title: Influence of phenobarbital on morphine metabolism and disposition: LC-MS/MS determination of morphine (M) and morphine-3-glucuronide (M3G) in Wistar-Kyoto rat serum, bile, and urine.
abstract: A simple LC-MS/MS method has been developed and validated for the simultaneous determination of morphine (M) and morphine-3-glucuronide (M3G) in rat serum, bile, and urine. Deuterated D3-M and D3-M3G were used as internal standards (IS) for M and M3G, respectively. Serum samples were processed by acetonitrile precipitation. Bile samples were prepared by solid-phase extraction (SPE) using Oasis MCX cartridges. Urine samples were directly analyzed after dilution with mobile phase. Chromatography was performed using a Luna C18 column (5 microm, 150x2.1 mm I.D.). The mobile phase consisted of acetonitrile (ACN) and 7.5 mM ammonium formate (pH 9.3) delivered from separate pumps with a simple gradient. The method was validated to quantify M in the range of 1-1000 ng/ml in bile and serum, and 0.025-25 microg/ml in urine. M3G was quantified in the range of 1-1000 ng/ml in serum, 0.1-100 microg/ml in bile, and 0.05-25 microg/ml in urine. The method was applied to study the pharmacokinetics and disposition of M and M3G in Wistar-Kyoto (WKY) rats, and the effect of phenobarbital (PB) on M and M3G disposition. M is metabolized to M3G at a lower rate in male than female rats leading to higher M levels and lower M3G levels in serum, urine, and bile of male than female rats. PB administration induces M glucuronidation to M3G in male, but not female WKY rats, and abolishes the gender differences in M and M3G pharmacokinetics.
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Yazen M
authors.initials: YM
authors.lastname: Alnouti
authors.forename: Melinda K
authors.initials: MK
authors.lastname: Shelby
authors.forename: Chuan
authors.initials: C
authors.lastname: Chen
authors.forename: Curtis D
authors.initials: CD
authors.lastname: Klaassen
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry*; D005260:Female; D008297:Male; D009020:Morphine / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D009022:Morphine Derivatives / Q000097:blood / Q000378:metabolism / Q000652:urine; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D011921:Rats, Inbred WKY
chemical_list: D009022:Morphine Derivatives; D009020:Morphine; C018108:morphine-3-glucuronide; D010634:Phenobarbital