Medicinal plants produce secondary metabolites with special biological activities, which may be used as new therapeutic alternatives. For instance, tea tree essential oil (TTO) was shown to exert antimicrobial, antifungal, anthelmintic, antiviral, anti-tumor and anti-inflammatory activities. Due to their thermal instability, active principles can be easily degraded by physicochemical processes; therefore, they must be protected to increase their time of action and improve their controlled release. The aim of this review is to discuss formulations incorporating encapsulated TTO as the active ingredient. Micro and nanoencapsulated systems proved to be more thermostable than TTO and to exert better antimicrobial, antifungal, antiparasitic and larvicidal effects. Nanoencapsulation also reduced oil toxicity. Emulsified and hybrid systems developed by various methods showed improved repellent, antibacterial, antifungal and anti-inflammatory activities, thereby proving promising for the pharmaceutical industry. Liposomal formulations produced by hydration of lipid films exhibited constant rate of terpinen-4-ol release. In addition, their incorporation into biomaterials, such as sponges, nanofibers and films, showed great potential for treating infections. Mainly due to the advantages of their incorporation into new drug delivery systems over conventional formulations, there is an interest in the development of systems containing TTO as a pharmaceutical ingredient of plant origin.

The insertion of topical antimicrobials in wound treatment represented an important role in patient management. Among these agents, silver sulfadiazine (AgSD), introduced in the therapy of wounds and burns in the 1960s, is considered the gold standard in treatment due to its mechanism of action, in addition to its proven efficacy and safety. The association of AgSD with polymers for the development of curative formulations has been reported. The evaluation of the physical-chemical properties of these systems with the aid of analytical techniques of characterization is essential for the determination of their activities, besides allowing the detection of possible incompatibilities between AgSD and polymers. Thus, this review presents the main techniques of physicochemical characterization used in the evaluation of systems containing AgSD with curative purposes in order to provide parameters to ensure the efficacy and safety of these new therapeutic options. Microscopic, thermoanalytical, and spectroscopic techniques, for example, provide information on system properties such as surface chemical composition, crystallinity, morphology, and thermal stability of curative formulations containing AgSD. These techniques are important in the selection of the most appropriate techniques during the development of a polymeric curative system containing AgSD, in addition to providing information for cost reduction of a possible scale-up and the establishment of methodologies for quality control of these systems to ensure their efficacy and safety.

Simvastatin (SIM) is widely prescribed to treat hyperlipidemia, despite its limitations, such as a short half-life and low oral bioavailability. To overcome these drawbacks, the development of a controlled-release formulation is desirable. This study aims to develop a microparticulate system based on cellulose acetate (ACT) obtained from Agave sisalana Perrine to promote a controlled SIM release. SIM-loaded microparticles (SMP) were prepared using the solvent emulsification-evaporation method. Several parameters were evaluated, including particle size, surface charge, morphology, encapsulation efficiency, thermochemical characteristics, crystallinity, and in vitro release profile. ACT exhibited favorable flow properties after acetylation, with a degree of substitution values superior to 2.5, as confirmed by both the chemical route and H-NMR, indicating the formation of cellulose triacetate. The obtained SMP were spherical with an average size ranging from 1842 to 1857 nm, a zeta potential of −4.45 mV, and a high SIM incorporation efficiency (98%). Thermal and XRD analyses revealed that SIM was homogeneously dispersed into the polymeric matrix in its amorphous state. In vitro studies using dialysis bags revealed that the controlled SIM release from microparticles was higher under simulated intestinal conditions and followed the Higuchi kinetic model. Our results suggest that ACT-based microparticles are a promising system for SIM delivery, which can improve its bioavailability, and result in better patient compliance.