In
pharmacology, an
active moiety is the part of a molecule or ion—excluding appended inactive portions—that is responsible for the
physiological or pharmacological action of a
drug substance. Inactive appended portions of the drug substance may include either the alcohol or acid moiety of an
ester, a
salt (including a salt with
hydrogen or
coordination bonds), or other
noncovalent derivative (such as a
complex,
chelate, or
clathrate). The parent drug may itself be an inactive
prodrug and only after the active moiety is released from the parent in free form does it become active. ==See also==