Rapid HPLC‐Determination of Ibuprofen and Flurbiprofen in Plasma for Therapeutic Drug Control and Pharmacokinetic Applications

Abstract

Ibuprofen has wide applications in the treatment of rheumatoid arthritis and osteoarthroses as an effective non-steroidal antiinflammatory drug. The drug is still being investigated regarding its possible ability to reduce myocardial infarct size. The more potent biphenyl propionic analogue, flurbiprofen, has recently been introduced. Both drugs are strong inhibitors of cyclooxygenase. The specific HPLC-method described requires plasma samples of 100 .mu.l which are deproteinized and simultaneously extraced with acetonitrile containing either of the drugs as intenral standard. Aliquot of 25 .mu.l of this primary extract were directly injected on a .mu.Bondapack C18 column. For elution was used a mixture of 60% methanol and 40% 50 mM phosphate buffer adjusted to pH 4.6. The detection limit (at 214 nm) for both drugs corresponded to plasma concentrations of about 0.2 .mu.g .cntdot. ml-1. The applicability of the method was determined in a pharmacokinetic ibuprofen experiment in an adult person.