The Collaborative International Dictionary
Pharmacon \Phar"ma*con\, n. [NL., fr. Gr. fa`rmakon.]
A medicine or drug; also, a poison.
--Dunglison.
Wiktionary
n. 1 A medicine or drug. 2 (context obsolete English) A poison.
Wikipedia
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 agonists and 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 active ingredient.
Usage examples of "pharmacon".
I have heard it said that by devouring the flesh of the dead, together with a certain pharmacon, they are able to relive the lives of their victims.