A single-dose study of the pharmacodynamic effects of chlormethiazole, temazepam and placebo in elderly parkinsonian patients.

Nine elderly parkinsonian volunteers took single doses of 384 mg of chlormethiazole, 10 mg of temazepam and placebo capsules in a double-blind three-way cross-over study on separate visits at least one week apart. In the 6 hours following the dose, the level of drowsiness, performance on a series of psychomotor tests, effects on parkinsonian symptoms and signs, and standing and lying blood pressure were recorded. Chlormethiazole produced drowsiness on all tests and impaired psychomotor performance, as compared with placebo, without affecting parkinsonian symptoms and signs, or postural blood pressure. Temazepam was consistently less potent than chlormethiazole on tests of drowsiness and psychomotor performance. Both treatments were well tolerated. It is suggested that chlormethiazole is safe to use as a hypnotic at this dosage in this group of patients with Parkinson's disease, while temazepam did not appear to be effective as a hypnotic at this dosage.