Dopamine D2 and serotonin 5-HT2A/5-HT2C receptors (antagonist)

Class

atypical (second-generation) antipsychotic; olanzapine is a broad monoaminergic antagonist (dopamine D1-D4, serotonin 5-HT2A/5-HT2C, muscarinic M1-5, histamine H1, alpha-1 adrenergic); TV-44749 is Teva's once-monthly subcutaneous extended-release olanzapine using MedinCell's BEPO/SteadyTeq copolymer depot delivery technology, designed to avoid the post-injection delirium/sedation syndrome (PDSS) risk seen with IM olanzapine pamoate (Zyprexa Relprevv)

Pathway

central dopamine D2 receptor antagonism (with rapid ligand-receptor dissociation kinetics) is proposed to underlie antipsychotic effect while limiting extrapyramidal symptoms; stronger 5-HT2A/2C than D2 blockade is proposed to contribute to effects on negative symptoms

Dopamine D2 receptors and serotonin 5-HT2A/5-HT2C receptors are G-protein-coupled receptors distributed across brain circuits that govern mood, cognition, and perception. Excessive dopaminergic signaling through D2 receptors in mesolimbic pathways is strongly associated with psychotic symptoms such as hallucinations and delusions, making D2 blockade the cornerstone of antipsychotic pharmacology. Second-generation, or atypical, antipsychotics pair this D2 antagonism with meaningful blockade of serotonin 5-HT2A and 5-HT2C receptors. This combination is thought to preserve antipsychotic efficacy against positive symptoms while offering some benefit for negative symptoms (blunted emotion, social withdrawal) and reducing movement-related side effects compared with older, D2-only agents. Because these receptors are expressed outside the circuits directly involved in psychosis, modulating them broadly also affects appetite regulation, sleep, and motor control, which underlies much of the side-effect burden associated with this drug class. This mechanism is broadly relevant across schizophrenia, bipolar disorder, and other conditions marked by psychotic or mood symptoms, and it remains the pharmacological foundation for most antipsychotic medicines developed to date, including newer long-acting formulations intended to sustain drug exposure over extended intervals.