Trihexyphenidyl dependence

ABSTRACT– Trihexyphenidyl, a synthetic anticholinergic, is frequently used concurrently with neuroleptics to control extrapyramidal side effects. We present two case reports of trihexyphenidyl abuse which concur with the increasing concern expressed regarding the abuse potential of trihexyphenidyl. In one of the cases a double‐blind, placebo‐controlled withdrawal was conducted and monitored on a number of physiological parameters and the Hamilton Anxiety Rating Scale. A recognizable withdrawal syndrome followed discontinuation of the drug. In addition to the abuse potential it is suggested that dependence liability be considered in maintenance therapy with trihexyphenidyl and other antiparkinsonians.