Saline cathartics and adsorptive capacity of activated charcoal for doxycycline.

The effects of sodium chloride and sodium citrate on the in vitro adsorption of doxycycline to activated charcoal have been studied. Solutions of doxycycline alone and doxycycline with 7.5 mg/ml cathartic solutions were vortex-mixed for 30 s with different quantities of activated charcoal, incubated for 30 min at 37 degrees C and analyzed for free doxycycline spectrophotometrically at 348 nm. Addition of NaCl had a significant (p<0.05) increase while sodium citrate produced a significant (p<0.05) decrease in the adsorption of doxycycline on activated charcoal. In all, the adsorption doxycycline on activated charcoal obeyed quantity-dependent kinetics.