Risperidone-Loaded Mucoadhesive Microemulsion for Intranasal Delivery: Formulation Development, Physicochemical Characterization and Ex Vivo Evaluation

This paper describes the formulation development, physicochemical characterization and ex vivo evaluation of a microemulsion drug delivery system designed for intranasal administration of risperidone. Drug-loaded microemulsions which contained 4 % oleic acid, 30 % surfactant mixture of [Labrasol: Cremophor RH 40 (1:1)]:[Transcutol P] (3:1) and 66 % (w/w) aqueous were successfully prepared by a water titration method. The microemulsion formulation which displayed an optical transparency of 99.96 %, globule size of 21.08 ± 1.35 nm, and a polydispersity index of 0.109 ± 0.017 was selected for the incorporation of polyelectrolytic polymer (polycarbophil) as the mucoadhesive component. The mucoadhesive microemulsion of risperidone containing 0.5 % w/w of polycarbophil showed a higher in vitro mucoadhesive potential (17.0 ± 1.5 min) and diffusion coefficient (3.72 × 10-6 ± 0.022 × 10- 6) as compared to microemulsion. All formulations were found to be free from nasal cilio toxicity and were stable for six months.