Phenylacetylrinvanil (IDN-5890) is a synthetic analogue of capsaicin which acts as a potent and selective agonist for the TRPV1 receptor, with slightly lower potency than resiniferatoxin, though still around 300 times the potency of capsaicin. It is used to study the function of the TRPV1 receptor and its downstream actions, and has also shown anti-cancer effects in vitro.