Design of Microdialysis-CLC Method for Measurement of Drug Behavior in Lacrimal Fluid after Instillation

Abstract

The ophthalmic application is the main route for the therapy of glaucoma, and is well-accepted by glaucoma patients. Therefore, it is important to measure the drug behavior in lacrimal fluid after instillation of eye drops. In this study, we used ophthalmic formulation (eye drops) containing timolol maleate (TM), in anti-glaucoma eye drops, and attempted to measure the drug behavior after instillation of TM eye drops. First, we collected the lacrimal fluid (5 μL) every 10 time after instillation using micropipette, and measured by the HPLC method. The TM concentration in lacrimal fluid was 21.2 μg/mL at 5 min after the instillation, and the TM was remained for 30 min after the instillation. Next, we collected the lacrimal fluid via the dialysis prove, and measured by the HPLC method. The retention of TM in lacrimal fluid was observed for 45 min after the instillation, and the measurement accuracy was enhanced by system with an automatic injection of TM solution via dialysis prove (microdialysis-HPLC method). In addition, the measurement accuracy increased more by using a capillary liquid chromatography (CLC) instead of an HPLC (microdialysis-CLC method), and the retention time of TM in lacrimal fluid was extended to 75 min after the instillation. In conclusion, we showed that the microdialysis-CLC method was suitable to measure the drug behavior in lacrimal fluid after instillation. These findings provide significant information that can be used in the design and evaluation of ophthalmic formulation.