Variable Bioavailability of Oral Mercaptopurine

Abstract

Induction therapy is now successful in producing a complete remission in more than 90 per cent of patients with acute lymphoblastic leukemia.^{1 , 2} However, maintenance of remission remains a major problem, since a third of patients with a standard risk and approximately 80 per cent of patients with a high risk relapse despite periodic intensification of chemotherapy and continual maintenance chemotherapy.³ The daily administration of oral mercaptopurine forms the backbone of maintenance chemotherapy for acute lymphoblastic leukemia; most treatment regimens also include weekly or biweekly administration of oral methotrexate. The rationale for giving mercaptopurine orally has been based on clinical studies . . .