Smecta, dioctahedral smectite, is a natural adsorbent clay used for symptomatic treatment of irritable bowel syndrome and gastroesophageal reflux. It is also used for acute and chronic diarrhea.Smecta is known to adsorb avidly certain compounds, especially basic drugs.In this study,the extent of adsorption of two basic drugs disopyramide and quinidne onto Smecta was determined in viro at ph4.5 phosphate buffer solution, in order to predict the potential for in vivo drug-drug interactions.For disopyramide, the extent of adsorption onto therapeutic dose of Smecta was very high at both of the concentrations tesed, with mean values of 98.32+-0.10(S.D, n=3)and 96.48+-0.17% at concentration of 40 and 400g/ml (disopyramide phosphate),respctively.For quinidne, the extent of adsorption was also very high at both of the concentratrations tested with mean valuesof 99.99+-0.004(S.D, n=3)and99.88+-0.01% at concentration of 80 and 800g/ml (quinidne sulfate),respectively. Because both disopyramide ane quinidne are significant adsorded by Smecta,which may decrease their rate and/or extent of adsorption in vivo, they should not be co-administered with smecta. based on literature and the the present results, it is recommended not to adminster any other basic drugs at the same time as smecta.
