Poducts
Mercaptopurine is commercially available in tablet and oral suspension form (Puri-Nethol, Xaluprine). The active ingredient has been approved in many countries since 1955.
Structure and properties
Mercaptopurine (C5H4N4S – H2O, Mr = 170.2 g/mol) exists as a yellow crystalline powder that is practically insoluble in water. It is an analog of the purine bases adenine and hypoxanthine. Mercaptopurine is a prodrug.
Effects
Mercaptopurine (ATC L01BB02) has cytotoxic and immunosuppressive properties. It is active intracellularly as an antimetabolite. The effects are due in part to inhibition of the enzyme hypoxanthine-guanine phosphoribosyl transferase (HGPRTase). This results in inhibition of purine synthesis and formation of cell-toxic metabolites.
Indications
- Acute lymphocytic and myeloid leukemias.
- Chronic myeloid leukemia
Dosage
According to the professional information. The tablets or suspension are taken once daily fasting, 1 hour before or at least 3 hours after a meal and with sufficient liquid.
Contraindications
Mercaptopurine is contraindicated in cases of hypersensitivity (including to azathioprine). It should not be co-administered with a yellow fever vaccine. For complete precautions, see the drug label.
Interactions
Drug-drug interactions have been reported with the following agents:
- Live vaccines
- Xanthine oxidase inhibitors: allopurinol inhibits the degradation of mercaptopurine.
- Aminosalicylates
- Ribavirin
- Methotrexate
- Salicylate
- Sulfonamides
- Sedatives such as benzodiazepines
- Anticoagulants
Adverse effects
The most common possible adverse effects include leukopenia, granulocytopenia, thrombocytopenia, and anemia (bone marrow depression), increased bleeding tendency, cholestasis, liver toxicity, nausea, and vomiting.
