Phenylpropanolamine decreases food intake in rats made hyperphagic by various stimuli.

Phenylpropanolamine (PPA, d,l-norephedrine), found in many over-the-counter appetite suppressants and nasal decongestants, induces anorexia by a yet unidentified mechanism. The present study evaluates the effects of PPA on different types of non-drug- and drug-induced hyperphagias (i.e., food deprivation, 2-deoxy glucose, ketocyclazocine and insulin). Phenylpropanolamine (15, 25 and 35 mg/kg IP) significantly reduced food intake in a dose-related fashion at the 1 hr and 3 hr time intervals in the food deprivation-, insulin- and 2-deoxy glucose-induced hyperphagic models. Phenylpropanolamine produced a non-dose-related 99% reduction of food intake in the ketocyclazocine-induced model at the 1 and 3 hr measurement, which was most likely due to a combination of the appetite suppressant activity of PPA and the sedation produced by ketocyclazocine in combination with PPA. We conclude that PPA is capable of suppressing appetite in rats made hyperphagic by various stimuli.