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Thioguanine Dosage

Applies to the following strength(s): 40 mg

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

Usual Adult Dose for:

Usual Geriatric Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Acute Nonlymphocytic Leukemia

Single Agent Chemotherapy: Usual Initial dose: 2 mg/kg/day orally.
If, after 4 weeks on this dosage, there is no clinical improvement and no leukocyte or platelet depression, the dosage may be cautiously increased to 3 mg/kg per day. The total daily dose may be given at one time.

As a part of combination therapy for induction of remission in patients with acute nonlymphocytic leukemia: 75 to 200 mg/m2/day in 1 to 2 divided doses for 5 to 7 days or until remission is attained.

Usual Geriatric Dose for Acute Nonlymphocytic Leukemia

Single Agent Chemotherapy: Usual Initial dose: 2 mg/kg/day orally.
If, after 4 weeks on this dosage, there is no clinical improvement and no leukocyte or platelet depression, the dosage may be cautiously increased to 3 mg/kg per day. The total daily dose may be given at one time.

As a part of combination therapy for induction of remission in patients with acute nonlymphocytic leukemia: 75 to 200 mg/m2/day in 1 to 2 divided doses for 5 to 7 days or until remission is attained.

Because clinical studies of thioguanine did not include sufficient numbers of subjects 65 years of age or over to determine whether they respond differently from younger subjects, dose selection for elderly patients should be cautious, usually starting at the low end of the dosing range.

Usual Pediatric Dose for Acute Nonlymphocytic Leukemia

<3 years: As a part of combination drug therapy for Acute Nonlymphocytic Leukemia: 3.3 mg/kg/day in divided doses twice a day for 4 days.

>1 year: As a part of combination therapy for induction of remission in patients with acute nonlymphocytic leukemia: 75 to 200 mg/m2/day in 1 to 2 divided doses for 5 to 7 days or until remission is attained.

Single Agent Chemotherapy: Usual Initial dose: 2 mg/kg/day orally.
If, after 4 weeks on this dosage, there is no clinical improvement and no leukocyte or platelet depression, the dosage may be cautiously increased to 3 mg/kg per day. The total daily dose may be given at one time.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

The decision to increase, decrease, continue, or discontinue a given dosage of thioguanine must be based not only on the absolute hematologic values, but also upon the rapidity with which changes are occurring. In many instances, particularly during the induction phase of acute leukemia, complete blood counts will need to be done more frequently in order to evaluate the effect of the therapy. The dosage of thioguanine may need to be reduced when this agent is combined with other drugs whose primary toxicity is myelosuppression.

Myelosuppression is often unavoidable during the induction phase of adult acute nonlymphocytic leukemias if remission induction is to be successful. Whether or not this demands modification or cessation of dosage depends both upon the response of the underlying disease and a careful consideration of supportive facilities (granulocyte and platelet transfusions) which may be available. Life-threatening infections and bleeding have been observed as consequences of thioguanine-induced granulocytopenia and thrombocytopenia.

There are individuals with an inherited deficiency of the enzyme thiopurine methyltransferase (TPMT) who may be unusually sensitive to the myelosuppressive effects of thioguanine and prone to developing rapid bone marrow suppression following the initiation of treatment. Substantial dosage reductions may be required to avoid the development of life-threatening bone marrow suppression in these patients.

Precautions

Thioguanine is not recommended for maintenance therapy or similar long term continuous treatments due to the high risk of liver toxicity associated with vascular endothelial damage.

The most consistent, dose related toxicity is bone marrow suppression. This may be manifested by anemia, leukopenia, thrombocytopenia, or any combination of these. Any one of these findings may also reflect progression of the underlying disease. Since thioguanine may have a delayed effect, it is important to withdraw the medication temporarily at the first sign of an abnormally large fall in any of the formed elements of the blood.

Dialysis

Data not available

Other Comments

Thioguanine should not be used unless a diagnosis of acute nonlymphocytic leukemia has been adequately established

It is recommended that evaluation of the hemoglobin concentration or hematocrit, total white blood cell count and differential count, and quantitative platelet count be obtained frequently while the patient is on thioguanine therapy. In cases where the cause of fluctuations in the formed elements in the peripheral blood is obscure, bone marrow examination may be useful for the evaluation of marrow status.

The dosage which will be tolerated and effective varies according to the stage and type of neoplastic process being treated. Because the usual therapies for adult and pediatric acute nonlymphocytic leukemias involve the use of thioguanine with other agents in combination, physicians responsible for administering these therapies should be experienced in the use of cancer chemotherapy and in the chosen protocol.

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