Description_x000D_ Biochem/physiol Actions_x000D_ ADX-47273 is a brain-penetrating, potent and selective metabotropic glutamate receptor 5 (mGlu5; mGluR5) positive allosteric modulator (PAM) that enhances glutamate-stimulated Ca2+ response in rat cortical astrocytes (EC50 = 170 nM, Emax = 380%; [glutamate] = EC20 = 200 nM) via direct mGlu5 binding in a MPEP-, but not Quisqualate-, competitive manner (Ki = 4.3 μM against 2 nM MPEP; rat mGlu5 HEK293) with little mGlu5 agonist activity, no potency toward other rat/human family III GPCRs (mGlu1–8 and GABA-B), nor affinity to 56 GPCRs/transporters/enzymes/ion channels. ADX-47273 shows in vivo antipsychotic-like and procognitive efficacy in mice and rats in vivo (1-300 mg/kg i.p.) with good pharmacokinetic properties (B/P ratio >2, bioavailability ∼40%, T1/2 ∼2 hrs in rats).