Drug Interaction Report

ADJUST DOSE: The concomitant use of memantine may potentiate the anticholinergic effects of trihexyphenidyl such as dry mouth, blurry vision, or urinary hesitancy. The mechanism is unknown. Clinical data have not been reported.

MANAGEMENT: Patients should be monitored for adverse effects. Dose adjustments of the anticholinergic agent may be required during coadministration.

GENERALLY AVOID: Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.

MANAGEMENT: Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.