Savoxepine (also known as cipazoxapine), a tetracyclic compound, possesses a potent neuroleptic-like effects. This compound acts via dopamine D(2)-receptor blockade. Savoxepine was studied in phase II clinical trials in Europe for the treatment of patients with psychotic disorders; however, these studied were discontinued.

Ibazocine is an analgesic that has never been marketed.

Tazadolene was developed as a novel non-opioid analgesic with antidepressant properties. Experiments on rodents have revealed that unique analgesia properties of tazadolene was due to the ability of this compound to activate both serotonergic and alpha 2 adrenergic antinociceptive systems. Information about the current use of this drug is not available.

Talampanel (TLP) was developed as a noncompetitive (allosteric) antagonist of the AMPA receptor. Talampanel does not act directly on the AMPA receptor, but at an allosteric site referred to as the GYKI receptor. Talampanel is being studied in the treatment of brain tumors and other brain disorders, such as epilepsy, Parkinson disease, amyotrophic lateral sclerosis, dyskinesias, glioblastoma, multiple sclerosis. It is a type of AMPA receptor antagonist. Dizziness has been the most commonly reported adverse event, with some sedation and ataxia, drowsiness and headaches reported at higher doses.

Solabegron (GW427353), a beta-3 adrenoceptor agonist, is in development with AltheRx (now Velicept Therapeutics) for the treatment of irritable bowel syndrome (IBS) and overactive bladder (OAB). Solabegron was discovered and first developed by GlaxoSmithKline. It was acquired by AltheRx, which merged with Velicept in 2015 to continue development of the program. Solabegron has been tested in over 800 study subjects in a twice-a-day formulation and demonstrated efficacy in the treatment of OAB as well as IBS. A once daily formulation designed to optimize patient convenience as well as efficacy has been developed and is currently being evaluated in a phase 2b dose ranging clinical trial. A Phase 2b dose ranging study with the twice daily formulation also began enrollment in Q1 2018.

Trepipam is a benzazepine derivative. It is a D1-dopamine antagonist. Trepipam significantly reduced aggression in behaviorally disturbed adolescents and in acute schizophrenics without producing concomitant sedation. Trepipam specifically reduces aggressive and hyperactive behaviors in a wide range of laboratory tests in various species, without producing signs of overt CNS depression or neurological impairment. The drug is effective in reducing many forms of aggression including brain stimulated emotional behavior. Trepipam actually had little effect on gross behavior in mice or rats and only produced ataxia at lethal doses.

Solypertine (WIN-18413-2) is an antiadrenergic drug. Solypertine selectively blocked the conditioned avoidance response in rats. Solypertine potentiated hexobarbitone sleeping time, caused hypothermia and afforded protection from amphetamine toxicity inaggregated mice.

Sergolexole [LY 281067] is an ergoline ester similar in structure to amesergide [LY 237733], with potent and highly selective antagonist activity at serotonin 2. The preclinical pharmacologic activity of LY 281067 shows it to be a potent and highly selective serotonergic (5-HT2) receptor antagonist. Based upon binding studies with 5-HT2 receptors in brain cortical membranes and block of 5-HT-induced contractions in the rat jugular vein, LY 281067 showed high affinity at 5-HT2 receptors with a dissociation constant of approximately 1 nM. LY 281067 was a highly selective 5-HT2 receptor antagonist without appreciably binding to 5-HT1, D1 or D2 receptors or interacting with histamine (H1), cholinergic, beta adrenergic or alpha-1 adrenergic receptors in smooth muscle. LY 281067 had modest affinity at alpha-2 receptors with a dissociation constant of approximately 100 nM. Oral bioavailability of LY 281067 in spontaneously hypertensive rats was excellent with an oral to i.v. dose ratio approximating 4. Sergolexole was undergoing phase II clinical trials with Eli Lilly in the USA as a potential treatment for migraine and anxiety, but development of this compound, but development of this compound has been discontinued.

Renzapride (BRL-24924) is a mixed 5-hydroxytryptamine type 4 (5-HT4) agonist and 5-HT3 receptor antagonist. This compound has a stimulatory effect on gastrointestinal motility and transit. Renzapride has been evaluated for use in treatment of irritable bowel syndrome (IBS). Data also suggested a potentially beneficial effect on abdominal pain/discomfort in women with constipation-predominant irritable bowel syndrome. Phase III clinical trials investigated if this drug could help alleviate the symptoms associated with this type of IBS. However, one phase III study has been terminated due to inefficient efficacy (compared to placebo).

Sibopirdine (EXP921) is a cognition enhancing agent structurally related to linopirdine that was in preclinical development with Bristol-Myers Squibb in the USA as a treatment of Alzheimer's disease. EXP921 was a potential drug candidate for the improvement of cognitive performance in patients with Alzheimer's-type dementia. It has been shown to improve cognitive performance in rodent and primate models of learning and memory. EXP921 was observed to increase the depolarization induced release of acetylcholine, dopamine, and, to a lesser extent, serotonin using slices from the rat cerebral cortex, hippocampus, and caudate nucleus.