Effect of Additives on the Polymorphic Transformation of Chlortetracycline Hydrochloride Crystals

概要

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The effect of various additives on the polymorphic transformation of the more energetic chlortetracycline hydrochloride (CTC-HCl) β form to the water stable α form in aqueous suspensions was studied by infrared spectrophotometric method. This transformation was found to be retarded by the addition of some pharmaceutical additives such as sodium carboxymethylcellulose (CMC-Na), pectin, gelatin, and acacia ; which have been commonly coadministered with drugs. The attempt was made to elucidate possible mechanisms of this effect. The results suggest that the effect of CMC-Na or pectin on transformation rates may be mainly due to the increased viscosity. On the other hand, the adsorption of gelatin or acacia on drug particles may be one of several factors which retard the transformation. The effect of these additives on the blood levels of the CTC-HCl β form in suspensions was also tested using the rat as the test animal. Higher blood levels were observed when the CTC-HCl β form was administered with CMC-Na or pectin than those in its absence, probably because the additives retarded the transformation. Administration of the CTC-HCl β form with gelatin or acacia resulted in slightly lower or almost identical blood levels compared to control values. It is suggested that gelatin or acacia may interfere with intestinal absorption of the drug.
公益社団法人日本薬学会の論文
1976-09-25