Development and in-vitro Evaluation of a Topical Drug Delivery System Containing Betamethazone Loaded Ethyl Cellulose Nanospheres

Purpose: Lipid nanospheres are used for the passive targeting of cosmetic agents to skin, thereby achieving major benefits such as reduction of total dose and avoidance of systemic absorption. The present study was carried out to exploit the feasibility of using polymeric nanospheres as an alternative and cheaper carrier for targeting corticosteroids to the skin.
Methods: Nanospheres were prepared from ethyl cellulose by a modified method of desolvation and cross linking. The drug betamethazone was incorporated into nanospheres and the drug: polymer ratio was evaluated to determine the carrier capacity of the polymer. In vitro release studies of drug-loaded nanospheres were carried out by the centrifugal ultrafiltration method. The kinetics of release was determined and fitted to an empirical equation. The release of drug from drug-loaded nanospheres dispersing in a conventional cream was evaluated. A comparative in vitro diffusion study was carried out between a commercial brand of cream and the cream incorporating nanospheres.
Results: Formulation of nanospheres of betamethazone by a modified method produced discrete particles. Studies on drug:polymer ratio showed a linear relationship between drug concentration and percentage of loading. The in vitro release of drug-loaded nanospheres was found to be first order. The comparative in vitro diffusion study between the commercial cream and the formulated cream showed a marked reduction in release rate from nanospheres-bound cream.
Conclusion: Formulated topical cream containing nanospheres of betamethazone was found to be a potential dermal delivery system for sustaining the release of the drug.

Keywords
Nanospheres, desolvation and cross-linking method, ethyl cellulose, betamethazone, in-vitro diffusion studies.