Long-term treatment with slow release oxprenolol alone, or in combination with other drugs: effects on blood pressure, lipoproteins and exercise performance.

Twenty-eight patients with mild essential hypertension were treated with placebo for six weeks and then with active medication for a further 32 weeks. Twelve patients were well-controlled with 160-320 mg/day of slow release oxprenolol alone, 12 required oxprenolol and chlorthalidone, and four also required hydrallazine. beta-adrenergic blockade reduced the basal level of plasma free fatty acid (FFA) by 41%. A sub-maximal exercise test reduced the level of FFA by 34% during placebo treatment. The same exercise test during beta-blockade reduced the already lowered basal FFA level by a further 45%. Only female subjects experienced exercise-induced leg fatigue during beta-blockade. They always had higher FFA levels than males, but the relative changes in FFA concentration were similar in both sexes. Exercise testing induced a 52 mmHg rise in systolic blood pressure, but this was reduced to only 14 mmHg during treatment. Patients controlled on oxprenolol alone showed no significant change in plasma lipid and lipoprotein levels. Those patients ultimately requiring combination drug therapy experienced a statistically significant rise in plasma triglycerides and a significant fall in high density lipoprotein cholesterol. The biological importance of these changes is uncertain.