Drug Interaction Report

MONITOR: Use of anticholinergic drugs after administration of botulinum toxin may potentiate systemic anticholinergic effects such as dry mouth, blurred vision, and urinary disorders. Botulinum toxin inhibits the release of acetylcholine from peripheral cholinergic nerve endings, thus additive or synergistic anticholinergic effects may occur when these agents are used together.

MANAGEMENT: Patients should be advised that systemic anticholinergic side effects such as dry mouth, blurred vision, and urinary disorders may increase if agents with anticholinergic properties (e.g., sedating antihistamines; antispasmodics; neuroleptics; phenothiazines; skeletal muscle relaxants; tricyclic antidepressants; disopyramide) are used after administration of botulinum toxin.

GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.