Development of Dioctyl Phthalate@Fe3O4 Nanocomposite Reinforced Hollow Fiber Solid/ Liquid Phase Microextraction Followed by HPLC-DAD for the Determination of Atorvastatin and Gemfibrozil in Human Urine

Background: The desirable levels of lipids, especially in patients with coronary artery disease, might not be achievable with a single lipid-lowering drug; thus, combination therapy using atorvastatin and gemfibrozil seems to be a promising approach. However, the potential for drug-drug interaction needs to be taken into consideration, and the combination (atorvastatin and gemfibrozil) is recommended only when other options for reducing lipids have been exhausted. Objectives: Many studies are conducted for the determination of atorvastatin or gemfibrozil in biological fluids and tablets; however, the simultaneous determination of the two drugs in complex biological matrices is limited. Consequently, the development of a sensitive method for simultaneous determination of atorvastatin and gemfibrozil in urine samples is urgently needed to make sure that the doses of both medications are given to patients correctly to prevent the risk of side effects outcomes associated with the adverse drug-drug interaction. Methods: A synthesized nanocomposite sorbent, dioctyl phthalate coated on the surface of magnetite (DOP@Fe3O4), was reinforced and immobilized into the pores of 2.5 cm segment hollow fiber microtube via ultrasonication, and the lumen of the microtube was filled with 1-octanol as an organic solvent with two ends heat-sealed. The prepared (DOP@Fe3O4-HF-SLPME) device was directly immersed into 10 mL of a sample solution containing atorvastatin and gemfibrozil with agitation. Subsequently, the microextraction device was transferred to HPLC-micro-vial containing an appropriate solvent, and the selected analytes were desorbed under ultrasonication prior to HPLC-DAD analysis. The main factors influencing the adsorption and desorption process of the selected drugs have been optimized. Results: The DOP@Fe3O4-HF-SLPME combined with the HPLC-DAD method was analytically evaluated for the simultaneous determination of atorvastatin and gemfibrozil in human urine samples using the optimized conditions. In spiked urine samples, the method showed a good linearity R2˃ 0.998, RSD from 1.41- 5.33%, and the limits of detection/ quantification (LOD/ LOQ) were 0.11/ 0.36 and 0.73/ 2.42 µg L-1 for atorvastatin and gemfibrozil, respectively. The enrichment factors of atorvastatin and gemfibrozil were 83.4 and 101.2, with extraction recoveries of 80.9% and 99.0%, respectively. The developed method demonstrated comparable results against referenced methods and a satisfactory result for determining the selected drugs in the patient’s urine samples. Conclusion: The DOP@Fe3O4-HF-SLPME followed by HPLC-DAD was proved to be an efficient, sensitive, and cost-effective biopharmaceutical analysis method for trace levels of atorvastatin and gemfibrozil in the biological fluid matrix.