Can drugs work in patients who do not take them? The problem of non-adherence in resistant hypertension.

Patients with uncontrolled hypertension on adequate combination and doses of blood pressure-lowering drugs present a diagnostic and therapeutic dilemma. Currently, hypertension guidelines point out uncommon causes of hypertension (either organic such as secondary hypertension or drugs/substances interfering with blood pressure-lowering drugs or causing hypertension) as a cause of hypertension resistance. Non-adherence to drugs, however, is equally, if not more, a cause of hypertension resistance. True resistance to pharmacotherapy is relatively uncommon, as in the majority of patients with non-adherence and/or secondary hypertension, the diagnosis of the problem may potentially lead to better control. Conventionally applied indirect methods to detect non-adherence are inadequate to uncover all cases of non-adherence, especially intentional non-adherence. Rigorous methods to detect non-adherence including direct observed therapy and measuring drug/metabolite levels in body fluids should be considered simultaneously if not before costly and invasive investigations for patients with difficult to control hypertension. However, data on the effectiveness of whether diagnosing non-adherence ultimately controls hypertension is still awaited.