L 741742 is an effective and highly selective antagonist of the D4 dopaminereceptor (Ki: 1700, 770, and 3.5 nM at cloned human D2, D3, and D4 receptors).
Mesdopetam (IRL790) is a dopamineD3receptor antagonist with a Ki of 90 nM and an IC50 of 9.8 μM for the human recombinant D3receptor. It exhibits psychomotor stabilizing properties and is utilized in the study of motor and psychiatric complications associated with Parkinson's disease.
N-Despropyl ropinirole is an active metabolite of the dopamine D2 receptor agonist ropinirole. It increases extracellular acidification rates in CHO cells expressing humandopamine D2, D3, and D4 receptors (EC50s = 0.63, 0.063, and 1.23 µM, respectively). N-Despropyl ropinirole is also a potential impurity found in commercial preparations of ropinirole.