title: Determination of oseltamivir quality by colorimetric and liquid chromatographic methods.
abstract: We developed a colorimetric and chromatographic assay for oseltamivir to assess the authenticity of Tamiflu (F. Hoffmann-La Roche Ltd., Basel, Switzerland) because of a growing concern about counterfeit oseltamivir. The colorimetric assay is quantitative and relies on an extractable colored ion-pair complex of oseltamivir with Congo red or bromochlorophenol blue. The reverse-phase chromatographic assay uses an alkaline mobile phase with UV detection. Both methods were evaluated for variability and selectivity and subsequently applied to batches of oseltamivir products acquired through the Internet. The Congo red test showed greater assay sensitivity, linearity, and accuracy. Colorimetric and chromatographic analysis showed all batches of oseltamivir product were within +/-15% of the stated amount of active ingredient.
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. mgreen@cdc.gov
authors.forename: Michael D
authors.initials: MD
authors.lastname: Green
authors.forename: Henry
authors.initials: H
authors.lastname: Nettey
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wirtz
mesh_terms: D000998:Antiviral Agents / Q000737:chemistry / Q000592:standards*; D001978:Bromphenol Blue / Q000031:analogs & derivatives; D002851:Chromatography, High Pressure Liquid; D003124:Colorimetry; D004396:Coloring Agents; D003224:Congo Red; D015394:Molecular Structure; D053139:Oseltamivir / Q000737:chemistry / Q000592:standards*; D011786:Quality Control
chemical_list: D000998:Antiviral Agents; D004396:Coloring Agents; D001978:Bromphenol Blue; D053139:Oseltamivir; C021155:bromochlorophenol blue; D003224:Congo Red