Possible Mechanisms Involved in the Vasorelaxant Effect Produced by Anorexigenic Drugs in Rat Aortic Rings

Anorexigenics are compounds capable of reducing or suppressing appetite. Their three main types act on different neurotransmitters, either norepinephrine, serotonin or a combination of both. Among the drugs that act on norepinephrine are fenproporex, amfepramone and clobenzorex. Derivatives of the thyroid hormone triiodothyronine have also been associated with weight loss and used as a controversial treatment for obesity, despite their known cardiovascular side effects. Recent data suggest a possible vasodilating effect for these four substances that might be beneficial in a subset of patients. Herein we performed a systematic review of the literature (with emphasis on recent reports) to determine the implications and mechanisms of the vasodilating effects of some anorectics, specifically fenproporex, clobenzorex, amfepramone and triiodothyronine. Data analysis showed these four drugs to be vasodilating agents for rat aortic rings. The different mechanisms of action include endothelium-dependent vasodilation via activation of the NO-cGMP-PKG pathway and the opening of calcium-activated potassium channels. The finding of vasodilating activity indicates a potential role for some anorexigenic drugs in the treatment of obesity in hypertensive patients. Further in vivo studies are needed to test the clinical benefits of these four drugs.