Twenty-four-hour ambulatory blood pressure evaluation of antihypertensive agents

EVALUATION OF A SMOOTH BLOOD PRESSURE RESPONSE TO TREATMENT: Smooth or uniform blood pressure control is an obvious goal of antihypertensive therapy, but it is difficult to assess by the traditional clinic blood pressure measurements. Ambulatory blood pressure monitoring is therefore increasingly being used to evaluate new antihypertensive drugs and to assess the adequacy of treatment. The use of ambulatory blood pressure monitoring is based on two assumptions: that treatment must be continuously optimal, and that more frequent blood pressure measurements during treatment, particularly at different times and during various types of activity and mental states, may lead to a more accurate assessment than infrequent measurements in the clinic. When ambulatory blood pressure monitoring is used, the effect of a given antihypertensive agent or of a given antihypertensive regimen can be tested on the average blood pressure values over 24 h, or on day- or night-time values. The actual verification of the achievement of a uniform reduction of blood pressure throughout the 24-h time span can be achieved by comparing 24-h blood pressure profiles before treatment and during treatment. The so-called trough: peak ratio is generally used in an attempt at a more quantitative assessment of smooth control. Recently, we have developed the Smoothness Index, defined as the ratio between the mean hourly change in blood pressure (calculated over the 24-h period), divided by the standard deviation of these hourly changes. We have some indication that this may be a more accurate measurement of smooth blood pressure control under therapy than trough: peak ratios. TWENTY-FOUR-HOUR BLOOD PRESSURE CONTROL BY IRBESARTAN: Ambulatory blood pressure assessments are important during the clinical testing of new antihypertensive agents. Our group recently performed a multicenter study to compare the anti-hypertensive effect of three irbesartan dose regimens (75 mg once a day, 150 mg once a day, 75 mg twice a day) and placebo as measured by 24-h ambulatory blood pressure monitoring and confirmed by office blood pressure measurements. All irbesartan regimens were significantly more effective than placebo. Irbesartan at 150 mg once a day provided clinically significant and sustained blood pressure reductions over a full 24 h and had the highest trough: peak ratio and Smoothness Index. No additional benefit was observed with twice-daily dosing using irbesartan at 75 mg compared with a single daily at 150 mg. Therefore irbesartan at a single daily dose of 150 mg offers real efficacy with the potential for greater ease of administration compared with twice-daily antihypertensive therapy.