(a) General. Except as provided in paragraph (b) of this section, any change of ingredients or quantities of ingredients listed in an appoved formula shall constitute a different article for which a different approved formula is required by § 20.91.

(b) Exceptions. A different approved formula is not required for the following—

(1) A change from an ingredient identified in the formula by a brand name to the same quantity of a chemically identical ingredient acquired under a different brand name, or

(2) A change of an ingredient which is a coloring material.