In vivo evaluation of submicron emulsions with pilocarpine: the effect of pH and chemical form of the drug

The potential of lipid emulsion for ocular delivery of lipophilic drugs

For nearly a decade, oil-in-water lipid emulsions containing either anionic or cationic droplets have been recognized as an interesting and promising ocular topical delivery vehicle for lipophilic drugs. The aim of this review is to present the potential of lipid emulsions for ocular delivery of lipophilic drugs. The review covers an update on the state of the art of incorporating the lipophilic drugs, a brief description concerning the components and the classification of lipid emulsions. The ocular fate following topical instillation, safety evaluation experiments and the applications of lipid emulsions are thoroughly discussed.

Micellar solutions of triblock copolymer surfactants with pilocarpine

Solutions of surface active triblock copolymer Pluronic F127 in the vicinity of the critical micellar concentration (cmc) were prepared with or without pilocarpine (either as the hydrochloride salt or the free base) in water and phosphate buffer. The characteristics parameters of the surface activity (cmc, Gamma and a) were determined for F127 solutions. Additionally, it was found that the pilocarpine solutions without F127 in water exhibits a certain surface activity. The solutions containing F127 (2 wt.%) well above the cmc and pilocarpine (2 wt.% for the salt, or equimolar 1.7 wt.% for the base) were further tested in vivo (miotic response) on rabbit eye. Though the entrapment efficiency of the drug in the micelles was rather low (maximal 1.9%) the pharmacokinetic parameters (duration of miotic response and the area under miotic curve) were improved when compared to the standard pilocarpine solutions. The best results were obtained for the micellar pilocarpine base solution which exhibits significant prolongation of miotic activity and an increase of AUC for 64%.