Which drug class blocks over 80% of D2 receptor sites and is indicated for treating schizophrenia?

The correct choice pertains to the first generation antipsychotics (FGAs). This class of medication is primarily known for its efficacy in treating schizophrenia by blocking dopamine D2 receptors, which is a key mechanism believed to contribute to both the antipsychotic effects and the side effects associated with these drugs.

FGAs such as haloperidol and chlorpromazine have been shown to be effective in managing the positive symptoms of schizophrenia, which include hallucinations and delusions. The significant D2 receptor blockade—often described as 80% or more—helps reduce these symptoms; however, it also leads to a higher risk of extrapyramidal side effects due to the dopamine blockade in the nigrostriatal pathway.

In contrast, second generation antipsychotics and atypical antipsychotics generally have a more complex mechanism of action, often involving serotonin receptor antagonism along with some D2 receptor antagonism, leading to a different side effect profile. Monoamine oxidase inhibitors are primarily used for mood disorders rather than schizophrenia, which makes them less relevant in this context.

Understanding the distinct mechanisms and classifications of antipsychotic medications, particularly the strong D2 receptor blockade associated with FGAs, is crucial for effective treatment planning and patient management