Orthostatic hypotension after delta 9-tetrahydrocannabinol marihuana inhalation.

3 male glaucoma subjects experienced orthostatic hypotension within 10 min after completing 2% delta 9-THC ranging from 57 to 233 ng/ml were found 5 min after smoking. Peripheral venodilation appeared responsible for the precipitous decrease in systolic blood pressure in all 3 subjects. These orthostatic episodes which clinically simulated the typical 'faint' were characterized by the absence of tachycardia and their relief by assuming a reclining position. The postural hypotension occurred despite differences in inhalation technique, level of delta (9)-THC present in plasma, previous marihuana experience of body habitus.