Adherence to medication and drug monitoring in apparent treatment-resistant hypertension.

Poor drug adherence is one of the main reasons for the failure to achieve treatment targets in hypertensive patients. In patients who receive pharmacological treatment, assessment of drug adherence is of the utmost importance. The aim of this review is to present an update of the methods available to reveal and monitor non-adherence in patients with apparent treatment-resistant hypertension. Methods for monitoring adherence are divided into indirect and direct methods. The indirect methods are mainly based on self-reported adherence and can easily be manipulated by the patient. Directly observed therapy and therapeutic drug monitoring are examples of direct methods. There are limitations and advantages to all of the methods, and because of the patient's ability to manipulate the outcome of indirect methods, direct methods should be preferred. Therapeutic drug monitoring and directly observed therapy with subsequent ambulatory blood pressure measurement are considered to be reliable methods and should be used more in the routine assessment of patients with apparent treatment-resistant hypertension.