Intravenous benztropine and propranolol challenges in tardive akathisia.

We challenged five patients suffering from tardive akathisia (TA) with intravenous benztropine (2 mg), propranolol (1 mg) and placebo (saline) using a random, double-blind cross-over design to examine the effects of the drugs on the subjective, objective and global manifestations of neuroleptic-induced akathisia. Benztropine produced a marginally significant, and propranolol a significant improvement in the overall manifestations of the disorder. The patients demonstrated a considerable placebo effect and marked variation in their responses to the drugs. The implications of these findings for the pathophysiology of TA in relation to acute akathisia and tardive dyskinesia are discussed.