Comparison of the cardiovascular effects of tamsulosin oral controlled absorption system (OCAS) and alfuzosin prolonged release (XL).
OBJECTIVE
The cardiovascular (CV) effects of tamsulosin oral controlled absorption system (OCAS) 0.4 mg were compared with those of alfuzosin prolonged release (XL) 10 mg.


METHODS
Two single-dose, crossover studies were performed. In study 1, CV alpha1-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.


RESULTS
In 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 6h 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 t(max) values for both treatments were comparable.


CONCLUSIONS
Tamsulosin OCAS 0.4 mg produces smaller vascular effects than does alfuzosin XL 10 mg.
Michel
Martin C
MC
Department of Pharmacology & Pharmacotherapy, University of Amsterdam, AMC, Amsterdam, The Netherlands. M.C.Michel@amc.uva.nl
Chapple
Christopher R
CR
D000284:Administration, Oral; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D000367:Age Factors; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D003692:Delayed-Action Preparations; D004244:Dizziness / Q000139:chemically induced; D006801:Humans; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine; D011799:Quinazolines / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D013449:Sulfonamides / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D000077409:Tamsulosin; D014655:Vascular Resistance / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D003692:Delayed-Action Preparations; D011799:Quinazolines; D013449:Sulfonamides; D010656:Phenylephrine; C047638:alfuzosin; D000077409:Tamsulosin