Mesna Drug Information

Mesna Injection is indicated as a prophylactic agent in reducing the incidence of ifosfamide-induced hemorrhagic cystitis. Limitation of Use: Mesna Injection is not indicated to reduce the risk of hematuria due to other pathological conditions such as thrombocytopenia.

Intravenous Dosing

Mesna injection may be given on a fractionated dosing schedule of three bolus intravenous injections as outlined below. Mesna 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 mesna injection is 60% of the ifosfamide dose.

The recommended dosing schedule is outlined below in Table 1. Table 1. Recommended Intravenous Dosing Schedule may be given on a fractionated dosing schedule of a single bolus injection followed by two oral administrations of mesna tablets as outlined below.

Mesna 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 mesna is 100% of the ifosfamide dose. The recommended dosing schedule is outlined in Table 2.

Table 2. Recommended Intravenous and Oral Dosing Schedule The efficacy and safety of this ratio of intravenous and oral mesna has not been established as being effective for daily doses of ifosfamide higher than 2 g/m 2. Patients who vomit within two hours of taking oral mesna should repeat the dose or receive intravenous mesna injection.

Monitoring for Hematuria

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 mesna injection is given according to the recommended dosage schedule, dosage reductions or discontinuation of ifosfamide therapy may be required.

Preparation for Intravenous Administration and Stability Preparation Determine the volume of mesna injection for the intended dose. Store diluted solutions at 25°C (77°F). Use diluted solutions within 24 hours.

Do not mix mesna injection with epirubicin, cyclophosphamide, cisplatin, carboplatin, and nitrogen mustard. The benzyl alcohol contained in mesna injection vials can reduce the stability of ifosfamide. Ifosfamide and mesna injection may be mixed in the same bag provided the final concentration of ifosfamide does not exceed 50 mg per mL.

Higher concentrations of ifosfamide may not be compatible with mesna injection and may reduce the stability of ifosfamide. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. Any solutions which are discolored, hazy, or contain visible particulate matter should not be used.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Mesna adverse reaction data are available from four Phase 1 studies in which single intravenous doses of 600 to 1200 mg mesna injection without concurrent chemotherapy were administered to a total of 53 healthy volunteers. The most frequently reported side effects (observed in two or more healthy volunteers) for healthy volunteers receiving single doses of mesna injection alone were headache, injection site reactions, flushing, dizziness, nausea, vomiting, somnolence, diarrhea, anorexia, fever, pharyngitis, hyperesthesia, influenza-like symptoms, and coughing.

In two Phase 1 multiple-dose studies where healthy volunteers received mesna tablets alone or intravenous mesna followed by repeated doses of mesna tablets, flatulence and rhinitis were reported. In addition, constipation was reported by healthy volunteers who had received repeated doses of intravenous mesna. Additional adverse reactions in healthy volunteers receiving mesna alone included injection site reactions, abdominal pain/colic, epigastric pain/burning, mucosal irritation, lightheadedness, back pain, arthralgia, myalgia, conjunctivitis, nasal congestion, rigors, paresthesia, photophobia, fatigue, lymphadenopathy, extremity pain, malaise, chest pain, dysuria, pleuritic pain, dry mouth, dyspnea, and hyperhidrosis.

In healthy volunteers, mesna was commonly associated with a rapid (within 24 hours) decrease in lymphocyte count, which was generally reversible within one week of administration. Because mesna is used in combination with ifosfamide or ifosfamide-containing chemotherapy regimens, it is difficult to distinguish the adverse reactions which may be due to mesna from those caused by the concomitantly administered cytotoxic agents. Adverse reactions reasonably associated with mesna administered intravenously and orally in four controlled studies in which patients received ifosfamide or ifosfamide-containing regimens are presented in Table 3.

Table 3: Adverse Reactions in ≥5% of Patients Receiving Mesna in combination with Ifosfamide-containing Regimens 1 Intravenous dosing of ifosfamide and mesna followed by either intravenous or oral doses of mesna according to the applicable dosage schedule. 1 6

Postmarketing Experience

The following adverse reactions have been reported in the postmarketing experience of patients receiving mesna in combination with ifosfamide or similar drugs, making it difficult to distinguish the adverse reactions which may be due to mesna from those caused by the concomitantly administered cytotoxic agents. Because these reactions are reported from a population of unknown size, precise estimates of frequency cannot be made. Cardiovascular: Hypertension Gastrointestinal: Dysgeusia Hepatobiliary: Hepatitis Nervous System: Convulsion Respiratory: Hemoptysis

No clinical drug interaction studies have been conducted with mesna.

Pregnancy Risk Summary Mesna 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.

Mesna injection contains the preservative benzyl alcohol. Because benzyl alcohol is rapidly metabolized by a pregnant woman, benzyl alcohol exposure in the fetus is unlikely. The estimated background risk of major birth defects and miscarriage for the indicated populations are unknown.

All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is respectively. Data Animal Data Mesna is used in combination with ifosfamide or other cytotoxic agents.

Ifosfamide can cause fetal harm including embryo-fetal lethality. In embryo-fetal development studies, oral administration of mesna to pregnant rats mg/kg and rabbits (500 and 1,000 mg/kg) during the period of organogenesis revealed no adverse developmental outcomes at doses approximately 10 times the maximum recommended total daily human equivalent dose based on body surface area.

Pediatric Use Mesna 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 mesna injection in premature neonates and low-birth weight infants.

Mesna is contraindicated in patients known to be hypersensitive to mesna or to any of the excipients. Known hypersensitivity to mesna or to any of the excipients in mesna, including benzyl alcohol.

There is no known antidote for mesna. Patients also received ifosfamide or cyclophosphamide. Adverse reactions included nausea, vomiting, diarrhea and fever.

An increased rate of these adverse reactions has also been found in oxazaphosphorine-treated patients receiving ≥80 mg mesna per kg per day intravenously compared with patients receiving lower doses or hydration treatment only. Postmarketing, administration of 4.5 grams to 6.9 grams of mesna resulted in hypersensitivity reactions including mild hypotension, shortness of breath, asthma exacerbation, rash, and flushing.