Key Terms: Acrolein, Bladder, Chemotherapy, Food and Drug Administration, Hemorrhagic cystitis.
Definition
Mesna is a medicine that helps protect the inside lining of the bladder from damage due to certain chemotherapy drugs. Mesna may also be referred to as 2-mercaptoethane sulfonate, sodium salt, or Mesnex (its brand name).
Purpose
Mesna is a medicine that is approved by the Food and Drug Administration (FDA) for use in combination with the chemotherapy drug ifosfamide to protect the bladder lining from irritation due to the chemotherapy. It has also been shown useful in protecting the bladder lining when used in combination with large doses of the chemotherapy drug cyclophosphamide. Irritation to the bladder lining can cause bleeding and this is referred to as hemorrhagic cystitis. Mesna is not administered to treat cancer.
Description
Mesna is a clear, colorless solution with a foul odor. It is usually administered intravenously through a vein to prevent bleeding of the inside lining of the bladder. Sometimes it can be given to a patient to mix in a beverage and drink. When ifosfamide and cyclophosphamide are given, they break down in the body and form a poisonous substance called acrolein. Acrolein concentrates in the bladder and causes irritation that can lead to severe bleeding from the bladder into the urine. When mesna is administered it also concentrates in the bladder and combines with the toxic acrolein to form a nontoxic substance that is removed from the body by urinating.
Recommended Dosage
Mesna is usually administered through a vein over at least five minutes. This same drug can also be mixed with a beverage and taken by mouth (flavored drinks like grape juice, cola, and chocolate milk are good choices to hide the taste of the mesna).
The mesna dose depends on the amount of chemotherapy drugs, ifosfamide or cyclophosphamide, that a patient receives. The mesna dose can vary with the time frame the chemotherapy drugs are being administered. The standard mesna dose is equal to 20% of the total ifosfamide dose given at three separate time intervals through a vein infused over at least five minutes. The first dose is right before the ifosfamide, often referred to as hour 0. The second dose is four hours after the start of the infusion and the third dose is eight hours after the start of the infusion. Mesna is given in this way each day the ifosfamide is administered.
Mesna can be given at a dose of 100% (the same dose as the ifosfamide) of the ifosfamide. This mesna would be mixed directly with the ifosfamide in the same intravenous infusion bag. This type of dosing may or may not have the patient receive a small dose of mesna right before or after the ifosfamide infusion.
Precautions
Mesna can cause allergic reactions that range from a mild rash to severe life-threatening, full-body allergic reactions. Patients with a known previous allergic reaction to mesna or thiol-like medicines should tell their doctor before receiving mesna.
Mesna that contains the preservative benzyl alcohol must not be used in premature babies or infants and must be used with caution in older children.
Mesna should prevent most bleeding from the bladder, however patients may be asked to check their urine for traces of blood with a chemical strip that is dipped into the urine sample.
Side Effects
Side effects due only to the mesna are uncommon and difficult to determine since the drug is not given alone. However in clinical studies mesna has been known to cause nausea and vomiting, diarrhea, abdominal pain, and a bad taste in the mouth. Other reported side effects include; headache, fatigue, pain in arms and legs, drop in blood pressure, and allergic reactions.
All side effects a patient experiences should be reported to his or her doctor.
Interactions
Mesna can cause a false positive test of the urine for ketone bodies. This may be most important in diabetic patients who routinely check their urine for ketones.
—Nancy J. Beaulieu, RPh., BCOP
