Efficacy of Attapulgite Clay as Adsorbent for Metronidazole Drug Overdose in vitro.


AbstractSurface active materials have many applications in medicine. Attapulgite clay used in medicine as antidiarrheal, and as additives in some pharmaceutical formulations. Metronidazole drug is widely used as antiprotozoal drug in the treatment of amoebic dysentery and amoebic liver abscess. Drug overdose may treated by adsorbents especially by activated charcoal suspension to prevent further absorption, but usually it is unacceptable to drink. Hence, in this work a study was carried out to estimate the ability of attapulgite clay as adsorbent for metronidazole overdose in vitro as a possible alternative for activated charcoal. The change in the concentration of metronidazole after incubation of known concentration of aqueous metronidazole solutions with attapulgite was measured as the adsorbed quantity. UV-Visible spectrophotometry technique was used to follow the quantity of the adsorbed drug. The adsorption also occurred in 0.1N HCl solution to simulate the acidity of the stomach. The adsorption experiments were repeated at (12, 25, 37.5, and 50ºC) to measure the thermodynamical parameters (ΔHº, ΔGº, ΔSº). Adsorption of metronidazole on attapulgite obeyed Freundlich adsorption isotherm of S2 type according to Giles classification of adsorption isotherm in solution. The maximum quantity adsorbed tends to be slightly increased in acidic medium (0.1N HCl) especially at low concentration of the drug. The thermodynamic parameters values were (ΔHº=-19.86 KJ.mol-1, ΔGº=-17.994 KJ.mol-1, and ΔSº=6.25 J.mol-1ºK-1).Metronidazole drug can be adsorbed by attapulgite clay surface at low concentration of the drug and the quantity of the adsorbed drug increased with increasing the initial concentration of the drug. The adsorption quantities were decreased with increasing temperature indicating an exothermic adsorption process which also reinforced by the values of thermodynamic parameters. Acidity has a slight effect on adsorption.