I found that apomorphine (racemat mix) is a strong D4 (Ki=4 nM) and 10-fold less D2 agonist (Ki=50 nM). It is also one order of magnitude less a D1 Receptor agonist (Ki=480 nM). It is also a 5-HT2 (higher affinity as on D1, ki=100-130 nM) and alpha-adrenergic receptor (approx. like D2, ki= 40 nM) antagonist with high affinity.

ok. most of this reactivity should belong to the R-(-)-enantiomere of it. and S-(+)-apomorphine does nothing. However there are studies which show that S binds with high affinity to the D1 and D2 receptors. so it should act in some way, or? It would be nice if anyone can help...

btw: I found one study saying the S-apomorphine acts on the Nrf2-ARE pathway in ALS.