Long term effects of the anorectic agent fenfluramine alone and in combination with aminorex on pulmonary and systemic circulation in the pig.

We have investigated the effects of chronic oral administration of two anorectic substances, fenfluramine and aminorex, especially on the pulmonary circulation in young pigs with one ligated pulmonary artery. The pulmonary vascular reactivity was tested by alveolar hypoxia, alveolar hyperoxia and infusion of prostaglandin F2ALPHA. No elevation of pulmonary arterial pressures or resistances were found due to the intake of fenfluramine or aminorex over a three month period. The responses to the vasoconstrictor stimuli, hypoxia and prostaglandin F2alpha, and to the vasodilator stimulus, hyperoxia, were equal and not augmented in the drug groups. Fenfluramine or aminorex could therefore could therefore not be shown to have an adverse effect on the pulmonary circulation or on the reactivity of the pulmonary vascular bed in the pig, but fenfluramine elevated systemic arterial pressure.