Pharmacology · Antiproliferative immunosuppressants
Mycophenolate mofetil !
An immunosuppressant used after transplants that blocks an enzyme lymphocytes need to make DNA. It can cause diarrhoea and is very harmful in pregnancy.
Updated 2026-11-01
The figure shows mycophenolic acid, the active form, bound to IMPDH type 2 of the Chinese hamster, nearly identical to the human enzyme, next to its product IMP.
Mechanism of action
Mycophenolate mofetil is an ester prodrug that is rapidly converted to mycophenolic acid. Mycophenolic acid is a selective, reversible inhibitor of IMPDH, the enzyme in the de novo pathway of guanine nucleotide synthesis. B and T lymphocytes depend heavily on this pathway, so their proliferation and antibody production fall while most other cells, which can use the salvage pathway, are spared.
- Hydrolysed to mycophenolic acid
- Mycophenolic acid inhibits IMPDH
- Guanine nucleotides fall in lymphocytes
- B and T cells stop proliferating
Pharmacokinetics
- Absorption
- Rapidly absorbed and converted to mycophenolic acid; also given intravenously
- Metabolism
- Mycophenolic acid is glucuronidated; the glucuronide is recycled through the bile and gut
- Half-life
- About 18 hours for mycophenolic acid
Indications
- Prevention of rejection of kidney, heart and liver transplants, with a calcineurin inhibitor and glucocorticoids
- Crohn disease (off label) Crohn disease →
Adverse effects
Common
- Diarrhoea
- Nausea and vomiting
- Abdominal pain
- Leukopenia
- Infections
Contraindications
- Hypersensitivity to mycophenolate mofetil or mycophenolic acid
- Hereditary HGPRT deficiency (Lesch-Nyhan, Kelley-Seegmiller syndromes)
Key interactions
- Antacids with magnesium or aluminium hydroxide, proton pump inhibitors, calcium-free phosphate binders
- Reduce mycophenolic acid exposure and efficacy.
- Cholestyramine and drugs that interrupt enterohepatic recycling (some antibiotics, rifampicin)
- Lower mycophenolic acid levels.
- Drugs eliminated by renal tubular secretion
- Its glucuronide metabolite may compete with them and raise their levels.
- Hormonal contraceptives
- May be less effective; additional contraception is needed.
- Live vaccines
- Avoided during treatment.
What is monitored
- Complete blood count
- Pregnancy test before starting and during treatment
- Signs of infection
- Kidney and liver tests
- Skin checks
Administration and safety
- Oral capsules, tablets or suspension, and an intravenous form.
- Do not crush tablets or open capsules; avoid inhaling the powder or letting it touch skin or mucous membranes, because it is teratogenic.
- Mycophenolate mofetil and delayed-release mycophenolic acid tablets are not interchangeable without specialist supervision.
Nursing care
- Confirm a negative pregnancy test and effective contraception before the first dose in women who could become pregnant.
- Teach that men also use contraception with their partners during treatment and for some months after.
- Ask about diarrhoea and abdominal pain; report black stools or vomiting blood.
- Teach the signs of infection.
- Separate antacids from doses and report new medicines.
Pregnancy and breastfeeding
Contraindicated unless no safer option exists: it causes first-trimester pregnancy loss and multiple congenital malformations.
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme does mycophenolic acid inhibit?
Inosine monophosphate dehydrogenase (IMPDH), in the de novo pathway of guanine nucleotide synthesis.
What must be confirmed before a woman of reproductive age starts mycophenolate?
A negative pregnancy test and effective contraception, because it causes pregnancy loss and major malformations.
Why can an antacid with magnesium hydroxide make mycophenolate less effective?
It lowers the absorption of mycophenolate, so mycophenolic acid exposure falls.
Related drugs
Related conditions
← Back to the class: Antiproliferative immunosuppressants
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Mycophenolate: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2024); DailyMed - MYCOPHENOLATE MOFETIL tablet (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Crystal structure of Inosine Monophosphate Dehydrogenase in complex with Mycophenolic Acid (RCSB Protein Data Bank, 2001).
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Representative model, for educational purposes only.