Clinical Adverse Events Profile during Combination Therapy with Amlodipine and Hydrochlorothiazide in Hypertensive Nigerians

Abstract

Background: Combination therapy with antihypertensive drugs from different classes has been recommended as an effective strategy to attain blood pressure (BP) goal. Although amlodipine (AML) and hydrochlorothiazide (HCZ) are frequently used as combination therapy in Nigeria, information regarding the adverse events associated with this regimen is scarce. Objective: To evaluate the clinical adverse events profile associated with a regimen of AML and HCZ therapy for 48 weeks (wks) in hypertensive Nigerians. Methods: Ninety male (M) and female (F) Nigerians aged 31-86 years with newly diagnosed uncomplicated essential hypertension (BP > 160/90 ≤ 180/120 mmHg), were enrolled. Patients, who were 30 each (15 Ms and 15 Fs) in AML, HCZ and AML-HCZ groups, were treated, respectively, with AML 5mg for 6 wks and the dose increased to 10mg till wk 12 (end of monotherapy) after which HCZ 25mg was added; HCZ 25mg till wk 6 (end of monotherapy) after which AML 5-10mg was added as needed; and AML 5-10mg + HCZ 25mg. Body mass index (BMI), BP and heart rate (HR) were assessed at baseline and at the end of wks 1, 3, 6, 12, 24, 36, and 48 during treatment. Adverse drug events were similarly monitored beginning from wk 1. Results: The three combination regimens comparably significantly reduced BP, though the effect in AML group was greater than the rest (P<0.05). Changes in BMI and HR were not statistically significant. Sixty one events of which polyuria, tachycardia and slight weight reduction were commonest as well as nausea and diaphoresis were recorded in AML group. Similarly, 91 events were observed in HCZ group, polyuria, tachycardia and weight loss being commonest plus impotence and visual disturbance. Although tachycardia and weight loss were more prominent among the 74 events in AML-HCZ group, polyuria was surprisingly uncommon. It is demonstrated that a regimen of AML to which HCZ is subsequently added provides superior tolerability and less bother to patients when compared with a regimen of HCZ to which AML is added as needed or with ab initio AML-HCZ combination therapy.