An experimental evaluation of the euphoric properties of antiparkinson drugs on psychotic patients.

Seven psychotic inpatients (two women and five men) aged between 18 and 74 years, treated with neuroleptic and antiparkinson drugs, participated in a double-blind study with 1/3 DDD (Defined Daily Dose) of procyclidine, orphenadrine, or trihexyphenidyl hydrochloride against placebo. Euphoric effects were scored on a self-rating scale and extrapyramidal side-effects on the Simpson-Angus rating scale at drug administration and 1, 3 and 6 h thereafter. With regard to euphoric effect, there was a significant (P less than 0.02) difference between start and end point (0 and 6 h) for placebo but not for the active antiparkinson drugs. There was no significant difference in extrapyramidal side-effects. No preference of drug was found, and it was not possible to recognize the patient's own drug among the tested drugs. Side-effects from the antiparkinson drugs were also measured prior to the administration. Five patients did not return to their earlier antiparkinson drugs after the study.