Experimental design, formulation and in vivo evaluation of a novel topical in situ gel system to treat ocular infections

In situ gels have been extensively explored as ocular drug delivery system to enhance bioavailability and efficacy. The objective of present study was to design, formulate and evaluate ion-activated in situ gel to enhance the ocular penetration and therapeutic performance of moxifloxacin in ophthalmic delivery. A simplex lattice design was utilized to examine the effect of various factors on experimental outcomes of the in situ gel system. The influence of polymers (independent variables) such as gellan gum (X(1)), sodium alginate (X(2)), and HPMC (X(3)) on gel strength, adhesive force, viscosity and drug release after 10 h (Q(10)) were assessed. Selected formulation (MH7) was studied for ex vivo permeation, in vivo irritation and pharmacokinetics in rabbits. Data revealed that increase in concentration of polymers led to higher gel strength, adhesive force and viscosity, however, decreases the drug release. MH7 exhibited all physicochemical properties within acceptable limits and was stable for 6 months. Release profile of moxifloxacin from MH7 was comparable to the check point batches and followed Korsmeyer-Peppas matrix diffusion-controlled mechanism. Ocular irritation study signifies that selected formulation is safe and non-irritant for ophthalmic administration. In vivo pharmacokinetics data indicates significant improvement of moxifloxacin bioavailability (p < 0.0001) from MH7, as evidenced by higher C(max) (727 ± 56 ng/ml) and greater AUC (2881 ± 108 ng h/ml), when compared with commercial eye drops (C(max); 503 ± 85 ng/ml and AUC; 978 ± 86 ng h/ml). In conclusion, developed in situ gel system (MH7) could offers a more effective and extended ophthalmic therapy of moxifloxacin in ocular infections when compared to conventional eye drops.