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Busulfan Dosage

Medically reviewed on December 1, 2017.

Applies to the following strengths: 2 mg; 6 mg/mL

Usual Adult Dose for Chronic Myelogenous Leukemia

Initial dose: 60 mcg/kg or 1.8 mg/m2 orally once a day. The usual dosage range for remission induction is 4 to 8 mg/day.

Usual Adult Dose for Bone Marrow Transplantation

2 to 4 mg/kg (up to 560 mg) orally every 6 hours for 4 days. High dose cyclophosphamide has been used in combination with busulfan to prepare patients for bone marrow transplantation.

Usual Pediatric Dose for Chronic Myelogenous Leukemia

Initial Dose:
Less than or equal to 12 kg : 1.1 mg/kg (based on actual body weight.)
Greater than 12 kg: 0.8 mg/kg (based on actual body weight.)

Doses are administered every 6 hours as 2 hour infusions over 4 days for a total of 16 doses.

Therapeutic drug monitoring and dose adjustment following the first dose is recommended.

Adjust subsequent doses to achieve the desired target AUC (1125 uM/min) using the formula below:

Adjusted Dose (mg) = Actual Dose (mg) x Target AUC (uM/min) / Actual AUC (uM/min)

Usual Pediatric Dose for Bone Marrow Transplantation

Marrow-ablative conditioning regimen:
0.5 mg/kg to 1 mg/kg orally every 6 hours for 4 days.

Hematopoetic stem cell transplant program:
Less than or equal to 6 years:
40 mg/m2/dose every 6 hours for 4 days.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

Obesity has been reported to increase busulfan clearance. Dosing based on body surface area or adjusted ideal bodyweight (defined by Gibbs as an ideal body weight plus 25% of the difference between actual and ideal body weight) should be considered in obese patients.

Dosages of busulfan may depend upon the specific indication for use and protocol. When combined with other myelosuppressive drugs, dosages may need to be decreased.

Precautions

US BOXED WARNING:
-BONE MARROW SUPPRESSION: The injection formulation of this drug causes severe and prolonged myelosuppression at the recommended dosage. Hematopoietic progenitor cell transplantation is required to prevent potentially fatal complications of the prolonged myelosuppression. The tablet form of this drug can induce severe bone marrow hypoplasia. Reduce or discontinue the dosage immediately at the first sign of any unusual depression of bone marrow function as reflected by an abnormal decrease in any of the formed elements of the blood. Perform a bone marrow examination if the bone marrow status is uncertain.
-EXPERIENCED PHYSICIAN: Due to the potency of this drug, it should not be used unless a diagnosis of chronic myelogenous leukemia (CML) has been adequately established and the responsible physician is knowledgeable in assessing response to chemotherapy.

Consult WARNINGS section for additional precautions.

Since the rate of fall of the leukocyte count is dose related, daily doses exceeding 4 mg should be reserved for patients with the most compelling symptoms. Patients should be instructed to immediately report the development of fever, sore throat, signs of local infection, bleeding from any site, or symptoms suggestive of anemia.

Dialysis

Data not available

Other Comments

Mg/kg dosages should be based on ideal body weight.

During remission, the patient should be examined at monthly intervals and treatment resumed with the induction dosage when the total leukocyte count reaches approximately 50,000/mcL. When remission is less than 3 months, maintenance therapy of 1 to 3 mg/day may be advisable in order to keep the hematological status under control and prevent rapid relapse. A decrease in leukocyte count is not usually seen during the first 10 to 15 days of treatment. The leukocyte count may increase during this period but should not be interpreted as resistance to the drug, nor should the dose be increased. The leukocyte count may continue to fall for greater than 1 month after discontinuation of the drug. It is important to discontinue the drug prior to the total leukocyte count falling into the normal range. It is suggested that the drug be withheld when the total leukocyte count falls to 10,000 to 15,000/mcL. With a constant dose of busulfan, the total leukocyte count declines exponentially. With the recommended dose, a normal leukocyte count is usually achieved in 12 to 20 weeks.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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