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Marijuana has a wide range of pharmacologic effects that suggest actions like those of stimulants such as the AMPHETAMINES, hallucinogens such as LSD, and depressants such as alcohol, SEDATIVES, atropine, or MORPHINE. Thus, marijuana does not fit any single traditional pharmacologic classification, and, hence, must be considered as a separate class.
The experienced smoker of marijuana is usually aware of a drug effect after two or three inhalations. As smoking continues, the effects increase, reaching a maximum about twenty minutes after the smoke has been finished. Most effects of the drug have usually vanished after three hours, by which time tests show that concentrations of THC in the body's plasma are low. Peak effects after eating marijuana may be delayed for three to four hours, but may then last for six to eight hours.
The early stage is one of being high, characterized by euphoria, uncontrollable laughter, alteration of one's sense of time, depersonalization, and sharpened vision. Later, the user becomes relaxed and experiences introspective and dreamlike states, if not actual sleep. Thinking or concentrating becomes difficult, although by force of will the person can concentrate to some extent.
Two characteristic signs of Cannabis intoxication are increased pulse rate and reddening of the conjunctiva (the whites of the eyes). The latter correlates well with the presence of detectable concentrations of THC in the plasma. Pupil size is not changed. The blood pressure may fall, especially in the upright position (orthostatic hypotension). An antiemetic (decrease in sense of nausea) effect may be present, and muscle weakness, tremors, unsteadiness, and increased deep-tendon reflexes (such as the knee jerk) may also be noted.
Virtually any performance test shows impairment if the doses are large enough and the test is difficult enough, although no distinctive biochemical changes have been found in human beings.
TOLERANCE to Cannabis has been demonstrated in virtually every animal species that has been tested. It is apparent in human beings only among heavy long-term users. Different degrees of tolerance develop for different effects of the drug, with tolerance for the tachycardiac effect (increased pulse rate) developing fairly rapidly. A mild WITHDRAWAL syndrome has been noted following very high doses.