A potent inhibitor of adenosine deaminase. The drug is effective in the treatment of many lymphoproliferative malignancies, particularly hairy-cell leukemia. It is also synergistic with some other antineoplastic agents and has immunosuppressive activity. [PubChem]
Indication
For the treatment of hairy cell leukaemia refractory to alpha interferon.
Pharmacology
Pentostatin is an antineoplastic anti-metabolite used in the treatment of several forms of leukemia including acute nonlymphocytic leukemia and hairy cell leukemia. Anti-metabolites masquerade as purine or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the "S" phase (of the cell cycle), stopping normal development and division. It is a 6-thiopurine analogue of the naturally occurring purine bases hypoxanthine and guanine. Intracellular activation results in incorporation into DNA as a false purine base. An additional cytotoxic effect is related to its incorporation into RNA. Cytotoxicity is cell cycle phase-specific (S-phase).
Toxicity
LD50=128 mg/kg (mouse), side effects include lethargy, rash, fatigue, nausea and myelosuppression.
Affected Organisms
Humans and other mammals
Biotransformation
Primarily hepatic, but only small amounts are metabolized.
Absorption
Not absorbed orally, crosses blood brain barrier.
Half Life
5.7 hours (with a range between 2.6 and 16 hrs)
Protein Binding
4%
Elimination
In man, following a single dose of 4 mg/m2 of pentostatin infused over 5 minutes, approximately 90% of the dose was excreted in the urine as unchanged pentostatin and/or metabolites as measured by adenosine deaminase inhibitory activity.
