Adsorptive capacity of activated charcoal for rifampicin with and without sodium chloride and sodium citrate.

The effects of two saline cathartics (sodium chloride and sodium citrate) on the adsorptive capacity of activated charcoal (AC) for rifampicin were studied. Solutions of rifampicin alone and rifampicin with 7.5 mg/ml cathartic solution were vortex-mixed for 30 s with different quantities of AC. These were incubated for 30 min at 37 degrees C and analyzed for free rifampicin spectrophotometrically at 320 nm. The addition of sodium citrate significantly increased (p<0.05) the adsorptive capacity of AC for rifampicin with a resulting decrease in B-50 values at both the therapeutic and simulated toxic doses. Sodium chloride addition reduced the binding of rifampicin to AC at the toxic doses. The adsorption of rifampicin to activated charcoal, both alone and with the two saline cathartics, obeyed quantity-dependent kinetics. AC may be co-administered with sodium citrate in the management of rifampicin overdose.