Baicalin nano-micelles for dry eye disease: LC–MS/MS method validation, pharmacokinetics and pharmacodynamics in preclinical models

This study aimed to establish a method for quantifying baicalin (BC) in rabbit ocular tissues and plasma, and evaluate the pharmacological efficacy and pharmacokinetic properties of BC and BC@HS15/DSPE-PEG2000-L-Val, a novel ocular formulation for dry eye treatment. BC@HS15/DSPE-PEG2000-L-Val or free BC was administered via eye drops to benzalkonium chloride (BAC)-induced dry eye mice. Corneal and conjunctival tissues were assessed for anti-dry eye efficacy. BC concentrations in cornea, conjunctiva, aqueous humor, and ocular plasma were quantified using LC-MS/MS. Noncompartmental pharmacokinetic parameters (AUC, Tmax) were calculated using DAS 2.0 software. The method demonstrated excellent linearity (0.50-500.00 ng/mL, r > 0.9905), precision (RSD < 10%), and accuracy (± 13%). Compared to free BC, BC@HS15/DSPE-PEG2000-L-Val significantly increased tear secretion, reduced MMP-3/MMP-9 expression, and preserved corneal epithelium integrity. In the micelle group, corneal and conjunctival Cmax values were 2.7- and 3.6-fold higher than the solution group, respectively. A sensitive and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to measure baicalin concentrations in ocular plasma and tissues of rabbits. BC@HS15/DSPE-PEG2000-L-Val for treating dry eye demonstrated significantly superior outcomes. The nano-micelle notably enhanced BC concentration on the ocular surface and effectively prolonged its retention time.