Stabilization by ethylenediaminetetraacetic acid of amide and other groups in drug compounds

Ethylenediaminetetraacetic acid (EDTA) was shown to be effective in stabilizing pharmaceutical compounds, which contain acetamido groups, from degradation by light, e.g. paracetamol. Its addition is particularly effective in stabilizing such compounds from the action of ascorbic acid in the light or dark. EDTA was also shown to stabilize lignocaine, sulphadiazine and succinylsulphathiazole. Previous studies had shown that EDTA stabilizes the acetamido group present in two synthetic food colouring compounds.