Paliperidone is the primary active metabolite of risperidone. The two antipsychotics are also metabolized differently, as risperidone is metabolized in the liver mainly by the polymorphic cytochrome P450 2D6 (CYP2D6) to its active metabolite 9-hydroxyrisperidone (paliperidone). Paliperidone, by contrast, is predominantly excreted unchanged in the urine The mechanism of action of paliperidone is unknown but it is likely to act via a similar pathway to risperidone as second generation antipsychotics. It has been proposed that the drug's therapeutic activity in schizophrenia is mediated through a combination of central dopamine Type 2 (D2) and serotonin Type 2 (5HT2A) receptor antagonism. Paliperidone is also active as an antagonist at alpha 1 and alpha 2 adrenergic receptors and H1 histaminergic receptors, which may explain some of the other effects of the drug. It is available as an extended-release tablet, a once-monthly intramuscular injection, an every-three-month intramuscular injection, and a twice-yearly gluteal injection.

Paliperidone Dopamine Antagonist Pathway References