The adsorption of metronidazole and tinidazole to activated charcoal and the effect of magnesium sulfate.

The effect of magnesium sulfate on the in vitro adsorption of metronidazole and tinidazole to activated charcoal was studied. Solutions of metronidazole and tinidazole were prepared at low concentrations of 6.25, 12.5, 25.0 and 50 micrograms/ml and at simulated toxic concentrations of 0.5, 1.0, 2.0, 5.0 and 10 mg/ml in distilled water. Drug charcoal slurries were vortex-mixed, centrifuged and analyzed for free drug. Metronidazole gave adsorption capacities of 62.2-82.7% with 50 and 200 mg activated charcoal. Fifty and 200 mg activated charcoal adsorbed 80-90% of tinidazole. Metronidazole at 0.5 mg/ml had 16.7, 30.0, 56.7, 75.0 and 83.3% adsorption with 12.5, 50, 125, 250 and 500 mg charcoal respectively. There was a corresponding increase in the adsorption of metronidazole and tinidazole at the increasing concentrations of activated charcoal. The adsorption of metronidazole and tinidazole also seemed to be dose dependent. Magnesium sulfate (7.5 mg/ml) enhanced the adsorption of metronidazole to activated charcoal, but had no effect on tinidazole-charcoal adsorption.