Differences in pharmacology and their translation into differences in clinical efficacy--a comparison of the renin angiotensin blocking agents irbesartan and losartan.

Guidelines recommend five antihypertensive drug classes, but which particular drug to choose is up to the treating physician. We aimed at an in-depth comparison of two frequently used angiotensin receptor blockers to provide evidence for this decision. Pharmacology of irbesartan and losartan, their blood-pressure-lowering efficacy, their tolerability/safety, end-organ protective effects and economic evaluation. Both drugs differ in their oral bioavailability, potential for food interactions, degree of metabolism, dosing interval, time to peak, volume of distribution and terminal half-life. Irbesartan provides a greater and longer-lasting antihypertensive effect and was determined to be cost effective over losartan in Denmark and Sweden. Irbesartan was more effective in preventing deterioration of kidney function in patients with diabetic nephropathy, being cost effective from a German perspective. There is only one end point trial for either drug in patients with left ventricular hypertrophy, heart failure and atrial fibrillation, but no direct comparison. There is an incremental clinical benefit of irbesartan over losartan in the treatment of hypertension and diabetic nephropathy which can be substantiated by corresponding preclinical study evidence. This has translated into an economic benefit in a number of country-specific evaluations.