Background: The angiotensin II (AII) receptor antagonists are effective agents for the treatment of mild to moderate hypertension. Agents within this drug class differ with respect to their pharmacologic and pharmacokinetic properties, which may translate into differences in antihypertensive effect. Objective: The purpose of this study was to compare the antihypertensive efficacy of the AII receptor antagonists losartan, valsartan, and telmisartan using 24-hour ambulatory blood pressure monitoring (ABPM). Methods: Outpatients aged 40 to 60 years with mild to moderate hypertension (sitting diastolic blood pressure [DBP] ≥95 mm Hg and ≤115 mm Hg) were enrolled. After a 4-week placebo washout period, patients were randomized to receive losartan 50 mg, valsartan 80 mg, telmisartan 40 mg, or placebo once daily for 4 weeks according to a 4-period crossover design. Each treatment period was separated by a 2-week placebo washout period. Every 2 weeks, 24-hour ABPM was performed. To assess the homogeneity of blood pressure (BP) control, the trough-to-peak (T/P) ratio and the smoothness index (SI) for systolic blood pressure (SBP) and DBP were calculated. Results: After 2 and 4 weeks of treatment, all 3 agents produced significant reductions in 24-hour, daytime, and nighttime SBP and DBP, compared with placebo (P <0.001). Valsartan, however, induced significantly greater BP reductions than did losartan and telmisartan at 2 weeks (P <0.01) and after 4 weeks (P <0.05) of treatment. At 2 weeks, the T/P ratio was significantly higher with valsartan and telmisartan than with losartan, whereas at 4 weeks all drugs resulted in a T/P ratio >50%. The SI for SBP and DBP was significantly higher with valsartan than with losartan and telmisartan both at 2 weeks (P <0.001) and 4 weeks (P <0.01). A positive correlation between SI for SBP and SI for DBP was found at both 2 and 4 weeks with losartan and valsartan treatments, whereas for telmisartan this correlation was present only at 4 weeks. At 4 weeks, plasma active renin (PAR) levels increased significantly with all drugs compared with placebo (P <0.01 vs placebo), whereas at 2 weeks PAR levels increased significantly (P <0.05 vs placebo) only with losartan and valsartan. Conclusions: In the present study, treatment with valsartan resulted in an earlier, greater, and smoother antihypertensive effect compared with treatment with losartan or telmisartan; this differential effect was likely due to differences in the pharmacologic properties of these agents. Analysis of SI revealed a qualitative difference in the antihypertensive action of telmisartan at the beginning of treatment.
- Ambulatory blood pressure monitoring
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