Prazosin kinetics in XXXX .

@entity1 @entity101 @entity5893 @entity3159 @entity12095
Prazosin kinetics were studied after single doses (intravenous and oral, 0.5 mg) and after increasing multiple doses (0.5 to 5 mg three times daily) in eight @entity1 with @entity101 . After intravenous administration the kinetics could be described by a linear two-compartment open model. Terminal half-life ( @entity5893 ) was about 3 hr and apparent volume of distribution ( @entity12095 ) about 0.6 l/kg. After oral doses bioavailability ranged between 55% and 82%. Since total plasma clearance was low (0.14 l/kg x hr) incomplete bioavailability was the result of incomplete absorption rather than of first-pass liver metabolism. The estimated extraction ratio was about 14%. Renal clearance was negligible; only 1% to 2% of the dose was recovered unchanged in urine. Binding to plasma proteins to both albumin and alpha 1-acid glycoprotein was substantial (97%), with albumin being most important. Increasing multiple doses showed that @entity3159 followed first-order kinetics with a linear correlation between dose and steady-state plasma concentration (P less than 0.001). There were substantial variations in plasma concentrations between @entity1 and there were also day-to-day variations in concentration within the same @entity1 .
