Drug Interaction Report

MONITOR: The coadministration of altretamine with a monoamine oxidase inhibitor (MAOI) or tricyclic antidepressant may result in severe orthostatic hypotension. The mechanism of interaction has not been established. According to one case report, four patients over 60 years of age experienced symptomatic hypotension after 4 to 7 days of concomitant therapy with altretamine and one of the following: amitriptyline, imipramine, or phenelzine. All patients became asymptomatic within 24 to 96 hours after discontinuing the antidepressant. One patient subsequently received and tolerated nortriptyline without clinical symptoms, although a postural drop in systolic blood pressure was observed.

MANAGEMENT: Caution is advised if altretamine must be used with a MAOI or tricyclic antidepressant, particularly in elderly patients. All patients receiving the combination should be advised to avoid rising abruptly from a sitting or lying position and to contact their physician if they experience symptoms of hypotension such as dizziness, lightheadedness, or fainting.

GENERALLY AVOID: Concomitant use of ethanol and a tricyclic antidepressant (TCA) may result altered TCA plasma levels and efficacy, and additive impairment of motor skills, especially driving skills. Acute ethanol ingestion may inhibit TCA metabolism, while chronic ingestion of large amounts of ethanol may induce hepatic TCA metabolism.

MANAGEMENT: Patients should be advised to avoid alcohol during TCA therapy. Alcoholics who have undergone detoxification should be monitored for decreased TCA efficacy. Dosage adjustments may be required.