Poly(sebacic acid) microparticles loaded with azithromycin as potential pulmonary drug delivery system: Physicochemical properties, antibacterial behavior, and cytocompatibility studies

Recurrent bacterial infections are a common cause of death for patients with cystic fibrosis and chronic obstructive pulmonary disease. Herein, we present the development of the degradable poly(sebacic acid) (PSA) microparticles loaded with different concentrations of azithromycin (AZ) as a potential powder formulation to deliver AZ locally to the lungs. We characterized microparticle size, morphology, zeta potential, encapsulation efficiency, interaction PSA with AZ and degradation profile in phosphate buffered saline (PBS). The antibacterial properties were evaluated using the Kirby-Bauer method against Staphylococcus aureus. Potential cytotoxicity was evaluated in BEAS-2B and A549 lung epithelial cells by the resazurin reduction assay and live/dead staining. The results show that microparticles are spherical and their size, being in the range of 1-5 μm, should be optimal for pulmonary delivery. The AZ encapsulation efficiency is nearly 100 % for all types of microparticles. The microparticles degradation rate is relatively fast - after 24 h their mass decreased by around 50 %. The antibacterial test showed that released AZ was able to successfully inhibit bacteria growth. The cytotoxicity test showed that the safe concentration of both unloaded and AZ-loaded microparticles was equal to 50 μg/ml. Thus, appropriate physicochemical properties, controlled degradation and drug release, cytocompatibility, and antibacterial behavior showed that our microparticles may be promising for the local treatment of lung infections.

Poly(octamethylene citrate) Modified with Glutathione as a Promising Material for Vascular Tissue Engineering

One of the major goals of vascular tissue engineering is to develop much-needed materials that are suitable for use in small-diameter vascular grafts. Poly(1,8-octamethylene citrate) can be considered for manufacturing small blood vessel substitutes, as recent studies have demonstrated that this material is cytocompatible with adipose tissue-derived stem cells (ASCs) and favors their adhesion and viability. The work presented here is focused on modifying this polymer with glutathione (GSH) in order to provide it with antioxidant properties, which are believed to reduce oxidative stress in blood vessels. Cross-linked poly(1,8-octamethylene citrate) (cPOC) was therefore prepared by polycondensation of citric acid and 1,8-octanediol at a 2:3 molar ratio of the reagents, followed by in-bulk modification with 0.4, 0.8, 4 or 8 wt.% of GSH and curing at 80 °C for 10 days. The chemical structure of the obtained samples was examined by FTIR-ATR spectroscopy, which confirmed the presence of GSH in the modified cPOC. The addition of GSH increased the water drop contact angle of the material surface and lowered the surface free energy values. The cytocompatibility of the modified cPOC was evaluated in direct contact with vascular smooth-muscle cells (VSMCs) and ASCs. The cell number, the cell spreading area and the cell aspect ratio were measured. The antioxidant potential of GSH-modified cPOC was measured by a free radical scavenging assay. The results of our investigation indicate the potential of cPOC modified with 0.4 and 0.8 wt.% of GSH to produce small-diameter blood vessels, as the material was found to: (i) have antioxidant properties, (ii) support VSMC and ASC viability and growth and (iii) provide an environment suitable for the initiation of cell differentiation.

Inhalable microparticles as drug delivery systems to the lungs in a dry powder formulations

Inhalation-administrated drugs remain an interesting possibility of addressing pulmonary diseases. Direct drug delivery to the lungs allows one to obtain high concentration in the site of action with limited systemic distribution, leading to a more effective therapy with reduced required doses and side effects. On the other hand, there are several difficulties in obtaining a formulation that would meet all the criteria related to physicochemical, aerodynamic and biological properties, which is the reason why only very few of the investigated systems can reach the clinical trial phase and proceed to everyday use as a result. Therefore, we focused on powders consisting of polysaccharides, lipids, proteins or natural and synthetic polymers in the form of microparticles that are delivered by inhalation to the lungs as drug carriers. We summarized the most common trends in research today to provide the best dry powders in the right fraction for inhalation that would be able to release the drug before being removed by natural mechanisms. This review article addresses the most common manufacturing methods with novel modifications, pros and cons of different materials, drug loading capacities with release profiles, and biological properties such as cytocompatibility, bactericidal or anticancer properties.

Insight in Superiority of the Hydrophobized Gentamycin in Terms of Antibiotics Delivery to Bone Tissue

Bone infections are a serious problem to cure, as systemic administration of antibiotics is not very effective due to poor bone vascularization. Therefore, many drug delivery systems are investigated to solve this problem. One of the potential solutions is the delivery of antibiotics from poly(L-actide-co-glycolide) (PLGA) nanoparticles suspended in the gellan gum injectable hydrogel. However, the loading capacity and release kinetics of the system based on hydrophilic drugs (e.g., gentamycin) and hydrophobic polymers (e.g., PLGA) may not always be satisfying. To solve this problem, we decided to use hydrophobized gentamycin obtained by ion-pairing with dioctyl sulfosuccinate sodium salt (AOT). Herein, we present a comparison of the PLGA nanoparticles loaded with hydrophobic or hydrophilic gentamycin and suspended in the hydrogel in terms of physicochemical properties, drug loading capacity, release profiles, cytocompatibility, and antibacterial properties. The results showed that hydrophobic gentamycin may be combined in different formulations with the hydrophilic one and is superior in terms of encapsulation efficiency, drug loading, release, and antibacterial efficacy with no negative effect on the NPs morphology or hydrogel features. However, the cytocompatibility of hydrophobic gentamycin might be lower, consequently more extensive study on its biological properties should be provided to evaluate a safe dose.