Desenvolvimento de nanoemulsão contendo óleo de Melaleuca alternifolia e terbinafina destinado à infecções fúngicas tópicas

Abstract

The search for alternative antimicrobials capable of surpassing the structure composed by the nail remains a great challenge for the treatment of fungal nail infections. A promising strategy to control these infections may be based on the use of natural compounds. Essential oils, extracted from aromatic plants, are well-known antimicrobial agents characterized by a broad spectrum of activities, including antifungal properties. Tea tree oil (TTO) is a volatile essential oil derived primarily from the native Australian plant Melaleuca alternifolia. Widely used for its antimicrobial properties, TTO is incorporated as an active ingredient in many topical formulations. This oil has terpinen-4-ol as its main constituent, which has a broad spectrum of antimicrobial activity, as well as antifungal activity. Terbinafine is a drug belonging to the allylamine class, acting on the epoxidase enzyme of the fungal cell, especially indicated for skin infections caused by fungi. Among the strategies that can reduce the doses of actives and allow the cutaneous penetration of terbinafine associated with TTO, nanoemulsions (NE) stand out. Characterized as a heterogeneous system, NE are composed of a liquid (the internal phase) dispersed in another (the external phase) in the form of droplets, in the presence of an emulsifying agent, which, due to its particle size, promotes better adhesion to the keratinized tissue of the nail. Thus, the objective of this work was to develop and characterize nanoemulsions containing different TTO concentrations (1.6, 2.4 e 3.2 mg.mL-1) combined to terbinafine intended for topical use. The NE were prepared by the spontaneous emulsification technique. The formulations were characterized for droplet size distribution (laser diffractometry). The NE showed a monomodal distribution profile on the nanometer scale, with an average diameter of 371 nm, 449 nm and 400 nm and a Span value (polydispersion) of 0.556, 0.573 and 0.576, being considered suitable for the intended use. Future experiments will be carried out to evaluate the microbiological activity of TTO and terbinafine contained in NE.