To determine the effects of pharmacological therapy on weight loss and subsequent changes in blood pressure levels, 10 RCT articles were examined (386-395). Weight loss studies using pharmacotherapy were conducted predominantly in white women and assumed that dietary changes were uniform in the active drug and placebo groups. All of these studies had a placebo-control group for which dietary recommendations for weight loss were provided; weight loss also occurred in the placebo group. No studies examined whether weight loss using pharmacotherapy results in blood pressure reductions similar to weight loss produced by diet therapy, nor were the results compared with a pure control group with no weight loss. In addition, none of the studies that examined the effect of pharmacotherapy on blood pressure controlled for weight loss.
In general, the use of phentermine, fenfluramine, and dexfenfluramine resulted in similar or better weight loss than that seen in the control or placebo group, and reductions in systolic and diastolic blood pressure were concomitantly similar to or better than those observed in the diet plus placebo group (386, 390-393, 395). However, one study on dexfenfluramine (394) showed increased blood pressure compared to controls, even though weight loss was greater with dexfenfluramine than with placebo. Another study showed blood pressure lowering consistent with weight reduction produced by dexfenfluramine in women with upper-body obesity, but not in women with lower-body obesity (387).
In a combined summary of data on orlistat presented at the FDA Endocrinologic and Metabolic Drugs Advisory Committee Meeting (held in Bethesda, Maryland, in May 1997), only a small decrease in systolic (approximately 2 mm Hg) and diastolic (approximately 1 mm Hg) blood pressure was observed compared to the placebo (388). In a study of sibutramine, a net weight loss at 3 months of approximately 2 kg (4.4 lb) did not result in lower blood pressure compared with placebo controls (389). Eleven double-blind placebo-controlled trials lasting from 12 to 52 weeks showed that sibutramine is associated with mean increases in systolic blood pressure of 1 to 3 mm Hg, in diastolic pressure of 1 to 2 mm Hg, and mean increases in pulse rate of 3 to 5 beats per minute relative to placebo. In hypertensive obese patients, the mean change in blood pressure was the same in the sibutramine group and the placebo group; both dropped. Systolic pressure decreased 5.4 mm Hg in the sibutramine group and 5.8 mm Hg in the placebo group, while the diastolic drop was 5.9 mm Hg and 3.7 mm Hg, respectively. At the FDA-recommended doses, 45 percent of patients had an increase, 35 percent had a decrease, and 20 percent had no change in blood pressure (389).