caa a22 4500 477126499 CHVBK 20180405111651.0 cr unu---uuuuu 170330e19971201xx s 000 0 eng 10.1023/A:1012104518554 doi (NATIONALLICENCE)springer-10.1023/A:1012104518554 Stereoselective Disposition of Suspensions of Conventional and Wax-matrix Sustained Release Ibuprofen Microspheres in Rats [Elektronische Daten] [Christianah Adeyeye, Fen-Fang Chen] Purpose. The aim of the study is to evaluate stereoselective in vivo disposition of suspensions of conventional and wax-matrix sustained release ibuprofen microspheres in rats. Methods. Male wistar rats were dosed IV with 20 mg/kg, or orally with conventional suspension, and three suspension formulations of sustained release microspheres (having three different particle sizes) of racemic ibuprofen. Blood samples were analyzed stereoselectively by reverse phase HPLC. Results. The mean Cmax for (S)- and (R)- ibuprofen decreased with increased particle size of the drug or microspheres in the suspension dosage forms, while the Tmax increased with increased particle size. The mean S/R ratio (AUC0−48) of the suspensions decreased with increase in particle size of the drug or microspheres and these ratios (for both conventional and sustained formulations) were higher than that of the IV, an indication of presystemic inversion. Decrease in the ratios with increased particle size is suggestive of formulation dependent inversion. The plasma concentration-time data of the sustained release formulations showed bimodal profiles, irrespective of the particle size of the microspheres. The second peak observed after 8 hours is indicative of colonic absorption. Conclusions. Stereoselective disposition of ibuprofen microspheres showed higher bioavailability compared to the conventional suspension. Bimodal disposition is influenced by dosage form while presystemic inversion is both site-specific, and dosage form dependent. Plenum Publishing Corporation, 1997 Stereoselective disposition nationallicence microspheres nationallicence ibuprofen nationallicence particle size nationallicence Adeyeye Christianah Graduate School of Pharmaceutical Sciences, Duquesne University, 15282, Pittsburgh, Pennsylvania aut Chen Fen-Fang Graduate School of Pharmaceutical Sciences, Duquesne University, 15282, Pittsburgh, Pennsylvania aut Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/12(1997-12-01), 1811-1816 0724-8741 14:12<1811 1997 14 11095 https://doi.org/10.1023/A:1012104518554 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1012104518554 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Adeyeye Christianah Graduate School of Pharmaceutical Sciences, Duquesne University, 15282, Pittsburgh, Pennsylvania aut NATIONALLICENCE 700 1- Chen Fen-Fang Graduate School of Pharmaceutical Sciences, Duquesne University, 15282, Pittsburgh, Pennsylvania aut NATIONALLICENCE 773 0- Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/12(1997-12-01), 1811-1816 0724-8741 14:12<1811 1997 14 11095 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer