Simultaneous UHPLC-PDA Method Development and Validation for Quantification of Quercetin and Erlotinib in Liquid Crystalline Nanoparticle Formulation and Pharmacokinetic Study

Combining anticancer drugs and phytomolecules with anticancer activity has opened up new avenues for cancer treatment and could be a potent alternative to conventional cancer therapy. Quercetin (QUR) and Erlotinib (ERB) exhibit potential anticancer properties. However, both drugs manifest low oral bioavailability due to low aqueous solubility, and interestingly, there is not a single validated UHPLC-PDA method for quantifying QUR and ERB simultaneously. Thus, the current study aims to address pharmaceutical challenges by encapsulating the two drugs in liquid crystalline nanoparticles (LCNPs) and to develop and validate a sensitive, accurate analytical, and bioanalytical method, as per guidelines, to quantify QUR and ERB simultaneously in LCNPs. Effective chromatographic elution of QUR and ERB has been achieved using a C8 reversed-phase column with an isocratic mobile phase at a flow rate of 1 mL/min, and both drugs were detected at 252 nm wavelength. The retention time was 5.3 and 7.7 min for QUR and ERB, respectively, while LOQ was less than 0.5 µg/mL for both drugs, appropriate for monitoring therapeutic drugs in preclinical and clinical research settings. The validated method was successfully applied to estimate the %drug entrapment efficiency, %drug loading, and %drug release for the simultaneous analysis of QUR and ERB in the LCNPs. The technique investigated both drugs’ pharmacokinetic characteristics in Sprague–Dawley rats. The results were deemed reliable, and the validated method was found to be precise and accurate as per guidelines for the simultaneous estimation of QUR and ERB, which have applications in formulation development and bioanalytical studies.