Background: Modern drugs should be given once daily. Smoothness index (SI) can measure the 24hour effectiveness of antihypertensive drugs. Objective: To determine the 24hour effectiveness of metoprolol tartrate ušed once daily using SI. Patients and methods: Thirty newly diagnosed hypertension patients treated with metoprolol tartrate at a mean dose of 150 mg once a day. Blood pressure measurement using mercury sphygmomanometer and 24hour ambulatory blood pressure monitoring according to the WHO criteria. Determination of the SI by calculating the average BP values for each hour of the 24-hour monitoring period, both before and during treatment. Obtain all hourly changes in BP induced by treatment. The average of these hourly values divi-ded by its standard deviation. Data from individual patients average to obtain mean values (+ standard devi-ation and 95 % confidence interval) for the group as a whole. Results: SI of metoprolol tartrate for systolic blood pressure was 1, 26 ± 0, 87 (95 % CI, 0, 95-1, 57) and for diastolic blood pressure was 1, 46 + 1, 13 (95% CI, 1, 06-1, 86). Conclusion: SI of metoprolol tartrate is higher than 1.0 for both systolic and diastolic blood pressure values. According to the value of SI metoprolol tartrate has sufficient 24hour effectiveness and may be ušed once daily.

        Key words: hypertension, beta-blockers, metoprolol tartrate, smoothness index.