RESUMO
A drug with cationic characteristics such as procaine can be conveyed in a Carbomer hydrogel in two different ways: (i) in the form of salt in solution in the aqueous phase, and (ii) in the base form salified with the same polymer. Introduction of the drug into the hydrogel with different concentrations of polymer produced, in both cases, a reduction in viscosity in relation to drug concentration. The gels with procaine salified with the polymer showed greater viscosity. The drug release rate, in general, diminished with the increase in polymer concentration. Nevertheless, when this concentration was maintained, there was no variation in release rate when the viscosity produced as a consequence of drug concentration was changed. Gels with procaine salified with the carboxyvinylic polymer had a faster release rate than those with procaine in the hydrochloride form dissolved in the aqueous phase. These results have also been confirmed by a simulated absorption test.
Assuntos
Resinas Acrílicas , Sistemas de Liberação de Medicamentos , Hidrogéis , Disponibilidade Biológica , Cátions , Humanos , Técnicas In Vitro , Procaína/administração & dosagem , Procaína/química , Procaína/farmacocinética , Reologia , ViscosidadeRESUMO
Samples of calcium carbonate tablets produced by different manufacturers were subjected to various tests in order to evaluate tablet quality parameters, mostly indicative for calcium availability. Indications about tablet suitability for treatment of renal osteodystrophy in uremic patients were also tested. The disintegration test turned out to be the most useful in evaluating calcium carbonate availability from tablets. Samples from several manufacturers varied in their behaviour to disaggregation. The availability of calcium dissolved in gastric fluid and the extent of phosphorus binding appeared to depend on disintegration behaviour.
Assuntos
Carbonato de Cálcio/análise , Distúrbio Mineral e Ósseo na Doença Renal Crônica/tratamento farmacológico , Carbonato de Cálcio/administração & dosagem , Carbonato de Cálcio/uso terapêutico , Testes de Dureza , Humanos , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Fósforo/química , Controle de Qualidade , Solubilidade , ComprimidosRESUMO
Silica gel confirmed its function as viscosity agent for lipophylic excipients for suppositories, ensuring homogeneous drug distribution in the suppository mass. The influence on release rate of a water-soluble drug (benzydamine hydrochloride) was clearly different according to type of silica gel. With Aerosil 200 (hydrophylic), after a progressive decrease in release rate at the lowest concentrations, an increase was observed at the highest concentrations, until it reached that of the suppositories without silica gel. With Aerosil R972, release rate decreased progressively with increased silica gel concentration, until release was practically inhibited even at low concentrations.
