Hypertension is characterized by endothelial dysfunction and frequently clusters with metabolic disorders that are characterized by insulin resistance (1,2). These comorbidities may be explained, in part, by reciprocal relationships between endothelial dysfunction and insulin resistance (1). By contrast with calcium channel blockers (CCBs), treatment of hypertension with -blockers and diuretics is associated with a higher risk of type 2 diabetes (3). This advantage of CCBs may relate to specific mechanisms that target the vicious synergy between endothelial dysfunction and insulin resistance. CCBs activate nitric oxide (NO) synthase in vitro and enhance NO production in vivo (4). This may impact on the roles of adiponectin, leptin, and resistin to influence metabolic signals, inflammation, and atherosclerosis (5-7).Efonidipine hydrochloride is a 1,4-dihydropyridine-type CCB with longlasting vasodilator actions and little reflex tachycardia (8). Efonidipine improves endothelial function in patients with hypertension when compared with doses of nifedipine that result in comparable decreases in mean blood pressure (9). Therefore, we hypothesized that efonidipine therapy may simultaneously improve endothelial dysfunction, adipocytokine profiles, and other metabolic parameters in nondiabetic patients with hypertension.
RESEARCH DESIGN ANDMETHODS -We evaluated effects of efonidipine in a randomized, doubleblind, placebo-controlled, crossover study. Thirty-nine hypertensive patients (systolic blood pressure [SBP] Ͻ180 mmHg and diastolic blood pressure [DBP] Ͻ110 mmHg) were considered eligible for this study. We excluded patients with severe hypertension, unstable angina, acute myocardial infarction, or renal insufficiency. None of our subjects were diabetic (based on history or criteria according to the Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus [10]) or smokers. To minimize acute side effects, during an initial run-in period, study medication was titrated from 40 to 80 mg efonidipine upwards over a 2-week period if no hypot e n s i o n ( S B P Ͻ 1 0 0 m m H g ) o r hypertension (SBP Ͼ140 mmHg) was noted. After the run-in period, all patients underwent a 3-week washout period. At the end of the washout period, participants were randomly assigned to either 40 -80 mg efonidipine or placebo daily during 8 weeks. Patients were then crossed over to the second treatment arm on completion of the first treatment arm (without washout phase). The Green Cross Pharmaceutical company (Yongin, Korea) provided the identical placebo (purchased by investigators). One patient suffered from facial flushing and was withdrawn. Thus, data from 38 patients were analyzed. This study was approved by the Gil Hospital Institute Review Board.Blood samples were obtained at 8:00 A.M. following an overnight fast before and after each treatment period. Assays for plasma insulin, malondialdehyde, adiponectin, leptin, and resistin were performed in duplicate by immunoradiometric assay or by enzymel i n k e ...