Hydroxyurea

Product: 
Hydroxyurea
Formalary: 
Specialty Formalary
Category: 
Oncology
Trade Name: 
Hydrea and Droxia
Packing: 
Capsule
Potency: 
500mg
In Treatment of: 
Significant tumor response to Hydroxyurea capsules USP has been demonstrated in melanoma, resistant chronic myelocytic leukemia, and recurrent, metastatic, or inoperable carcinoma of the ovary. Hydroxyurea, USP used concomitantly with irradiation therapy is intended for use in the local control of primary squamous cell (epidermoid) carcinomas of the head and neck, excluding the lip.
Adverse Effects: 
Reported side-effects are: drowsiness, nausea, vomiting and diarrhea, constipation, mucositis, anorexia, stomatitis, bone marrow toxicity (dose-limiting toxicity; may take 7–21 days to recover after the drug has been discontinued), alopecia (hair loss), skin changes, abnormal liver enzymes, creatinine and blood urea nitrogen. Due to its effect on the bone marrow, regular monitoring of the full blood count is vital, as well as early response to possible infections. In addition, renal function, uric acid and electrolytes, as well as liver enzymes, are commonly checked. Moreover, because of this, severe anemia and neutropenia are contradicted. Hydroxycarbamide has been used primarily for the treatment of myeloproliferative diseases, which has an inherent risk of transforming to acute myeloid leukemia. There has been a longstanding concern that hydroxycarbamide itself carries a leukemia risk, but large studies have shown that the risk is either absent or very small. Nevertheless, it has been a barrier for its wider use in patients with sickle-cell disease.
Contraindication: 
Hydroxyurea is contraindicated in patients with marked bone marrow depression, i.e., leukopenia (< 2500 WBC) or thrombocytopenia (< 100,000), or severe anemia. Hydroxyurea capsules are contraindicated in patients who have demonstrated a previous hypersensitivity to Hydroxyurea or any other component of its formulation.
Special Precaution: 
General Therapy with Hydroxyurea requires close supervision. The complete status of the blood, including bone marrow examination, if indicated, as well as kidney function and liver function should be determined prior to, and repeatedly during, treatment. The determination of the hemoglobin level, total leukocyte counts, and platelet counts should be performed at least once a week throughout the course of Hydroxyurea therapy. If the white blood cell count decreases to less than 2500/mm3, or the platelet count to less than 100,000/mm3, therapy should be interrupted until the values rise significantly toward normal levels. Severe anemia, if it occurs, should be managed without interrupting Hydroxyurea therapy. Hydroxyurea should be used with caution in patients with marked renal dysfunction. Hydroxyurea is not indicated for the treatment of HIV infection; however, if HIV-infected patients are treated with Hydroxyurea, and in particular, in combination with didanosine and/or stavudine, close monitoring for signs and symptoms of pancreatitis is recommended. Patients who develop signs and symptoms of pancreatitis should permanently discontinue therapy with Hydroxyurea. An increased risk of hepatotoxicity, which may be fatal, may occur in patients treated with Hydroxyurea, and in particular, in combination with didanosine and stavudine. This combination should be avoided. Carcinogenesis, Mutagenesis, Impairment of Fertility Impairment of Fertility Hydroxyurea administered to male rats at 60 mg/kg/day (about 0.3 times the maximum recommended human daily dose on a mg/m2 basis) produced testicular atrophy, decreased spermatogenesis, and significantly reduced their ability to impregnate females. Pregnancy Teratogenic Effects Pregnancy Category D Nursing Mothers Hydroxyurea is excreted in human milk. Because of the potential for serious adverse reactions with Hydroxyurea, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Pediatric Use Safety and effectiveness in pediatric patients have not been established. Geriatric Use Elderly patients may be more sensitive to the effects of Hydroxyurea, and may require a lower dose regimen. This drug is known to be excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. Drug Interactions Prospective studies on the potential for Hydroxyurea to interact with other drugs have not been performed. Concurrent use of Hydroxyurea and other myelosuppressive agents or radiation therapy may increase the likelihood of bone marrow depression or other adverse events Studies have shown that there is an analytical interference of Hydroxyurea with the enzymes (urease, uricase, and lactate dehydrogenase) used in the determination of urea, uric acid and lactic acid, rendering falsely elevated results of these in patients treated with Hydroxyurea. Information for Patients Hydroxyurea capsules are a medication that must be handled with care. People who are not taking Hydroxyurea capsules should not be exposed to it. To decrease the risk of exposure, wear disposable gloves when handling Hydroxyurea capsules or bottles containing Hydroxyurea capsules. Anyone handling Hydroxyurea capsules should wash their hands before and after contact with the bottle or capsules. If the powder from the capsule is spilled, it should be wiped up immediately with a damp disposable towel and discarded in a closed container, such as a plastic bag. The medication should be kept away from children and pets. Contact your doctor for instructions on how to dispose of outdated capsules.
Interaction: 
Prospective studies on the potential for Hydroxyurea to interact with other drugs have not been performed. Concurrent use of Hydroxyurea and other myelosuppressive agents or radiation therapy may increase the likelihood of bone marrow depression or other adverse events Studies have shown that there is an analytical interference of Hydroxyurea with the enzymes (urease, uricase, and lactate dehydrogenase) used in the determination of urea, uric acid and lactic acid, rendering falsely elevated results of these in patients treated with Hydroxyurea.
Dosages: 
The dose depends on the indication, but tends to be 500 milligrams once a day when treatment is initiated. In myeloproliferative disease, further increases are determined by the response of the cell count and whether myelosuppression (decreased production of other blood cells) develops. In sickle-cell disease, the initial daily dose is 15 mg per kilogram body weight (or less in reduced kidney function); after two weeks, a fall in the hemoglobin and platelet count and an increase in MCV (mean corpuscular volume) (size of the red blood cells) is to be expected. The dose is then increased every two weeks with monitoring of the full blood count until the dose is either 35 mg/kg or cytopenias develop.

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