Influence of the formulation type (o/w, w/o/w emulsions and ointment) on the topical delivery of paromomycin

Abstract

Ointments containing paromomycin (PA) have been used for topical treatment of cutaneous leishmaniasis. Although influence of the vehicle on skin permeation is crucial for optimization of formulations containing PA, this aspect has not been investigated experimentally. In this study, we have evaluated the influence of the formulation type [oil-in-water (o/w), water-in-oil-in-water (w/o/w) emulsions and ointment] on in vitro release and skin permeation of PA and experiments were carried out on cellulose acetate membrane and skin biopsies from hairless mice, respectively. PA release from o/w emulsion (51.7% ± 0.9 of dose applied) was faster than that observed for w/o/w emulsion (3.0% ± 0.5). PA absorption from o/w emulsion (87.1% ± 3.9) through stripped skin was 5 to 6 times higher than that observed for w/o/w multiple emulsion (14.7% ± 0.5) and ointment (16.6% ± 0.1). PA permeation through intact (normal) skin was negligible for all tested formulations. Skin uptake from o/w emulsion (0.9% ± 0.1) was greater than that observed for w/o/w multiple emulsion (0.3% ± 0.1) and ointment (0.1% ± 0.1). These results suggest that a hydrophilic vehicle (o/w emulsion) could be an interesting alternative to improve topical delivery of PA.