Varenicline (chantix) for Smoking Cessation

Varenicline (Chantix) blocks the mesolimbic dopamine system activation brought on by nicotine addiction.

It is used in the treatment of smoking cessation.

E-Cigarettes once thought to become a good aid for the cessation of smoking, are now considered more harmful. Recently, a lot of patients have developed serious lung diseases from its use. It is also considered a gateway to addiction.

Chantix (Varenicline) Dose in Adults

Chantix (Varenicline) Dose in the treatment of Smoking cessation:

It is not available over the counter.

  • Initial dosage
    • Days 1-3: 5mg are administered once a day orally.
    • Days 4 through 7: 5mg are administered orally twice daily.
  • Maintenance (≥ Day 8):
    • 1mg is taken orally twice daily for eleven weeks.
    • If the usual dose is not tolerated, think about reducing it temporarily or permanently.
  • One week before the intended quit date, it should be begun.
    The company advises patients to think about planning a stop date up to 35 days after taking varenicline.
  • Lower smoking by 50% from baseline within the first 4 weeks of starting varenicline treatment, by another 50% within the next 4 weeks, and continue to reduce the goal of total abstinence by 12 weeks for patients who are unsure that they can quit quickly.
  • If the patient successfully quits smoking at the conclusion of the 12-week period, continue for an additional 12-week period to support success.
  • Patients who have attempted to quit smoking before without success but were unsuccessful or who relapse after treatment should be encouraged to try varenicline again.

Chantix (Varenicline) Dose in Children

Not recommended for use in children. 

Pregnancy Risk Factor: C

  • It is difficult to find information on the use of varenicline during pregnancy.
  • Both the moms and the fetus might exhibit negative occurrences.
  • All expectant mothers should give off smoking.

Varenicline (Chantix) use during breastfeeding:

  • It is unknown if breast milk contains varenicline.
  • Varenicline is not recommended for breastfeeding mothers as there is insufficient information.
  • The drug's maker advises making a choice between stopping nursing and stopping use of the medication.
  • This is in consideration of the possible side effects for breastfed infants.
  • Breastfeeding infants should be checked for seizures and excessive vomiting.

Chantix dose in Kidney disease:

  • End-stage renal disease (ESRD) (obtaining hemodialysis):
    • A daily dose of 0.5 mg is the maximum.
  • CrCl less than 30 mL per minute:
    • Starting at 0.5mg once daily, work your way up to 0.5mg twice daily.
  • CrCl more than 30 mL per minute:
    • No change in dose is necessary.

Dose in liver disease:

  • No dosage adjustment is required. 

Common Side Effects of Varenicline (Chantix) Include:

  • Gastrointestinal:
    • Vomiting
    • Nausea
  • Central Nervous System:
    • Abnormal Dreams
    • Irritability
    • Headache
    • Insomnia
    • Suicidal Ideation
    • Depression

Less Common Side Effects of Varenicline (Chantix) Include:

  • Dermatologic:
    • Skin Rash
  • Cardiovascular:
    • Peripheral Edema
    • Myocardial Infarction
    • Angina Pectoris
    • Chest Pain
  • Respiratory:
    • Dyspnea
    • Upper Respiratory Tract Infection
    • Rhinorrhea
  • Central Nervous System:
    • Agitation
    • Sleep Disorder
    • Anxiety
    • Malaise
    • Tension
    • Lethargy
    • Nightmares
    • Drowsiness
    • Hostility
  • Gastrointestinal:
    • Increased Appetite
    • Anorexia
    • Dysgeusia
    • Abdominal Pain
    • Diarrhea
    • Flatulence
    • Constipation
    • Xerostomia
    • Dyspepsia
    • Decreased Appetite
    • Gastroesophageal Reflux Disease

Contraindication to Varenicline (Chantix) Include:

  • Varenicline and any other component can cause severe allergic reactions or skin reactions.

Warnings and precautions

  • CNS depression:
    • CNS depression can lead to mental or physical impairments.
    • It is important to warn patients about tasks that require mental alertness, such as driving or operating machinery.
  • Hypersensitivity reactions
    • Severe skin responses, including angioedema and hypersensitive reactions like Stevens-Johnson syndrome or erythema multifemale, have only rarely been reported.
    • If symptoms or signs develop, patients should stop using the medication and consult their doctor immediately.
  • Nausea:
    • Nausea can be dose-dependent
    • We have seen both persistent and transient nausea.
    • A dosage reduction may be necessary for nausea that is not controlled.
  • Neuropsychiatric effects
    • Serious neuropsychiatric events, such as suicidal ideation and attempts, have occurred in patients with and without a prior mental condition.
    • Every patient has to be watched for any behavioral modifications or mental signs (eg depression, agitation, suicidal ideation, suicidal behavior).
    • Patients should consider contacting their doctor and stop taking any medications if they encounter changes in their mood or behavior.
  • Somnambulism:
    • There have been cases of somnambulism, which can lead to harm to oneself, others, or property.
    • Stop treatment if somnambulism occurs.
  • Cardiovascular events
    • The risk of developing a heart attack can be increased by treatment.
    • If you experience symptoms of cardiovascular disease, it is important to notify your doctor immediately.
  • Renal impairment
    • Patients with impaired renal function should be careful
    • With severe impairment, dosage adjustment may be required.
  • Seizures:
    • Seizures have occurred in both individuals with and without medical histories.
    • The first month of therapy is when seizures are most prevalent.
    • Prior to beginning treatment, individuals who have a history of seizures or other risk factors should assess the advantages against the disadvantages.
    • If seizures occur during therapy, stop immediately.

Varenicline: Drug Interaction

Risk Factor C (Monitor therapy)

Alcohol (Ethyl)

Varenicline may intensify Alcohol's harmful or hazardous effects (Ethyl). Particularly, the risk for neuropsychiatric side effects may rise while alcohol tolerance may decline.

Erdafitinib

OCT2 Substrates' serum concentration can rise.

Histamine H2 Receptor Antagonists

Varenicline serum levels can rise. Management: Keep an eye out for any increased varenicline side effects while cimetidine or other H2-antagonists are also being used, especially in patients with severe renal impairment. Different international standards exist for product labeling. Look up the relevant labels.

Nicotine

Varenicline may intensify nicotine's harmful or toxic effects.

Quinolones

Varenicline serum levels can rise. Management: Keep an eye out for any increased varenicline side effects while levofloxacin or other quinolone antibiotics are also being used, especially in patients who have severe renal impairment. Different international standards exist for product labeling. Look up the relevant labels.

Trimethoprim

Varenicline serum levels can rise. Management: Keep an eye out for any increased varenicline side effects when using trimethoprim concurrently, especially in patients with severe renal impairment. Different international standards exist for product labeling. Look up the relevant labels.

Risk Factor D (Consider therapy modification)

Tafenoquine

May raise the serum level of OCT2 Substrates. Management: Prevent using OCT2 substrates with tafenoquine; if you must use them together, watch out for any signs of toxicity and think about using a lower dose of the OCT2 substrate in accordance with the labeling.

Monitor:

  • Keep an eye out for mental symptoms and changes in behavior (eg, agitation, depression, suicidal behavior, and suicidal ideation).

How to administer Varenicline (Chantix)?

Use a full glass of water and administer it after eating.

Mechanism of action of Varenicline:

  • A partial neuronal nicotinic a4- and b4-receptor agonist
  • It prevents the mesolimbic dopamine system from being stimulated by nicotine, which is linked to nicotine addiction.
  • Additionally, it interacts with a moderate affinity to 5-HT3 receptors.
  • Although to a lesser extent than nicotine, varenicline enhances dopamine activity.
  • Cravings and withdrawal symptoms lessen as a consequence.

Half-life elimination is about 24 hrs

Absorption: Unaffected by meals and well absorbed

Bioavailability is about 90%

Protein binding is less than 20%

It is excreted mainly in the urine (92% as unchanged drug)  

Metabolism: minimal (metabolism accounts for 10% of clearance)

The time to reach peak plasma concentration is about 3-4 hrs

International Brands of Varenicline:

  • Chantix
  • Chantix Continuing Month Pak
  • APO-Varenicline
  • Champix
  • Champix Starter Pack
  • TEVA-Varenicline
  • Chantix Starting Month Pak
  • Champix
  • Varni

Varenicline brands in Pakistan:

Varenicline [Tabs 1 Mg]

Chantix Pfizer Laboratories Ltd.

Varenicline [Tabs 0.5 Mg]

Chantix Pfizer Laboratories Ltd.