The pharmacology and formulation of paliperidone extended release.

Paliperidone, or 9-hydroxyrisperidone (Invega(®), Janssen, Antwerp, Belgium) is the major active metabolite of the atypical antipsychotic risperidone (Risperdal(®), Janssen). It possesses a similar, though not identical, receptor pharmacology to the parent molecule. There are additional differences in terms of its predominant renal metabolism, lower protein binding and decreased inhibition of P-glycoprotein leading to decreased potential for drug-drug interactions. Paliperidone is approved as an extended release (ER) tablet based on an osmotic-controlled release oral Push-Pull™ delivery system (Oral Osmotic System, OROS(®), Alza Corporation) for the treatment of schizophrenia. The ER formulation results in decreased fluctuations in plasma drug levels and allows for once-daily administration with initial tolerability that permits treatment initiation at a clinically effective dose without the need for titration. This achieves therapeutic levels rapidly and simplifies dosing regimens, leading to potentially better adherence and improved outcome. The present review focuses on the clinical implications of the pharmacology and formulation of paliperidone ER.