ABSTRACT
INTRODUCTION: Loteprednol etabonate (submicron) ophthalmic gel 0.38% (LE SM gel 0.38%) is a corticosteroid formulation designed to retain the nonsettling characteristics of loteprednol etabonate ophthalmic gel 0.5%, but with reduced drug particle size to improve ocular penetration, allowing for reduced dosing frequency. This study compared the dose uniformity of LE SM gel 0.38% with branded and generic prednisolone acetate (PA) 1% suspensions under simulated in-use dosing conditions. METHODS: Drug concentrations in drops of LE SM gel 0.38% and PA 1% suspensions, expressed from bottles that were shaken or not shaken, were determined during 2 weeks of simulated on-label dosing (LE SM gel 0.38%: three times daily; PA suspensions: four times daily). Sedimentation of drug particles was assessed for each product using dispersion analysis. RESULTS: The mean (SD) percent declared drug concentration of LE SM gel 0.38% over 2 weeks was 103.2% (1.3%) when the drug was dispensed from shaken bottles and 103.3% (1.5%) when dispensed from unshaken bottles. However, for branded and generic PA suspensions, mean (SD) percent declared concentrations were 102.2% (1.4%) and 98.3% (2.9%), respectively, when dispensed from shaken bottles; and 89.2% (18.6%) and 78.3% (13.5%), respectively, when dispensed from unshaken bottles. Dispersion analysis showed that drug particles in LE SM gel 0.38% remained fully suspended under accelerated sedimentation conditions, whereas both branded and generic PA suspension drug particles settled out of suspension. CONCLUSIONS: LE SM gel 0.38% delivered the drug consistently at the declared concentration over the entire 2 weeks of simulated in-use dosing conditions, regardless of whether the drug was dispensed from shaken or unshaken bottles. However, both branded and generic PA suspensions required the bottle to be shaken to provide a consistent drug concentration.
ABSTRACT
INTRODUCTION: Loteprednol etabonate (LE) ophthalmic gel 0.5% (Lotemax®) is a new polycarbophil-based, nonsettling topical ophthalmic formulation. The formulation is a semisolid gel at rest and a shear thinning fluid when expressed through a dropper tip. The present study was undertaken to determine how the nonsettling character of LE ophthalmic gel affects dose uniformity. Prednisolone acetate ophthalmic suspension 1% (Pred Forte®) and a generic prednisolone acetate suspension 1% were used as comparators. METHODS: Drug concentrations of LE ophthalmic gel, Pred Forte, and a generic prednisolone acetate suspension were determined following simulated dosing - consisting of 2 drops, expressed four times daily for 2 weeks, with bottles that were shaken or not shaken immediately prior to expressing the drops. Drug concentrations were determined using a reverse-phase high-performance liquid chromatography (HPLC) method and reported as a percentage of the declared (labeled) concentration. Comparative kinetics of drug particle sedimentation were also determined for each formulation, using dispersion analysis under gravity. RESULTS: Mean drug concentrations in drops of all three formulations were within a few percentage points of the declared concentration when the bottles were shaken for 5 seconds prior to dispensing. Only LE ophthalmic gel showed consistent and on-target concentrations when the bottles were unshaken prior to dispensing, with a mean (standard deviation [SD]) percent declared concentration of 102% (1.92%) over the 2-week dosing regimen. Drug concentrations for the branded and generic prednisolone acetate suspensions following expression from unshaken bottles were highly variable (overall relative SDs of 16.8% and 20.3%, respectively), with mean concentrations for both falling significantly below the declared concentration for drops expressed at the beginning of the 2-week dosing regimen and significantly above the declared concentration for drops expressed near the end of the dosing regimen. Dispersion analysis at 120× g showed no drug particle sedimentation for LE ophthalmic gel over the 24-hour testing period, whereas the prednisolone acetate suspensions settled in less than 6 hours. CONCLUSION: LE ophthalmic gel 0.5% provided consistent dose uniformity at the declared concentration whether or not the bottle was shaken prior to dispensing, whereas Pred Forte® and the generic prednisolone acetate required shaking to provide consistent drug concentrations. LE ophthalmic gel may be beneficial to patients because it eliminates the potential impact on the clinical response of both under- and overdosing.
