Metronidazole is an antimicrobial agent utilized for the treatment of protozoa
and anaerobic bacteria infections. Many times, it is necessary to modify the
metronidazole release, and the development of modified release systems may be
suggested. In this study, we are able to investigate the use of the residue normally
thrown out from the preparation of propolis extracts (BP) as strategy to modify the
metronidazole release. We prepared films containing polymeric adjuvant (gelatin or
ethylcellulose) and metronidazole, by solvent casting method. Density, mechanical
properties, water vapor permeability (WVP), moisture uptake capacity (MUC),
thermogravimetry, differential scanning calorimetry, Fourier transform infrared
spectroscopy (FT-IR), and in vitro metronidazole release were investigated. Thickness
and density of the preparations indicated that the compounds were homogeneously dispersed
throughout. Mechanical properties were influenced by film composition. Films containing gelatin
showed higher resistance to stress while those containing ethylcellulose presented greater flexibility.
The greater the adjuvant concentrations lower the resistance to rupture and the elasticity, but higher
MUC and WVP of formulations. FT-IR tests suggested interactions between BP and the adjuvants.
Films were capable to protect the metronidazole and changed its release profile. BP films are of great
practical importance constituting a novel strategy to modify the metronidazole release.
Keywords: Drug release, ethylcellulose, gelatin, metronidazole, physicochemical properties, propolis byproduct.
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