Urosaph

Each ampoule contains: Mesna, BP 400 mg, Disodium Edetate, BP 1 mg.
Clear colorless solution.

Antineoplastic.
Pharmacology: Pharmacodynamics: Mesna is an antidote that can reliably prevent urotoxic side effects associated with aggressive cancer chemotherapy using oxazaphosphorine cytostatics. Extensive and wide-ranging pharmacological and toxicological investigations have shown that mesna has no intrinsic pharmacodynamics and low toxicity. The pharmacological and toxicological inertness of mesna administered systemically and its excellent detoxifying effect in the efferent urinary tract and bladder, are due to the nature of its pharmacokinetics.
Pharmacokinetics: Mesna, a free thiol, is easily and rapidly transformed by auto-oxidation into its only metabolite mesna-disulfide (dimesna). Dimesna remains in the intravascular compartment and is quickly transported to the kidneys.
In the epithelium of renal tubule, dimesna is again reduced to the free thiol compound, which is then able to react chemically in the urine with toxic oxazaphosphorine metabolites.
Elimination (being almost exclusively renal) starts immediately after administration. Excretion is as the free thiol (mesna) in the first 4 hours after a single dose, and almost exclusively as the disulfide (dimesna) thereafter. Renal elimination is almost complete after approximately 8 hours.
Approximately 30% of an intravenous dose is bioavailable as free thiol (mesna) in the urine.

For the prevention of urothelial toxicity including hemorrhagic cystitis, microhematuria, and macrohematuria in patients treated with ifosfamide and cyclophosphamide, in doses considered to be urotoxic.

Sufficient mesna must be given to adequately protect the patient from the urotoxic effects of oxazaphosphorine.
The duration of mesna treatment should equal that of the oxazaphosphorine treatment plus the time taken for the urinary concentration of oxazaphosphorine metabolites to fall to non-toxic levels. This usually occurs within 8-12 hours after the end of oxazaphosphorine treatment but may vary depending on the scheduling of oxazaphosphorine. Urinary output should be maintained at 100 mL/hr (as required for oxazaphosphorine treatment) and the urine monitored for hematuria and proteinuria throughout the treatment period.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration.
Any solutions which are discolored, hazy, or contain visible particulate matter should not be used.
Where ifosfamide or cyclophosphamide is used as an I.V. bolus: Mesna is given by intravenous injection over 15-30 minutes at 20% of the simultaneously administered oxazaphosphorine on a weight per weight basis (w/w). The same dose of mesna is repeated after 4 and 8 hours. The total dose of mesna is 60% (w/w) of the oxazaphosphorine dose. This is repeated on each occasion that the cytotoxic agents are used.
Example of dosage schedule: see Table 1.

Click on icon to see table/diagram/image

If necessary, the dose of mesna can be increased to 40% of the oxazaphosphorine dose given four times at three hourly intervals (0, 3, 6 and 9 hours). (Total dose=160% (w/w) of the oxazaphosphorine dose). This larger dose is recommended in children, in patients whose urothelium may be damaged from previous treatment with oxazaphosphorine or pelvic irradiation, or in patients who are not adequately protected by the standard dose of mesna.
Example of dosage schedule: see Table 2.

Click on icon to see table/diagram/image

Where cyclophosphamide is used orally: The same dose regimen of mesna applies as though cyclophosphamide were used as an I.V. bolus.
Where ifosfamide is used as a 24-hour infusion: Mesna can be used as a concurrent infusion. An initial 20% (w/w) of the total ifosfamide dose is given as an I.V. bolus, then an infusion of 100% (w/w) of the ifosfamide over 24 hours, followed by a further 12-hour infusion of 60% (w/w) of the ifosfamide dose. Total mesna dose=180% of the ifosfamide dose.
Example of dosage schedule: see Table 3.

Click on icon to see table/diagram/image

Where ifosfamide is used as a long-term infusion: An initial 20% (w/w) of the first 24 hours ifosfamide dose is given as an I.V. bolus as the ifosfamide infusion starts. Then each 24-hour infusion of ifosfamide is given with a concurrent 24-hour infusion (100% w/w) of mesna. A 12-hour infusion of mesna (60% (w/w) of the final 24-hour dose of ifosfamide) should be commenced as the ifosfamide-mesna infusion finishes.
Example of dosage schedule: see Table 4.

Click on icon to see table/diagram/image

The final 12-hour infusion of mesna, after long-term or 24-hour infusion of ifosfamide, may be replaced by boluses at 28, 32 and 36 hours, each of 20% (w/w) of the ifosfamide dose, or by oral mesna.
Mesna can be mixed in the same infusion bag as the ifosfamide.
Oral use of mesna ampoules: Mesna has been shown to be effective when taken orally. Compared with intravenous administration, overall availability of mesna in urine after oral administration is approximately 50%; the onset of urinary excretion is delayed by up to 2 hours and is more prolonged than following intravenous dosing.
With the exception of continuous long-term infusions of oxazaphosphorines with mesna, intravenously administered mesna may be replaced by oral administration of mesna. The dosage should be 40% w/w of the dosage of the oxazaphosphorines. The contents of the ampoule should be added to a flavored soft drink (e.g. orange juice, cola). This mixture is stable when refrigerated in a sealed container for 24 hours.
For intermittent oxazaphosphorine therapy following an initial intravenous injection of mesna at a dose of 20% (w/w) of the oxazaphosphorine dose, oral mesna (40% w/w) should be administered at 2 hours and again at 6 hours after the initial intravenous dose. Alternatively, three oral doses of mesna may be administered, replacing the I.V. dose with an oral dose (40% w/w) 2 hours prior to administration of oxazaphosphorines.
Example dosage schedule: see Table 5.

Click on icon to see table/diagram/image

Where ifosfamide is used as a long-term continuous infusion with concomitant mesna, oral mesna may be taken as the infusion of ifosfamide and mesna finishes, then at 2 hours and 6 hours after the time at the finish of the infusion. All oral mesna doses should be 40% (w/w) of the final 24-hour ifosfamide dose.
Example dosage schedule: see Table 6.

Click on icon to see table/diagram/image

Children: Children generally micturate more frequently than adults and therefore it may be necessary to shorten the interval between doses and/or to increase the number of individual doses.
Elderly: No specific information is available.

Reports of inadvertent overdose and observations from a high-dose tolerability study in healthy volunteers showed that, in adults, single doses in the range of approximately 4 g to 7 g of mesna can cause symptoms such as nausea, vomiting, abdominal pain/colic, diarrhea, headache, fatigue, limb and joint pains, rash, flushing, hypotension, bradycardia, tachycardia, paresthesia, fever, and bronchospasm.
A markedly increased rate of nausea, vomiting and diarrhea 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.
A specific antidote to mesna is not known.

Known hypersensitivity to mesna or any of the excipients.

Hypersensitivity: Hypersensitivity reactions to mesna have been reported following administration of mesna as an uroprotectant. These include various skin and subcutaneous tissue symptoms.
In addition, cases of severe bullous and ulcerative skin and mucosal reactions were reported.
In some cases, skin reactions were accompanied by one or more other symptoms, such as fever, cardiovascular symptoms, pulmonary symptoms, hematological abnormalities, nausea, vomiting, pain in the extremities, arthralgia, myalgia, malaise, and conjunctivitis.
Some reactions have presented as anaphylaxis.
Fever accompanied by, e.g., hypotension but no skin manifestations has also been reported.
Some patients with a history of a reaction have shown positive delayed-type skin test results. However, a negative delayed reaction does not exclude hypersensitivity to mesna. Positive immediate-type skin test reactions have occurred in patients regardless of previous mesna exposure or history of hypersensitivity reactions, and may be related to the concentration of the mesna solution used for testing.
Prescribers should be aware that: Severe as well as minor reactions were reported with the use of mesna in regimens to treat both severe systemic autoimmune disease and malignancy and that mesna should be suspected in any hypersensitivity reaction, these reactions may occur with first exposure or after several months of exposure and in some cases can be life-threatening, the occurrence and severity of reactions appeared to vary with the dose administered with a tendency to shorter intervals following subsequent exposures, hypersensitivity reactions to mesna were interpreted to resemble the clinical picture of sepsis and, in patients with autoimmune disorders, resemble an exacerbation of the underlying disease.
Thiol Compounds: Mesna is a thiol compound, i.e., a sulfhydryl (SH) group-containing organic compound. Thiol compounds show some similarities in their adverse reaction profile, including a potential to elicit severe skin reactions. Examples of drugs that are thiol compounds include amifostine, penicillamine, and captopril.
It is not clear whether patients who experienced an adverse reaction to such a drug are at increased risk for any reactions, or similar reactions, to another thiol compound. However, when considering subsequent use of another thiol compound in such patients, the possibility of an increased risk should be taken into account.

Mesna does not prevent hemorrhagic cystitis in all patients. Patients should be monitored accordingly. Sufficient urinary output should be maintained, as required for oxazaphosphorine treatment.
Sodium content: Mesna solution for injection contains approximately 59 mg of sodium per 400 mg mesna.
Lab test interferences: Mesna treatment may cause false positive reactions in nitroprusside sodium-based urine tests (including dipstick tests) for ketone bodies. The addition of glacial acetic acid can be used to differentiate between a false positive result (cherry-red color that fades) and a true positive result (red-violet color that intensifies).
Mesna treatment may cause false positive reactions in Tillman's reagent-based urine screening tests for ascorbic acid.
Effects on the ability to drive and use machines: Patients undergoing treatment with mesna may experience undesirable effects (including, e.g., syncope, light-headedness, lethargy/drowsiness, dizziness, and blurred vision) which could affect the ability to drive or use machines. The decision to drive or operate machinery should be made on an individual basis.

There are no adequate data from the use of mesna in pregnant or lactating women. Physicians should carefully consider the potential risks and benefits for each specific patient before prescribing mesna.
Pregnancy and lactation are contraindications for cytostatic treatment, and consequently, Mesna is not likely to be used under these circumstances.
Should an individual patient be undergoing oxazaphosphorine therapy during pregnancy then Mesna should be administered to this patient.
Mothers should not breastfeed while being treated with these drugs.

The most frequently occurring adverse reactions (>10%) associated with use of mesna are: Headache, infusion site reactions, abdominal pain/colic, lightheadedness, lethargy/drowsiness, pyrexia, rash, diarrhea, nausea, flushing, and influenza-like illness.
The most severe adverse reactions associated with use of mesna are: bullous skin reactions, anaphylaxis, and drug rash with eosinophilia and systemic symptoms (DRESS).
Because mesna is used in combination with oxazaphosphorines or oxazaphosphorine-containing combination chemotherapy, it is often difficult to distinguish adverse reactions that may be due to mesna from those caused by concomitantly administered cytotoxic agents.
ADR frequency is based upon the following scale: Very common (≥1/10); Common (≥1/100-<1/10), Uncommon (≥1/1,000-<1/100), Rare (≥1/10,000-<1/1,000), Very rare (<1/10,000), Unknown (adverse reactions reported in the post-marketing experience). (See Table 7.)

Click on icon to see table/diagram/image

Infusion site reactions: In some subjects experiencing local cutaneous infusion site reactions, subsequent exposure to mesna resulted in a cutaneous event in other areas.
Cutaneous/mucosal reactions: Cutaneous and mucosal reactions were reported to occur after both intravenous and oral mesna. These reactions included rashes, pruritus, flushing, mucosal irritation, pleuritic pain, and conjunctivitis. Approximately one-quarter of subjects with any event experienced cutaneous/mucosal reactions in conjunction with other adverse symptoms, which included, dyspnea, fever, headache, gastrointestinal symptoms, drowsiness, malaise, myalgia, and influenza-like symptoms.
Gastrointestinal reactions: Gastrointestinal reactions reported in healthy subjects included nausea, vomiting, diarrhea, abdominal pain/colic, epigastric pain/burning, constipation, and flatulence and were reported to occur after intravenous and oral mesna administration.
In vivo effect on lymphocyte counts: In pharmacokinetic studies in healthy volunteers, administration of single doses of mesna was commonly associated with a rapid (within 24 hours) and in some cases marked decrease in lymphocyte count, which was generally reversible within 1 week of administration. Data from studies with repeated dosing over several days are insufficient to characterize the time course of lymphocyte count changes under such conditions.
In vivo effect on serum phosphorus levels: In pharmacokinetic studies in healthy volunteers, administration of mesna on single or multiple days was in some cases associated with moderate transient increases in serum phosphorus concentration.
These phenomena should be considered when interpreting laboratory results.
Seek medical attention immediately at the first sign of any adverse drug reaction.

The systemic effects of oxazaphosphorines are not affected by mesna.
Mesna also does not affect the antineoplastic efficacy of other cytostatics (e.g. adriamycin, BCNU, methotrexate, vincristine), nor the therapeutic effect of other drugs such as digitalis glucosides.
Food does not influence the absorption and urinary elimination of mesna.

Store at temperatures not exceeding 30°C. Do not refrigerate.

Antidotes & Detoxifying Agents / Supportive Care Therapy

V03AF01 - mesna ; Belongs to the class of detoxifying agents used in antineoplastic treatment.

Rx