Rx Pharmaceuticals
Zylet®: Loteprednol Etabonate - Novel Corticosteroid Component
The loteprednol etabonate molecule was designed as the world's first ester
corticosteroid, derived from the prednisolone molecule, in an effort to develop
a drug which had the potency of the older ketone class of steroids (i.e.,
prednisolone, dexamethasone) but which also had a much improved safety
profile.15 Loteprednol etabonate is an example of intelligent
"retrometabolic" drug design, where the focus was first on identifying
inactive metabolites, followed by a molecular synthesis process that started
with these metabolites, and then ultimately ending with the creation of the
desired active ingredient molecule (i.e., loteprednol etabonate).15
This sort of "reverse engineering" approach to the drug development
process allowed scientists to create an active ingredient which possesses
exceptionally strong corticosteroid receptor binding capability (which allows
for loteprednol etabonate to exert its anti-inflammatory activity), followed by
a predictable, single-step, chemical modification of any remaining freely
circulating or unbound active by naturally occuring esterases into inactive
metabolites (thereby helping minimize the unwanted side
effects).2
Loteprednol etabonate is a re-engineered analogue of prednisolone; however, the
number 20 ketone group, which has been implicated in the formation of
cataracts, is absent.2,17,18,19
