Therapeutic Research

Abstract

Objective：This study was conducted in essential hypertension patients showing inadequate response to a combined antihypertensive drug regimen including olmesartan medoxomil, to clarify whether additional antihypertensive and organ−protective effects could be obtained by substituting olmesartan medoxomil with valsartan.Methods：In 14 patients（8 males, 6 females；mean age, 71 years）who showed systolic blood pressure readings of 140 mmHg or over despite 6 months or longer treatment with oral olmesartan medoxomil at 20 to 40 mg／day, the systolic blood pressure, diastolic blood pressure, pulse rate, and urinary albumin excretion were measured. Then, olmesartan medoxomil 20 mg／day was switched to valsartan 80 mg／day, and olmesartan medoxomil 40mg／day to valsartan 160 mg／day. Until 1 year after the drug switch, the same measurements were performed every 3 months. In addition, echocardiography and brachial−ankle pulse wave velocity（baPWV）measurement were performed at the time of the drug switch to valsartan and at 1 year after the drug switch.Results：Significant reduction of both the systolic and diastolic blood pressures were obtained following the drug switch from olmesartan medoxomil to valsartan（p＝0.0010, p＝0.0369）. No significant change in the heart rate was detected（p＝0.4169）. Urinary albumin excretion was also significantly reduced by the switch to valsartan（p＝0.0443）. No significant change was detected in the left ventricular diameter or left ventricular wall thickness when comparing the echocardiograms obtained before and after the drug switch to valsartan, but the peak systolic wall stress and baPWV were significantly reduced after the change to valsartan（p＝0.0417, 0.0229）.Conclusions：In patients who failed to show adequate control of the blood pressure while receiving a combined antihypertensive drug regimen including olmesartan medoxomil,significant antihypertensive and organ−protective effects were produced when olmesartan medoxomil was switched to valsartan. The present results suggest that a change of olmesartan medoxomil to valsartan in patients receiving, but showing poor response, to a combined antihypertensive drug regimen containing the former might prove effective in achieving the treatment objectives.