mesna
Mesnex

Available forms
Available by prescription only
Injection: 100 mg/ml in 2- and 10-ml vials
Tablets: 400 mg

Indications and dosages
 Prevention of ifosfamide-induced hemorrhagic cystitis. Adults: Calculate daily dose as 60% of the ifosfamide dose. Administer in three equally divided bolus doses: Give first dose at time of ifosfamide injection. Subsequent doses are given at 4 and 8 hours following ifosfamide. Or, administer in four divided doses just before ifosfamide dose and then at 4, 8, and 12 hours after ifosfamide. Or, administer at time of ifosfamide dose and then at 3, 6, and 9 hours after ifosfamide dose.
 Protocols that use 1.2 g/m² ifosfamide would employ 240 mg/m² mesna at 0, 4, and 8 hours after ifosfamide.
 Alternatively, calculate daily dose as 100% of the ifosfamide dose. Administer as a single bolus injection (20%) followed by two oral administrations (40% each). Protocols that use 1.2 g/m² ifosfamide would employ 240 mg/m² I.V. mesna at 0 hours, then 480 mg/m² P.O. at 2 and 6 hours.
 Continuous mesna I.V. infusion is given at 100% ifosfamide dosage and may be mixed in the same I.V. solution. Continue regimen as long as ifosfamide is given; it may have to continue for additional 8 to 24 hours as a result of shorter mesna half-life.
 Prophylaxis in bone marrow recipients receiving cyclophosphamides ◇. Adults: 60% to 160% of the cyclophosphamide daily dose given in three to five divided doses or by continuous infusion. Or, in patients receiving cyclophosphamide, 50 to 60 mg/kg I.V. daily for 2 to 4 days; give 10 mg/kg I.V. loading dose of mesna followed by 60 mg/kg by way of continuous I.V. infusion over 24 hours. Give mesna regimen with each cyclophosphamide dose and continue for an additional 24 hours.

Pharmacodynamics
Uroprotectant action: Mesna disulfide is reduced to mesna in the kidney and reacts with the urotoxic metabolites of ifosfamide to detoxify the drug and protect the urinary system.

Pharmacokinetics
Absorption: Administered I.V.
Distribution: Remains in the vascular compartment; doesn’t distribute through tissues.
Metabolism: Rapidly metabolized to mesna disulfide, its only metabolite.
Excretion: In the kidneys, 33% of the dose is eliminated in the urine in 24 hours; half-life of mesna and mesna disulfide are 1/2 and 1 1/2 hours, respectively.

Contraindications and precautions
Contraindicated in patients hypersensitive to mesna or thiol-containing compounds.

Interactions
None reported.

Adverse reactions
CNS: fatigue, fever, asthenia, dizziness, headache, somnolence, anxiety, confusion, insomnia, pain.
CV: chest pain, edema, hypotension, tachycardia, flushing.
GI: nausea,vomiting, diarrhea, constipation, anorexia, abdominal pain, dyspepsia.
GU: hematuria.
Hematologic: leukopenia, thrombocytopenia, anemia, granulocytopenia.
Metabolic: hypokalemia, dehydration.
Musculoskeletal: back pain.
Respiratory: dyspnea, coughing, pneumonia.
Skin: alopecia, increased sweating, injection site reaction, pallor.
Other: hypersensitivity reactions.

Effects on lab test results
None reported.

Overdose and treatment
No information available. No antidote known.

Special considerations
• Because mesna is used with ifosfamide and other chemotherapeutic drugs, it’s difficult to determine adverse reactions attributable solely to mesna.
• The parent form of the drug has been administered orally by preparing extemporaneous oral solutions by mixing injection with flavored syrup to produce a concentration of 20 to 50 mg/ml. Solutions are stable for 7 days at 75° F (24° C). If carbonated beverage, apple juice, or orange juice is used, solution is stable for at least 24 hours at 41° F (5° C).
• Patients receiving mesna for ifosfamide-induced hemorrhagic cystitis should be adequately hydrated (2 L of oral or I.V. fluid before and during ifosfamide therapy).
• Multidose vials may be stored and used for up to 8 days.
• Discard unused mesna from open ampules. It will form an inactive oxidation product (dimesna) upon exposure to oxygen.
• Dilute appropriate dose in D₅W injection, normal saline solution injection, or lactated Ringer’s injection to a level of 20 mg/ml. Once diluted, solution is stable for 24 hours at room temperature. However, the manufacturer recommends refrigerating the solution and using within 6 hours (contains no preservatives).
• Infuse I.V. solution over 15 to 30 minutes.
• Mesna is physically incompatible with cisplatin and carboplatin. Don’t add mesna to cisplatin infusions.
• Patients who vomit 2 hours or less after taking P.O. mesna should repeat the dose or receive I.V. mesna.
• Drug may cause falsely elevated serum glucose and uric acid values when sequential multiple analyzer is used.
• Monitor morning urine specimen for erythrocytes, which may precede hemorrhagic cystitis.
• Store drug at 59° to 86° F (15° to 30° C); expires 5 years from date of manufacture.
Breast-feeding patients
• It isn’t known if mesna appears in breast milk.
Pediatric patients
• Safety in children hasn’t been established. However, drug has been used for prophylaxis of ifosfamide-induced hemorrhagic cystitis in infants and children ages 4 to 16 and for prophylaxis of cyclophosphamide-induced hemorrhagic cystitis in children age 5 months and older.
• Multidose vials contain benzyl alcohol.

Patient education
• Instruct patient to report hematuria or allergy immediately.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use