Combination of trazodone and phenothiazines: a possible additive hypotensive effect.

Trazodone a triazolepyridine derivative is known for its therapeutic effect in the treatment of depression since early 60's. It has little catecholamine potentiation or anticholinergic action. It has been reported to have less severe cardiotoxic effect. Mild or transient as well as orthostatic hypotension may be its main cardiovascular complication. Additive hypotensive side effect following combined use of Trazodone and Phenothiazine in two hospitalized patients was observed and documented. Each case is detailed. While the mechanism of action of both agents and their effect on alpha 1 and alpha 2 adrenergic receptors has been described, some suggestions are made to explain a possible mechanism for the observed side effect. This finding might be implemented into further research work.