Comparative intraocular levels of pilocarpine achieved with drops and repository preparations

The concentrations of pilocarpine in aqueous humor and iris-ciliary body of rabbits following topical treatment with repository preparations or conventional drop therapy were measured using high performance liquid chromatography (HPLC). Higher concentrations of pilocarpine occurred both in aqueous humor and iris-ciliary body following topical administration of the 4% gel product than with 4% drops. At 1 hour after administration, 2% drops produced a higher concentration of pilocarpine in the aqueous humor than occurred with the 1.86% pilocarpine emulsion product; however, isopilocarpine present in the emulsion product entered the aqueous humor in equal amounts with the pilocarpine. At 4 hours, equal concentrations of pilocarpine were present in aqueous humor and iris-ciliary body samples with both the 2% drop and 1.86% emulsion therapy. Pilocarpine concentrations were maintained within the aqueous humor of the eye for longer durations with both the gel and emulsion repository preparations than with comparable drop therapy.