Opioid responsiveness in patients with neuroleptic-induced akathisia.

Five patients with either acute or tardive neuroleptic-induced akathisia (5 weeks to 1 1/2 years duration) were videotaped before, during, and after a 2-week trial of propoxyphene (Darvon), 100 mg q.i.d., or acetaminophen (Tylenol) with 30 mg codeine, two tabs, q.i.d. Three "blinded" observers, experienced in movement disorders, rated the involuntary movements shown on the videotapes and agreed that, on opioids, all patients showed substantial to complete improvement of their stereotyped restless akathitic movements. Matching placebo was not beneficial. One patient who had improved on opioids was challenged with naloxone while on the opioids. There was a brief but severe reactivation of the akathisia. Our results suggest that opioids offer a selective therapy for patients with neuroleptic-induced akathisia and further suggest that the endogenous opiate system may be involved in patients with neuroleptic-induced akathisia.