RP-HPLC ASSAY OF IBUPROFEN IN PLASMA USING DIFFERENT EXTRACTION PROCEDURES

An isocratic reverse phase high performance liquid chromatographic (RP-HPLC) method with ultra violet detection at 220 nm was used for a simple, selective and precise quantitation of a non-steroidal anti-inflammatory drug i.e. ibuprofen (IBF) from rat plasma. The procedure employed mefenamic acid as an internal standard (IS). A good chromatographic separation between IBF, the internal standard and interfering endogenous peaks was achieved using a Octadecyl Silane column and acetonitrile (ACN) - water - methanol - ortho-phosphoric acid (OPA) (in ratio of 58: 37: 5: 0.05 v/v/v/v) as the mobile phase at a flow rate of 1.0 ml/min. Two different extraction procedures for RP-HPLC quantitation of IBF were analysed. In the first method acetonitrile was used for extraction of the drug from plasma whereas the second method involved extraction of drug from plasma using diethyl ether. The second method proved to be more suitable for quantitation of the drug from plasma. The applicability of procedure includes the requirement of less sample volume, lesser organic solvent consumption and good plasma clean up for pharmacokinetic studies, in case of small animals, neonates and children as well.