The actions of the ephedra alkaloids on the central nervous system depend on their ability to penetrate the blood-brain barrier. Ephedrine, similar to amphetamine, readily crosses the blood-brain barrier, and produces a range of central nervous system effects from increased alertness and mood elevation to euphoria, insomnia, and even psychosis. Studies in humans and animals have shown that (—)-ephedrine is a more potent central nervous system stimulant than ( + )-pseudoephedrine (24,43). The anorexigenic effects of ephedrine and norephedrine are believed to be related to a1 activity in the satiety center of the hypothalamus. The mechanism of action of the other central nervous system effects is not entirely clear, but may be related to indirect release of brain norepinephrine and dopamine (44).
Insomnia is a well-known side effect of ephedrine taken by patients with asthma. Chronic use and misuse of ephedrine to ''get high'' has also been associated with addictive behavior (45), and cases of mania and psychosis similar to amphetamine-related psychotic syndromes have been described (46,47). Several cases of acute psychosis have recently been reported in persons taking ''herbal ecstasy,'' a term coined for ephedra-containing products that were formally marketed as legal stimulants (48). Herbal products labeled, marketed, and sold under this name or for the purpose of getting high are now illegal. The use of ephedra for weight loss and athletic performance enhancement may also result in significant central-nervous-system effects, possibly associated with long-term use. A recent study of 36 female weight lifters found that 19% displayed signs of ephedrine dependence (49).
Ephedrine has also been reported to cause seizures in apparently healthy persons (50). This would be an expected adverse outcome of any central-nervous-system-stimulant drug, particularly if taken in high doses.
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