Drug substance
Drug substance means an active ingredient that is intended to furnish pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the human body, but does not include intermediates use in the synthesis of such ingredient.
Source
21 CFR § 314.3
Scoping language
The definitions and interpretations contained in section 201 of the act apply to those terms when used in this part.