Which drug is known to act as a competitive antagonist at D2 dopamine receptors?

Haloperidol is known for its action as a competitive antagonist at D2 dopamine receptors. This mechanism is central to its effectiveness as an antipsychotic, particularly in the management of schizophrenia and other psychotic disorders. By blocking the D2 receptors in the mesolimbic pathway, haloperidol reduces dopaminergic overactivity, which is associated with positive symptoms of psychosis, such as hallucinations and delusions.

Haloperidol's specific mechanism allows it to influence the dopaminergic system significantly, leading to the reduction of psychotic symptoms. This action distinguishes it from other antipsychotics that may have additional mechanisms or receptor affinities, such as acting on serotonin receptors or having partial agonist activity at dopamine receptors, which can result in different clinical effects.