Poloxamer 407 (Pluronic(®) F127)-based polymeric micelles for amphotericin B: In vitro biological activity, toxicity and in vivo therapeutic efficacy against murine tegumentary leishmaniasis.

In the present study, a Poloxamer 407-based amphotericin B (AmpB)-containing polymeric micelles system (AmpB/M) was employed in the treatment of Leishmania amazonensis-infected BALB/c mice. Initially, the in vitro antileishmanial activity (IC50 value) of AmpB/M and B-AmpB/M (empty micelles) against stationary promastigotes and amastigotes-like forms of the parasites was determined, and results were of 1.83 ± 0.4 and 22.1 ± 0.7 µM, respectively, for the promastigotes, and of 2.27 ± 0.5 and 33.98 ± 2.6 µM, respectively, for the amastigotes-like. The cytotoxic concentration (CC50) values of these products were also evaluated, and we found the results of 119.5 ± 9.6 and 134.7 ± 10.3 µM, respectively. With these values, the selectivity index (SI) was calculated and results were of 65.3 and 5.4, respectively, for the promastigotes, and of 59.3 and 3.96, respectively, for the amastigotes-like of the parasites. Free AmpB showed IC50 values of 1.2 ± 0.3 and 2.5 ± 0.5 µM for the promastigotes and amastigotes-like, respectively, whereas the CC50 value was of 9.5 ± 0.4 µM. The SI values of this drug were of 7.9 and 3.8, respectively, for the promastigote and amastigote-like stages of the parasites. After, animals were infected and received saline or were treated subcutaneously with free AmpB, AmpB/M or B-AmpB/M. In the results, free AmpB-treated and infected mice showed reductions in their body weight, which were associated with hepatic and renal damage; however, no organic alteration was observed in the AmpB/M-treated animals. In addition, these animals showed significant reductions in their lesion average size and in the parasite burden in all evaluated infected tissue and organs, when compared to the other groups; as well as significantly higher levels of antileishmanial IFN-γ, IL-12, GM-CSF and nitrite, which were associated with low production of IL-4, IL-10 and IgG1 isotype antibodies. In conclusion, this AmpB/M system could be considered as an alternative for future studies in the treatment of tegumentary leishmaniasis.

Propolis--based chitosan varnish: drug delivery, controlled release and antimicrobial activity against oral pathogen bacteria.

BACKGROUND: Dental caries is the most prevalent oral disease in several Asian and Latin American countries. It is an infectious disease and different types of bacteria are involved in the process. Synthetic antimicrobials are used against this disease; however, many of these substances cause unwarranted undesirable effects like vomiting, diarrhea and tooth staining. Propolis, a resinous substance collected by honeybees, has been used to control the oral microbiota. So, the objective of this study was to develop and characterize sustained-release propolis-based chitosan varnish useful on dental cariogenic biofilm prevention, besides the in vitro antimicrobial activity. METHODS: Three formulations of propolis - based chitosan varnish (PCV) containing different concentrations (5%, 10% and 15%) were produced by dissolution of propolis with chitosan on hydro-alcoholic vehicle. Bovine teeth were used for testing adhesion of coatings and to observe the controlled release of propolis associated with varnish. It was characterized by infrared spectroscopy, scanning electron microscopy, casting time, diffusion test in vitro antimicrobial activity and controlled release. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were tested for the main microorganisms involved in the cariogenic biofilm through the microdilution test in 96-well plates. RESULTS: The formulations presented a tooth surface adherence and were able to form films very fast on bovine tooth surface. Also, propolis-based chitosan varnishes have shown antimicrobial activity similar to or better than chlorhexidine varnish against all oral pathogen bacteria. All microorganisms were sensitive to propolis varnish and chitosan. MIC and MBC for microorganisms of cariogenic biofilme showed better results than chlorhexidine. Propolis active components were released for more than one week. CONCLUSION: All developed formulations turn them, 5%, 10% and 15% propolis content varnish, into products suitable for clinical application on dental caries prevention field, deserving clinical studies to confirm its in vivo activity.

Chitosan/hydroxyethyl cellulose inserts for sustained-release of dorzolamide for glaucoma treatment: In vitro and in vivo evaluation.

Eye drops containing hydrophilic drugs are commonly used to reduce intraocular pressure (IOP) in glaucoma patients, but compliance to the treatement is commonly reduced by frequent dosing and eventual systemic side effects. Sustained-release drug delivery systems, such as ocular inserts, can reduce dosing, limit systemic exposure, reduce side effects, and, then, improve patient adherence to therapy. Here, we developed and evaluated chitosan/hydroxyethyl cellulose-based ocular inserts for sustained release of dorzolamide, a hydrophilic drug. Dorzolamide inserts (DI) were produced by solvent/casting method and characterized by various physicochemical techniques. Pharmacokinetics studies were performed using scintigraphic images and ex vivo biodistribution. The effectiveness of inserts was tested in glaucomatous rats. Characterization studies showed that the drug strongly interacted with the polymeric matrix, but in vitro results showed that DI took only 3 h to release 75% of dorzolamide entraped. However, scintigraphic images and ex vivo biodistribution studies revealed that more than 50% of 99mTc-dorzolamide remained in the eye after 18 h of DI administration, while only about 30% of the drug remained in the eye after drops instilation. DI exerted significant hypotensive effect for two weeks, after single administration, while IOP values remained high in placebo and untreated groups. Eye drops were effective only during the treatment period. Only DI treatment prevented retinal ganglion cells death. Altogether, these findings evidenced the potential application of polymeric-based inserts for sustained release of dorzolamide in glaucoma management.