Quantification of the Anticancer Drug Avapritinib in Human Plasma Using 2,2-Dihydroxyindane-1,3-Dione: Application to a Pharmacokinetic Study

The study examined the effectiveness of 2,2-dihydroxyindane-1,3-dione, commonly utilized as a derivatizing reagent for quantifying avapritinib (AVB) in pure form, pharmaceutical dosage formulations, and human plasma samples. In 2020, the United States Food and Drug Administration (US FDA) approved AVB, marking it as the inaugural precision therapy for individuals suffering from unresectable or metastatic gastrointestinal stromal tumors and advanced systemic mastocytosis. Therefore, adjusting the AVB dose is essential for drug monitoring. Hence, the described spectrofluorimetric technique relies on a condensation reaction involving 2,2-dihydroxyindane-1,3-dione and the primary amine group found in AVB in the presence of phenylacetaldehyde. This reaction yields a highly fluorescent compound detectable at 468 nm (excitation wavelength of 395 nm). The calibration curve was established within a range of 0.4–4.0 µg/mL, demonstrating an excellent correlation coefficient of 0.9993 and a lower limit of quantification of 0.10 µg/mL. The methodology proved effective in estimating AVB in spiked plasma samples and assessing content uniformity. The research protocol was established and validated through bioanalytical methods by the ICH and US FDA guidelines. Additionally, this approach was employed to verify the drug concentration in each tablet, achieving a high recovery rate of 101.37% during the content uniformity test. This method was designed for pharmacokinetic analysis and easily applied in clinical laboratories.