Efficacy and effects on lipid metabolism of combination treatment with losartan + hydrochlorothiazide versus losartan + amlodipine: a 48-week prospective, multicenter, randomized, open-label trial.

BACKGROUND

Both combination therapies of an angiotensin II receptor blocker (ARB) with the thiazide diuretic hydrochlorothiazide (HCTZ) and an ARB with a calcium channel blocker (CCB) are recommended to achieve blood pressure (BP) goals in antihypertensive treatment. However, although HCTZ is known to have unfavorable effects on lipid metabolism, the effects of HCTZ in the ARB + HCTZ combination on lipid metabolism have not been fully elucidated.

OBJECTIVE

The aim of this study was to compare the effects on lipid metabolism of combination treatment with the ARB losartan + HCTZ and losartan + the CCB amlodipine and to assess the efficacy in BP lowering of these 2 combination therapies. The metabolism of glucose, uric acid (UA), and high-sensitivity C-reactive protein (hs-CRP), an inflammation marker of atherosclerosis, were also assessed in association with lipid metabolism.

METHODS

This 48-week, prospective, randomized, open-label trial was conducted at 2 clinics and 2 hospitals in Tokorozawa City (Saitama, Japan) and Shinjuku-ku Ward (Tokyo, Japan). Eligible patients had a systolic BP (SBP) >140 mm Hg and/or diastolic BP (DBP) >90 mm Hg despite a >1-month history of monotherapy with an ARB. Patients were randomly assigned to receive losartan 50 mg/d + HCTZ 12.5 mg/d (LOS + HCTZ) or losartan 50 mg/d + amlodipine 5 mg/d (LOS + CCB) for 48 weeks. Follow-up visits were scheduled at 4, 8, 12, 24, and 48 weeks. Biochemical measurements were centrally measured at a single institute. Tolerability and treatment compliance were assessed by physicians every 4 weeks.

RESULTS

A total of 112 patients were enrolled; 26 were excluded from the final analysis, leaving 42 and 44 patients in the LOS + HCTZ and LOS + CCB groups, respectively, included in the final analysis. At 48 weeks, SBP and DBP were significantly decreased in the 2 treatment groups (both, P < 0.0001). The decrease in SBP was significantly greater in the LOS + HCTZ group than in the LOS + CCB group (P < 0.001). The difference in the decrease in DBP between the 2 groups was nonsignificant. There were no significant differences in the changes from baseline (Δ) in any of the lipid parameters between the 2 groups. The decreases at 8 and 12 weeks in LDL-C, TC, and apolipoprotein (apo) B were significantly greater in the LOS + CCB group compared with those in the LOS + HCTZ group. The between-group differences in ΔTG, ΔHDL-C, ΔapoA-1, and ΔapoE throughout the study were nonsignificant. Changes in fasting plasma glucose (FPG), hemoglobin A1c, and hs-CRP were not significantly different between the 2 groups. The between-group difference in ΔUA in men was not significant, but a significant difference was found in women (LOS + HCTZ, 0.74 mg/dL; LOS + CCB, 0.28 mg/dL [P = 0.0017]). No clinically significant adverse events were reported with either treatment throughout the study.

CONCLUSIONS

The findings from the present study suggest that LOS + HCTZ was more efficacious in decreasing SBP than was LOS + CCB in the management of hypertension refractory to ARB monotherapy. Unfavorable effects on lipid metabolism were not observed with either combination therapy.