Effect of particle size on ophthalmic bioavailability of dexamethasone suspensions in rabbits.

Three suspensions of 0.1% [3H]dexamethasone were prepared with mean particle sizes of 5.75, 11.5, and 22.0 micron. The suspensions were dosed topically to the right eyes of rabbits. Their bioavailability was compared by measuring aqueous humor and corneal levels over 5 hr. A statistically significant rank-order correlation was observed between increasing drug levels and decreasing particle size.