Associating chitosan and microemulsion as a topical vehicle for the administration of herbal medicines

A viscous solution of low molecular weight chitosan (CH) at 5% w/v (10.2 kDa, 75 % deacetylated, 1451 cP at 25 degrees C) was associated with a microemulsion (ME) that undergoes a phase transition after water absorption in situ (approximate to 28 % w/w), forming a more viscous liquid crystal, which was potentially evaluated as a topical vehicle. The ME was selected from a phase diagram, selecting a composition based on Tween (R) 80 (52 %), myristate isopropyl (28 %), and the aqueous phase (water and polyethylene glycol 400, 60:40 w/w) (20 %), which was after replaced by CH and herbal medicines (HM). HM are alternatives to treat candidiasis, and Stryphnodendron adstringens shell extract, characterized by molecular networking, and Melaleuca alternifolia Chell essential oil (46 % of terpinen-4-ol), showed in vitro activity against Candida albicans. Associating CH in ME improved the mechanical properties of the topical formulation, as adhesiveness, which is an advantageous feature for the topical treatment of vulvovaginal candidiasis.

Automated summary

By associating low molecular weight chitosan with a microemulsion, a more viscous liquid crystal topical vehicle was formed. Experimental results with Brazilian Stryphnodendron adstringens shell extract and Melaleuca alternifolia essential oil showed activity against Candida albicans. Incorporating chitosan in the microemulsion improved the mechanical properties of the topical formulation, providing advantages for the topical treatment of vulvovaginal candidiasis.