General Information

Mesnex Tablets are approved for use as a detoxifying agent to inhibit the hemorrhagic cystitis induced by Ifex (ifosfamide). This condition involves bladder problems, such as irritation due to blood being in the urine. Ifex is an antineoplastic drug used for treatment of testicular cancer. Along with Ifex, Mesnex Injection was approved for use in 1988.

Mesnex Tablets are to be used in a dosing regimen with Ifex and Mesnex Injection. If only using Mesnex Injection, the dosing regimen lasts eight hours. With the addition of Mesnex Tablets, it is reduced to six hours. Tablets also allow for quicker administration that can easily be done if not at home.

Clinical Results

Approval of Mesnex Tablets is supported by two clinical studies with over 100 cancer subjects receiving Ifex. Trials compared three intravenous doses of Mesnex to an initial intravenous dose followed by two oral doses for the prevention of hemorrhagic cystitis induced by treatment with Ifex. Both dosing regimens successfully reduced incidences of grade three or four hematuria, the primary efficacy endpoint.

Mesnex Tablets are given orally two and six hours after the co-administartion of Ifex and Mesnex Injection. Mesnex should only be prescribed along with Ifex.

Side Effects

Adverse effects associated with the use of Mesnex may include (but are not limited to) the following:

Nausea

Vomiting

Fatigue

Constipation

Leukopenia

Anemia

Asthenia

Because Mesnex is used in combination with Ifex, it is difficult to distinguish the adverse reactions which may be due to Mesnex from those caused by Ifex.

Mechanism of Action

Mesnex (mesna) was developed as a prophylactic agent to reduce the risk of hemorrhagic cystitis induced by Ifex (ifosfamide). Mesna is rapidly oxidized to its major metabolite, mesna disulfide, which then remains in the intravascular compartment and is rapidly eliminated by the kidneys. In the kidney, mesna disulfide is reduced to mesna, which reacts with the urotoxic ifosfamide metabolites, resulting in their detoxification. (From Mesnex Prescribing Information)