Paliperidone

Paliperidone (Sold as INVEGA) is an atypical antipsychotic developed by Janssen Pharmaceutica. Invega is an extended release formulation of paliperidone that uses the OROS extended release system to allow for once-daily dosing. Chemically, paliperidone is primary active metabolite of the older antipsychotic risperidone (paliperidone is 9-hydroxyrisperidone, i.e. risperidone with an extra hydroxyl group).

Pharmacology
While its specific mechanism of action is unknown, it is believed paliperidone and risperidone act via similar, if not the same, pathways. The therapeutic effect may be due to a combination of central dopamine Type 2 (D2) and serotonin Type 2 (5HT2a) receptor antagonism. Paliperidone also antagonizes at α1 and α2 adrenergic receptors and H1 histaminergic receptors.[1]

Invega tablets use osmotic pressure to deliver paliperidone at a controlled rate. Peak plasma concentrations occur approximately 24 hrs after dosing; steady state concentrations are attained within 4–5 days.

Since paliperidone is the major active metabolite of risperidone, consideration should be given to the additive paliperidone exposure if risperidone is coadministered with paliperidone.[1]

Paliperidone (as Invega) was approved by the FDA for treatment of schizophrenia on December 20, 2006. This agent will initially be marketed for the treatment of schizophrenia and then for bipolar mania. Clinical trials of paliperidone for the treatment of schizoaffective disorder are also planned. It may also be used off-label for other conditions. Like risperdal, it's possible use in Autism and Asperger's Syndrome may be studied.

Superscript text ==Adverse Reactions== Tachycardia, extrapyramidal effects, akathisia, dizziness, anxiety, somnolence, headache, GI upset; may cause neuroleptic malignant syndrome, tardive dyskinesia, QT prolongation, hyperglycemia, orthostatic hypotension, syncope, hyperprolactinemia, priapism.[1]