Suboptimal adherence to once-daily antihypertensives, tracked via electronic dosing histories, is a major driver of poor blood pressure control.
Early discontinuation of treatment and suboptimal daily execution of the prescribed regimens are the most common facets of poor adherence with once a day antihypertensive drug treatments. The shortfalls in drug exposure that these dosing errors create might be a common cause of low rates of blood pressure control and high variability in responses to prescribed antihypertensive drugs.
Vrijens et al. (2008) studied this question.