سرعت انحلال و پايداري فيزيكي سيستم همرسويي ايندومتاسين - پوويدون

Evaluation of dissolution rate and physical stability of Indomethacin-povidone coprecipitate

Background: The role of solid dispersion system in enhancement of dissolution rate of drugs was first explained in 1961, .We have studied the dissolution rate, physical stability, and distribution of IIndomethacin (Ind) in coprecipitation with povidone. Materials and methods: During this experimental study, to determine the kind of dispersion and causes of enhanced dissolution rate of Ind. in coprecipitation with povidone, the following tests were carried out: 1) dissolution ratesʹ studies of mechanical mixes as well as coprecipitation mixtures with the same percentage of M. 2) simultaneous dissolution rate of povidone and Ind. 3) microscopic photography of dissolution process. 4) solubility of pure Ind. in different concentrations of povidone, and 5) electron scanning micrography of coprecipitate. Results: We have found that the dissolution rate of Ind. in coprecipitate is a function of povidone molecular weight and percentage of drug. Thus, dissolution rate of drug in low molecular weight of povidone was about 10 fold faster than that of high molecular weight povidone. Meanwhile, dissolution rate in low fraction weight of drug was about 110 times greater than that of high fraction weight. Conclusion: Our findings have provided the formation of colloidal or molecular dispersion of Ind. in povidonc in fraction weight under 13.5% of Ind. Stability of coprecipitate in different relative humidity was varied. At relative humidity of 60%, stability of sample was too low due to salting-out phenomenon, however, at relative humidity of 70% and higher, the dissolution rate is increased mainly because of reduced glass transition temperature, viscosity of polymer and plasticizing effects of water.