Background: To study the penetration and metabolism of dexamethasone phosph
ate in the cornea and lens from rabbit following topical administration.
Methods: After topical administration of 0.1, 1 and 10% dexamethasone phosp
hate solutions, respectively, the cornea and lens were removed and extracte
d with either perchloric acid (PCA) or with chloroform/methanol to study th
e lipophilic and hydrophilic metabolites of the drug. The extracts were ana
lyzed with H-1 and F-19 NMR spectroscopy.
Results: Using F-19 NMR spectroscopy, both dexamethasone and dexamethasone
phosphate were detected simultaneously in the extract of the cornea and len
s obtained from the eyes denuded of the epithelium before the treatment. Us
ing 10 and 1% drug solutions, the signals from dexamethasone were also dete
ctable in the H-1 NMR spectra among many endogenous metabolites.
Conclusion: H-1 and F-19 NMR spectroscopy was shown to be a useful method i
n the study of penetration and metabolism of dexamethasone in the eye, part
icularly because both the lipophilic and hydrophilic metabolites of the dru
g could be detected simultaneously.