Antiproliferative immunosuppressants

Lymphocytes activated by an antigen must copy their DNA to multiply, and these drugs cut their supply of purine nucleotides. Azathioprine releases mercaptopurine, whose thioguanine nucleotides block purine synthesis and enter DNA; mycophenolate's active form inhibits IMPDH, the enzyme lymphocytes rely on to make guanine nucleotides. Fewer T and B cells expand, and antibody production falls.

• AzathioprineNUDT15 deficiency is rare in people of European or African ancestry but much more common in East Asians, who are then at higher risk of severe myelosuppression.
• Mycophenolate mofetilMycophenolic acid is also sold as delayed-release mycophenolate sodium tablets, which are not interchangeable with mycophenolate mofetil.

• Preventing transplant rejection
• Rheumatoid arthritis (azathioprine)
• Crohn's disease and ulcerative colitis (azathioprine)
• Lupus

• Bone marrow suppression (low white cells)Known forSerious
• Serious and opportunistic infectionsKnown forSerious
• LymphomaSerious
• Skin cancerSerious
• Nausea, vomiting and diarrhea
• Miscarriage and birth defectsSerious
• Liver damage (azathioprine)Serious
• Pancreatitis (azathioprine)Serious
• JC virus brain infection (PML)Serious
• Anemia

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• Blood counts are checked often, most closely in the first months; azathioprine also needs liver tests.
• TPMT and NUDT15 status guides azathioprine dosing, and allopurinol or febuxostat greatly raise its toxicity.
• Mycophenolate causes miscarriage and birth defects, so pregnancy is ruled out and effective contraception is used.
• Both raise the risk of serious infections, lymphoma and skin cancer; live vaccines are avoided and sun exposure limited.

Written for biofideX in plain words, after checking these references:

• Azathioprine tablets: label (DailyMed)
• Mycophenolate mofetil: label (DailyMed)
• Azathioprine (NCI Thesaurus)
• Mycophenolate Mofetil (NCI Thesaurus)
• Azathioprine (NHS)
• Azathioprine 50 mg film-coated tablets: SmPC (emc)
• Voclosporin capsules: label (DailyMed)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.