Microemulsões contendo azitromicina: Formulação, caracterização e atividade antibacteriana

Abstract

Bacterial Skin Infections (BSIs) includes a varied group of diseases caused by the invasion of bacteria into the epidermidis and adjacent soft tissues. Although the skin can host bacteria belonging to the normal cutaneous microbiota, such as, several speciessuch as, Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa can be considered pathogens for several IBPs. Among the various antibiotic groups used in treatment of BSIs, azithromycin is mentioned in the literature. Azithromycin (AZ), is a semi-synthetic macrolide antibiotic of the azalide class and is a promising candidate for the treatment of BSIs due to their capacity of penetration in the tissues and wide spectrum of action for several bacterial species. The incorporation of AZ into new drugs delivery systems such as microemulsion (ME) can ensure release control, lower toxicity, lower doses, decrease in plasma peaks, protection of drug degradation or inactivation. The present work aims to encapsulate AZ into microemulsion systems, perform the characterization and confirm its antibacterial activity. From the pseudoternary phase diagram were developed and selected one type of O/W formulations composed of deionized water, isopropyl myristate, LAS , and Brij 52 for the encapsulation of AZ. Both formulations in the absence (MEB) and presence of drug (MEAZ) were presented as clear and stable systems. For MEAZ, the pH value (6.75) indicated an excellent compatibility for dermal administration. In addition, its high conductivity (630.1), allied with the differential scanning calorimetry (DSC) studies, suggested an O/A type system. The refractive index revealed the isotropic character, confirmed by the technique of polarized light microscopy. Transmission electron microscopy (MET) indicated the nanometric droplet size of the systems and the dynamic light scattering (DLS) technique was able to measure a diameter of 18.72 and 20.89 nm for MEB and MEAZ, respectively. From the rheological analysis we can attest to the Newtonian type behavior for both formulations. Finally, the antimicrobial activity of MEAZ against the strains of S.aureus, S.epidermidis and P.aeruginosa was confirmed. Studies necessary to trace the release profile and determination of minimal inhibitory concentration will be conducted so that the developed ME may represent a new safe and effective alternative in the complementary treatment of PPIs.