Microemulsions are fluid and isotropic formulations that have been widely studied as delivery systems for a variety of routes, including the skin. In spite of what the name suggests, microemulsions are nanocarriers, and their use as topical delivery systems derives from their multiple advantages compared to other dermatological formulations, such as ease of preparation, thermodynamic stability and penetration-enhancing properties. Composition, charge and internal structure have been reported as determinant factors for the modulation of drug release and cutaneous and transdermal transport. This manuscript aims at reviewing how these and other characteristics affect delivery and make microemulsions appealing for topical and transdermal administration, as well as how they can be modulated during the formulation design to improve the potential and efficacy of the final system.

Introduction and objective: Previous studies indicate that miltefosine (MFS) may be an alternative as an antifungal agent; however, it presents several adverse effects. Thus, the aim of this study was to produce miltefosine-loaded alginate nanoparticles (MFS.Alg) for toxicity reduction to be used as an alternative for the treatment of cryptococcosis and candidiasis. Methods: Alginate nanoparticles were produced using the external emulsification/gelation method, and their physicochemical and morphological characteristics were analyzed. MFS encapsulation efficiency, release assay and toxicity on red blood cells and on Galleria mellonella larvae were assessed. The antifungal activity was evaluated using in vitro and in vivo larval models of G. mellonella infected with Candida albicans (SC5314 and IAL-40), Cryptococcus neoformans H99 and Cryptococcus gattii ATCC 56990. The treatment efficacy was evaluated by survival curve, colony forming unit (CFU) counting and histopathological analysis. Results: MFS.Alg nanoparticles presented a mean size of 279.1±56.7 nm, a polydispersity index of 0.42±0.15 and a zeta potential of −39.7±5.2 mV. The encapsulation efficiency of MFS was 81.70±6.64%, and its release from the nanoparticles occurred in a sustained manner. MFS in alginate nanoparticles presented no hemolytic effect and no toxicity in G. mellonella larvae. Treatment with MFS.Alg extended the survival time of larvae infected with C. albicans and C. gattii. In addition, the fungal burden reduction was confirmed by CFU and histopathological data for all groups treated with 200 mg/Kg of MFS.Alg. Conclusion: These results support the use of alginate-based drug delivery systems as carriers for MFS for drug toxicity reduction and control of the fungal infection in the in vivo model of G. mellonella.

The small heat shock protein, HSPB6, is a 17-kDa protein that belongs to the small heat shock protein family. HSPB6 was identified in the mid-1990s when it was recognized as a by-product of the purification of HSPB1 and HSPB5. HSPB6 is highly and constitutively expressed in smooth, cardiac, and skeletal muscle and plays a role in muscle function. This review will focus on the physiologic and biochemical properties of HSPB6 in smooth, cardiac, and skeletal muscle; the putative mechanisms of action; and therapeutic implications.