XANTHAN AND GALACTOMANANN FROM SEEDS OF M. scabrella AS HYDROPHYLIC MATRICES OF THEOPHYLLINE / GOMA XANTANA E GALACTOMANANA (M. scabrella): DESENVOLVIMENTO DE MATRIZES HIDROFÍLICAS PARA LIBERAÇÃO MODIFICADA DE TEOFILINA

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Directly compressed theophylline tablets were produced containing commercial Xanthan (X) (Keltrol) and a highly hydrophyllic galactomannan (G) from the seeds of Mimosa scabrella, (a Brazilian leguminous tree, called bracatinga) as a release-controlling agent, isolated or in mixture (X:G 1:1), at 8, 12.5 and 25% of gums. In the galactomannan extraction process the biopolymer was dried by vacuum oven (VO) or spray dryer (SD) in a pilot scale. The drug release in vitro was evaluated at different time intervals during 8h using apparatus I USP, 100 rpm. The dissolution medium of pH 1.4 was altered to 4.0 and 6.8 after 2 and 3h, respectively. The tablets containing G(SD) resulting in more uniform tablet than G(VO) due to less average size of the former particles. The drug release decreased with the increase of polymer concentration and all formulations at 25% of gums showed excessive sustained release effect. The matrices made with isolated X showed higher drug retention in all concentration while the G matrices released too fast the drug. The XG matrices were capable to produce near zero order drug release. The XG(SD) 8% provided the required release rate, with liberation kinetics of zero order (it liberated about 90% at the end of 8 h). In some there was a complete erosion (tablets made with G(VO) in low concentration), while the others demonstrated fast hydration and swellable in contact with the dissolution medium. The predominant mechanism of release varies with matrices composition and was both the diffusion and relaxation. The XG(SD) 8% matrix showed higher contribution of polymer relaxation.

ASSUNTO(S)

farmacologia drug release liberação controlada xanthan galactomanana xantana farmacia galactomanann

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