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# 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

- Class: [Antiproliferative immunosuppressants](https://durgical.com/en/pharmacology/classes/antiproliferative-immunosuppressants/)
- Enzyme: Inosine monophosphate dehydrogenase (IMPDH)
- ATC code: L04AA06

✂**Inosine monophosphate dehydrogenase (IMPDH)**Mycophenolate mofetil

ⓘ 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.

**Target in 3D:** Inosine monophosphate dehydrogenase (IMPDH). PDB structure 1JR1 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1JR1) · Drag to rotate · pinch to zoom

## 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 →](https://durgical.com/en/conditions/crohn-disease/)

## Adverse effects

### Common

- Diarrhoea
- Nausea and vomiting
- Abdominal pain
- Leukopenia
- Infections

### Serious (rare, important)

- First-trimester pregnancy loss and congenital malformations
- Lymphoma and skin cancer
- Serious and opportunistic infections, including progressive multifocal leukoencephalopathy
- Severe neutropenia and pure red cell aplasia
- Gastrointestinal bleeding or perforation

## 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.

## Memory aid

MycoPHENOlate gives lymphocytes no guaNINE: IMPDH blocked, DNA stalled. And in pregnancy: NEVER.

## 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.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/mycophenolate-mofetil/)

## Related drugs

- [Azathioprine](https://durgical.com/en/pharmacology/azathioprine/)
- [Tacrolimus](https://durgical.com/en/pharmacology/tacrolimus/)
- [Ciclosporin](https://durgical.com/en/pharmacology/ciclosporin/)

## Related conditions

- [Crohn disease](https://durgical.com/en/conditions/crohn-disease/)

[← Back to the class: Antiproliferative immunosuppressants](https://durgical.com/en/pharmacology/classes/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](https://medlineplus.gov/druginfo/meds/a601081.html) (MedlinePlus (U.S. National Library of Medicine), 2024); [DailyMed - MYCOPHENOLATE MOFETIL tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0f1704e2-a66a-4be5-8127-ebb5947c7b64) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L04AA06) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [Crystal structure of Inosine Monophosphate Dehydrogenase in complex with Mycophenolic Acid](https://www.rcsb.org/structure/1JR1) (RCSB Protein Data Bank, 2001).

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Representative model, for educational purposes only.

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