title: Pharmacokinetics of an immediate and extended release oral morphine formulation utilizing the spheroidal oral drug absorption system in dogs.
abstract: This study investigated the pharmacokinetics of a human-labeled oral morphine formulation consisting of both immediate and extended release components in dogs. In a randomized design, 14 dogs were administered either 1 or 2 mg/kg morphine orally. Blood samples were collected up to 24 h post drug administration. Plasma concentrations of morphine were measured using high-pressure liquid chromatography with electrochemical coulometric detection. For both groups, maximal concentration occurred at 3 h post drug administration followed by a gradual decrease in morphine concentration over 24 h. There was substantial variability in morphine concentrations among dogs. The higher dose group produced a greater exposure (higher area-under-the-curve), higher peak concentration, longer half-life and a shorter time to peak concentration (t(max)). The specific oral morphine formulation used in this study produced sustained plasma morphine concentrations over 24 h compared with previous intravenous dosing and immediate-release oral morphine studies. However, the low morphine plasma concentrations and high variability produced from this formulation, suggest that the clinical application of this formulation at the doses evaluated in this study are limited.
authors.affiliation: Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA, USA. aragon8@msn.com
authors.forename: C L
authors.initials: CL
authors.lastname: Aragon
authors.forename: M R
authors.initials: MR
authors.lastname: Read
authors.forename: J S
authors.initials: JS
authors.lastname: Gaynor
authors.forename: M D
authors.initials: MD
authors.lastname: Barnhart
authors.forename: D
authors.initials: D
authors.lastname: Wilson
authors.forename: M G
authors.initials: MG
authors.lastname: Papich
mesh_terms: D000284:Administration, Oral; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D003692:Delayed-Action Preparations; D004285:Dogs / Q000097:blood / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006207:Half-Life; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D010146:Pain / Q000188:drug therapy / Q000662:veterinary; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D003692:Delayed-Action Preparations; D009020:Morphine