title: High-performance liquid chromatographic assay for morphine in small plasma samples: application to pharmacokinetic studies in rats.
abstract: In order to perform a reliable pharmacokinetic study of morphine during subchronic treatment in rats, an easy, rapid, sensitive and selective analytical method was proposed and validated. The analyte and internal standard (naloxone) were extracted from plasma samples (100 microL) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography (HPLC) along with electrochemical detection (ED). Standard calibration graphs were linear within a range of 3.5-1,000 ng/mL (r=0.999). The intra-day coefficients of variation (CV) were in the range of 5.8-8.5% at eight concentration levels (7-1,000 ng/mL) and the inter-day coefficient of variation ranged from 7.4 to 8.8%. The intra-day assay accuracy was in the range of -5-10% and the inter-day assay accuracy ranged from 3.0 to 9.3% of relative error (RE). The limit of quantification was 3.5 ng/mL using a plasma sample of 100 microL (15.8% of CV and 12.8% of RE). Plasma samples were stable for 2 months at -20 degrees C. This method was found to be suitable for pharmacokinetic studies in rats, after subcutaneous administration of morphine (5.6 mg/kg per day) in subchronic treatment for 6 and 12 days.
authors.affiliation: Departamento Sistemas Biológicos, UAM-Xochimilco, Calzada del Hueso 1100, Col. Villa Quietud, 04960 Delegación Coyoacán, México D.F., México. adoming@correo.xoc.uam.mx
authors.forename: Adriana Miriam
authors.initials: AM
authors.lastname: Domínguez-Ramírez
authors.forename: Alma Rosa
authors.initials: AR
authors.lastname: Cortés-Arroyo
authors.forename: Marcela Hurtado Y de la
authors.initials: MH
authors.lastname: Peña
authors.forename: Kazuko
authors.initials: K
authors.lastname: Aoki-Maki
authors.forename: José Raúl Medina
authors.initials: JR
authors.lastname: López
authors.forename: Camilo
authors.initials: C
authors.lastname: Ríos-Castañeda
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: López-Muñoz
mesh_terms: D000701:Analgesics, Opioid / Q000097:blood* / Q000493:pharmacokinetics*; D000818:Animals; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D005260:Female; D007202:Indicators and Reagents; D009020:Morphine / Q000097:blood* / Q000493:pharmacokinetics*; D011786:Quality Control; D051381:Rats; D017208:Rats, Wistar; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D000701:Analgesics, Opioid; D007202:Indicators and Reagents; D009020:Morphine