Merriam-Webster's Collegiate Dictionary:
-agogue
noun combining form
Etymology: French `; New Latin; French, from Late Latin
-agogus promoting the expulsion of, from Greek
-agōgos, from
agein to lead; New Latin
-agogon, from Greek, neuter of
-agōgos — more at
agent
substance that promotes the secretion or expulsion of
Example: emmenagogue 
