RESUMO
Photodynamic therapy (PDT) has been based on using photosensitizers (PS) and applying light of a specific wavelength. When this technique is used for treating infections, it is known as antimicrobial photodynamic therapy (aPDT). Currently, the use of lighting sources for in vitro studies using aPDT is generally applied in multiwell cell culture plates; however, depending on the lighting arrangement, there are usually errors in the application of the technique because the light from a well can affect the neighboring wells or it may be that not all the wells are used in the same experiment. In addition, one must be awarded high irradiance values, which can cause unwanted photothermal problems in the studies. Thus, this manuscript presents an in vitro antimicrobial photodynamic therapy for a Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) inhibition study using an arrangement of thermally isolated and independently illuminated green light source systems for eight tubes in vitro aPDT, determining the effect of the following factors: (i) irradiance level, (ii) exposure time, and (iii) Rose Bengal (RB) concentration (used as a PS), registering the Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) inhibition rates. The results show that in the dark, RB had a poor antimicrobial rate for P. aeruginosa, finding the maximum inhibition (2.7%) at 30 min with an RB concentration of 3 µg/mL. However, by applying light in a correct dosage (time × irradiance) and the adequate RB concentration, the inhibition rate increased by over 37%. In the case of MRSA, there was no significant inhibition with RB in complete darkness and, in contrast, the rate was 100% for those experiments that were irradiated.
RESUMO
Sodium alendronate is a nitrogen-containing bisphosphonate, widely used for osteoporosis treatment. However, due to its several oral administration drawbacks, the transdermal route represents an interesting option. The aim of this study was to formulate sodium alendronate in two submicron delivery systems, microemulsions, and solid-in-oil nanosuspensions, both systems possessing permeation enhancing properties. The composition of microemulsions was determined through the construction of pseudo-ternary phase diagrams. Solid-in-oil nanosuspensions were prepared by an emulsification-freeze-drying method, evaluating the effect of sonication time and the type of surfactant. According to the results of drug loading capacity, droplet/particle size, and polydispersity index, two microemulsions and two nanosuspensions were selected to perform the subsequent evaluations. The results showed that microemulsions allowed a faster release of alendronate than nanosuspensions. The permeation capacity of alendronate formulations was assessed through the synthetic membrane Strat M®, as well as through pigskin, finding higher fluxes with microemulsions than with nanosuspensions. In order to elucidate the effect of the formulations on the permeability barrier of the stratum corneum, techniques such as ATR-FTIR and TEWL were used. Finally, measurements of erythema intensity showed that neither of the two nanosystems caused skin irritation after 2 h of contact. The results suggest that alendronate formulated in a microemulsion can be a viable transdermal nanocarrier for osteoporosis treatment.