Simultaneous bioanalytical method development and validation of ibuprofen and phenyramidol HCl in human plasma using high–performance liquid chromatography with photodiode array detection and its application in a pharmacokinetic study

The co-administration of ibuprofen (IBU) and phenyramidol HCl (PHE) is frequently preferred for the management of musculoskeletal disorders to enhance therapeutic efficacy. This study aimed to develop and validate a rapid, sensitive and cost-effective high-performance liquid chromatography-photodiode array (HPLC-PDA) method for the simultaneous determination of IBU and PHE in human plasma and pharmaceutical preparations, and to demonstrate its applicability in pharmacokinetic studies. Chromatographic separation was achieved on a C18 column using a mobile phase consisting of phosphate buffer (pH 6.0 ± 0.05) and methanol (30:70, v/v) at a flow rate of 1.0 mL·min -1. The retention times of IBU and PHE were 3.7 and 2.7 min, respectively, with a total analysis time of 6 min. The method showed excellent linearity within the range of 0.05-40.0 μg·mL -1 for both drugs, with LLOQ values of 0.05 μg·mL-1 for IBU and 0.0025 μg·mL-1 for PHE. The plasma samples were collected at four time points (0.0, 1.0, 4.0 and 8.0 h) after oral administration of IBU and PHE. Cmax, Tmax and AUC0-8 were calculated, with Cmax of 16.14 μg·mL-1 for IBU and 3.71 μg·mL-1 for PHE, while Tmax was 1.0 h for both. Despite limitations in the number of sampling time points, the method proved highly applicable for determining pharmacokinetic profiles and for routine quality control analyses. Its short analysis time, high sensitivity and low sample volume requirement make it a powerful tool for clinical research and therapeutic monitoring. This is the first validated HPLC-PDA method applied to the simultaneous pharmacokinetic evaluation of IBU and PHE in human plasma.