PMID: 8938652Nov 1, 1996Paper

Comparison of the antagonistic activity of tamsulosin and doxazosin at vascular alpha 1-adrenoceptors in humans

Naunyn-Schmiedeberg's Archives of Pharmacology
K HaradaA Fujimura

Abstract

alpha 1-Adrenoceptor blockers such as prazosin and doxazosin are used to treat hypertension as well as benign prostatic hyperplasia (BPH), whereas the new alpha 1-adrenoceptor blocker tamsulosin is used only for BPH and does not reduce blood pressure at the doses used to relax prostatic smooth muscle. In contrast to prazosin, tamsulosin has a higher affinity for prostatic than vascular alpha 1-adrenoceptors in vitro. The functional correlate of this observation in humans is the subject of this study. The alpha 1-adrenoceptor blockade by oral tamsulosin (0.2 mg), doxazosin (1 mg) or placebo on finger tip vascular and dorsal hand venous alpha 1-adrenoceptors stimulated by cold treatment (immersion in ice water) and the alpha 1-adrenoceptor agonist phenylephrine, was thus studied in a 3-way crossover study in eight, healthy, male adults. Finger tip vasoconstriction after cold stimulation was assessed by laser Doppler flowmetry. A linear variable differential transformer was used to assess the drug effect on phenylephrine-induced venoconstriction. All study parameters were assessed at around 2 and 3.5 h after oral intake of doxazosin and tamsulosin respectively. The drug plasma levels were not significantly different. No significan...Continue Reading

Citations

Oct 13, 2001·Urology·M C MichelP Narayan
Dec 18, 2001·Pharmacology & Therapeutics·S W TamM Wyllie
May 9, 2006·Urologia Internationalis·Minoru KobayashiTatsuo Morita
Aug 15, 2001·BJU International·K Harada, A Fujimura
Jan 16, 2002·Drugs·Katherine A Lyseng-WilliamsonAntona J Wagstaff
Mar 12, 1999·British Journal of Clinical Pharmacology·R F SchäfersM C Michel

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