Description_x000D_ Biochem/physiol Actions_x000D_ FR194921 is a blood-brain barrier-permeable A1R adenosine receptor antagonist. The measured Ki values of FR194921 for the human adenosine A1 receptors have been in the low nM range with no binding affinity for A2A and A3 receptors up to 1μM. It is orally active and has good bioavailability. FR194921 was used in a recent study to restore auditory cortex plasticity. Paired with sound exposure, FR194921 resulted in cortical map plasticity and improved auditory perception in adult mice.