CTEP (Ro4956371) is a research drug developed by Hoffmann-La Roche that acts as a selective allosteric antagonist of the metabotropic glutamate receptor subtype mGluR<sub>5</sub>, binding with nanomolar affinity and over 1000 times selectivity over all other receptor targets tested. In animal studies it was found to have a high oral bioavailability and a long duration of action, lasting 18 hours after a single dose, giving it considerably improved properties over older mGluR<sub>5</sub> antagonists such as MPEP and fenobam.