RESUMO
Several authors have studied the release profile of drugs incorporated in different devices. However, to the best of our knowledge, although many studies have been done on the release of tetracycline, in these release devices, no study has investigated if the released compound is actually the tetracycline, or, instead, a degraded product. This approach is exploited here. In this work, we analyse the influence of two drying methods on the tetracycline delivery behaviour of synthesised glasses using the sol-gel process. We compare the drying methods results using both theoretical models and practical essays, and analyse the chemical characteristic of the released product in order to verify if it remains tetracycline. Samples were freeze-dried or dried in an oven at 37°C and characterised by several methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), differential thermogravimetric analysis (DTG), differential thermal analyses (DTA) and gas adsorption analysis (BET). The released concentration of tetracycline hydrochloride was studied as a function of time, and it was measured by ultraviolet spectrophotometry in the tetracycline wavelength. The drug delivery profiles were reasonably consistent with a diffusion model analysis. In addition, we observed higher release rates for the freeze-dried compared to those dried in an oven at 37°C. This higher release can be attributed to larger pore size for the freeze-dried sample systems with tetracycline, which promoted more water penetration, improving the drug diffusion. The analysis of the solution obtained in the release tests using high-performance liquid chromatography- mass spectrometry (HPLC-MS) confirmed that tetracycline was being released.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Tetraciclinas/síntese química , Antibacterianos/administração & dosagem , Antibacterianos/síntese química , Antibacterianos/farmacocinética , Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/síntese química , Preparações de Ação Retardada/farmacocinética , Difusão , Composição de Medicamentos/métodos , Liofilização/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Tetraciclinas/administração & dosagem , Tetraciclinas/farmacocinéticaRESUMO
Pd(II) complexes with three antibiotics of the tetracycline family (tetracycline, doxycycline and chlortetracycline) were synthesized and characterized by elemental, thermogravimetric, and conductivity analyses, and infrared spectroscopy. The interactions between Pd(II) ions and tetracycline were investigated in aqueous solution by (1)H NMR. All the tetracyclines studied form 1:1 complexes with Pd(II) via the oxygen of the hydroxyl group at ring A and that of the amide group. The effect of the three complexes on the growth of bacterial strains sensitive and resistant to tetracycline was studied. The Pd(II) complex of tetracycline is practically as efficient as tetracycline in inhibiting the growth of two Escherichia coli (E. coli) sensitive bacterial strains and 16 times more potent against E. coli HB101/pBR322, a bacterial strain resistant to tetracycline. Pd(II) coordination to doxycycline also increased its activity in the resistant strain by a factor of 2.
Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Compostos Organometálicos/síntese química , Compostos Organometálicos/farmacologia , Paládio/farmacologia , Tetraciclinas/síntese química , Tetraciclinas/farmacologia , Antibacterianos/química , Escherichia coli/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Compostos Organometálicos/química , Paládio/química , Tetraciclinas/química , TermodinâmicaRESUMO
A tetracycline-platinum(II) complex, [PtCl2(C22H24N2O8)], was synthesized and characterized by elemental analysis, conductivity and thermogravimetric analyses, and infrared spectroscopy. The interaction of tetracycline (Tc) with platinum(II) ions was also studied in aqueous solution by 1H NMR and circular dichroism spectroscopies. Tetracycline forms a 1:1 complex with platinum via the oxygen of the hydroxyl group at the A ring and that of the amide group. The complex is as efficient as tetracycline in inhibiting the growth of two Escherichia coli sensitive bacterial strains and six times more potent against E. coli HB101/pBR322, a bacterial strain resistant to tetracycline. This finding is very important because the use of tetracycline to treat bacterial infections has declined due to the emergence of resistant organisms.
Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Compostos Organoplatínicos/síntese química , Compostos Organoplatínicos/farmacologia , Tetraciclinas/síntese química , Tetraciclinas/farmacologia , Antibacterianos/química , Dicroísmo Circular , Escherichia coli/efeitos dos fármacos , Compostos Organoplatínicos/química , Resistência a Tetraciclina , Tetraciclinas/químicaRESUMO
A produçäo de antibióticos em meio granular sólido foi feita utilizando-se apenas vidraria simples e matérias-primas acessíveis a qualquer laboratório. Foram utilizados como suporte de nutrientes materiais granulares (malte moído grosseiramente, arroz polido, milho em gräo, canjica, amendoim e farelo de milho) e material fibroso (bagaço de cana). Volumes variáveis de três suspensöes nutrientes foram adicionados aos materiais suporte e os meios foram inoculados com o Streptomyces aureofaciens para produçäo de tetraciclina e com o Amycolatopsis mediterranei para produçäo de rifamicina SV. Os seguintes rendimentos de tetraciclina após 14 dias de fermentaçäo (mg/L de suspensäo nutriente) foram obtidos: 1.502 em amendoim, 1.050 em arroz e 816 em canjica. Os rendimentos de rifamicina SV em bagaço de cana e em canjica foram 83 e 87 (mg/L), respectivamente. O processo pode ser utilizado para produçäo de antibióticos em pequena escala para fins demonstrativos, para pesquisas de novos antibióticos e antitumorais e para a investigaçäo de estruturas de muitos antibióticos usualmente rejeitados pelo fato de os microrganismos näo produzirem em culturas submersas. Para produçäo em escala industrial com meio granular é necessário desenvolver equipamentos, que iräo onerar os custos da instalaçäo