Abstract. Dilutable nanoemulsions are potent drug delivery vehicles for ophthalmic use due to their numerous advantages as sustained effect and high ability of drug penetration into the deeper layers of the ocular structure and the aqueous humor. The aim of this article was to formulate the antiglaucoma drug dorzolamide hydrochloride as ocular nanoemulsion of high therapeutic efficacy and prolonged effect. Thirty-six systems consisting of different oils, surfactants, and cosurfactants were prepared and their pseudoternary-phase diagrams were constructed by water titration method. Seventeen dorzolamide hydrochloride nanoemulsions were prepared and evaluated for their physicochemical and drug release properties. These nanoemulsions showed acceptable physicochemical properties and exhibited slow drug release. Draize rabbit eye irritation test and histological examination were carried out for those preparations exhibiting superior properties and revealed that they were nonirritant. Biological evaluation of dorzolamide hydrochloride nanoemulsions on normotensive albino rabbits indicated that these products had higher therapeutic efficacy, faster onset of action, and prolonged effect relative to either drug solution or the market product. Formulation of dorzolamide hydrochloride in a nanoemulsion form offers, thus, a more intensive treatment of glaucoma, a decrease in the number of applications per day, and a better patient compliance compared to conventional eye drops.

The aim of this study was to investigate the presence of a possible direct correlation between vesicle elasticity and the amount of drug reaching the brain intranasally. Therefore, transfersomes were developed using phosphatidylcholine (PC) as the lipid matrix and sodium deoxycholate (SDC), Span® 60, Cremophor® EL, Brij® 58, and Brij® 72 as surfactants. The influence of the type of surfactant and PC-to-surfactant ratio on vesicle morphology, size, membrane elasticity, drug entrapment, and in vitro drug release was studied. The prepared transfersomes were mainly spherical in shape, with diameters ranging from 310 to 885 nm. Transfersomes containing SDC and Span 60 with optimum lipid-to-surfactant molar ratio showed suitable diameters (410 and 380 nm, respectively) and deformability indices (17.68 and 20.76 mL/sec, respectively). Values for absolute drug bioavailability in rat plasma for transfersomes containing SDC and those containing Span 60 were 24.75 and 51.35%, whereas AUC(0-360 min) values in rat brain were 22,334.6 and 36,486.3 ng/mL/min, respectively. The present study revealed that the deformability index is a parameter having a direct relation with the amount of the drug delivered to the brain by the nasal route.

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