<p>The mechanism of action of risperidone in schizophrenia is unclear. The drug&rsquo;s therapeutic activity in schizophrenia could be mediated through a combination of dopamine Type 2 (D2) and serotonin Type 2 (5HT2) receptor antagonism. The clinical effect from risperidone results from the combined concentrations of risperidone and its major active metabolite, 9-hydroxyrisperidone (paliperidone). Antagonism at receptors other than D2 and 5HT 2 may explain some of the other effects of risperidone.</p>