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Precipitation of Calcium Gluceptate From Aqueous Solutions

R Suryanarayanan, A G Mitchell

J Pharm Sci. 1984 Jan;73(1):78-82.

PMID: 6694089

Abstract:

A precipitate encountered in solutions of calcium gluceptate was identified as hydrated calcium gluceptate. Precipitation was associated with a change from a very soluble amorphous anhydrous form to a sparingly soluble crystalline hydrate, the presence of seed crystals inducing crystallization, and unsuitable proportions of the alpha- and beta-epimers of calcium gluceptate. Various commercial samples and the corresponding precipitates were examined by elemental analysis, thermal analysis, X-ray diffraction, IR spectroscopy, and GC-MS. The proportion of the alpha- and beta-epimers in commercial samples was quantitated by GC. In this method, an aqueous solution of calcium gluceptate was converted into a mixture of glucoheptonic acids and their corresponding lactones by passage through a cation-exchange resin. The solution was freeze-dried, the acid-lactone mixture converted to the gamma-lactones using concentrated hydrochloric acid, and the resulting material trimethylsilylated with trimethylsilylimidazole. Stability studies of solutions prepared from calcium gluceptate obtained from various commercial sources indicate that above approximately 50% alpha-epimer, stability decreased with an increase in the relative proportion of the alpha-epimer. Material complying with USP specifications (pure alpha-epimer) is the least stable in solution. It is suggested that calcium gluceptate containing approximately equal proportions of the alpha- and beta-epimers be introduced in the USP monograph together with a method for estimating the proportions of the epimers.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP29039007 Calcium gluceptate Calcium gluceptate 29039-00-7 Price
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