Pyridobenzodiazepines

Pirenzepine (Gastrozepin), an M1 selective antagonist, is used in the treatment of peptic ulcers, as it reduces gastric acid secretion and reduces muscle spasm. It is in a class of drugs known as muscarinic receptor antagonists; acetylcholine is the neurotransmitter of the parasympathetic nervous system which initiates the rest-and-digest state (as opposed to fight-or-flight), resulting in an increase in gastric motility and digestion; whereas pirenzepine would inhibit these actions and cause decreased gastric motility leading to delayed gastric emptying and constipation. It has no effects on

Clazolam (SAH-1123), also referred to as isoquinazepon, is a drug which is a fused benzodiazepine and tetrahydroisoquinoline derivative. It was developed in the 1960s but was never marketed. It possesses anxiolytic effects and is also claimed to have antidepressant properties.

Propizepine (brand names Depressin, Vagran) is a tricyclic antidepressant (TCA) used in France for the treatment of depression which was introduced in the 1970s.

Vabicaserin (codenamed SCA-136) was a novel antipsychotic and anorectic under development by Wyeth. As of 2010 it is no longer in clinical trials for the treatment of psychosis. It was also under investigation as an antidepressant but this indication appears to have been dropped as well.

AFDX-384 (BIBN-161) is a drug which acts as a selective antagonist of the muscarinic acetylcholine receptors, with selectivity for the M2 and M4 subtypes. It is used mainly for mapping the distribution of M2 and M4 muscarinic receptors in the brain, and studying their involvement in the development and treatment of dementia and schizophrenia.

Tampramine (AHR-9,377) is a tricyclic antidepressant (TCA) which was developed in the 1980s but was never marketed. Despite being a TCA, it acts as a selective norepinephrine reuptake inhibitor and has negligible affinity for adrenergic, histaminergic, and muscarinic receptors. It was found to be effective in the forced swim test (FST) model of depression in animal studies but is not known to have ever been trialed in humans.