A pharmacodynamic assessment of the impact of antihypertensive non-adherence on blood pressure control

Objectives - To evaluate if antihypertensive regimens that conform to prese nt FDA guidelines by maintaining greater than or equal to 50% of their peak effect at the end of the dosing interval protect patients during sporadic lapses in adherence. Methods - 169 patients on monotherapy for high blood pressure underwent ele ctronic adherence monitoring for 3 months. Blood pressures were measured du ring non-study office visits and were retrieved from automated medical reco rds. Questionnaires were used to obtain other covariate information. The ra tio of the dosing interval to the half-life of drug activity (I') was used to capture conformity with FDA guidelines. Data analysis focused on the int eraction between I' and the impact on blood pressure of delayed dosing. Results - The average (+/- standard deviation) blood pressure during the st udy was 139.0(+/-12.0)/85.0(+/-6.9) mm Hg. Lisinopril followed by sustained -release verapamil, atenolol, and hydrochlorothiazide were the most frequen tly prescribed agents. The majority of regimens (99%) conformed to FDA dosi ng guidelines. Of the patients 23% missed a dose before their blood pressur e check. Non-adherence, however, did not have a direct impact on blood pres sure, and no interaction with I' of was detected. Conclusions - Among patients with relatively mild hypertension on single-dr ug therapy, regimens that conform to current FDA dosing guidelines may prev ent losses of blood pressure control during episodic lapses of adherence. T hese findings should be replicated in other patient populations with standa rdized blood pressure measurement to confirm their validity. Copyright (C) 2000 John Wiley & Sons, Ltd.