The thermogenic properties of ephedrine/methylxanthine mixtures: animal studies.

An over-the-counter preparation containing ephedrine, caffeine, and theophylline was examined for thermogenic anti-obesity properties. Administration of the methylxanthines to MSG-induced obese mice for 6 wk had no effect on energy balance or body composition. In contrast, treatment with ephedrine alone caused losses of 14% in body weight and 42% in body fat, effects brought about mainly by a 10% increase in energy expenditure. These changes were accentuated when ephedrine was administered together with one or both methylxanthines: energy expenditure was increased by a further 10%, and led to a reduction of about 25% in body weight and 75% in body fat, while the total food intake and body protein were unaltered. These results indicate that dietary methylxanthines like caffeine and theophylline, although alone have little effect on energy balance, can nevertheless markedly potentiate the thermogenic anti-obesity effect of ephedrine and normalize the body composition of the obese to the lean levels.