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Detection of dexamethasone in the cornea and lens by NMR spectroscopy
A Midelfart1, A Dybdahl, J Krane
1Department of Ophthalmology, Faculty of Medicine, Norwegian University of Science and Technology, University Hospital, Trondheim. anna.midelfart@medisin.ntnu.no
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.