High Quality Content by WIKIPEDIA articles! 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) is a research drug that was developed by Merck & Co. as a selective allosteric antagonist of the metabotropic glutamate receptor subtype mGluR5. Identified through structure-activity relationship studies on an older mGluR5 antagonist MPEP, MTEP has subsequently itself acted as a lead compound for newer and even more improved drugs.