Seldom do they last longer than 2 to 3 h after a single cigarette, although users prolong the effects by repeated smoking. Oral doses delay the onset of symptoms for 30 min to over 2 h, as well as prolonging the span of action of the drug. These time schedules are consistent with knowledge of the pharmacokinetics of the drug. All observers have commented on the constant increase in pulse rate, often one of the first effects of the drug. Conjunctival reddening is also consistently observed.
Muscle strength is decreased.
Observed physiological effects have not included changes in pupil size, respiratory rate, or deep tendon reflexes. Perceptual and psychic changes are biphasic. Time sense is altered, hearing is less discriminant, and vision is apparently sharper with many visual distortions. Depersonalization, difficulty in concentrating and thinking, dream-like states are prominent. Many of these symptoms are similar to those produced by psychotomimetics.