<p>Paliperidone palmitate is hydrolyzed to paliperidone. Paliperidone is the major active metabolite of risperidone. The mechanism of action of paliperidone is unclear. However, the drug&rsquo;s therapeutic effect in schizophrenia could be mediated through a combination of central dopamine Type 2 (D2 ) and serotonin Type 2 (5HT 2A ) receptor antagonism.<br />
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In vitro, paliperidone acts as an antagonist at the central dopamine Type 2 (D2) and serotonin Type 2 (5HT 2A) receptors with binding affinities (Ki values) of 1.6-2.8 nM for D 2 and 0.8-1.2 nM for 5HT 2A receptors. Paliperidone is also active as an antagonist at the &alpha; 1 and &alpha; 2 adrenergic receptors and H 1 histaminergic receptors, which may explain some of the other effects of the drug. Paliperidone has no affinity for cholinergic muscarinic or &beta;1 and &beta;2-adrenergic receptors. The pharmacological activity of the (+)- and (-)- paliperidone enantiomers is qualitatively and quantitatively similar in vitro.</p>