Application of Imaging Mass Spectrometry to Assess Ocular Drug Transit

Matrix-assisted laser desorption/ionizationimaging mass spectrometry (MALDI IMS) is becoming an important technology to determine the distribution of drugs and their metabolites in the tissue of preclinical species after dosing. Interest in IMS is growing in the ophthalmology field, but little work to this point has been done to investigate ocular drug transit using this technology. Information on where and how a drug is distributing through the eye is important in understanding efficacy and whether it is reaching the desired target tissue. For this study, ocular distribution of brimonidinewas investigated in rabbits following topical administration. Brimonidinehas been shown to lower intraocular pressure and is approved to treat glaucoma, the second leading cause of blindness in the world. We have developed IMS methods to assess transit of topically administered brimonidinefrom the anterior to the posterior segment of rabbit eyes. Using IMS, brimonidinewas detected in the cornea, aqueous humor, iris...