Detection of dexamethasone in the cornea and lens by NMR spectroscopy

Abstract 

· Background: To study the penetration and metabolism of dexamethasone phosphate in the cornea and lens from rabbit following topical administration. · Methods: After topical administration of 0.1, 1 and 10% dexamethasone phosphate solutions, respectively, the cornea and lens were removed and extracted with either perchloric acid (PCA) or with chloroform/methanol to study the lipophilic and hydrophilic metabolites of the drug. The extracts were analyzed with ¹H and ¹⁹F NMR spectroscopy. · Results: Using ¹⁹F NMR spectroscopy, both dexamethasone and dexamethasone phosphate were detected simultaneously in the extract of the cornea and lens obtained from the eyes denuded of the epithelium before the treatment. Using 10 and 1% drug solutions, the signals from dexamethasone were also detectable in the ¹H NMR spectra among many endogenous metabolites. · Conclusion: ¹H and ¹⁹F NMR spectroscopy was shown to be a useful method in the study of penetration and metabolism of dexamethasone in the eye, particularly because both the lipophilic and hydrophilic metabolites of the drug could be detected simultaneously.