テトラサイクリンの数種の固相の物性と消化管吸収

抄録

Four different solid phases of tetracycline (trihydrate, anhydrate, dehydrate, and amorphous) were isolated. These phases were characterized by using IR spectroscopy, X-ray powder diffraction, and thermogravimetric and differential thermal analyses. Dissolution behavior of these phases in distilled water was investigated and an appreciable difference in the dissolution behavior was detected between the amorphous and the other solid phases. The effect of the solid phases on bioavailability of tetracycline was also studied. Blood plasma levels obtained in rabbits and blood levels in rats after intraduodenal administration of the trihydrate and amorphous were compared, and its results indicated that the solubility difference between the two phases has an effect on the bioavailability of tetracycline. The cumulative excretion of tetracyc1ine in urine after oral administration of the two phases to human subjects was also examined and its results indicated that the cumulative amount after administration of the amorphous was slightly higher than that of the trihydrate.