A pharmacodynamic and pharmacokinetic assessment of a new alpha-adrenoceptor antagonist, doxazosin (UK33274) in normotensive subjects.
1 Doxazosin is a quinazoline derivative, related to prazosin, recently developed for the treatment of hypertension. 2 The intravenous administration of doxazosin (12 micrograms/kg) to six healthy normotensive subjects resulted in significant fall in erect blood pressure, with a corresponding increase in heart rate, but there were no significant changes in supine blood pressure or heart rate. 3 The changes in blood pressure and heart rate were maximal at 6 h after intravenous dosing. With prazosin the maximum effects occurred within the first hours. 4 Pressor response studies with phenylephrine confirmed that doxazosin is a relatively selective postsynaptic alpha-adrenoceptor antagonist. 5 The mean elimination half-life of doxazosin was 11 h. This compared with a T1/2 of 2.5 h for prazosin.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000328:Adult; D000959:Antihypertensive Agents / Q000378:metabolism / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D017292:Doxazosin; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008297:Male; D011224:Prazosin / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D000959:Antihypertensive Agents; D011799:Quinazolines; D017292:Doxazosin; D011224:Prazosin