An antimetabolite antineoplastic agent with immunosuppressant properties. It interferes with nucleic acid synthesis by inhibiting purine metabolism and is used, usually in combination with other drugs, in the treatment of or in remission maintenance programs for leukemia. [PubChem]
Indication
For remission induction and maintenance therapy of acute lymphatic leukemia.
Pharmacology
Mercaptopurine is one of a large series of purine analogues which interfere with nucleic acid biosynthesis and has been found active against human leukemias. It is an analogue of the purine bases adenine and hypoxanthine. It is not known exactly which of any one or more of the biochemical effects of mercaptopurine and its metabolites are directly or predominantly responsible for cell death.
Toxicity
Signs and symptoms of overdosage may be immediate such as anorexia, nausea, vomiting, and diarrhea; or delayed such as myelosuppression, liver dysfunction, and gastroenteritis. The oral LD50 of mercaptopurine was determined to be 480 mg/kg in the mouse and 425 mg/kg in the rat.
Affected Organisms
Humans and other mammals
Biotransformation
Hepatic. Degradation primarily by xanthine oxidase. The catabolism of mercaptopurine and its metabolites is complex. In humans, after oral administration of 35S-6-mercaptopurine, urine contains intact mercaptopurine, thiouric acid (formed by direct oxidation by xanthine oxidase, probably via 6-mercapto-8-hydroxypurine), and a number of 6-methylated thiopurines. The methylthiopurines yield appreciable amounts of inorganic sulfate.
Absorption
Clinical studies have shown that the absorption of an oral dose of mercaptopurine in humans is incomplete and variable, averaging approximately 50% of the administered dose. The factors influencing absorption are unknown.
Half Life
Triphasic: 45 minutes, 2.5 hours, and 10 hours.
Protein Binding
Plasma protein binding averages 19% over the concentration range 10 to 50 µg/mL (a concentration only achieved by intravenous administration of mercaptopurine at doses exceeding 5 to 10 mg/kg).
Research Area: Infection Biological Activity: Mercaptopurine is used to treat leukemia. It is also used for pediatric non-Hodgkin’s lymphoma, polycythemia vera, psoriatic arthritis, and inflammatory bowel disease. It has demonstrated some in vitro effectiveness against Mycobacterium paratuberculosis 6-MP ribonucleotide inhibits purine nucleotide synthesis and metabolism. This alters the synthesis and function of RNA and DNA. Mercaptopurine interferes with nucleotide interconversion and glycoprotein synthesis. [1]
