The relationship between hydrocortisone acetate distribution and efficacy in inflamed eyes: continuous vs...

Hydrocortisone acetate was administered to rabbit eyes intermittently in 250mug doses (given twice daily or once hourly) or continuously at 10mug/hr from an experimental ocular therapeutic system. Tissue drug distribution was measured over a 1 to 4 day period in experimental conjunctivitis. Anti-inflammatory efficacy was evaluated over a 4 day period in the same model. Statistically significant improvement in inflammation was observed 48 hours after initiation of continuous delivery treatment and after 4 days of the twice daily eyedrop regimen. Drug uptake by ocular tissues correlated with drug efficacy. Continuous delivery at 10mug/hr produced conjunctival steriod concentrations exceeding 1mug/g during 8 through 24 hours of treatment, and average levels of 1mug/g from days 2 through 4. Conjunctival steroid concentations generally did not exceed 1mug/g in eyedrop treated eyes until the fourth treatment day, when their clinical improvement matched that observed in the continuously treated eyes.