Allergic reactions to mesna ranging from mild hypersensitivity to systemic anaphylactic reactions have been reported. Patients with autoimmune disorders who were treated with cyclophosphamide and mesna appeared to have a higher incidence of allergic reactions. The majority of these patients received mesna orally.

Mesnex (mesna) has been developed as an agent to reduce the risk of ifosfamide induced hemorrhagic cystitis. It will not prevent or alleviate any of the other adverse reactions or toxicities associated with ifosfamide therapy.

Mesnex (mesna) does not prevent hemorrhagic cystitis in all patients. Up to 6% of patients treated with mesna have developed hematuria (>50 RBC/hpf or WHO grade 2 and above). As a result, a morning specimen of urine should be examined for the presence of hematuria (microscopic evidence of red blood cells) each day prior to ifosfamide therapy. If hematuria develops when Mesnex (mesna) is given with ifosfamide according to the recommended dosage schedule, depending on the severity of the hematuria, dosage reductions or discontinuation of ifosfamide therapy may be initiated.

In order to reduce the risk of hematuria, Mesnex (mesna) must be administered with each dose of ifosfamide as outlined in the DOSAGE AND ADMINISTRATION section. Mesnex (mesna) is not effective in reducing the risk of hematuria due to other pathological conditions such as thrombocytopenia.

Because of the benzyl alcohol content, the multidose vial should not be used in neonates or infants and should be used with caution in older pediatric patients.

Information for Patients

Healthcare providers should advise patients taking Mesnex (mesna) to drink at least a quart of liquid a day. Patients should be informed to report if their urine has turned a pink or red color, if they vomit within 2 hours of taking oral Mesnex (mesna) , or if they miss a dose of oral Mesnex. See PATIENT INFORMATION Leaflet for Mesnex (mesna) Tablets.

Laboratory Tests

A false positive test for urinary ketones may arise in patients treated with Mesnex (mesna) . In this test, a red-violet color develops which, with the addition of glacial acetic acid, will return to violet.

Carcinogenesis, Mutagenesis, and Impairment of Fertility Carcinogenesis

No long-term studies in animals have been performed to evaluate the carcinogenic potential of Mesnex.

Mutagenesis

Mesna was not genotoxic in the in vitro Ames bacterial mutagenicity assay, the in vitro mammalian lymphocyte chro-mosomal aberration assay or the in vivo mouse micronucleus assay.

Impairment of Fertility

No studies on male or female fertility were conducted. No signs of male or female reproductive organ toxicity were seen in 6-month oral rat studies (at doses up to 2000 mg/kg/day) or 29-week oral dog studies (520 mg/kg/day; both studies approximately 10-fold higher than the maximum recommended human dose on a body surface area basis).

Pregnancy

Pregnancy Category B.Reproduction studies have been performed in rats and rabbits at oral doses of 1000 mg/kg in rabbits and 2000 mg/kg in rats (approximately 10 times the maximum recommended total daily IV-oral-oral human dose on a body surface area basis) and have revealed no evidence of harm to the fetus due to mesna. There are how-ever, no adequate and well-controlled studies in pregnant women. Because animal reproductive studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Nursing Mothers

It is not known whether mesna or dimesna is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for adverse reactions in nursing infants from mesna, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

Safety and effectiveness of Mesnex (mesna) Tablets in pediatric patients have not been established.

Because of the benzyl alcohol content in Mesnex (mesna) Injection, the multidose vial should not be used in neonates or infants and should be used with caution in older pediatric patients.

Geriatric Use

Clinical studies of mesna did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. However, the ratio of ifosfamide to mesna should remain unchanged.

Last reviewed on RxList: 10/8/2008
This monograph has been modified to include the generic and brand name in many instances.