Abstract: AIM: To explore the operation points and quantitative measures of clinical trial of once daily antihypertensive drugs using 24 h ambulatory blood pressure monitoring (24 h ABPM) to evaluate 24 h antihypertensive coverage. METHODS: Combined with the literature and international guideline, the collecting and recording methods of ABPM data and the calculation of trough: peak (T/P) ratios are introduced. The T/P ratios and smoothness index (SI) are analysed with primary data simulated from a real example. RESULTS: The values of individual T/P ratios are more evident than the global T/P ratios'. The T/P ratios and SI values of SBP of ABPM responders show statistical significant differences between two groups. Nevertheless the corresponding indexes of two groups are comparable for all subjects. CONCLUSION: Both the global and individual T/P ratios should be calculated and considered when evaluating the duration of action of antihypertensive agents. We should separately analysis the whole subjects and ABPM responders.

Key words: Essential hypertension, Clinical trial design, Ambulatory blood pressure, Trough peak ratio, Smoothness index