice	May increase the serum concentration of Ribociclib.
Idelalisib	May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors).
Ivabradine	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivabradine.
Lefamulin	May enhance the QTc-prolonging effect of QT-prolonging CYP3A4 Substrates. Management: Do not use lefamulin tablets with QT-prolonging CYP3A4 substrates. Lefamulin prescribing information lists this combination as contraindicated.
Lomitapide	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lomitapide.
Naloxegol	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Naloxegol.
Natalizumab	Immunosuppressants may enhance the adverse/toxic effect of Natalizumab. Specifically, the risk of concurrent infection may be increased.
Neratinib	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Neratinib.
Pimecrolimus	May enhance the adverse/toxic effect of Immunosuppressants.
Pimozide	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pimozide.
Pimozide	May enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk).
Pomegranate	May increase the serum concentration of Ribociclib.
Posaconazole	May increase the serum concentration of QT-prolonging CYP3A4 Substrates. Such increases may lead to a greater risk for proarrhythmic effects and other similar toxicities.
QT-prolonging Agents (Highest Risk)	May enhance the QTc-prolonging effect of Ribociclib.
Simeprevir	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Simeprevir.
St John's Wort	May decrease the serum concentration of Ribociclib.
Tacrolimus (Topical	May enhance the adverse/toxic effect of Immunosuppressants.
Ulipristal	CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ulipristal. Management: This is specific for when ulipristal is being used for signs/symptoms of uterine fibroids (Canadian indication). When ulipristal is used as an emergency contraceptive, patients receiving this combination should be monitored for ulipristal toxicity.
Vaccines (Live)	Immunosuppressants may enhance the adverse/toxic effect of Vaccines (Live). Immunosuppressants may diminish the therapeutic effect of Vaccines (Live). Management: Avoid use of live organism vaccines with immunosuppressants; live-attenuated vaccines should not be given for at least 3 months after immunosuppressants.

Monitoring Parameters:

Monitor lipid profile, liver functions, bone density, blood complete picture, serum electrolytes, and ECG.
Perform a pregnancy test before treatment initiation. For further details, refer to individual drugs: Letrozole and Ribociclib.

How to administer Kisqali Femara Co-Pack (Ribociclib and letrozole)?

It is administered orally once daily in the morning for 21 days followed by seven days off-treatment.

Mechanism of Action of Kisqali Femara Co-Pack (Ribociclib and letrozole):

Ribociclib

It is a small-molecule inhibitor of cyclin-dependent (CDK), which is selective for CDK 4/6
It prevents progression of the cell cycle and causes arrest in G1phase. Combining ribociclib with fulvestrant led to tumor growth inhibition in estrogen receptor positive breast cancer models.
Combining ribociclib with an aromatase inhibitor results in greater inhibition of tumor growth than either agent alone.

Letrozole:

It is a nonsteroidal competitive inhibitor of the aromatase enzyme system which binds to the heme group of aromatase, a cytochrome P-450 enzyme that catalyzes the conversion of androgens to estrogens (specifically, androstenedione to estrone and testosterone to estradiol).
This leads to inhibition of the enzyme and a significant reduction in plasma estrogen (estrone, estradiol, and estrone sulfate) levels.
Letrozole appears not to have any effect on the synthesis or production of adrenal hormones or thyroid hormones, aldosterone or androgens.
For details, refer to individual drug monographs: letrozole and ribociclib.