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Oldřich Farsa; Jan ˇSubert; Marie Marečková (2016)
Publisher: International Pharmaceutical Excipients Council
Journal: Journal of Excipients and Food Chemicals
Languages: English
Types: Article
Subjects: boric acid, 3-dihydroxypropyl 4-hydroxy-benzoate, H-NMR, DOAJ:Technology and Engineering, Parabens, TP1-1185, Technology, glycerol, 1H-NMR, 2, TP368-456, T, transesterification, Chemical technology, 3-dihydroxypropyl 4 -hydroxy-benzoate, DOAJ:Chemical Technology, hydrolysis, Food processing and manufacture
In a solution containing 0.067% methylparaben, 0.033% propylparaben, 3.4% glycerol and 2.0% boric acid, concentrations of both parabens, 4 hydroxybenzoic acid and 2,3-dihydroxypropyl 4-hydroxybenzoate were monitored for up to 68 months storage. 4-hydroxybenzoic acid is the main hydrolysis product of parabens, while 2,3-dihydroxypropyl 4 hydroxybenzoate was proposed as the main product of transesterification of parabens with glycerol. Results of an HPLC evaluation of parabens, 4-hydroxybenzoic acid and 2,3- dihydroxypropyl 4-hydroxybenzoate showed that the decomposition of 68 months old samples stored at room temperature did not exceed 2.0%. The stability of both parabens in a medicinal preparation of the stated composition has thus been satisfactorily demonstrated after more than 5 years of storage under ambient conditions. The transesterification reaction was shown to influence the chemical stability of parabens to an extent comparable to hydrolysis. Moreover, the presence of 2,3-dihydroxypropyl 4-hydroxybenzoate in the solution containing glycerol and boric acid was confirmed by 1H-NMR spectroscopy.

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