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Hydroxyurea Dosage

Applies to the following strength(s): 500 mg ; 200 mg ; 300 mg ; 400 mg ; 1000 mg

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Additional dosage information:

Usual Adult Dose for Solid Tumors

SOLID TUMORS:
-INTERMITTENT THERAPY: 80 mg/kg administered orally as a single dose every third day
-CONTINUOUS THERAPY: 20 to 30 mg/kg administered orally as a single dose daily
-CONCOMITANT THERAPY WITH IRRADIATION: Carcinoma of the head and neck: 80 mg/kg administered orally as a single dose every third day

Comments:
-Administration of therapy should be begun at least 7 days before initiation of irradiation and continued during radiotherapy as well as indefinitely afterwards provided that the patient may be kept under adequate observation and there is no evidence of unusual or severe reactions.
-Pain or discomfort from inflammation of the mucous membranes at the irradiated site (mucositis) is usually controlled by measures such as topical anesthetics and orally administered analgesics. If the reaction is severe, hydroxyurea therapy may be temporarily interrupted; if it is extremely severe, irradiation dosage may, in addition, be temporarily postponed. However, it has rarely been necessary to terminate these therapies.
-Severe gastric distress, such as nausea, vomiting, and anorexia, resulting from combined therapy may usually be controlled by temporary interruption of hydroxyurea administration.

Uses:
-Significant tumor response to this drug has been demonstrated in melanoma, resistant chronic myelocytic leukemia, and recurrent, metastatic, or inoperable carcinoma of the ovary.
-This drug 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.

Usual Adult Dose for Sickle Cell Anemia

INITIAL DOSE: 15 mg/kg per day as a single dose
MAXIMUM DOSE: 35 mg/kg/day

DOSING BASED ON BLOOD COUNTS:
-Counts in acceptable range: Increase dose 5 mg/kg/day every 12 weeks to a maximum dose of 35 mg/kg/day
-Counts between acceptable and toxic range: Do not increase dose. If in toxic range, discontinue therapy until hematologic recovery.
-Dosing after hematologic recovery: Reduce dose by 2.5 mg/kg/day. Reduce the dose from the dose associated with hematologic toxicity. May titrate up or down every 12 weeks in 2.5 mg/kg/day increments. The patient should be at a stable dose with no hematologic toxicity for 24 weeks. Discontinue treatment permanently if a patient develops hematologic toxicity twice.

-BLOOD COUNTS IN THE ACCEPTABLE RANGE:
Neutrophils greater than or equal to 2500 cells/mm3
Platelets greater than or equal to 95,000/mm3
Reticulocytes greater than or equal to 95,000/mm3 if the hemoglobin concentration is less than 9 g/dL
-BLOOD COUNTS IN THE TOXIC RANGE:
Neutrophils less than 2000 cells/mm3
Platelets less than 80,000/mm3
Hemoglobin less than 4.5 g/dL
Reticulocytes less than 80,000/mm3 if the hemoglobin concentration is less than 9 g/dL

Comments:
-Dosage is based on the actual or ideal patient weight, whichever is less.
-The patient blood count should be monitored every 2 weeks.
-Fetal hemoglobin (HbF) levels may be used to evaluate the efficacy of therapy in clinical use. Obtain HbF levels every 3 to 4 months. Monitor for an increase in HbF of at least 2-fold over the baseline value.
-Prophylactic administration of folic acid is recommended.

Use: To reduce the frequency of painful crises and to reduce the need for blood transfusions in patients with sickle cell anemia with recurrent moderate to severe painful crises.

Usual Adult Dose for Chronic Myelogenous Leukemia

Until the intermittent therapy regimen has been evaluated, continuous therapy at 20 to 30 mg/kg administered orally as a single dose per day is recommended.

Comments:
-An adequate trial period for determining the antineoplastic effectiveness of this drug is 6 weeks of therapy. When there is regression in tumor size or arrest in tumor growth, therapy should be continued indefinitely.
-Therapy should be interrupted if the white blood cell count drops below 2500/mm3, or the platelet count below 100,000/mm3. In these cases, the counts should be rechecked after 3 days, and therapy resumed when the counts rise significantly toward normal values. Since the hematopoietic rebound is prompt, it is usually necessary to omit only a few doses. If prompt rebound has not occurred during combined drug and irradiation therapy, irradiation may also be interrupted. However, the need for postponement of irradiation has been rare. Radiotherapy has usually been continued using the recommended dosage and technique.
-If severe anemia occurs, it should be corrected without interrupting therapy. Because hematopoiesis may be compromised by extensive irradiation or by other antineoplastic agents, it is recommended that this drug be administered cautiously to patients who have recently received extensive radiation therapy or chemotherapy with other cytotoxic drugs.
-Pain or discomfort from inflammation of the mucous membranes at the irradiated site (mucositis) is usually controlled by measures such as topical anesthetics and orally administered analgesics. If the reaction is severe, therapy may be temporarily interrupted; if it is extremely severe, irradiation dosage may, in addition, be temporarily postponed. However, it has rarely been necessary to terminate these therapies.
-Severe gastric distress, such as nausea, vomiting, and anorexia, resulting from combined therapy may usually be controlled by temporary interruption of this drug.

Use:
-Resistant chronic myeloid leukemia

Renal Dose Adjustments

Renal Dose Adjustments for Adults:
-SICKLE CELL ANEMIA:
CrCl 60 mL/minute or Greater: Initial dose: 15 mg/kg/day
CrCl Less than 60 mL/minute or end stage renal disease (ESRD): Reduce initial dose to 7.5 mg/kg/day
-OTHER INDICATIONS:
CrCl 10 to 50 mL/minute: 50% of normal dose
CrCl Less than 10 mL/minute: 20% of normal dose

Liver Dose Adjustments

There are no data that support specific guidance for dosage adjustment in patients with hepatic impairment. Close monitoring of hematologic parameters is advised.

Dose Adjustments

-Concurrent use of this drug with other myelosuppressive agents may require adjustment of dosages.
-Although no specific dose adjustment guidelines have been suggested, elderly patients may require a lower dose of this drug.

Precautions

US BOXED WARNINGS:
-MYELOSUPPRESSION: This drug may cause severe myelosuppression. Blood counts should be monitored at baseline and throughout treatment. Treatment should be interrupted and the dose should be reduced as necessary.
MALIGNANCIES: This drug is carcinogenic. Patients should use sun protection and be monitored for malignancies.

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Hemodialysis: Administer the dose following hemodialysis.

Other Comments

Administration advice:
-All dosage should be based on the patient's actual or ideal weight, whichever is less.
-The contents of capsules may be emptied into a glass of water and administered immediately. The contents of the capsule should not be inhaled or allowed to come into contact with the skin or mucous membranes.

General:
-Different individual products are used for specific indications. The manufacturer product information should be consulted prior to using a product.

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