Tetracyclines Kaolin

TETRACYCLINES KAOLIN l tetracycline levels 1 absorption Separate doses by at least 2 hours... 

The adsorbent properties of kaolin may influence the absorption of other orally administered drugs. Drugs rraortedly affected by kaolin include amoxicillin ampicillin cimeti-dine digoxin lincomycin phenytoin and tetracycline. 

Digoxin is nearly completely absorbed from the gut. In some patients, absorption may be deaeased due to digoxin inactivation by gut bacteria (i.e., Eubacterium lentum) Digoxin absorption is reduced by concomitant administration of antacids, cholestyramine, kaolin/pectin, tetracycline, and neomycin. Radiation malabsorption and gastrointestinal motility drugs such as metoclopramide can also reduce absorption. ... 

Adsorption of some drugs, especially vitamins, on diluents such as kaolin. Fuller s earth or hentonite can occur in capsule and tablet dosage forms. The physical adsorption can retard dissolution and, hence, hioavailahility. Some calcium salts (e.g. dicalcium phosphate) are extensively used as diluents in tablet and capsule dosage forms. The original use of dicalcium phosphate in a tetracycline capsule formation resulted in poor bioavailability. Lactose tends to react with amine compounds causing discoloration. 

Healthy subjects were given tetracycline 250 mg as a solution or as a capsule, with and without 30 rtiL of kaolin-pectin (Kaopectate). The absorption of both formulations was reduced by about 50% by the kaolin-pectin. Even when the kaolin-pectin was given 2 hours before or after the tetracycline, the drug absorption was still reduced by about 20%. The likely reason for this interaction is that tetracycline becomes adsorbed onto the kaolin-pectin so that less is available for absorption. 

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