The effects of clonidine hydrochloride versus atenolol monotherapy on serum lipids, lipid subfractions, and apolipoproteins in mild hypertension

Abstract

The study objective was to determine the effects of monotherapy with clonidine and atenolol versus placebo on serum lipids, apolipoproteins, and blood pressure in patients with mild primary hypertension. The protocol comprised a double blind, randomized, placebo-controlled 5-month prospective study carried out in an outpatient general internal medicine clinic in a university medical center. There were 92 patients ages 18 to 70, with mild primary hypertension (sitting diastolic blood pressure of > 90 mm Hg and < 105 mm Hg) without significant cardiac, renal, cerebrovascular, hepatic, neoplastic, or hematologic disorders. Patients with severe hyperlipidemia or peripheral vascular disease were also excluded. All factors known to effect serum lipids were held constant throughout the study (i.e., diet, weight, exercise, caffeine, tobacco). Atenolol and clonidine significantly reduced blood pressure when compared with placebo. Atenolol caused significant increases in serum triglycerides and apolipoprotein B ( p < 0.05) and significant reductions in high-density lipoprotein-cholesterol, apolipoproteins A-I and A-II ( p < 0.05). Atenolol also induced a significant adverse effect on all lipid ratios, increasing total cholesterol/high density lipoprotein-cholesterol, low density lipoprotein-cholesterol/high density lipoprotein-cholesterol, apolipoprotein B/apolipoprotein A-I and apolipoprotein B/apolipoprotein A-II ratios and decreasing low density lipoprotein-cholesterol/apolipoprotein-B ratio ( p < 0.05). Clonidine caused significant reductions in high-density lipoprotein-cholesterol, apolipoproteins A-I and A-II ( p < 0.05 but was neutral on all other lipids, lipid subfractions, and apolipoproteins. Clonidine did not significantly alter any of the lipid ratios. It was concluded that monotherapy with either clonidine or atenolol was equally effective in reducing blood pressure when compared with placebo. Overall, atenolol had an unfavorable effect on serum lipids, inereas clonidine had a neutral effect on serum lipids. These lipid changes must be considered in the overall evaluation of coronary heart disease risk when hypertensive patients are treated.