Comparison of the Cardiovascular Effects of Tamsulosin Oral Controlled Absorption System (OCAS®) and Alfuzosin Prolonged Release (XL)

ObjectiveThe cardiovascular (CV) effects of tamsulosin oral controlled absorption system (OCAS®) 0.4 mg were compared with those of alfuzosin prolonged release (XL) 10 mg.MethodsTwo single-dose, crossover studies were performed. In study 1, CV α1-adrenoceptor antagonism was assessed by measuring the inhibition of phenylephrine (PE)-induced increases in diastolic blood pressure (DBP) and total peripheral resistance (TPR) before and after dosing with placebo, tamsulosin OCAS, and alfuzosin XL in 18 young subjects. In study 2, orthostatic stress tests (OTs) were performed before and after dosing with tamsulosin OCAS and alfuzosin XL in 40 elderly subjects. Pharmacokinetics were assessed in both studies.ResultsIn study 1, tamsulosin OCAS induced statistically significantly less inhibition of PE-induced increases in DBP at 2 h after dosing and in TPR at 2 and 4 h after dosing than alfuzosin XL. In study 2, tamsulosin OCAS had a lower incidence of positive OTs than did alfuzosin XL, with the difference between both treatments being statistically significant at 6 h after dosing and for all time points after dosing combined. This was in line with smaller changes in vital signs observed for tamsulosin OCAS. The tmax values for both treatments were comparable.ConclusionsTamsulosin OCAS 0.4 mg produces smaller vascular effects than does alfuzosin XL 10 mg.