title: Development and validation of a rapid HPLC method for simultaneous determination of tramadol, and its two main metabolites in human plasma.
abstract: Tramadol, an analgesic agent, and its two main metabolites O-desmethyltramadol (M1) and N-desmethyltramadol (M2) were determined simultaneously in human plasma by a rapid and specific HPLC method. The sample preparation was a simple extraction with ethyl acetate. Chromatographic separation was achieved with a Chromolith Performance RP-18e 50 mm x 4.6 mm column, using a mixture of methanol:water (13:87, v/v) adjusted to pH 2.5 by phosphoric acid, in an isocratic mode at flow rate of 2 ml/min. Fluorescence detection (lambda(ex)=200 nm/lambda(em)=301 nm) was used. The calibration curves were linear (r(2)>0.997) in the concentration range of 2.5-500 ng/ml, 1.25-500 ng/ml and 5-500 ng/ml for tramadol, M1 and M2, respectively. The lower limit of quantification was 2.5 ng/ml for tramadol, 1.25 ng/ml for M1 and 5 ng/ml for M2. The within- and between-day precisions in the measurement of QC samples at four tested concentrations were in the range of 2.5-9.7%, 2.5-9.9% and 5.9-11.3% for tramadol, M1 and M2, respectively. The developed procedure was applied to assess the pharmacokinetics of tramadol and its two main metabolites following administration of 100mg single oral dose of tramadol to healthy volunteers.
authors.affiliation: Biopharmaceutics and Pharmacokinetics Division, Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran 14155-6451, Iran.
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Rouini
authors.forename: Yalda Hosseinzadeh
authors.initials: YH
authors.lastname: Ardakani
authors.forename: Faezeh
authors.initials: F
authors.lastname: Soltani
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein
authors.forename: Alireza
authors.initials: A
authors.lastname: Foroumadi
mesh_terms: D000701:Analgesics, Opioid / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D014147:Tramadol / Q000097:blood* / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D000701:Analgesics, Opioid; D014147:Tramadol