Adapalene-d3 is primarily used in dermatological research as a stable isotope-labeled internal standard for quantitative analysis. It enables accurate measurement of adapalene levels in biological samples such as plasma, serum, and skin tissues using techniques like liquid chromatography-mass spectrometry (LC-MS). This application is critical in pharmacokinetic and metabolic studies, where precise tracking of drug concentration and distribution is required. Due to its structural similarity to adapalene with minimal mass difference, Adapalene-d3 ensures high analytical accuracy without altering the chemical behavior during sample processing. It is not used therapeutically but serves as an essential tool in drug development and bioanalysis.