Capmerin Special Precautions

Mercaptopurine is an active cytotoxic agent for use only under the direction of physicians experienced in the administration of such agents.
Since Mercaptopurine is strongly myelosuppressive, full blood counts must be taken daily during remission induction. Patients must be carefully monitored during therapy.
Treatment with Mercaptopurine causes bone marrow suppression leading to leukopenia and thrombocytopenia. The leukocyte and platelet counts continue to fall after treatment is stopped, so at the first sign of an abnormally large fall in the counts, treatment should be interrupted immediately.
Bone marrow suppression is reversible if Mercaptopurine is withdrawn early enough. During remission induction in acute myelogenous leukemia the patient may frequently have to survive a period of relative bone marrow aplasia and it is important that adequate supportive facilities are available.
Mercaptopurine is hepatotoxic and liver function tests should be monitored weekly during treatment. More frequent monitoring may be advisable in those with pre-existing liver disease or receiving other potentially hepatotoxic therapy. The patient should be instructed to discontinue Mercaptopurine immediately if jaundice becomes apparent.
During remission induction when rapid cell lysis is occurring, uric acid levels in blood and urine should be monitored as hyperuricemia and/or hyperuricosuria may develop, with the risk of uric acid nephropathy.
Mercaptopurine in common with other antimetabolites is potentially mutagenic and chromosome damage has been reported in rats and man.
In view of its action on cellular deoxyribonucleic acid (DNA) 6-mercaptopurine is potentially carcinogenic and consideration should be given to the theoretical risk of carcinogenesis with this treatment.
It is advised that care should be taken when handling or dividing these tablets so as not to contaminate hands or to inspire drug.
Use in pregnancy & lactation: Mercaptopurine is embryotoxic in rats. This effect is dose dependent.
Normal offspring have been born after Mercaptopurine therapy during human pregnancy, but abortion, prematurity and malformation have been reported.
Mercaptopurine should be used during pregnancy only if the expected benefits to the mother outweigh the potential risks to the fetus.
Mothers receiving Mercaptopurine should not breast feed.