Stability of Aqueous and Oily Ophthalmic Solutions of Moxifloxacin

Objective. The purpose of this study was to investigate the stability of aqueous and oily ophthalmic solution of moxifloxacin fourth generation of fluoroquinolone. Method. The stability studies on the aqueous and oily ophthalmic formulations of moxifloxacin were carried out by exposing the formulations to accelerated (40° C and 75% RH) and room temperature storage conditions. During storage period, the formulations were periodically examined for pH and the remaining drug concentrations. Results. The accelerated and long term stability studies conducted on aqueous isotonic ophthalmic solutions of moxifloxacin indicate that moxifloxacin (0.5%, w/v) formulation of pH 7.2; containing, BAK (0.01%) and EDTA (0.01%) could provide a shelf life (t90) of 2 years, and the formulation appears promising from corneal permeation point of view. Among all the oily formulations, moxifloxacin (0.05%, w/v) ophthalmic solution in castor oil, with adequate overage, containing benzyl alcohol (0.5%, v/v) appears ideal from stability point of view. Conclusions. Presence of benzyl alcohol, however, appears necessary to maintain sterility of the formulation during use, as eye drops are normally dispensed in multi dose containers. The degradation of moxifloxacin was found to follow first order kinetics..