A pharmacon or pharmakon (from Greek: (φάρμακον), adapted from pharmacos) is a biologically active substance. It is used more broadly than the term
drug because it includes
endogenous substances, and biologically active substances which are not used as drugs. Typically the word pharmacon includes pharmacological
antagonists, but also
enzyme inhibitors (such as
monoamine oxidase inhibitors).
 Spelt with a "k", is acceptable in English, but more common in German. In most cases pharmacon is the equivalent to