RESUMO
Gabapentin is a gamma-aminobutyric acid analogue, which has been shown to be an effective antiepileptic. The solution stability of gabapentin in buffered systems was studied in order to facilitate the formulation of a liquid product. The degradation of the drug was followed as a function of pH, buffer concentration, ionic strength, and temperature. The results indicated that the rate of degradation was proportional to the buffer concentration and temperature. The pH-rate profile of gabapentin degradation showed that the rate of degradation was minimum at an approximate pH of 6.0. Further, the data suggested a slower solvent-catalyzed degradation rate for the zwitterionic species compared to the cationic or anionic species in the pH range of 4.5 to 7.0. There was no influence of ionic strength on the rate of degradation. Arrhenius plots of the data indicated that a shelf life of 2 years or more at room temperature may be obtained in an aqueous solution at a pH value of 6.0.
Assuntos
Acetatos/química , Aminas , Anticonvulsivantes/química , Ácidos Cicloexanocarboxílicos , Água/química , Ácido gama-Aminobutírico , Soluções Tampão , Estabilidade de Medicamentos , Gabapentina , Concentração de Íons de Hidrogênio , Cinética , Estrutura Molecular , Concentração Osmolar , Soluções , TemperaturaRESUMO
In vitro dissolution studies of microencapsulated indomethacin showed that the USP paddle method was superior to the USP basket method in that the drug release was higher and more uniform with the paddle. Simulated intestinal fluid (pH 7.2) was an appropriate medium to use for dissolution studies on prolonged-release microcapsules.