Human orthostatic reflexes after taking temazepam at night

1. Cardiovascular orthostatic reflexes have been studied at night in 12 healthy male subjects who were given two soft gelatin capsules each containing 0 or 10 mg temazepam at 21.30 h. 2. The changes in heart rate, blood pressure and forearm blood flow on consecutive 5 min exposures to lower body negative pressure (suction) at 30, 40 and 50 mm Hg were measured before and then 1.5 and 9.5 h after giving doses of 10 or 20 mg temazepam in a placebo-controlled double-blind cross-over study. 3. Pre-suction resting values were not affected by temazepam, but 1.5 h after giving the capsules there were significant differences in the responses to suction between the placebo and 20 mg temazepam experiments: the tachycardia after 20 mg temazepam was about one-third greater and the forearm vasoconstriction was about 50% less. The effect of the 10 mg dose was equivocal. No residual effects were detected the next morning. 4. These alterations in orthostatic reflexes soon after the administration of temazepam at night did not impair the maintenance of arterial blood pressure in these healthy subjects.