Abstract
A new spectrodensitometric method was developed for the simultaneous determination of a quaternary mixture of antihyperlipidemics containing niacin, atorvastatin, and bezafibrate with either ezetimibe or simvastatin. Densitometric analysis was carried out using high-performance thin-layer chromatographic (HPTLC) silica gel 60G F-254 plates as the stationary phase. The plates were developed with benzene-ACN-n-butanol (7:2:1, v/v) + 1.50%, v/v, glacial HOAC in absorbance mode at 242 nm. The retention factors of niacin, atorvastatin, bezafibrate, ezetimibe, and simvastatin were 0.17, 0.38, 0.51, 0.65, and 0.66, respectively. The method was validated according to the United States Pharmacopeia and National Formulary (USP 31-NF 26) and the International Conference on Harmonization (ICH) guidelines. Linearity ranges of all studied drugs were found to be in the range of 15-650 ng band-1 with correlation coefficient values of 0.9975 or more. Limits of detection and quantitation were 5-50 and 15-150 ng band-1, respectively. Upon applying polynomial regression to the same concentration ranges of standard solutions of all investigated drugs as well as spiked bezafibrate samples to rabbit plasma, correlation coefficient values had greatly improved. The proposed method was successfully applied for the simultaneous determination of the studied antihyperlipidemic drugs in plasma and in their pharmaceutical formulations. The developed method was utilized to study the pharmacokinetic behavior of bezafibrate and its drug-drug interaction with atorvastatin in rabbit males. This study has proven the increased myotoxicity risk upon coadministration of atorvastatin with bezafibrate.