Assessment of antihypertensive activity in the regulatory setting.

Before a new antihypertensive drug receives regulatory approval, it must demonstrate a significant blood pressure-lowering effect over its entire dosing interval. The Food and Drug Administration recognizes several different methods for demonstrating antihypertensive activity, the gold standard continuing to be the office/casual blood pressure at the end of the dosing interval (trough). There should be at least two studies demonstrating a significant antihypertensive effect, at least one of which should include a placebo. Data obtained using ambulatory blood pressure monitoring are used for showing the time-course of the antihypertensive effect, particular attention being given to possible marked differences between the drug's maximum (peak) effect and its activity during the trough. In Europe, the Committee for Proprietary Medicinal Products also considers the office/casual blood pressure at trough to be a primary measure of outcome, responder rates using office/casual readings also being noted. The Committee recommends that data be obtained using ambulatory blood pressure monitoring in order to demonstrate a drug's antihypertensive activity. In addition, it specifically requests that a trough : peak ratio be calculated, whereas the Food and Drug Administration does not require this information.