Mucoadhesive polymer-coated liposomes as a promising approach to counteract bacteria responsible for aerobic vaginitis

Aerobic vaginitis is an infectious disease characterized by the overgrowth of abnormal vaginal microflora. Conventional local dosage forms are not always effective, due to their inadequate drug release and residence time within the vaginal cavity. Therefore, this study aimed to develop azithromycin (AZT)-loaded liposomes, coated with two mucoadhesive polymers, chitosan (CS) and sodium hyaluronate (HYA), to increase thedrug's stay at the site of infection and to control its release. Liposomes were developed through the thin film hydration method followed by extrusion and subsequently added to the polymer solution. Later, they were characterized by their size, surface charge, morphology, and encapsulation efficiency. Furthermore, mucoadhesive properties and drug release behavior were investigated at different pH values, e.g., 4.5 and 7.4, mimicking the physiological and pathological conditions, respectively. Finally, antimicrobial tests and in vitro permeation studies were carried out. Results showed size and surface charge variations of coated LP with respect to the uncoated ones, confirming the success of the coating process. LP possessed a good capacity to encapsulate the drug. Among all the formulations, CS-LP demonstrated superior control of drug release and greatest mucoadhesive properties at both tested pHs, as well as the highest drug accumulation inside the vaginal tissue, maintaining at the same time AZT antimicrobial effect. Overall, CS-LP could be proposed as a promising nanocarrier for AZT vaginal delivery, in virtue of its ability to achieve locally a sustained release of drug, helping to lower the dosage and administration frequency, and consequently improving treatment efficacy.