A validated bioanalytical method for the simultaneous estimation of telmisartan and gallic acid in rat plasma samples by high‐performance thin‐layer chromatography–mass spectrometry: Application to an oral pharmacokinetic study

Abstract

A novel and cost‐effective high‐performance thin‐layer chromatography (HPTLC) method, combined with densitometric quantification, was developed for the biomedical analysis of telmisartan (TEL) and gallic acid (GA). Recent research indicates that when used in combination, these compounds offer improved therapeutic efficacy for the treatment of cardiovascular diseases with reduced side effects. The study focused on the simultaneous quantification and pharmacokinetic analysis of drugs in rat plasma. The separation was conducted using HPTLC silica gel 60 F254 plates with dimensions of 20 × 10 cm and a thickness of 0.2 mm. The mobile phase used for separation consisted of a mixture of ethyl acetate, methanol, chloroform, and acetic acid in the ratio of 4:2:2:0.2 (v/v). GA and TEL were analyzed using ultraviolet detection at specific wavelengths, with GA at 280 nm and TEL at 296 nm. Peak purity was assessed through spectral correlation analysis using Vision CATS software. The method underwent validation following the guidelines of the US Food and Drug Administration (US FDA). Calibration plots demonstrated linearity in the concentration range of 200–1200 ng/spot, with high correlation coefficients (R2). The retention factors (Rf) were 0.67 for TEL and 0.60 for GA. The identity of the separated compounds was further confirmed using MS, with GA having a mass‐to‐charge ratio (m/z) of 168.9 in negative mode and TEL with m/z 515.2 in positive mode. In the pharmacokinetic study, the maximum peak plasma concentration (Cmax) for GA was 899.7 ng/mL, and for TEL, it was 1013 ng/mL. The time to reach maximum concentration (Tmax) was 2 h for GA and 6 h for TEL. This simultaneous qualitative and quantitative determination of the drugs in an oral pharmacokinetic study involving Wistar rats can serve as a valuable tool for future investigations into pharmacokinetic interactions, quality control, and routine analysis of these drugs, both in their pure forms and in novel formulations.