receptors , and functions as a full agonist at all sites except the 5-HT 2A receptor, where it acts as a weak partial agonist or antagonist . [3] Unlike the related piperazine compound meta -chlorophenylpiperazine (mCPP), TFMPP has insignificant affinity for the 5-HT 3 receptor (IC 50 = 2,373 nM). [4]