Cerlapirdine is a selective and potent full antagonist of the serotonin 6 (5-HT6) receptor that has been investigated by Wyeth and Pfizer for the treatment of Alzheimer Disease.

Dilopetine is a racemic mixture of (+)-E-6006 citrate (E-6101) and (-)-E6006 citrate (E-6102) enantiomers being developed as a potential antidepressant. Initial experiments indicate that dilopetine exhibits an antidepressant profile in tests with mice and rats. Dilopetine has been observed to normalize the increased substance P levels in the periaqueductal gray of rats during stressor exposure (Hamon, personal communication), suggesting that the drug may function by inhibiting substance P release. Treatment with dilopetine reduced the vocalizing of isolated guinea pig pups in a dose-dependent fashion.

Piquindone is an antipsychotic pyrroloisoquinoline derivative that binds to dopamine D2 receptors. It is a potent D-2 antagonist. It has a low potential for extrapyramidal effects and tardive dyskinesia. Piquindone exhibited relatively weaker cataleptogenic and antistereotypic activity than haloperidol, and had minimal activity in a rat chronic stereotypy model of receptor supersensitivity. Piquindone almost as potent as haloperidol, with fewer or less intense extrapyramidal effects and low potential for tardive dyskinesia. Piquindone led to moderate but significant improvements in the positive symptoms of schizophrenia and to improvements in negative symptoms just below the level of statistical significance. Therapeutic efficacy of a piquindone antagonist in Tourette Syndrome can be achieved without production of disabling extrapyramidal-side effects.

Hexopyrronium is an antihistaminic agent. Its gastric antisecretory action was studied in human. Information about the current use of this drug is not available.

Quiflapon Sodium (MK-0591; (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(quinolin-2-yl-methoxy)- indol-2-yl]-2,2-dimethyl propanoic acid, previously L-686,708) had been in phase II clinical studies for the treatment of inflammatory bowel disease, but the study was discontinued later, because in spite of MK-591 markedly inhibited Leukotrienes (LT) biosynthesis, it did not differ significantly from placebo in clinical efficacy. Also was discovered, that MK-0591 may modify the airway changes associated with bronchial hyper responsiveness, as well as offer symptomatic relief in asthma. MK-0591 is a selective and specific 5-Lipoxygenase-activating protein (FLAP) inhibitor with an IC50 value of 1.6 nM in a FLAP binding assay. In additional, recently was discovered, that MK591 possesses all major attributes of a standard anti-metastatic agent with significant cancer-selective effect, and suggest that MK591 may turn out to be an effective agent for therapy of castration-resistant, bone-metastatic prostate cancer. Though details of the molecular underpinnings of the anti-metastatic action of MK591 are unknown at this time, this finding gives an opportunity for further exploration to better understand the signaling mechanisms involved by in vitro and in vivo experiments.

Methyldihydromorphine is a synthetic narcotic analgesic related to the morphine. This compound has no pharmaceutical value in the US.

Daledalin is a norepinephrine reuptake inhibitor, developed in the 1970s by Pfizer. In animal models, daledalin potentiates the action of catecholamines, reverses the hypothermia induced by noradrenaline or noradnamine injected into the cerebral ventricles of mice. Daledalin potentiates amphetamine-induced excitation in rats and antagonizes reserpine-hypothermia in mice, tetrabenazine-sedation in rats and reserpine- and tetrabenazine-induced ptosis in mice. It inhibits noradrenaline and 5-hydroxytryptamine uptake by rat brain slices in vitro. In a clinical trial on patients with a depressive illness, no difference in efficacy between daledalin and amitriptyline was found.

Candocuronium is bisquaternary aza steroid derivative with neuromuscular blocking, ganglion blocking, and vagolytic activities. Its potential adjunctive use in anesthesia to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation was briefly evaluated in clinical studies in India, but further development discontinued because of attendant cardiovascular effects, primarily tachycardia that was no worse than but also not an improvement over the clinically established pancuronium bromide.