PREPARATION AND EVALUATION OF HYDROCORTISONE MULTIPLE EMULSIONS IN RABBITS EYE

Multiple emulsione were prepared by the reemulsification of primary emulsions using two-step procedure in which surfactants (Tween 20 and Span 60) were used. The corresponding simple emulsions of w/o and o/w were also prepared and used for comparison. The in vivo performance was assessed via the influence of hydrocortisone on the intraocular pressure (IOP). The parameters of activity used to quantify the pharmacokinetics of the drug are: the area under the intraocular pressure/time curve (AUC); maximum response (MR); time of maximum response (TMR) of the mean change in IOP; half value duration of the percent mean change in IOP; ratio of the RHVD in hours and relative bioavailability percent for different pairs of comparison in different emulsion systems were determined. To provide a quantitative measure for the individual variations, the variance and the coefficient of variation percent were computed The bioavailability of hydrocortisone from emulsions based on liquid paraffin, corn oil or castor oil was found to increase in the following order solution, o/w, w/o/w, o/w/o emulsions. The intensity of drug action was found to increase in the order of solution, w/o/w, o/w, w/o, and o/w/o emulsions. The parameters of activity are dependent on the nature of the oil phase of the emulsion. Generally, o/w/o emulsion systems represent an optimal delivery system maximizing drug bioavailability and minimizing individual variations.