Mercaptopurinum Vis (Mercaptopurine)

• Mercaptopurine is used in the management of hematologic malignancies and certain inflammatory conditions.
• Acute lymphoblastic leukemia: induces remission clinically by inhibiting proliferation of leukemic lymphoblasts.
• Chronic myeloid leukemia: contributes to disease control, especially when combined with other cytoreductive agents.
• Inflammatory bowel disease: helps maintain remission by suppressing abnormal immune activation in the gut.
• Maintenance therapy in acute lymphoblastic leukemia: used to sustain remission after induction chemotherapy.
• Combination therapy in chronic myeloid leukemia: enhances efficacy when used with tyrosine kinase inhibitors.

• Mercaptopurine is a purine analogue that is converted intracellularly to thio‑inosine monophosphate, which competitively inhibits hypoxanthine‑guanine phosphoribosyltransferase. This blockade prevents the formation of purine nucleotides, thereby reducing DNA and RNA synthesis in rapidly dividing cells. The resulting cytotoxic effect preferentially targets malignant lymphoblasts and proliferating immune cells, contributing to its antineoplastic and immunosuppressive actions. The inhibition also interferes with de novo purine synthesis, amplifying the antiproliferative impact.

Mercaptopurine may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Vomiting: occasional episodes, especially after dose initiation.
• Diarrhea: loose stools that may affect hydration.
• Fatigue: generalized tiredness or weakness.

Serious or Rare Side Effects

• Bone marrow suppression: reduced blood cell production leading to anemia or infection risk.
• Hepatotoxicity: liver enzyme elevations or hepatitis.
• Severe infections: opportunistic infections due to immunosuppression.
• Secondary malignancies: rare development of new cancers after prolonged therapy.

Before initiating therapy, clinicians should evaluate baseline laboratory values and patient history.

• Monitor blood counts: perform regular CBC to detect marrow suppression.
• Assess liver function: check hepatic enzymes periodically.
• Evaluate renal function: adjust use if significant impairment exists.
• Avoid use in patients with known hypersensitivity: discontinue if allergic reaction occurs.
• Use caution in pregnancy: limited safety data, weigh benefits against risks.
• Store at room temperature: keep in the original pack, protect from moisture.

Mercaptopurine interacts with several medicines that can alter its efficacy or toxicity.

Major Interactions (Avoid)

• Allopurinol: increases mercaptopurine toxicity.
• Azathioprine: additive myelosuppression.
• Warfarin: enhanced anticoagulant effect.
• Methotrexate: increased risk of marrow suppression.

Moderate Interactions (Monitor Closely)

• Trimethoprim‑sulfamethoxazole: potential for heightened myelosuppression.
• NSAIDs: may affect renal clearance.
• Ribavirin: combined hematologic toxicity.