Thermogenic and anorectic effects of ephedrine and congeners in mice and rats.

(-)-Ephedrine has been shown to increase energy expenditure and cause the loss of body fat in rats and mice. The present study compares the effects of (-)- and (+)-ephedrine, (-)- and (+)- pseudoephedrine, (+)- and (+)-norephedrine and (-)- and (+)-norpseudoephedrine on food intake, energy expenditure and body composition in ob/ob and normal mice and food intake in rats. The most potent anorectic and thermogenic compounds had the S configuration at the C-2 position but the orders of potencies for the compounds for anorexia and thermogenesis were not identical. The potencies of the compounds in reducing body lipid content correlated better with their thermogenic than their anorectic potencies.