Design, characterization and evaluation of latanoprost niosomes for glaucoma treatment

Abstract

Eye being a most delicate organ, ocular drug delivery is a challenge for the formulator. A drop of an aqueous solution, irrespective of instilled volume is eliminated completely from the eye within 5 to 6 minutes of its application and only a small amount (1-3%) actually penetrates the cornea and reaches the intraocular tissue. This problem can be addressed by use of suitable carrier systems. Niosomal vesicular system is one of the potential approaches, which can be suitably used. The aim of the present investigation was to prepare, characterize and optimize the latanoprost niosomes using 2-factor 3-level full factorial design and carry out stability studies. Niosomes of latanoprost were prepared by heating method of mozafari and optimized using 2-factor 3-level full factorial design. The independent levels selected were cholesterol:span 60 ratio and mixing time, and the response optimized were entrapment efficiency and particle size. Contour and response surface plots were constructed to further elucidate the relationship between the independent and dependent variables. The formulated latanoprost niosomes were evaluated for their particle size, zeta potential, surface morphology, entrapment efficiency, in vitro drug release and in vivo corneal residence time studies. The niosomes showed a vesicle size of 2.58-3.13 μm and zeta potential of -9 to -13 mV. SEM revealed that niosomes were unilamellar and smooth in texture. The in vitro release studies showed 95.98% of latanoprost released in sustained manner following Higuchi model kinetics for 12 hours. The n value of 0.865 suggested non fickian diffusion from niosomes. The stability study confirmed that latanoprost niosomes were stable. In vivo corneal residence time studies showed the levels of drug concentration in tear fluid were maintained for 12 hr while for eye drops concentration was very less after 6 hr. The designed latanoprost niosomes with span 60 showed good physicochemical properties, good stability, prolonged action and improved bioavailability than the commercially available conventional dosage form which might be a potential carrier system to improve the patient compliance and reduce the side effects.