Simultaneous Determination of Paracetamol and Orphenadrine Citrate in Dosage Formulations and in Human Serum by RP-HPLC

Rapid liquid chromatographic procedures are proposed for analysis of paracetamol and orphenadrine citrate in pharmaceutical preparations and human serum using acetonitrile: water (50:50) as a mobile phase, adjusting pH to 2.6, UV detection at 215 nm and propylparaben sodium as internal standard. The advantages of this method include good and rapid separation, well resolved peaks, and only a small amount of sample is required for assay and adequate precision. The method showed good linearity in the range of 6 to 10000 ng/mL for paracetamol serum concentrations with a correlation coefficient 0.9999 (inter and intra clay CV < 3.15) and in the range 3-10000 ng/mL for orphenadrine citrate serum concentrations with a correlation coefficient of 0.9999 (inter and intra day CV < 3.58). The recovery of paracetamol and orphenadrine citrate was > 96.9% and > 96.7%, respectively. The proposed method may be used for the quantitative analysis of paracetamol and orphenadrine citrate alone or in combination from raw materials, in bulk drugs, dosage formulations and in serum.