Comparative effectiveness of irbesartan/hydrochlorthiazide and valsartan/hydrochlorthiazide combination in lowering blood pressure: an observational study in Oman

KA Al Balushi, J Qasim, I Al-Zakwani. Sultan Qaboos University, Pharmacology and clinical pharmacy, POBOX:35, Oman

Introduction:

Angiotensin II receptor blockers (ARBs) such as irbesartan and valsartan are an effective antihypertensive drug option with reno- and cardio-protective effects and few adverse effects.

ARBs differ in pharmacodynamic and pharmacokinetic properties which translate into significant differences in their relative antihypertensive potency. ARBs are also available in fixed-dose combination with other antihypertensive drugs such as thiazide diuretics and calcium channel blockers.

Aims:

To evaluate blood pressure (BP) control after six months of treatment in patients with mild to moderate hypertension receiving irbesartan/hydrochlorothiazide (HCTZ) and valsartan/HCTZ at a tertiary care hospital in Oman.

Methods:

This was a retrospective observational study, conducted over three months in 2010 at Sultan Qaboos University Hospital (SQUH) in Oman. Blood pressure measurements of the patients during the study period were captured along with the six months in prior-index period. Analyses were conducted using univariate statistical techniques.

Results:

The mean age of the cohort (N=232) was 58 ± 11 years (range: 21 to 88 years) old. Diabetic patients (62% versus 37%; p < 0.001) and those with diabetic nephropathy (12% versus 4%; p = 0.039) were more likely to be prescribed irbesartan/HCTZ than valsartan/HCTZ. The irbesartan/HCTZ group was associated with significant reductions in both systolic BP (SBP) (-9 ± 21 versus -2 ± 23 mmHg; p = 0.021) and diastolic BP (SBP) (-5 ± 13 versus 0 ± 13 mmHg; p = 0.022) when compared to the valsartan/HCTZ cohort. Blood pressure reductions were noted more in diabetics than non-diabetics with the irbesartan/HCTZ group associated with significant reductions in both DBP (-6.4 ± 10 versus 1.9 ± 13 mmHg, p = 0.001) and SBP (-12 ± 19 versus 5.1 ± 25, p < 0.001).

Conclusions:

Irbesartan/HCTZ combination was associated with significant reductions in both systolic and diastolic blood pressure when compared with the valsartan/HCTZ combination. Specifically, the reductions were noted more in diabetics than non-diabetics.