The differences between the D2, D3 and D4 receptors (clozapine and quinpirole binding)

The D2-like receptors include the D2, D3 and D4 receptor subtypes. Each receptor subtype has its own set of pharmacological properties with different affinities of specific drugs for each subtype. Clozapine is a D2-like selective antagonist with a broad range of pharmacological action, binding to all three D2-like receptors. However, it is 28 times more potent at the D4 receptor than the D2 receptor. Its antipsychotic effects are thought to be mediated primarily by 5-HT 2A/2C and D2 receptor antagonism. Quinpirole is a D2-like selective agonist, binding to all three D2-like receptors; no specific agonists have yet been identified for each subtype.

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References

Dopamine receptors; clinical correlates. Seeman P. The American College of Neuropsychopharmacology, 2000. http://www.acnp.org/g4/GN401000027/ Accessed on 7 October 2002.