Table 3. Clinical Trials of Psychostimulants in Cancer Patients continued...
Monoamine oxidase inhibitors
The use of monoamine oxidase inhibitors (MAOIs) in the cancer population has been limited because the nutritional requirements of a tyramine-free diet are generally more difficult to accomplish in patients receiving antineoplastic treatments. MAOIs are contraindicated in patients receiving opioids, sympathomimetics, and procarbazine because of the potential for developing hypertensive crisis.
MAOIs may cause adverse reactions when taken with other medications and certain foods. MAOIs impair the metabolism of morphine and other opioids as well as barbiturates and may lead to exaggerated ventilatory depression. Meperidine HCl (Demerol), an opioid, has been associated with hypertension, hyperpyrexia, skeletal muscle rigidity, seizures, and coma when used with MAOIs. Exaggerated effects of antihistamines, anticholinergics, and tricyclic antidepressants may be secondary to impaired metabolism by MAOIs. In addition, the hypoglycemic effects of insulin and oral sulfonylureas may be potentiated by MAOIs.
MAOIs may also interact with specific anesthetic drugs used during surgery. Cancer patients in particular may frequently undergo surgical procedures and should alert their anesthesiologist of all medications. Postoperative pain should not be treated with meperidine HCl. MAOIs should neither be taken with procarbazine, a chemotherapeutic agent used in the treatment of lymphomas and brain tumors, nor used with other antidepressants.
The FDA approved a transdermal antidepressant that may have particular value in the treatment of the depressed cancer patient who is unable to swallow or take medications by mouth. The antidepressant selegiline (sold under the trade name EMSAM) is an irreversible MAOI. The drug has not been evaluated for the treatment of depression in cancer patients.
Many of the usual dietary restrictions (low-tyramine diet) and drug-drug interactions (the product should not be used with meperidine, propoxyphone, or methadone) are germane to selegiline (see Table 4 below). However, according to the package insert, the 20-mg skin patch (which delivers 6 mg of selegiline in a 24-hour period) can be used without the dietary restrictions found on all MAOIs marketed to date. This recommendation is supported by clinical trials and other evidence submitted to the FDA. The two higher doses (a 30-mg patch that delivers 9 mg in 24 hours and a 40-mg patch that delivers 12 mg in 24 hours) carry the usual dietary warning. This drug has not been evaluated in cancer patients for safety and efficacy.