Latanoprost Quantification in Ocular Implants and Tissues: HPLC-Fluorescence vs HPLC-UV

Anti-glaucoma latanoprost-loaded ocular implants provide prolonged delivery and enhanced bioavailability relative to the conventional eye drops. This study aims at the development and validation of a reversed-phase high-performance liquid chromatography method for quantitative analysis of nanogram levels of latanoprost in the eye, and for the first time, compares the use of fluorescence vs ultraviolet (UV) detectors in latanoprost quantification. The mobile phase was composed of acetonitrile:0.1% v/v formic acid (60:40, v/v) with a flow rate of 1 mL/min and separation was done using a C18 column at temperature 40°C. The fluorescence excitation and emission wavelengths were set at 265 and 285 nm, respectively, while the UV absorption was measured at 200 nm. The latanoprost concentration-peak area relationship maintained its linearity (R2 = 0.9999) over concentration ranges of 0.063-10 μg/mL and 0.212-10 μg/mL for the fluorescence and UV detectors, respectively. The UV detector showed better precision, while the fluorescence detector exhibited higher robustness and greater sensitivity, with a detection limit of 0.021 μg/mL. The fluorescence detector was selected for quantification of latanoprost released from ocular implants in vitro and in porcine ocular tissues. The developed method is a robust, rapid and cost-effective alternative to liquid chromatography-mass spectrometry for routine analysis of latanoprost released from ocular implants.