Stability of cyanocobalamin in parenteral preparations.

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Karachi, Karachi-75270, Pakistan.
Pakistan journal of pharmaceutical sciences (Impact Factor: 0.95). 02/1993; 6(1):53-9.
Source: PubMed

ABSTRACT The stability of seven commercial parenteral preparations of cyanocobalamin (vitamin B(12)) on storage under normal laboratory conditions for a period of twelve months has been studied using a two component spectrophotometric method for the simultaneous determination of cyanocobalamin and the degradation product, hydroxocobalamin, at 550 and 525 nm. The single ingredient vitamin B(12) preparations have been found to be stable and the potency lies within the B.P. limits. In multi-ingredient (B(1) + B(6) + B(12)) preparations cyanocobalamin is unstable and degrades from 28% to 37% with concomitant formation of hydroxocobalamin (1.7% to 25.5%) and oxidation products amounting to 56.4% +/- 9.3. Thus more than half of the vitamin content is lost during storage and these preparations are not suitable for parenteral use.

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    ABSTRACT: Aqueous cyanocobalamin solutions (pH 1-7) have been photolysed in the presence of individual B (thiamine HCl, riboflavin, nicotinamide and pyridoxine HCl) and C (ascorbic acid) vitamins with visible light. The degraded solutions were subjected to thin-layer chromatography using several solvent systems and the Rf values of the vitamins and their photoproducts were determined. The major photoproducts have been identified by comparison of their Rf values with those of the authentic compounds. Cyanocobalamin leads to the formation of hydroxocobalamin. Thiamine HCl gives rise to 4-methyl-5-(Beta-hydroxyethyl) thiazole and 2-methyl-4-amino-5-hydroxymethyl-pyrimidine in trace amounts whereas riboflavin degrades extensively to formylmethylflavin and lumichrome, and to a smaller extent to lumiflavin and carboxymethylflavin. Ascorbic acid is oxidized to dehydroascorbic acid. Nicotinamide and pyridoxine HCl do not undergo any degradation. The extent of degradation depends upon the pH.
    Pakistan journal of pharmaceutical sciences 02/2004; 17(1):19-24. · 0.95 Impact Factor


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