Effect of dexfenfluramine treatment on body weight, blood pressure and noradrenergic activity in obese hypertensive patients.

The effect of dexfenfluramine (dF) on body weight, blood pressure and noradrenergic activity were studied in 30 obese hypertensive patients randomly divided into two groups and treated for 3 months either with dF (30 mg daily; 16 subjects) or placebo (Pl; 14 subjects). 11 patients from the dF group and 9 patients given Pl completed the entire experimental protocol, including monthly visits for metabolic and hormonal measurements, as well as a bicycle exercise test with arterial catheterisation for haemodynamic and catecholamine measurements performed before and after 3 months of treatment. A progressive significant decrease in body weight, averaging 6.0 kg after 3 months was observed in the dF-treated group, whereas loss of weight in the placebo group (1.4 kg) was not significant. While blood pressure and noradrenergic activity, assessed as changes in the plasma levels and urinary excretion of norepinephrine, remained unaffected in the Pl group, a significant drop in the supine systolic and diastolic blood pressures, as well as in the resting venous norepinephrine level and in urinary norepinephrine excretion was found after the first month of dF administration. In addition, the exercise-induced rise in systolic and diastolic blood pressure, as well as in arterial plasma norepinephrine and epinephrine concentrations, was significantly reduced after 3 months of dF administration; there were no such changes in the Pl-treated group. The results of the present study indicate that, in addition to the weight-reducing effect of dexfenfluramine, its hypotensive effect may be mediated by a decrease in noradrenergic activity.