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Uroprotectant Pregnancy: §8.1, verbatim: 'MESNEX is used in combination with ifosfamide or other cytotoxic agents. Ifosfamide can cause fetal harm when administered to a pregnant woman. Refer to the ifosfamide prescribing information for more information on use during pregnancy. MESNEX injection contains the preservative benzyl alcohol. Because benzyl alcohol is rapidly metabolized by a pregnant woman, benzyl alcohol exposure in the fetus is unlikely.' Animal data: 'oral administration of mesna to pregnant rats (500, 1000, 1500, and 2000 mg/kg) and rabbits (500 and 1000 mg/kg) during the period of organogenesis revealed no adverse developmental outcomes at doses approximately 10 times…' (sentence truncated at the source-fetch limit). This summary may be incomplete — check the full SPC.

Mesna

Brand names: Uromitexan

Mesna is a uroprotective agent given alongside the oxazaphosphorine cytotoxics ifosfamide and cyclophosphamide to prevent haemorrhagic cystitis.

Adult dose

Dose: SCOPE: uroprotection during IFOSFAMIDE therapy only. That is this page's primary indication (prevention of haemorrhagic cystitis) and the only regimen this label doses — ⚠ it contains NO cyclophosphamide regimen, although this page's existing entry names cyclophosphamide too, so nothing below may be applied to a cyclophosphamide protocol without a separate source. Mesna is dosed as a PERCENTAGE OF THE IFOSFAMIDE DOSE, and the two schedules below are alternatives that must not be mixed. (A) ALL-INTRAVENOUS SCHEDULE — mesna INTRAVENOUS bolus equal to 20% of the ifosfamide dosage weight-for-weight, given at the time of ifosfamide administration and again 4 hours and 8 hours after each ifosfamide dose; total daily mesna = 60% of the ifosfamide dose. Label's worked example, for ifosfamide 1.2 g/m2: mesna injection 240 mg/m2 INTRAVENOUSLY at 0 h, 4 h and 8 h. (B) INTRAVENOUS-THEN-ORAL SCHEDULE — mesna INTRAVENOUS bolus equal to 20% of the ifosfamide dose at 0 h, then mesna TABLETS BY MOUTH equal to 40% of the ifosfamide dose at 2 hours and at 6 hours after each ifosfamide dose; total daily mesna = 100% of the ifosfamide dose. Label's worked example, for ifosfamide 1.2 g/m2: 240 mg/m2 INTRAVENOUSLY at 0 h, then 480 mg/m2 ORALLY at 2 h and 480 mg/m2 ORALLY at 6 h. ⚠ THE 480 mg/m2 FIGURE IS AN ORAL-TABLET DOSE AND BELONGS ONLY TO SCHEDULE (B) — it is twice the intravenous per-dose figure and must never be given intravenously or on schedule (A)'s 0/4/8 h timing. Both schedules: 'The dosing schedule should be repeated on each day that ifosfamide is administered. When the dosage of ifosfamide is increased or decreased, the ratio of MESNEX to ifosfamide should be maintained.'
Route: TWO ROUTES, SCHEDULE-SPECIFIC: (A) intravenous bolus injection at 0, 4 and 8 h; or (B) intravenous bolus at 0 h followed by ORAL tablets at 2 h and 6 h. The per-dose percentages differ by route — 20% of the ifosfamide dose intravenously, 40% orally — so a figure may never be moved between routes. For infusion preparation (§2.4): dilute the injection in a listed compatible fluid 'to obtain a final concentration of 20 mg/mL'.
Frequency: Schedule (A): 0, 4 and 8 hours after each ifosfamide dose (all intravenous). Schedule (B): 0 hours intravenous, then 2 and 6 hours oral. 'The dosing schedule should be repeated on each day that ifosfamide is administered.'
This re-draft fixes that by naming the route beside every number, in both the dose and route fields, and by flagging the 480 mg/m2 figure explicitly as oral-only. || NO MAXIMUM DOSE IS STATED anywhere in this label — mesna is dosed as a fixed ratio to ifosfamide, so maxDose is deliberately empty. ⚠ Do NOT read the following sentence as a mesna ceiling (it is an eligibility limit on the IFOSFAMIDE dose for schedule B): 'The efficacy and safety of this ratio of intravenous and oral MESNEX has not been established as being effective for daily doses of ifosfamide higher than 2 g/m2.' || VERBATIM SOURCE WORDING (§2.1): 'MESNEX injection is given as intravenous bolus injections in a dosage equal to 20% of the ifosfamide dosage weight by weight (w/w) at the time of ifosfamide administration and 4 and 8 hours after each dose of ifosfamide. The total daily dose of MESNEX is 60% of the ifosfamide dose.' (§2.2): 'MESNEX injection is given as intravenous bolus injections in a dosage equal to 20% of the ifosfamide dosage (w/w) at the time of ifosfamide administration. MESNEX tablets are given orally in a dosage equal to 40% of the ifosfamide dose 2 and 6 hours after each dose of ifosfamide. The total daily dose of MESNEX is 100% of the ifosfamide dose.' The 240 mg/m2 and 480 mg/m2 values are the label's tabulated example against ifosfamide 1.2 g/m2 — they are NOT fixed doses; recalculate from the actual ifosfamide dose. || VOMITING (§2.2): 'Patients who vomit within two hours of taking oral MESNEX should repeat the dose or receive intravenous MESNEX.' || HYDRATION (§2.3): 'Maintain adequate hydration and sufficient urinary output, as required for ifosfamide treatment, and monitor urine for the presence of hematuria. If severe hematuria develops when MESNEX is given according to the recommended dosage schedule, dosage reductions or discontinuation of ifosfamide therapy may be required.' || PREPARATION/COMPATIBILITY (§2.4): dilute to a final concentration of 20 mg/mL in 5% dextrose, 5% dextrose with 0.2%/0.33%/0.45% sodium chloride, 0.9% sodium chloride or lactated Ringer's; 'Do not mix MESNEX injection with epirubicin, cyclophosphamide, cisplatin, carboplatin, and nitrogen mustard'; 'Ifosfamide and MESNEX may be mixed in the same bag provided the final concentration of ifosfamide does not exceed 50 mg/mL'; multidose vials 'may be stored and used for up to 8 days after initial puncture'; use diluted solutions within 24 hours. || ELDERLY (§8.5): 'In general, dose selection for an elderly patient should be cautious… The ratio of ifosfamide to MESNEX should remain unchanged.' || NEONATES (§5.3/§8.4): 'MESNEX injection contains the preservative benzyl alcohol which has been associated with serious adverse reactions and death when administered intravenously to premature neonates and low birth weight infants. Avoid use of MESNEX injection in premature neonates and low-birth weight infants.' || US labelling only — confirm against the UK SPC (Uromitexan) before UK use.

Dose adjustments

Renal

Not stated — no renal-impairment dosage adjustment appears in any fetched section of this label. Mesna is dosed as a fixed ratio to ifosfamide and §8.5 states 'The ratio of ifosfamide to MESNEX should remain unchanged' even where 'decreased hepatic, renal, or cardiac function' is more frequent (elderly). Acute renal impairment is listed in §5.1 as a feature of systemic hypersensitivity to mesna. Verify against the UK SPC.

Hepatic

Not stated — no hepatic-impairment dosage adjustment appears in any fetched section of this label; §8.5 (elderly) again directs that 'The ratio of ifosfamide to MESNEX should remain unchanged'. Increased liver enzymes are listed in §5.1 as a feature of systemic hypersensitivity to mesna. Verify against the UK SPC.

Dose independently re-sourced from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Known hypersensitivity to mesna or to any of the excipients, including benzyl alcohol — §4, verbatim: 'MESNEX is contraindicated in patients known to be hypersensitive to mesna or to any of the excipients.' This is the only contraindication in the label.
  • Not a contraindication but an explicit avoidance (§5.3 / §8.4): 'MESNEX injection contains the preservative benzyl alcohol which has been associated with serious adverse reactions and death when administered intravenously to premature neonates and low birth weight infants. Avoid use of MESNEX injection in premature neonates and low-birth weight infants.'

Side effects

  • Most common (§6, >10%, when given with ifosfamide), verbatim: 'nausea, vomiting, constipation, leukopenia, fatigue, fever, anorexia, thrombocytopenia, anemia, granulocytopenia, diarrhea, asthenia, abdominal pain, headache, alopecia, and somnolence.' Note these are reactions of the ifosfamide-containing regimen as a whole.
  • Hypersensitivity (§5.1), verbatim: 'MESNEX may cause systemic hypersensitivity reactions, including anaphylaxis. These reactions may include fever, cardiovascular symptoms (hypotension, tachycardia), acute renal impairment, hypoxia, respiratory distress, urticaria, angioedema, laboratory signs of disseminated intravascular coagulation, hematological abnormalities, increased liver enzymes, nausea, vomiting, arthralgia, and myalgia.'
  • Dermatologic toxicity (§5.2), verbatim: 'Skin rash with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, and toxic epidermal necrolysis have occurred. Skin rash, urticaria, and angioedema have also been seen.'
  • Benzyl alcohol toxicity (§5.3): 'Serious and fatal adverse reactions can occur in premature neonates and low-birth weight infants treated with benzyl alcohol-preserved drugs, including MESNEX injection.'
  • Laboratory interference (§5.4): 'False positive tests for urinary ketones and interference with enzymatic CPK activity tests have been seen.'
  • The §6 clinical-trials narrative was cut off at the source-fetch limit, so this list is not exhaustive.

Monitoring

  • Haematuria and urine output (§2.3), verbatim: 'Maintain adequate hydration and sufficient urinary output, as required for ifosfamide treatment, and monitor urine for the presence of hematuria.'
  • Action on severe haematuria (§2.3), verbatim: 'If severe hematuria develops when MESNEX is given according to the recommended dosage schedule, dosage reductions or discontinuation of ifosfamide therapy may be required.'
  • Hypersensitivity (§5.1): 'Monitor patients. If a reaction occurs, discontinue MESNEX and provide supportive care.'
  • Skin (§5.2): 'Monitor patients. If a reaction occurs, discontinue MESNEX and provide supportive care.'
  • Interpret urinary ketones and enzymatic CPK results with caution (§5.4) — false positive urinary ketones and CPK assay interference are documented.
  • Vomiting after an oral dose (§2.2): 'Patients who vomit within two hours of taking oral MESNEX should repeat the dose or receive intravenous MESNEX.'
  • No drug-level or routine laboratory monitoring of mesna itself is specified; §7 states 'No clinical drug interaction studies have been conducted with MESNEX.'

Clinical monograph

How it works

In the urinary tract its free thiol group binds and detoxifies acrolein and other urotoxic metabolites of these alkylating agents, preventing damage to the bladder urothelium.

Prescribing in practice

  • It protects only the urinary tract and provides no protection against systemic chemotherapy toxicity, so it must accompany rather than replace standard supportive care.
  • Hypersensitivity reactions, including skin and mucosal reactions, have been reported and may be more frequent in patients with autoimmune disorders.
  • Dosing is scheduled in relation to the cytotoxic agent and may be given by injection or by mouth as set out in the SPC.

Monitoring

Monitor for haematuria and other signs of bladder toxicity throughout the chemotherapy course.

Counselling the patient

  • This medicine protects your bladder from side effects of your chemotherapy.
  • Report blood in the urine or any rash or mouth soreness promptly.
  • Maintaining a good fluid intake helps protect the bladder.

Evidence & guidelines

Co-administration of mesna with ifosfamide and high-dose cyclophosphamide to prevent haemorrhagic cystitis is standard, evidence-based oncology practice.

Reference: SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways