Oxiperomide was developed as a dopamine-receptor antagonist. Clinical trials have shown that this drug decreased dyskinesia in patients with Parkinson's disease receiving levodopa or other dopamine agonists without necessarily increasing Parkinsonian symptoms. However, information about the further development of this drug is not available.

Ocaperidone [R 79598] is an equipotent antagonist of central dopamine D2 and serotonin2 receptors being investigated as a potential antipsychotic agent. Ocaperidone is a benzisoxazol piperidine antipsychotic primarily binds and with high affinity to 5-HT2 (serotonin) receptors, alpha1 and alpha 2 adrenergic receptors, dopamine D2 receptors and histamine H1 receptors. Ocaperidone is an antagonist primarily at the 5HT and D2 receptors. A proposed mechanism of action is the central D2 receptor blockade which is common to all neuroleptics that are used to treat positive symptoms of schizophrenia.

Tomelukast (previously known as LY171883), an orally active antagonist of the CysLT1 receptor (leukotriene D4), which was investigated to treat asthma, but this study was discontinued because of adverse gastrointestinal effect.

Tomelukast (previously known as LY171883), an orally active antagonist of the CysLT1 receptor (leukotriene D4), which was investigated to treat asthma, but this study was discontinued because of adverse gastrointestinal effect.