MESNEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MESNEX (MESNEX).
Mesna acts as a chemoprotectant by binding to and inactivating acrolein and other urotoxic metabolites of oxazaphosphorine alkylating agents (e.g., cyclophosphamide, ifosfamide) in the urinary tract. It is rapidly oxidized to dimesna (disulfide form) in plasma, which is then reduced back to mesna in the kidneys, allowing local detoxification in the bladder.
| Metabolism | Mesna is rapidly oxidized in plasma to its major metabolite, dimesna (disulfide form). Dimesna is then reduced back to mesna in the renal tubular epithelium. A minor metabolic pathway involves conjugation with glutathione. It is primarily eliminated renally as dimesna and unchanged mesna. |
| Excretion | Primarily renal, 60-80% as unchanged drug and 20-30% as dimesna; less than 5% fecal. Half-life 0.36 hours for mesna, 1.17 hours for dimesna. |
| Half-life | 0.36 hours for mesna, 1.17 hours for dimesna; clinical context: short half-life requires frequent dosing (e.g., 0, 4, 8 hours after ifosfamide). |
| Protein binding | Negligible (<10% bound to plasma proteins). |
| Volume of Distribution | 0.34 L/kg; distributes rapidly into extracellular fluid; does not penetrate cells due to hydrophilic nature. |
| Bioavailability | Oral: 45-79% (mean 50%); IV: 100%. |
| Onset of Action | IV: immediate; oral: 30-60 minutes. |
| Duration of Action | IV: 4-6 hours (requires repeat dosing every 4 hours); oral: 2-4 hours. |
IV: 240 mg/m² (or 20% of ifosfamide dose) administered at 0, 4, and 8 hours after ifosfamide; or continuous IV infusion: 600 mg/m² (or 100% of ifosfamide dose) over 24 hours. Oral: 400 mg (or 40% of ifosfamide dose) given at 0, 2, and 6 hours after ifosfamide.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min. For GFR <30 mL/min, consider reducing dose by 50% or increasing dosing interval to every 6-8 hours; use with caution. |
| Liver impairment | No specific dose adjustments recommended for Child-Pugh A or B. For Child-Pugh C, use with caution; no established guidelines. |
| Pediatric use | IV: 240 mg/m² (or 20% of ifosfamide dose) at 0, 4, and 8 hours after ifosfamide; or continuous infusion: 600 mg/m² (or 100% of ifosfamide dose) over 24 hours. Oral: 400 mg/m² (or 40% of ifosfamide dose) at 0, 2, and 6 hours after ifosfamide. |
| Geriatric use | No specific dose adjustments; use standard adult dosing with monitoring for renal function and fluid status. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MESNEX (MESNEX).
| Breastfeeding | It is unknown whether mesna is excreted in human breast milk. The M/P ratio has not been determined. Due to its short half-life and low systemic exposure, risk to nursing infant is likely low, but caution is advised. |
| Teratogenic Risk | Mesna is not expected to increase the risk of congenital anomalies based on limited human data and lack of teratogenicity in animal studies. No specific fetal risks have been identified across trimesters. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Known hypersensitivity to mesna or any of its components."]
| Precautions | ["Hypersensitivity reactions (including anaphylaxis) have been reported, especially in patients with autoimmune disorders.","False-positive urinary ketone tests (e.g., dipstick) may occur due to the presence of mesna metabolites.","Mesna does not prevent other toxicities of oxazaphosphorines (e.g., nephrotoxicity, neurotoxicity, myelosuppression)."] |
Loading safety data…
| No specific fetal monitoring is required. Standard obstetric monitoring is recommended. Maternal monitoring for hypersensitivity reactions and renal function should be continued. |
| Fertility Effects | No data available on effects of mesna on human fertility. Animal studies did not indicate impairment of fertility. |