Nelonicline citrate (ABT-126) is an orally active, selective α7 nicotinic receptor agonist with a high affinity for α7 nAChRs in the human brain (Ki = 12.3 nM), used in research on schizophrenia and Alzheimer's disease.

Nelonicline citrate acts as an agonist with strong affinity towards α7 nicotinic acetylcholine receptors (nAChRs) in the human brain, demonstrated by a binding affinity (K i ) of 12.3 nM. It effectively activates currents in Xenopus oocytes expressing recombinant human α7 nAChRs, with an EC 50 value of 2 μM and an intrinsic activity 74% that of acetylcholine. Although it also binds to α3β4* nAChRs in human IMR-32 neuroblastoma cells with a K i value of 60 nM, its efficacy is significantly lower, showing just 12% efficacy at a concentration of 100,000 nM in calcium flux assays. Additionally, nelonicline citrate acts as a 5-HT3 receptor antagonist, though its affinity for this receptor is more than 10-fold lower than for α7 nAChRs, with a K i of 140 nM, aligning with the behavior of some other α7 nAChR agonists.