4-(4-Chlorophenyl)-4-piperidinol (CPPO) is one of haloperidol metabolite. Neurotoxicity studies in frogs, which have been used to detect N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) action, showed that CPPO did not mimic the neurotoxicity of MPTP but caused a delayed and persistent freezing action in Rana pipiens frogs. It is proposed that this action may contribute to some of the delayed side-effects associated with haloperidol therapy.

Hordenine is a natural Phenethylamine compound that occurs in a number of different plants, but especially barley grass. It is structurally similar to the amino acid Tyramine. It antagonized D2-mediated beta-arrestin recruitment indicating functional selectivity. Hordenine inhibited melanogenesis by suppressing cAMP production, which is involved in the expression of melanogenesis-related proteins. Hordenine may be an effective inhibitor of hyperpigmentation. Hordenine is an indirectly acting adrenergic drug. It liberates norepinephrine from stores. In isolated organs and those structures with reduced epinephrine contents, the hordenine-effect is only very poor. Experiments in intact animals (rats, dogs) show that hordenine has a positive inotropic effect upon the heart, increases systolic and diastolic blood pressure, peripheral blood flow volume, inhibits gut movements but has no effect upon the psychomotorical behavior of mice. Hordenine is considered to be generally very safe and well-tolerated in healthy adults. Hordenine is a nootropic compound that works equally well for cognitive enhancement and athletic performance.

Canadine (tetrahydroberberine,THB) is an isoquinoline alkaloid (5,8,13,13a-tetrahydro-9,10-dimethoxy-6H-benzo[g]-1,3-benzodioxolo[5,6-a]quinolizine) from Corydalis tuber, it has micromolar affinity for dopamine D(2) (pK(i) = 6.08) and 5-HT(1A) (pK(i) = 5.38) receptors but moderate to no affinity for other relevant serotonin receptors (i.e., 5-HT(1B), 5-HT(1D), 5-HT(3), and 5-HT(4). Canadine enhances gastrointestinal motor function. THB, with D(2) receptor antagonist and 5-HT(1A) receptor agonist properties, has significant potential as a therapeutic for treatment of functional dyspepsia. THB is a potent inhibitor of platelet aggregation in vitro and in vivo and is a promising antithrombotic drug.

Alpha-ergocryptine is a component of the ergotoxine complex; it is the main ergot alkaloid of Japanese & South American wid grasses. Alpha-ergocryptine is an agonist at the D2 dopamine receptor. Alpha-ergocryptine effectively decreases intraocular pressure in the alpha-chymotrypsin-induced model of ocular hypertension.

P-88-8991, (-)- is a metabolite of Iloperidone. It has functional affinity for noradrenergic, dopaminergic and serotoninergic receptors. Humans produce only one enantiomer stereospecifically following administration of Iloperidone. Preclinical studies revealed that P-88-8991, (-)- might be useful for the treatment of psychotic disorders such as schizophrenia and bipolar disorders.

P-88-8991, (+)- is a metabolite of Iloperidone. It has functional affinity for noradrenergic, dopaminergic and serotoninergic receptors. Humans produce only one enantiomer stereospecifically following administration of Iloperidone. Preclinical studies revealed that P-88-8991, (+)- might be useful for the treatment of psychotic disorders such as schizophrenia and bipolar disorders.

LY-165163 is a partial agonist of serotonin receptors 5-HT1A and 5-HT1D. It exhibits marked activity at both pre- and postsynaptic dopaminergic D2 (D3 and D1) receptors. LY-165163 caused a significant and dose-dependent hypothermia in rats. As a 5-HT1D receptor agonist, LY-165163 was proposed for the ocular pain treatment.