The effect of losartan and amlodipine on serum adiponectin in Japanese adults with essential hypertension

Background:Adiponectin, an adipocyte-derived protein, is reduced in patients with hypertension and insulin resistance (IR). Angiotensin II receptor blockers (ARBs) have been reported to improve IR and reduce albuminuria. The purpose of this study was to evaluate the influence of an ARB and a calcium channel blocker on serum adiponectin levels in Japanese patients with hypertension who were treated with losartan or amlodipine for 3 months.Methods:Patients with essential hypertension (EHT) were randomized to treatment prospectively with losartan (50–100 mg/d) or amlodipine (5–10 mg/d) for 3 months. Patients with renal damage and/or macroproteinuria were excluded. The urine albumin/creatinine ratio, homeostasis model assessment (HOMA) index, adiponectin concentration, and tumor necrosis factor-alpha (TNF-α) concentration of each patient were evaluated before and after 3 months of treatment. When the HOMA index exceeded 1.73, a patient was considered to have IR.Results:All 40 participants completed both 3-month treatment periods. Study patients were primarily male (52.5%) with a mean (SD) age of 63.8 (10.6) years and a mean body weight of 60.7 (10.8) kg. Patients with EHT and diabetes mellitus (n = 9) and IR (n = 12) had significantly lower adiponectin concentrations than patients who had EHT without diabetes or IR (n = 19; mean [SD], 7.84 [5.54] vs 12.81 [7.36] μg/mL, P = 0.034; and 6.12 [3.04] vs 12.81 [7.36] μg/mL, P = 0.004, respectively). Adiponectin concentrations correlated negatively with body mass index (r = −0.393; P = 0.012) and HOMA index (r = −0.440; P = 0.005) and positively with high-density lipoprotein cholesterol (r = 0.441; P = 0.004) before treatment. Systolic blood pressure was significantly decreased in patients treated with losartan (n = 20; mean [SD], 166 [19] to 140 [15] mm Hg; P < 0.001) or amlodipine (n = 20; 164 [15] to 136 [15] mmHg; P < 0.001), and diastolic blood pressure also was significantly decreased with losartan (93 [14] to 83 [10] mm Hg; P = 0.031) or amlodipine (96 [12] to 82 [10] mm Hg; P < 0.001). Losartan increased adiponectin concentrations (9.56 [6.75] to 10.36 [6.94] μg/mL; P = 0.038), whereas amlodipine had no significant effect (9.67 [6.62] to 10.01 [6.79] μg/mL). The difference in TNF-α concentration before and after treatment with losartan and amlodipine did not reach statistical significance (mean [SD], 15.2 [1.4] to 14.8 [1.5] pg/mL; and 14.3 [1.4] to 14.5 [1.7] pg/mL, respectively).Conclusion:In this study, Japanese adults with EHT had significant increases in adiponectin after 3 months of treatment with 50 to 100 mg/d of losartan, but not with 5 to 10 mg/d of amlodipine.