Proterguride is a highly potent dopamine receptor agonist with a long duration of action patented by Schering A.-G. for the treatment of Parkinsonism, restless leg syndrome, or the prophylaxis of migraine. According to preclinical studies, Proterguride, unlike most dopamine receptor agonist, is suitable for transdermal administration. Especially in the case of dopamine agonists, the transdermal route of administration might become of great clinical importance due to the ability to achieve constant plasma levels and, thus, to imitate the physiological continuous release profile of dopamine. Pulsatile stimulation of dopaminergic receptors as it occurs with oral administration of dopaminergic drugs is considered the cause of treatment-associated motor complications.

Pyrinoline is a substituted 2,3-dicarboximide patented by McNeil Laboratories, Inc. for the treatment of cardiac arrhythmias.

Razinodil was developed as a coronary vasodilator, a drug that reduces blood pressure by dilating blood vessels. It was tested for its potential as a drug in ischemic myocardial diseases. In a canine heart-lung laboratory model, it increased coronary blood flow without increasing oxygen consumption. Only slight negative chronotropic (heart rate) and inotropic (cardiac contraction) effects were reported. Razinodil also improved the survival rate of miniature pigs after an induced heart attack.

Limiglidole belongs to the class of benzimidazole derivatives exhibiting various biological activities including inhibition of platelet aggregation and prolongation of clotting time in animal models. It inhibited platelet aggregation induced by ADP. Antithrombotic activity of hypoglycemic compound limiglidole that exhibits antiplatelet activity 2-fold exceeded activity of antiplatelet agent acetylsalicylic acid in the mouse model of systemic collagen-epinephrine thrombosis. Antithrombogenic properties of limiglidole are beneficial in the treatment of diabetes mellitus.

Tilapertin (also known as AMG 747) is a piperazineacetic acid derivative patented by Amgen Inc as glycine transporter-1 inhibitor useful for the treatment of negative symptoms of schizophrenia. Oral administration of AMG 747 dose-dependently increases cerebrospinal fluid(CSF) glycine concentration in rats. In humans, Tilapertin has linear pharmacokinetics, prolonged half-life, and acceptable safety and tolerability at multiple doses up to 60 mg daily dosing. Unfortunately, in clinical trials, Tilapertin failed to demonstrate superior efficacy compare antipsychotic therapy in clinically stable people with schizophrenia.

Clidafidine is a xylazine derivative, used in veterinary as a sedative analgesic drug under tradename Ursonarcon.

Citatepine is an antagonist of dopamine receptors. It attenuated dopamine-agonist induced behavioral stimulation (stereotypies in rats or climbing in mice). The compound displayed preferential action on hippocampal DA receptors as compared to the striatum. In addition, it shows antihistaminergic, antiserotonergic, anticholinergic and adrenolytic effects. The drug was investigated in the clinic for the treatment of schizophrenia. It was expected that this drug would show an antipsychotic efficacy in doses not causing extrapyramidal side-effects. This expectation has not been fulfilled.

Cinuperone is an antagonist of D2, alpha1 adrenergic and sigma receptors. The drug selectively inhibits dopamine agonists-dependent behaviors, mediated by the limbic system. The clinical development of the drug as an antipsychotic was terminated due to orthostasis.

Cinprazole (7110 MD) is an investigational benzimidazole derivative, discovered by Delalande S. A in 1972. The compound shows notable gastric antisecretory and antiulcer activity most likely due to a peripheral anti-acetylcholine action. Cinprazole also shows local anesthetic activity on rabbit cornea, and has no effect on the central nervous system in the mouse, rat and rabbit, or on the respiration in the rabbit.