Generation of formaldehyde by pharmaceutical excipients and its absorption by meglumine

Formaldehyde is a well-known air impurity. The possibility was investigated in this study that pharmaceutical excipients commonly used in oral solid dosage forms might also be sources of formaldehyde. The results showed that formaldehyde is generated by the excipients lactose, D-mannitol, microcrystalline cellulose, low-substituted hydroxypropylcellulose, magnesium stearate and light anhydrous silicic acid. Since the quality and safety of pharmaceutical products can be significantly affected by the presence of formaldehyde, various amines were then investigated for their ability to decrease levels of formaldehyde using an aqueous solution system. Of the four amines investigated, only meglumine proved capable of reducing formaldehyde levels. The reaction product between formaldehyde and meglumine was obtained by fractionation using the preparative HPLC system and the structure was clarified by (1)H-, (13)C-NMR, various types of two-dimensional NMR and mass spectroscopy. The reaction product was determined to be a compound with a 1,3-oxazinane skeleton and containing one more carbon than meglumine. It was presumed that formaldehyde reacted with the secondary amino group in meglumine to form the reaction product via an iminium salt intermediate by cyclization. As meglumine is permitted to be used as a pharmaceutical excipient in both oral and parenteral dosage forms by regulations worldwide, the addition of meglumine to pharmaceutical products can be expected to contribute to the stabilization of many drug substances.