Development of microsponges for topical delivery of mupirocin

Abstract

The goal of the present study was to develop and evaluate microsponge-based topical delivery system of mupirocin for sustained release and enhanced drug deposition in the skin. Microsponges containing mupirocin were prepared by an emulsion solvent diffusion method. The effect of formulation and process variables such as internal phase volume and stirring speed on the physical characteristics of microsponges were examined on optimized drug/polymer ratio by 3(2) factorial design. The optimized microsponges were incorporated into an emulgel base. In vitro drug release, ex vivo drug deposition, and in vivo antibacterial activity of mupirocin-loaded formulations were studied. Developed microsponges were spherical and porous, and there was no interaction between drug and polymer molecules. Emulgels containing microsponges showed desired physical properties. Drug release through cellulose dialysis membrane showed diffusion-controlled release pattern and drug deposition studies using rat abdominal skin exhibited significant retention of active in skin from microsponge-based formulations by 24 h. The optimized formulations were stable and nonirritant to skin as demonstrated by Draize patch test. Microsponges-based emulgel formulations showed prolonged efficacy in mouse surgical wound model infected with S. aureus. Mupirocin was stable in topical emulgel formulations and showed enhanced retention in the skin indicating better potential of the delivery system for treatment of primary and secondary skin infections, such as impetigo, eczema, and atopic dermatitis.

Fig. 1

DSC thermograms of a ethylcellulose, b MP, and c MP-loaded microsponges (1.5:1)

Fig. 2

SEM of MP loaded microsponges under ×500

Fig. 3

Comparative in vitro release profiles of MP from different formulations. Each value represents mean ± SD (n = 6)

Fig. 4

Amount of MP deposited in rat skin from different formulations. Each value represents mean ± SD (n = 3)

Fig. 5

a Mouse surgical wound infected with S. aureus. b Comparative efficacy of MP-loaded formulations against an experimental surgical wound infection in mice caused by S. aureus. Each value represents mean ± SD (n = 6)