title: Pharmacokinetics of intrarectal omeprazole in alpacas.
abstract: The purpose of this study was to evaluate the pharmacokinetics of omeprazole in three different vehicles when administered rectally to six alpacas. Alpacas were given single doses of omeprazole (4 mg/kg) in a double-blinded, randomized cross-over design with a 1 week washout period. Omeprazole formulations consisted of (1) Treatment A: omeprazole paste mixed in surgical lubricant (2) Treatment B: omeprazole capsule contents in 8.4% sodium bicarbonate and (3) Treatment C: omeprazole capsule contents in surgical lubricant and 8.4% sodium bicarbonate solution. Plasma samples were drawn at 0, 5, 10, 15, 30, 45, 60, 90, 120, 180, 300 and 480 min. Omeprazole plasma concentrations were determined by high-pressure liquid chromatography-mass spectrometry. Pharmacokinetic results demonstrated median peak plasma concentrations (C(max)) of 7.35 (3.2-15.2), 7.30 (1.7-10.9) and 8.65 (1.8-19.3) ng/mL and median area under the concentration curve (AUC((0-180))) of 747 (237-1681) min x ng/mL, 552.9 (39-1063) min x ng/mL, and 972 (107-1841) min x ng/mL for treatments A, B and C, respectively. The median half-lives were similar between groups: 38, 50, and 53 min. As a result of the low measured omeprazole plasma concentrations, it is assumed that rectal absorption of omeprazole is poor in alpacas and not an effective route of administration.
authors.affiliation: W.R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, CA 95616, USA. tlmarmulak@ucdavis.edu
authors.forename: T
authors.initials: T
authors.lastname: Marmulak
authors.forename: S
authors.initials: S
authors.lastname: Stanley
authors.forename: P H
authors.initials: PH
authors.lastname: Kass
authors.forename: V
authors.initials: V
authors.lastname: Wiebe
authors.forename: D
authors.initials: D
authors.lastname: McKemie
authors.forename: N
authors.initials: N
authors.lastname: Pusterla
mesh_terms: D000285:Administration, Rectal; D000818:Animals; D000897:Anti-Ulcer Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002161:Camelids, New World / Q000378:metabolism*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006207:Half-Life; D008297:Male; D013058:Mass Spectrometry; D009853:Omeprazole / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D017693:Sodium Bicarbonate / Q000008:administration & dosage
chemical_list: D000897:Anti-Ulcer Agents; D017693:Sodium Bicarbonate; D009853:Omeprazole