Interaction of cations and chelators with the intestinal absorption of tetracycline.
The influence of certain compounds on intestinal absorption of tetracycline was tested, using two different in vivo techniques: a) Disappearence of the drug from perfused intestinal segments of the rabbit; b) Measuring urinary excretion in the rat after oral dosage. Ca2+ and Fe2+ ions both reduced the permeation rate of tetracycline by about 30%. In presence of Ca2+ and salicylate ions, leading to ion-pair formation with the antibiotic, intestinal uptake was significantly increased in comparison to experiments where only calcium was present. A more pronounced increase was observed with EDTA. Phosphate ions had different effects on the uptake of the antibiotic in both experimental techniques. Possible mechanisms are discussed.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology*; D002614:Chelating Agents / Q000494:pharmacology*; D004347:Drug Interactions; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D007408:Intestinal Absorption / Q000187:drug effects*; D007501:Iron / Q000494:pharmacology; D008297:Male; D010710:Phosphates / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D012459:Salicylates / Q000494:pharmacology; D013752:Tetracycline / Q000378:metabolism* / Q000652:urine
D002412:Cations; D002614:Chelating Agents; D010710:Phosphates; D012459:Salicylates; D004492:Edetic Acid; D007501:Iron; D013752:Tetracycline; D002118:Calcium