Improved liquid chromatographic method for the simultaneous determination of tramadol and its three main metabolites in human plasma, urine and saliva

• Published in: Journal of pharmaceutical and biomedical analysis 2007-09, Vol.44 (5), p.1168-1173
• Main Authors: Ardakani, Yalda H., Rouini, Mohammad-Reza
• Format: Article
• Language: English
• Subjects: Analgesics, Opioid - blood; Analgesics, Opioid - chemistry; Analgesics, Opioid - metabolism; Analgesics, Opioid - pharmacokinetics; Analgesics, Opioid - urine; Analysis; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Calibration; Chromatography, Liquid - methods; Fundamental and applied biological sciences. Psychology; General pharmacology; Humans; Hydrogen-Ion Concentration; Medical sciences; Methanol - chemistry; Molecular Structure; Monolithic; N-Desmethyltramadol; O,N-Didesmethyltramadol; O-Desmethyltramadol; Pharmacology. Drug treatments; Phosphoric Acids - pharmacology; Plasma; Reference Standards; Reproducibility of Results; Saliva; Saliva - metabolism; Sensitivity and Specificity; Solutions - chemistry; Stereoisomerism; Tablets; Time Factors; Tramadol; Tramadol - blood; Tramadol - chemistry; Tramadol - metabolism; Tramadol - pharmacokinetics; Tramadol - urine; Urine; Water - chemistry
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2007.04.012

Tramadol, an analgesic agent, and its main metabolites O-desmethyltramadol (M1), N-desmethyltramadol (M2) and O,N-didesmethyltramadol (M5) were determined simultaneously in human plasma, saliva and urine by a rapid and specific HPLC method. The sample preparation was a simple, one-step, extraction with ethyl acetate. Chromatographic separation was achieved with a Chromolith™ Performance RP-18e 100 mm × 4.6 mm column, using a mixture of methanol:water (19:81, v/v) adjusted to pH 2.5 by phosphoric acid, in an isocratic mode at flow rate of 2 ml/min. Fluorescence detection ( λ ex 200 nm/ λ em 301 nm) was used. The calibration curves were linear ( r 2 > 0.996) in the concentration ranges in plasma, saliva and urine. The lower limit of quantification was 2.5 ng/ml for all compounds. The within- and between-day precisions in the measurement of QC samples at four tested concentrations were acceptable in all analyzed body fluids The developed procedure was applied to assess the pharmacokinetics of tramadol and its main metabolites following administration of 100 mg single oral dose of tramadol to healthy volunteers.