Drug resistance, inappropriate dosing and non‐compliance in hypertensive patients.

1 From an understanding of the biological fate and hypotensive effect of debrisoquine (D) we have assessed the relative importance of true drug resistance, inappropriately low dosage and non-compliance as causes of apparent resistance to treatment with this drug. 2 Among 37 hypertensive patients prescribed D, eleven (30%) were non-compliant on the day of testing. 3 Non-compliance was found in 64% of patients with poor blood pressure control but only 15% of patients with intermediate and good blood pressure control (P less than 0.02). 4 Five patients received doses which were too low for pharmacological effect while in a further five an increase in dose may have improved blood pressure control. 5 Resistance to D was uncommon indicating that non-compliance and inadequate dosing are the major causes of apparent resistance to treatment with this compound.