Comparative anorectic effects of metaraminol and phenylephrine in rats

Structure-anorectic activity relationship of two substituted amphetamines h as been investigated in this study. Literature reports showed conflicting r esults in their anorectic activities in spite of the similarity in chemical structures of metaraminol and phenylephrine. Hence, the effects of alpha-c arbon atom substitution and primary (metaraminol) and secondary amine (phen ylephrine) moieties of these substituted amphetamines on the anorexia of ra ts were investigated in this study in nonfood- and food-deprived rats. Food intake at 1, 3, 14, and 24 h intervals, water intake at a 24-h interval, a nd body weight alteration for 10 days were monitored after daily drug admin istration for 3 consecutive days. Both metaraminol and phenylephrine were f ound to be potent anorectic. The relative anorectic potencies of phenylephr ine were 0.54 and 0.81 of that of metaraminol at 1- and 3-h intervals, resp ectively. Body weight of rats treated with metaraminol (5.0 mg/kg) and phen ylephrine (10 mg/kg) decreased significantly from Days 1 to 9. Published by Elsevier Science Inc.