Mercaptopurine

Registered South African indications:

• Acute lymphoblastic leukaemia (ALL)
• Acute promyelocytic leukaemia (APL) / Acute myeloid leukaemia M3 (AML M3)

Contraindications

• Hypersensitivity to the active ingredient or any of its excipients

In view of the seriousness of the indications there are no other absolute contraindications

Cautions

• Pregnancy
• Breastfeeding
• Renal impairment
• Hepatic impairment
• Elderly
• Inherited mutated NUDT15 gene 
• Inherited deficiency of thiopurine methyltransferase 
• Autoimmune conditions
• Prior exposure to or infection with varicella zoster virus 
• Children
• Lesch-Nyhan syndrome
• Exposure to sunlight and ultraviolet light 
• Galactose intolerance
• Lactase deficiency 
• Glucose-galactose malabsorption

Forms avail. in SA and covered in this monograph: tab

Used for the treatment of

Acute lymphoblastic leukaemia (ALL) (additional agent required)
Acute promyelocytic leukaemia (APL) / Acute myeloid leukaemia M3 (AML M3) (additional agent required)

Consult specialist for dosages and regimens

See adult dosage

Pregnancy

• FDA Pregnancy Category D

Breastfeeding

• Caution; not recommended

Renal Impairment

• Caution; dose adjustment recommended

Hepatic Impairment

• Caution; dose adjustment recommended

Elderly

• Caution; no information available

Gastrointestinal Disorders

• Nausea and vomiting
• Pancreatitis
• Oral ulceration
• Intestinal ulceration

Hepatobiliary Disorders

• Biliary stasis
• Hepatotoxicity
• Hepatic necrosis

Genitourinary Disorders

• Transient oligospermia

Endocrine and Metabolic Disorders

• Anorexia
• Hypoglycaemia

Musculoskeletal Disorders

• Arthralgia

Skin and Subcutaneous Tissue Disorders

• Skin rash
• Facial oedema
• Alopecia
• Photosensitivity

Immune, Blood and Lymphatic System Disorders

• Neoplasms 
• Lymphoproliferative disorders
• Skin cancers 
• Sarcomas 
• Uterine cervical cancer in situ 
• Secondary leukaemia 
• Myelodysplasia
• Hepatosplenic T-cell lymphoma
• Bone marrow suppression
• Leucopenia 
• Thrombocytopenia
• Anaemia
• Hypersensitivity reactions
• Drug fever

• Immunosuppressives
• Xanthine oxidase inhibitors
• Warfarin 
• Acenocoumarol 
• Live vaccines
• Ribavirin 
• Myelosuppressive agents
• Aminosalicylate derivatives 
• Methotrexate
• Infliximab

• Full blood count and differential
• Hepatic function
• Renal function
• Uric acid levels
• Bone marrow examination
• Urinanalysis

Specific cases may require

• Thiopurine methyltransferase genotyping

Mercaptopurine is sulphydryl analogue of the purine bases, adenine and hypoxanthine and acts as a cytotoxic antimetabolite. Mercaptopurine is an inactive pro-drug which acts as a purine antagonist but requires cellular uptake and intracellular anabolism to thioguanine nucleotides (TGNs) for cytotoxicity. The TGNs and other metabolites inhibit de novo purine synthesis and purine nucleotide interconversions. The TGNs are also incorporated into nucleic acids and this contributes to the cytotoxic effects of the medicinal product.

Tablet 50mg

• Puri-Nethol (Pharmacare)