Novel MethodsTherapeutic Drug Monitoring to Assess Drug Adherence in Assumed Resistant Hypertension A Comparison With Directly Observed Therapy in 3 Nonadherent PatientsFeyz, Lida MD*; Bahmany, Soma BSc†; Daemen, Joost MD, PhD*; van den Meiracker, Anton H. MD, PhD‡; Koch, Birgit C. P. PhD†; van Gelder, Teun MD, PhD†,‡; Versmissen, Jorie PharmD, MD, PhD‡Author Information *Department of Cardiology, Thorax Center, Erasmus Medical Center, Rotterdam, the Netherlands; Departments of †Hospital Pharmacy; and ‡Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands. Reprints: Jorie Versmissen, MD, PhD, Department of Internal Medicine, Erasmus University Medical Center, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands (e-mail: firstname.lastname@example.org). The authors report no conflicts of interest. Received March 05, 2018 Accepted May 01, 2018 Journal of Cardiovascular Pharmacology: August 2018 - Volume 72 - Issue 2 - p 117-120 doi: 10.1097/FJC.0000000000000602 Buy Metrics Abstract Abstract: Resistant hypertension is a common health problem leading to suboptimal cardiovascular prevention. A large number of patients with resistant hypertension have poor medication adherence explaining their assumed resistance to therapy. We combined directly observed therapy (DOT) with therapeutic drug monitoring (TDM) in 3 patients at several time points to enable an extensive feedback on blood pressure (BP) and drug levels. BP was measured with an automatic oscillatory device at regular intervals of 5 minutes (directly before and after drug intake) and at 30-minute intervals (at night) during admission. Blood samples were obtained at different time points (t = in hours; t = 0, 2, 4, 6, 12, and 24 hours after drug intake). DOT was performed under supervision of the physician. In 2 of the 3 patients, automated BP decreased directly after DOT, −10/0 and −5/−5 mm Hg, respectively. Plasma drug levels for several drugs or active metabolites were 0 at t = 0, whereas plasma levels were positive at t = 24 hours after observed intake. We recommend a more frequent use of TDM combined with repeated BP measurements in clinical practice because this is a convenient, objective method of measurement and to ensure that actual drug levels reflect the BP at the time of measurement. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.