Hydroxyurea (Hydrea) is an antimetabolite that halts the cell cycle. It also alters RBCs interaction with the endothelium, increases Hemoglobin F, increases intracellular water content, and increases cellular permeability.

Hydroxyurea (Hydrea) Uses:

• Chronic myeloid leukemia, resistant (Hydrea):
  • Used for the treatment of resistant chronic myeloid leukemia (CML)
• Head and neck cancer (Hydrea):
  • Management (in combination with chemoradiation therapy) of locally advanced squamous cell head and neck cancer (excluding lip cancer)
• Sickle cell anemia (Droxia, Siklos):
  • Management of sickle cell anemia (to reduce the frequency of painful crises and to reduce the need for blood transfusions in patients with recurrent moderate to severe painful crises) in adults (Droxia) or in children of 2 years or more than 2 years, adolescents, and adults (Siklos)
• Off Label Use of Hydroxyurea in Adults:
  • Used in acute myeloid leukemia, cytoreduction
  • Used in essential thrombocythemia, high-risk
  • Used in hypereosinophilic syndrome
  • Used in meningioma
  • Used in polycythemia vera, high-risk

Hydroxyurea (Hydrea) Dose in Adults

Note: Hydroxyurea is a medicine used to treat certain cancers and blood problems. It works by slowing down the growth of cells that divide quickly. It can help with conditions like a type of leukemia, too many red blood cells, and sickle cell disease. It might cause side effects like upset stomach and skin changes. People need to have regular blood tests while taking it, and women should be careful if they're pregnant or planning to be. The right dose depends on the patient's weight, and taking folic acid along with it is a good idea.

Hydroxyurea (Hydrea) Dose in the treatment of chronic myeloid leukemia (Hydrea):

• How to take: By mouth.
• Starting dose: 40 mg/kg/day. (But reduce the starting dose if platelet counts are low.)
• Adjusting dose: If white blood cell (WBC) count goes below 2,000/mm, lower the dose to 20 mg/kg/day.
• Dose changes: Adjust the dose based on the WBC counts.
• Usage note: Hydroxyurea can be used for a short time to lower high WBC counts before starting another treatment called a TKI.

Hydroxyurea (Hydrea) Dose in the treatment of Head and neck cancer (Hydrea):

• How to take: By mouth.
• Dosing: 1,000 mg every 12 hours.
• Total doses: 11 doses per treatment cycle.
• Combined with: Continuous infusion of fluorouracil and radiation therapy.
• Note: Adjust treatment based on the type of tumor, how it's responding, and current medical practices.

Hydroxyurea (Hydrea) Dose in the treatment of Sickle cell anemia: Oral:

Droxia:

• Starting dose: 15 mg/kg/day, once daily.
• Dose adjustments: Monitor blood counts every 2 weeks. If counts are acceptable, increase by 5 mg/kg/day every 12 weeks. The highest dose should be 35 mg/kg/day or the highest dose that doesn't cause side effects for 24 weeks.
• If toxic levels: Stop, wait for recovery, then restart with 2.5 mg/kg/day less. If okay for 12 weeks, can slowly increase. Stop if there's a second toxicity event at the same dose.

Siklos:

• Starting dose: 20 mg/kg/day, once daily.
• Dose adjustments: Check blood counts every 2 weeks. If counts are good, can increase by 5 mg/kg/day every 8 weeks or after a pain episode, aiming for mild reduction of white blood cells (myelosuppression), up to 35 mg/kg/day max.
• If toxic levels: Stop, wait for recovery, then restart with 5 mg/kg/day less. Adjust every 8 weeks. Stop if there's toxicity twice.

Blood count ranges:

• Good levels: Neutrophils ≥2,500/mm (or ≥2,000/mm for Siklos); platelets ≥95,000/mm (or ≥80,000/mm for Siklos); hemoglobin >5.3 g/dL; more reticulocytes if low hemoglobin.
• Bad (toxic) levels: Too few neutrophils, platelets, or reticulocytes; hemoglobin <4.5 g/dL.

Dose calculations: Round doses to nearest 50 or 100 mg.

Note: Treatment effect can take 3-6 months. Try the highest tolerated dose for 6 months before stopping due to no results. It's vital to take hydroxyurea every day for it to work. If it helps, long-term use is suggested.

Hydroxyurea (Hydrea) Dose in the treatment of Acute myeloid leukemia (AML), cytoreduction (off-label):

• How to take: By mouth.
• Dosing options:
  • 50 to 100 mg/kg/day until white blood cell (WBC) count drops below 100,000/mm (based on Grund 1977).
  • 50 to 60 mg/kg/day until WBC count is between 10,000 to 20,000/mm (based on Dohner 2010).

This use of hydroxyurea for AML is off-label, meaning it's not the standard approved use but might be recommended based on certain studies or clinical experiences.

Hydroxyurea (Hydrea) Dose in the treatment of Essential thrombocythemia, high-risk (off-label):

• How to take: By mouth.
• Starting dose: Between 500 to 1000 mg daily.
• Goal: Adjust the dose to keep platelet count below 400,000/mm.
• Reference: Based on Harrison 2005.

Note: This use of hydroxyurea for Essential thrombocythemia is off-label, meaning it's not the standard approved use but might be based on certain studies or clinical experiences.

Hydroxyurea (Hydrea) Dose in the treatment of Hypereosinophilic syndrome (off-label):

• How to take: By mouth.
• Dosing range: Between 1,000 to 3,000 mg daily.
• Reference: Based on Klion 2006.

Note: This use of hydroxyurea for Hypereosinophilic syndrome is off-label, meaning it's not the standard approved use but is recommended based on specific studies or clinical experiences.

Hydroxyurea (Hydrea) Dose in the treatment of Meningioma (off-label):

• How to take: By mouth.
• Dose: 20 mg/kg once daily.
• Reference: Based on Newton 2000 and Rosenthal 2002.

Note: Using hydroxyurea for Meningioma is off-label, which means it's not the standard approved use but is suggested based on certain studies or clinical experiences.

Hydroxyurea (Hydrea) Dose in the treatment of high-risk Polycythemia vera (off-label):

• How to take: By mouth.
• Dose: 15 to 20 mg/kg daily.
• Reference: Based on Finazzi 2007.

Note: This use of hydroxyurea for high-risk Polycythemia vera is off-label, meaning it's not the standard approved use but is based on specific studies or clinical experiences.

Hydroxyurea (Hydrea) Dose in Childrens

Note:

• Take hydroxyurea by mouth.
• The dose should be 15 to 20 mg for every kg of your weight each day.
• Use your ideal weight or your real weight for the dose, whichever is lighter.
• When figuring out your dose, round to the closest 50 mg or 100 mg amount.

Hydroxyurea (Hydrea) Dose in the treatment of Sickle cell anemia:

For treating sickle cell anemia in infants (6 months or older), children, and teenagers:

• Starting Dose: Take the medicine by mouth. Begin with 20 mg for every kilogram of your body weight once a day.
• Monitoring: Get your blood checked every two weeks.
• Dose Increase: If your blood counts are okay, you might increase the dose by 5 mg for every kilogram of your weight every 8 weeks. This is to achieve mild myelosuppression (where certain blood cell counts go down a bit), or if you have painful episodes.
• Maximum Dose: Don't go over a total of 35 mg for every kilogram of your weight each day.
• Response Time: It might take 3 to 6 months to see how well the treatment works. It's recommended to try the highest dose your body can handle for 6 months before deciding it's not effective.
• Important: Remember, taking the medicine every day is important for it to work.
• Good Blood Counts: For the blood counts: Neutrophils (a type of white blood cell) should be between 2,000 to 4,000 per microliter (for younger patients with lower starting counts, it might be okay down to 1,250); platelets should be at least 80,000 per microliter; hemoglobin (a protein in red blood cells) should be above 5.3 grams per deciliter; and reticulocytes (young red blood cells) should be at least 80,000 per microliter if hemoglobin is below 9 grams per deciliter.

Hydroxyurea (Hydrea) Dosing adjustment for toxicity:

For infants (6 months or older), children, and teenagers with sickle cell disease:

• Toxic Myelosuppression: If your neutrophils are below 2,000 per microliter (or 1,250 per microliter for younger patients with lower counts), platelets go under 80,000 per microliter, hemoglobin drops below 4.5 grams per deciliter, or reticulocytes fall below 80,000 per microliter with hemoglobin under 9 grams per deciliter, stop taking the medicine. Wait until your blood counts recover (check weekly).
• Restarting: When you restart, take a dose that's 5 mg for every kilogram of your weight lower than the dose you were taking before the toxic effects happened. Some suggest starting with a dose 2.5 mg/kg/day lower instead.
• Dose Adjustment: Change your dose every 8 weeks by 5 mg/kg/day steps. Adjust until you find a dose that doesn't cause blood problems for 24 weeks.
• Repeat Toxicity: If blood problems happen again (twice), stop taking the medicine for good.

Non-Hematologic Toxicity:

• Skin Ulcers: If you develop ulcers on your skin due to vasculitis (inflammation of blood vessels), stop taking the medicine.
• Pancreatitis: If you get pancreatitis (inflammation of the pancreas), stop taking the medicine forever.

For adults, the presented adjustments are based on experience, but specific recommendations for children might be limited. Check specific protocols for managing pediatric patients if available.

Hydroxyurea (Hydrea) Pregnancy Category: D

• Hydroxyurea can harm an unborn baby based on animal tests and how the medicine works.
• So, if you're a woman who could become pregnant, make sure you're not pregnant before starting the medicine and use birth control during treatment and for 6 months after.
• Men taking the medicine might see changes in their sperm or damage to their testicles.
• So, they should also use birth control with their partners for 6 months to a year after treatment, depending on the specific medicine they're taking (Siklos for 6 months and Droxia or Hydrea for a year).
• Men might also want to think about saving their sperm before starting treatment since the medicine can reduce sperm count.

Use of hydroxyurea during lactation

• Hydroxyurea can be found in breast milk.
• Because it might cause serious side effects in babies who are breastfed, the company that makes the medicine suggests that mothers stop breastfeeding while taking it.

Hydroxyurea (Hydrea) Dose in Kidney Disease:

CML and Head and Neck Cancer:

• If kidneys are working well (CrCl ≥60 mL/minute): Regular dose.
• If kidneys are working less efficiently (CrCl <60 mL/minute): Start with half the usual dose, then adjust based on how you react.
• If on dialysis (End-stage renal disease, ESRD): Start with half the usual dose, given after dialysis on dialysis days, then adjust.

Sickle Cell Anemia:

For Droxia:

• If kidneys are working well (CrCl ≥60 mL/minute): Regular dose.
• If kidneys are working less efficiently (CrCl <60 mL/minute): Start with 7.5 mg/kg/day, then adjust based on how you react.
• If on dialysis (ESRD): Start with 7.5 mg/kg/dose, given after dialysis on dialysis days, then adjust.

For Siklos:

• If kidneys are working well (CrCl ≥60 mL/minute): Regular dose.
• If kidneys are working less efficiently (CrCl <60 mL/minute): Start with 10 mg/kg/day, then adjust based on how you react.
• If on dialysis (ESRD): Start with 10 mg/kg/day, then adjust.

General guidance (from NHLBI 2014): If you have chronic kidney disease, start with 5 to 10 mg/kg/day.

Dose in Liver Disease:

Manufacturer's labeling doesn't provided any dosage adjustments; Closely monitor for bone marrow toxicity.

Common Side Effects of Hydroxyurea (Hydrea):

• Dermatologic:
  • Eczema
• Hematologic & Oncologic:
  • Macrocytosis

Less Common Side Effects Of Hydroxyurea (Hydrea):

• Dermatologic:
  • Leg Ulcer
  • Dermal Ulcer
• Gastrointestinal:
  • Acute Mucocutaneous Toxicity
• Respiratory:
  • Asthma

Frequency of side effects not defined:

• Dermatologic:
  • Alopecia
  • Nail Discoloration (Melanonychia)
• Gastrointestinal:
  • Gastric Distress (Infrequent)
  • Gastritis (Potentiated With Radiation Therapy)
  • Mucositis (Potentiated With Radiation Therapy)
  • Oral Mucosa Ulcer (Infrequent)
• Hematologic & Oncologic:
  • Anemia
  • Bone Marrow Depression (Recovery: Within 2 Weeks)
  • Hemorrhage
  • Leukemia
  • Leukopenia
  • Reticulocytopenia (Wang 2011)
  • Thrombocytopenia
• Neuromuscular & Skeletal:
  • Panniculitis (Antonioli 2012)

Contraindications to Hydroxyurea (Hydrea):

US Labeling:

• Don't use if allergic to hydroxyurea or any ingredient in the medicine.

Canadian Labeling:

• Don't use if allergic to hydroxyurea or any ingredient in the medicine (same as US).
• Additionally, don't use if there's severe bone marrow depression, meaning:
  • White blood cell count is less than 2,500 per microliter.
  • Platelet count is less than 100,000 per microliter.
  • There's severe anemia.

So, in Canada, they have additional restrictions based on certain blood counts.

Warnings/Precaution:

Suppression of bone marrow: [US Boxed Warning]

• Hydroxyurea can seriously lower your bone marrow's activity.
• This could make your blood counts drop a lot.
• Keep an eye on your blood counts before and during treatment.
• If counts get too low, treatment might be paused or the dose could be lowered.
• Low white blood cells are common, and they usually drop before platelets and red blood cells.
• Severe bone marrow problems can happen even with the starting dose.
• These problems can be fixed if treatment is stopped or the dose is lowered.
• Be cautious if you've had chemotherapy or radiation before, as bone marrow issues could be more likely.
• Make sure anemia is treated before starting.
• If your bone marrow isn't working well, don't start the treatment.
• Kids might be more at risk for bone marrow problems when adjusting the dose because their weight changes.

Cutaneous Vasculitic Toxicities:

• Some patients, especially those who had another condition or were also on interferon therapy, developed skin problems like ulcers and gangrene while on hydroxyurea.
• If these skin issues occur, stop hydroxyurea or lower its dose, and think about other treatment options.
• In rare cases, these ulcers might be because of a specific type of inflammation in small blood vessels.
• It's best to not use hydroxyurea in patients who already have leg ulcers.

Hypersensitivity

• Hydroxyurea can sometimes cause a fever that's a sign of an allergic reaction.
• This fever can come with heart, skin, stomach, liver, muscle, or lung issues and might need hospital care.
• Typically, this reaction happens within the first 6 weeks of starting the medicine.
• If you stop taking hydroxyurea, the fever usually goes away.
• But, if you start the medicine again, the fever can come back within a day.

Macrocytosis

• While on hydroxyurea, your red blood cells might get bigger than normal, a condition called macrocytosis.
• This can happen early in treatment.
• It might look like a condition called pernicious anemia, but it's not because of a lack of vitamin B or folic acid.
• However, this change in blood cells can hide a real case of pernicious anemia.
• It's a good idea to take folic acid as a preventive measure while on hydroxyurea.

Secondary malignancy: [US-Boxed Warning]

• A serious warning – Hydroxyurea can cause cancer.
• While on this medicine, protect yourself from the sun and get checked regularly for any signs of cancer.
• Treating blood disorders with hydroxyurea for a long time has been linked to a type of cancer called leukemia.
• It's unclear if the medicine or the disorder itself causes this risk.
• Also, long-term use of hydroxyurea has been connected to skin cancer.
• So, keep an eye out for any unusual skin changes or other symptoms of cancer while taking hydroxyurea.

Tumor lysis syndrome

• When using hydroxyurea as a cancer treatment, there's a risk that a lot of cancer cells could break down all at once.
• This can lead to high levels of uric acid in the blood, a condition known as hyperuricemia.
• To prevent issues, it's important to drink plenty of water and possibly start or adjust medications like allopurinol that help the body get rid of extra uric acid.

HIV-infected patients

• When hydroxyurea is taken alongside certain HIV medicines, like didanosine and stavudine, there's a risk of pancreatitis (inflammation of the pancreas), liver problems (hepatotoxicity), and nerve issues in the hands and feet (peripheral neuropathy).

Renal impairment

• Be careful when using hydroxyurea if you have kidney issues. You might need a lower dose than usual..

Hydroxyurea (hydroxycarbamide): Drug Interaction

Risk Factor C (Monitor therapy)
Chloramphenicol (Ophthalmic)	May enhance the adverse/toxic effect of Myelosuppressive Agents.
CloZAPine	Myelosuppressive Agents may enhance the adverse/toxic effect of CloZAPine. Specifically, the risk for neutropenia may be increased.
Coccidioides immitis Skin Test	Immunosuppressants may diminish the diagnostic effect of Coccidioides immitis Skin Test.
Denosumab	May enhance the adverse/toxic effect of Immunosuppressants. Specifically, the risk for serious infections may be increased.
Ocrelizumab	May enhance the immunosuppressive effect of Immunosuppressants.
Pidotimod	Immunosuppressants may diminish the therapeutic effect of Pidotimod.
Promazine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
Siponimod	Immunosuppressants may enhance the immunosuppressive effect of Siponimod.
Tertomotide	Immunosuppressants may diminish the therapeutic effect of Tertomotide.
Trastuzumab	May enhance the neutropenic effect of Immunosuppressants.
Risk Factor D (Consider therapy modification)
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.
Echinacea	May diminish the therapeutic effect of Immunosuppressants.
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).
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.
Lenograstim	Antineoplastic Agents may diminish the therapeutic effect of Lenograstim. Management: Avoid the use of lenograstim 24 hours before until 24 hours after the completion of myelosuppressive cytotoxic chemotherapy.
Lipegfilgrastim	Antineoplastic Agents may diminish the therapeutic effect of Lipegfilgrastim. Management: Avoid concomitant use of lipegfilgrastim and myelosuppressive cytotoxic chemotherapy. Lipegfilgrastim should be administered at least 24 hours after the completion of myelosuppressive cytotoxic chemotherapy.
Nivolumab	Immunosuppressants may diminish the therapeutic effect of Nivolumab.
Palifermin	May enhance the adverse/toxic effect of Antineoplastic Agents. Specifically, the duration and severity of oral mucositis may be increased. Management: Do not administer palifermin within 24 hours before, during infusion of, or within 24 hours after administration of myelotoxic chemotherapy.
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.
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.
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.
Risk Factor X (Avoid combination)
BCG (Intravesical)	Immunosuppressants may diminish the therapeutic effect of BCG (Intravesical).
BCG (Intravesical)	Myelosuppressive Agents may diminish the therapeutic effect of BCG (Intravesical).
Cladribine	May enhance the immunosuppressive effect of Immunosuppressants.
Cladribine	May enhance the myelosuppressive effect of Myelosuppressive Agents.
Deferiprone	Myelosuppressive Agents may enhance the neutropenic effect of Deferiprone.
Didanosine	Hydroxyurea may enhance the adverse/toxic effect of Didanosine. An increased risk of pancreatitis, hepatotoxicity and/or neuropathy may exist. Didanosine may enhance the adverse/toxic effect of Hydroxyurea. An increased risk of pancreatitis, hepatotoxicity and/or neuropathy may exist.
Dipyrone	May enhance the adverse/toxic effect of Myelosuppressive Agents. Specifically, the risk for agranulocytosis and pancytopenia may be increased
Natalizumab	Immunosuppressants may enhance the adverse/toxic effect of Natalizumab. Specifically, the risk of concurrent infection may be increased.
Pimecrolimus	May enhance the adverse/toxic effect of Immunosuppressants.
Stavudine	Hydroxyurea may enhance the adverse/toxic effect of Stavudine. An increased risk of pancreatitis, hepatotoxicity and/or neuropathy may exist. Stavudine may enhance the adverse/toxic effect of Hydroxyurea. An increased risk of pancreatitis, hepatotoxicity and/or neuropathy may exist.
Tacrolimus (Topical)	May enhance the adverse/toxic effect of Immunosuppressants.
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:

General Checks:

• CBC (blood counts) with details and platelet count:
  • Every week for cancer treatment.
  • Every 2 weeks at the start for sickle cell anemia.
• Kidney and liver tests.
• Serum uric acid level.
• For women who can become pregnant: Check if they are pregnant before starting treatment.
• Watch out for skin reactions.

For Sickle Cell Disease:

• During Dose Increase:
  • Every 2 weeks: Check neutrophils, platelets, hemoglobin, reticulocytes.
  • At least every 4 weeks when adjusting dose: Full CBC with white blood cell details and reticulocyte count.
• Once on a Stable Dose:
  • Every 2 to 3 months: Full CBC with white blood cell details, reticulocyte count, and platelet count.
  • Check for consistency in RBC, MCV (cell size), and HbF (fetal hemoglobin) levels.
• Important: Make sure the patient is consistently taking the medication.

How to administer Hydroxyurea (Hydrea)?

General Instructions:

• Take it orally at the same time every day.
• Don't chew or open the capsules. Just swallow them whole.

For Siklos Tablets:

• Take them with water.
• If you can't swallow the whole tablet, you can dissolve it in water:
  • Place the tablet on a spoon.
  • Add a small amount of water.
  • Wait for about 1 minute for it to dissolve.
  • Take it immediately and drink another glass of water afterwards.
• The 1,000 mg tablets have score lines so you can split them into 4 parts:
  • Wear gloves and split them on a damp paper towel.
  • Properly throw away the gloves and paper towel afterwards.
• Do not break the 100 mg tablet into smaller pieces.

Safety Tips:

• Always wear gloves that don't let liquids through when handling the hydroxyurea bottles, tablets, or capsules.
• Wash your hands with soap and water before and after touching hydroxyurea.
• Be careful not to touch any crushed tablets or open capsules.
• If it gets on your skin, wash the area well with soap and water.
• If it gets in your eyes, rinse them with plenty of water or an eye wash for at least 15 minutes.
• If you spill any hydroxyurea:
  • Clean it up immediately with a wet disposable towel.
  • Put the towel and any empty capsules in a closed container, like a plastic bag.
  • Clean the spill area with soap and water.

Remember, hydroxyurea is a strong medication, so it's important to handle it carefully.

Mechanism of action of Hydroxyurea (Hydrea):

• Hydroxyurea is a medicine that stops cells from growing by interfering with their DNA repair and keeping them in a certain phase, making them more sensitive to radiation.
• For sickle cell anemia, hydroxyurea changes some properties of red blood cells: it increases the amount of a special kind of hemoglobin called F, makes the cells carry more water, helps the misshapen cells return to a more normal shape, and reduces the stickiness of these cells.
• However, for kids, the medicine's effects can vary a lot from one patient to another.

Notice:

• Large interpatient variability and phenotypic variations have been observed in pediatric patients.

Start of Effect for Sickle Cell Anemia:

• Increases special hemoglobin (Fetal hemoglobin): Takes between 4 to 12 weeks.

Absorption:

• It's quickly and mostly absorbed into the body (more than 80%).

Where it Goes in the Body (Distribution):

• Goes to many parts of the body, even the brain.
• Mainly found in white and red blood cells.
• Volume in the body:
  • Children: around 12 liters.
  • Adults: around 20 liters for every meter of their height.

How it's Processed (Metabolism):

• The liver and some gut bacteria process about 60% of it.

How Available it is in the Body:

• Almost all (100%) of what's taken can be used by the body.

Binding in the Blood:

• 75% to 80% of it attaches to proteins in the blood.

How Long it Stays (Half-life):

• Adults: 1.9 to 3.9 hours.
• Children with sickle cell anemia: 1.7 hours.

When it's Most Present (Time to Peak):

• Children:
  • "Fast" type: 15 to 30 minutes.
  • "Slow" type: 1 to 2 hours.
• Adults: 1 to 4 hours.

How it Leaves the Body (Excretion):

• Mainly goes out in urine (about 40% of the dose for those with sickle cell anemia).

Clearance (How Quickly it's Removed):

• Children: around 7 liters every hour.
• Adults: around 7.5 liters every hour.

International Brand Names of Hydroxyurea:

• Droxia
• Hidroxicarbamida
• Hydab
• Hydrea
• Hydrine
• Hydrea
• Siklos
• APO-Hydroxyurea
• MYLAN-Hydroxyurea
• Cytodrox
• Droxamida
• Hidrolid
• Hydronix
• Hydroxycarbamid
• Hydroxyurea medac
• Hytinon
• Krabinex
• Litalir
• MPL HiOxy
• Neodrea
• Onco-Carbide
• Siklos
• Syrea

Hydroxyurea Brand Names in Pakistan:

Hydroxyurea Capsules 500 mg in Pakistan
Hydra	Medinet Pharmaceuticals
Hydrea	Glaxosmithkline
Hydrine	Al-Habib Pharmaceuticals.
Hydrourea	Pharmedic (Pvt) Ltd.
Uro-Z	Z-Jans Pharmaceutical (Pvt) Ltd.