Which of the following is a second-generation antipsychotic (SGA)?

Risperidone is classified as a second-generation antipsychotic (SGA), which is designed to treat psychiatric conditions such as schizophrenia and bipolar disorder. Second-generation antipsychotics are characterized by their mechanism of action, which typically involves a more balanced blockade of dopamine and serotonin receptors compared to first-generation antipsychotics. This can lead to a lower incidence of certain side effects, such as extrapyramidal symptoms, which are more common with first-generation medications.

In contrast, the other options listed are all first-generation antipsychotics (FGAs). Haloperidol, chlorpromazine, and fluphenazine all primarily exert their effects through dopamine D2 receptor antagonism but are generally associated with a higher rate of movement disorders and other side effects linked to dopaminergic blockade. The use of SGAs like risperidone reflects the evolution of psychopharmacological treatments, emphasizing improved tolerability and efficacy for patients.