Pharmacokinetics of prazosin administered as gastro-intestinal-therapeutic-systems to 24 healthy volunteers
Fourtillan, J.B.; Brisson, A.M.; Couet, W.
Therapie 48(2): 115-118
1993
ISSN/ISBN: 0040-5957 PMID: 8351678 Document Number: 418770
Pharmacokinetics of prazosin was investigated after single dose administrations of four different formulations, according to a randomized trial, to 24 young healthy volunteers: immediate release tablets (3 x 1 mg) used as reference (Treatment A), two new Gastro-Intestinal-Therapeutic-Systems (GITS) containing 2.5 mg (Treatment B) and 5 mg (Treatment C) of prazosin, and a traditional sustained release formulation (4 mg, treatment D). Relative bioavailability of prazosin administered as GITS was only 49.4 +/- 19.5% (B) and 45.5 +/- 18.7 (C) versus 73.8 +/- 13.9% (D) (area under the curve normalized at 3 mg dosing); but absorption was sustained and plasma concentrations were maintained at a virtually constant level for a time period close to 24 h. As a result, mean residence time (MRT) of prazosin was considerably increased after GITS administration: 21.6 +/- 1.0 h (B), 22.5 +/- 1.6 h (C) instead of 5.9 +/- 0.2 h for the reference formulation (A) and 10.8 +/- 0.8 h for the traditional sustained release formulation (D). Although extrapolation to multiple dosing situations is difficult, this study demonstrates the potential suitability of prazosin GITS for once daily administrations.
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