Effects of olmesartan medoxomil, an angiotensin II type 1 receptor antagonist, on plasma concentration of B-type natriuretic peptide, in hypertensive patients with type 2 diabetes mellitus: A preliminary, observational, open-label study

Background and Objective: Angiotensin II type 1 (AT₁) receptor antagonists (angiotensin receptor blockers [ARBs]) are widely used for the treatment of not only hypertension but also cardiac dysfunction. B-type natriuretic peptide (BNP) is secreted mainly by the cardiac ventricle and plays an important role in the regulation of blood pressure (BP) and body fluid. It has been established that the plasma level of BNP is increased in patients with chronic heart failure in proportion to the severity of cardiac dysfunction. Because cardiac dysfunction is closely associated with a high risk of mortality in patients with diabetes mellitus, early identification and prevention of cardiac dysfunction are important. The objective of this study was to determine the effects of olmesartan medoxomil, a novel ARB, on the plasma level of BNP in hypertensive patients with type 2 diabetes. Methods: This was a preliminary, prospective, observational, open-label study. Sixty-eight type 2 diabetic patients with hypertension (systolic BP [SBP] ≥140 mmHg or diastolic BP [DBP] ≥90 mmHg) received olmesartan medoxomil 10-20mg/day for 24 weeks. Plasma levels of BNP, as well as several clinical parameters of glycaemic control and lipid metabolism, were compared before and after 24 weeks of treatment. Another group consisting of 22 ageand body mass index-matched subjects not treated with olmesartan medoxomil was observed for reference purposes. Results: In the olmesartan medoxomil group, mean±SD SBP decreased from 152.8±16.4 at baseline to 146.8±14.4 mmHg after 24 weeks' treatment (p < 0.05); similarly, mean±SD DBP decreased from 85.6±10.5 to 81.3±11.6 mmHg (p < 0.05). In 53 subjects in whom plasma levels of BNP could be measured both before and after treatment, mean±SD BNP decreased from 41.3±49.9 to 32.5±36.3 pg/mL (p < 0.05). Change in plasma BNP level over the 24-week treatment period in the olmesartan medoxomil group was not correlated with change in SBP or DBP. Multiple regression analysis revealed that change in plasma BNP level was not correlated with baseline value of or change in any other parameters. No other parameters in the olmesartan medoxomil group, and no parameters in the non-olmesartan medoxomil reference group, showed significant changes. Conclusion: The current preliminary study showed that olmesartan medoxomil treatment might decrease plasma BNP levels, independent of its BPlowering effect, in hypertensive patients with type 2 diabetes.