Apomorphine - Pharmacology

Pharmacology

Apomorphine possesses affinity for the following receptors:

D₁ (K_i = 372 nM)
D_2S (K_i = 35 nM)
D_2L (K_i = 83 nM)
D₃ (K_i = 26 nM)
D₄ (K_i = 4.4 nM)
D₅ (K_i = 15 nM)

5-HT_1A (K_i = 117 nM)
5-HT_2A (K_i = 120 nM)
5-HT_2B (K_i = 132 nM)
5-HT_2C (K_i = 102 nM)

α_1B-adrenergic (K_i = 676 nM)
α_1D-adrenergic (K_i = 65 nM)
α_2A-adrenergic (K_i = 141 nM)
α_2B-adrenergic (K_i = 66 nM)
α_2C-adrenergic (K_i = 36 nM)

It has > 1,000 nM affinity for 5-HT_1B, 5-HT_1D, and α_1A-adrenergic, and > 10,000 nM affinity for β-adrenergic, H₁, and mACh.

Apomorphine behaves as a partial agonist at D_2S ( IA = 79%), D_2L (IA= 53%), D₃ (IA = 82%), and D₄ (IA = 45%), and as an antagonist at 5-HT_1B, 5-HT_1D, 5-HT_2A, 5-HT_2B, 5-HT_2C, α₁-adrenergic, and α₂-adrenergic. Though its efficacies at D₁ and D₅ are unclear, it is known to act as an agonist at these sites.