Pharmacology · Chemotherapy supportive agents
Mesna !
A thiol drug that binds acrolein in the urine and protects the bladder from haemorrhagic cystitis caused by ifosfamide.
Updated 2026-11-01
Also called: sodium 2-mercaptoethanesulfonate
Mechanism of action
Ifosfamide (and cyclophosphamide) release acrolein and 4-hydroxy metabolites that reach the bladder and damage its lining. Mesna is a thiol (SH) compound: in the urine it binds 4-hydroxy-ifosfamide and the double bonds of acrolein, forming harmless products. In the blood it is quickly oxidised to dimesna, and both forms are excreted in the urine.
- Ifosfamide releases acrolein into the urine
- Mesna's thiol group binds acrolein in the bladder
- Harmless products: no haemorrhagic cystitis
Pharmacokinetics
- Absorption
- Intravenous or oral; food does not change the amount reaching the urine.
- Distribution
- Total body water.
- Metabolism
- Rapidly oxidised to dimesna (mesna disulfide).
- Elimination
- In the urine as mesna and dimesna.
- Half-life
- Very short (well under an hour for mesna), so doses are repeated to cover the whole ifosfamide exposure.
Indications
- Prevention of ifosfamide-induced haemorrhagic cystitis.
- Also used to protect the bladder in high-dose cyclophosphamide regimens.
Adverse effects
Common
- Nausea, vomiting, abdominal pain, diarrhoea or constipation (with ifosfamide)
- Headache, fatigue, drowsiness
- Skin and mucosal reactions: rash, itching, flushing
Contraindications
- Hypersensitivity to mesna or any excipient, including benzyl alcohol
Key interactions
- Urine ketone dipstick tests (nitroprusside)
- False-positive results.
- Enzymatic CPK tests that use a thiol reagent
- Falsely low CPK values.
- Ifosfamide in the same bag
- Higher ifosfamide concentrations, or the benzyl alcohol in mesna vials, can reduce ifosfamide stability.
What is monitored
- Urine for blood (microscopic haematuria) before each ifosfamide dose
- Skin reactions and signs of hypersensitivity
Administration and safety
- Given on a fixed schedule with each ifosfamide dose (at the start and repeated afterwards) because its effect is short.
- If an oral dose is vomited soon after it is taken, it is repeated or replaced by an intravenous dose.
- Multi-dose vials contain benzyl alcohol, which is toxic to premature and low-birth-weight infants.
Nursing care
- Check the timing of every mesna dose against the ifosfamide schedule; a missed dose leaves the bladder unprotected.
- Test a urine sample for blood before each ifosfamide dose and report any red or pink urine.
- Encourage fluids and frequent voiding unless restricted.
- Teaching: report blood in the urine, rash or mouth sores; tell the laboratory about mesna before urine tests.
Pregnancy and breastfeeding
Mesna is always given with ifosfamide or other cytotoxics, which can cause fetal harm.
Test yourself
Think of the answer, then tap the question to see it.
Which metabolite causes haemorrhagic cystitis with ifosfamide and cyclophosphamide?
Acrolein (with 4-hydroxy metabolites), excreted in the urine.
Where does mesna act, and what does it bind?
In the urine and bladder: its thiol group binds acrolein and 4-hydroxy-ifosfamide, forming harmless products.
Why must mesna doses be repeated during ifosfamide treatment?
Mesna has a very short half-life, while ifosfamide metabolites keep reaching the bladder for hours.
Which urine test can be falsely positive in a patient on mesna?
The nitroprusside (dipstick) test for urinary ketones.
Related drugs
← Back to the class: Chemotherapy supportive agents
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - MESNA injection, solution (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 70 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.