21 CFR 74.1331 - D&C Red No. 31.
(1) The color additive D&C Red No. 31 is principally the calcium salt of 3-hydroxy-4-(phenylazo)-2-naphthalenecarboxylic acid.
(2) Color additive mixtures for drug use made with D&C Red No. 31 may contain only those diluents that are suitable and that are listed in part 73 of this chapter as safe for use in color additive mixtures for coloring externally applied drugs.
(b)Specifications. D&C Red No. 31 shall conform to the following specifications and shall be free from impurities, other than those named, to the extent that such other impurities may be avoided by good manufacturing practice:
(c)Uses and restrictions. D&C Red No. 31 may be safely used in externally applied drugs in amounts consistent with good manufacturing practice.