title: Determination of oseltamivir carboxylic acid in human serum by solid phase extraction and high performance liquid chromatography with UV detection.
abstract: This study was aimed at developing a fast and sensitive method for determination of oseltamivir carboxylic acid (OCA), the active moiety of anti-influenza agent, oseltamivir phosphate, in human serum by high performance liquid chromatography and UV detection. The analyte and an internal standard (vanillin) were extracted from human serum by a solid phase extraction (SPE) procedure. Chromatographic separation was achieved using a reverse phase C18 column with a mobile phase consisting of 0.05M phosphate buffer containing triethylamine (1mL/L; pH 3.0) and acetonitrile (70:30, v/v). The detection wavelength was set at 215nm. The average recoveries of the drug and internal standard were 98 and 85%, respectively. The calibration curve was linear over a concentration range of 15-6400ng/mL of OCA in human serum. The lower limits of detection and quantification were 5 and 15ng/mL, respectively. The coefficient variation values of both inter- and intra-day analysis were less than 12% whereas the percentage error was less than 4.5. The stability of the drug at the serum samples maintained at -40 degrees C for 60 days was found to be 100% from the initial value and no interferences were found from either endogenous components in serum or commonly co-administrated antiviral drugs. The validated method was applied to a randomized cross-over bioequivalence study of two different oseltamivir phosphate preparations in 24 healthy volunteers.
authors.affiliation: Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran; School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran. gbahrami@kums.ac.ir <gbahrami@kums.ac.ir>
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Bahrami
authors.forename: Bahareh
authors.initials: B
authors.lastname: Mohammadi
authors.forename: Amir
authors.initials: A
authors.lastname: Kiani
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000097:blood*; D002264:Carboxylic Acids / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D018592:Cross-Over Studies; D004355:Drug Stability; D004791:Enzyme Inhibitors / Q000097:blood; D006801:Humans; D008297:Male; D009439:Neuraminidase / Q000037:antagonists & inhibitors; D053139:Oseltamivir / Q000097:blood* / Q000493:pharmacokinetics; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013810:Therapeutic Equivalency
chemical_list: D000998:Antiviral Agents; D002264:Carboxylic Acids; D004791:Enzyme Inhibitors; D053139:Oseltamivir; D009439:Neuraminidase