Studies on different controlled releasing ophthalmic systems with antihistaminic activity

Ocular allergy is one of the most frequently encountered disorders of the ocular surface. It is generally treated with antihistaminic active ingredients once diagnosed. Eyes present challenges for drug delivery systems due to their unique anatomy and natural protective mechanism. Reasons such as excretion by tears, drainage, low capacity of ocular liquid retention and low corneal permeability prohibit drug absorption. Olopatadine hydrochloride with histamine H1 receptor antagonistic action is an antiallergic agent which belong to second generation antihistamines. This generation causes less side effects in patients. Therefore olopatadine hydrochloride was selected as the active ingredient in this study. Ophthalmic formulations are mostly formulated as eye drops for topical application. However, conventional ophthalmic solution being eliminated rapidly after administration cannot provide and maintain active drug concentration in precorneal area. In this study, polymeric nanoparticles, microemulsion and in situ gelling systems which are promising for sustaining drug release were prepared. Behavior of formulations at different thermal conditions were investigated within the concept of stability study. Ocular residence time of formulations were compared using sheep. Ocular systems with longer residence period compared to a commercial preparation were successfully prepared and the desired ophthalmic properties were determined to be obtained. Keywords: Olopatadin hydrochloride, Ocular, Polymeric nanoparticle, Microemulsion, In situ gelling system