Haloperidol lactate works primarily by blocking dopamine D2 receptors in the brain. This dopamine antagonism is the key to its antipsychotic effects. By reducing dopamine activity, haloperidol helps alleviate the positive symptoms of schizophrenia, such as hallucinations and delusions.
Impact on Dopamine Pathways
Specifically, haloperidol’s high affinity for D2 receptors in the mesolimbic and mesocortical pathways contributes to its therapeutic actions. The mesolimbic pathway’s modulation helps reduce psychotic symptoms. However, blockade in the mesocortical pathway may contribute to negative symptoms, like flat affect and social withdrawal, a side effect clinicians carefully monitor.
Other Receptor Interactions
Beyond dopamine, haloperidol also interacts with other receptors, although to a lesser extent. These include serotonin 2A receptors (5-HT2A), muscarinic receptors, and histamine H1 receptors. These interactions contribute to both the therapeutic effects and the side effects of haloperidol.
| D2 Dopamine | Antagonism (strong) | Antipsychotic effect, extrapyramidal symptoms |
| 5-HT2A Serotonin | Antagonism (moderate) | May mitigate some extrapyramidal symptoms |
| Muscarinic | Antagonism (moderate) | Anticholinergic side effects (dry mouth, constipation) |
| H1 Histamine | Antagonism (moderate) | Sedation |
Clinical Implications
Understanding this mechanism is crucial for informed prescribing and managing potential side effects. Clinicians need to weigh the benefits of dopamine blockade against the risks of extrapyramidal symptoms (EPS), like Parkinsonism, akathisia, and tardive dyskinesia. Careful patient monitoring is therefore necessary.
