Cocaine addicts describe the euphoric effects of cocaine in terms that are almost indistinguishable from those used by amphetamine addicts. In the laboratory, subjects familiar with cocaine cannot distinguish between the subjective effects of 8-10 mg of cocaine and those of 10 mg of dextroamphetamine when both are given intravenously (Fischman et al., 1976), and the toxic syndrome seen with cocaine seems clinically indistinguishable from that produced by amphetamines. In addition animals exhibit similar patterns of self administration of cocaine and amphetamine. In short, while it is commonly assumed that the subjective effects of cocaine are more intense and it's abuse potential more significant than those of the amphetamines, the similarities in terms of subjective behavioral, pharmacological, and toxic effects are more striking than the differences. Amphetamine is thus taken as the prototype of this class of drugs.
Consideration of these drugs as a class does not imply they have identical mechanisms of action or that drug abusers cannot distinguish among them. For example, after intravenous administration of cocaine the effects are brief, lasting only a matter of minutes, whereas those of methamphetamine may last for hours. With appropriate selected doses and tasks it is possible to demonstrate differences between the effects of amphetamine and cocaine on motor performance, aggression, and facilitation of self-stimulation with electrical current. It is often assumed that cocaine's local anesthetic actions are unrelated to its euphorigenic and reinforcing properties, but animals will administer procaine to themselves and subjects who have had experience with cocaine are unable to distinguish lidocaine from cocaine when both are used intranasally; they produce a similar degree of euphoria (Van Dyke et al., 1978a) It is not clear whether all local anesthetics are euphorigenic.