Comparison of brown adipose tissue thermogenesis induced by congeners and isomers of phenylpropanolamine.

The present experiment compared the effects of intraperitoneal injection (.0223 mMol/kg) of several phenethylamine congeners and isomers including amphetamine (AMP), ephedrine (EPH), methoxyphenamine (MET), norpseudoephedrine (NOR), pseudoephedrine (PS) and phenylpropanolamine (PPA) on in vivo interscapular brown adipose tissue temperature in adult male rats. Comparisons of isomer potency revealed that the 1-isomer was more thermogenic than the d-isomer for EPH and PPA but not for AMP, NOR and PS. Congener potency order was: AMP greater than PPA greater than EPH greater than NOR = MET greater than PS. The implications of these data for the weight-reducing activity of these compounds is discussed.