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

Objectives - To evaluate if antihypertensive regimens that conform to present FDA guidelines by maintaining ≥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 electronic adherence monitoring for 3 months. Blood pressures were measured during non-study office visits and were retrieved from automated medical records. Questionnaires were used to obtain other covariate information. The ratio 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 interaction between I′ and the impact on blood pressure of delayed dosing. Results - The average (± standard deviation) blood pressure during the study was 139.0(±12.0)/85.0(±6.9) mm Hg. Lisinopril followed by sustained-release verapamil, atenolol, and hydrochlorothiazide were the most frequently prescribed agents. The majority of regimens (99%) conformed to FDA dosing guidelines. Of the patients 23% missed a dose before their blood pressure check. Non-adherence, however, did not have a direct impact on blood pressure, and no interaction with I′ of was detected. Conclusions - Among patients with relatively mild hypertension on single-drug therapy, regimens that conform to current FDA dosing guidelines may prevent losses of blood pressure control during episodic lapses of adherence. These findings should be replicated in other patient populations with standardized blood pressure measurement to confirm their validity.