Anorectic psychostimulants

The psychomotor stimulants, cocaine and D-amphetamine, are considered together because they share a similar psychopharmacological profile.19 20 Low to moderate doses of both drugs given acutely to nontolerant, nonanxious subjects produce increases in positive mood (euphoria), energy, and alertness. Experienced cocaine users were unable to distinguish between intravenous (IV) cocaine and D-amphetamine,21 and cross-tolerance between cocaine and D-amphetamine with respect to their anorectic effect has been demonstrated.22 Additionally, the toxic psychosis observed after days or weeks of continued use of both psychostimulants is very similar. The fully developed toxic syndrome, characterized by vivid auditory and visual hallucinations, paranoid delusions, and... 

Use in Obesity. As noted earlier, many of the psychostimulants have also been used as anorectics (anorexics anorexigenics), that is, as appetite suppressants. A few of them are still useful in this regard, but the high abuse potential of psychostimulants, coupled with the development of tolerance to their anorectic effects, has meant that prescribing psychostimulants for weight control has generally fallen into disfavor. 

In a related vein, the subjective psychostimulant effects of amphetamine were attenuated following a 2-h pretreatment with a tyrosine- and phenylalanine-free amino acid mixture (118).These amino acids are biosynthetic precursors of the catecholamines, and deprivation would be expected to produce transient reductions in endogenous dopamine and norepinephrine. The authors concluded that tyrosine depletion attenuates the release of dopamine required for the psychostimulant effect. Interestingly, the pretreatment did not reduce the subjective appetite-suppressant (anorectic) effect of amphetamine. The study authors attributed this latter finding to a continued release of norepinephrine by amphetamine. Tyrosine depletion, however, would also attenuate norepinephrine biosynthesis and it may be more reasonable to conclude that the anorectic effect might be related to the often-overlooked ability of amphetamine to release neuronal serotonin. 

Several psychostimulant anorectics have been withdrawn from the market or are less often prescribed due to increased numbers of reported adverse reactions such as hepatotoxicity (e.g. pemoline, Fig. 18.3) and cardiovascular problems (e.g. fenfluramine, Fig. 18.3, and phentermine, Fig. 18.4). It seems worthwhile to point out that despite these concerns many products remain to be used, either... 

Figure 18.3 Less commonly used psychostimulant anorectics.

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