A Study of the Effects of Paroxetine on the Pharmacokinetics of Paliperidone ER

This is a randomized, open-label, single-center, single-dose, 2 treatment, 2 way crossover study. It consists of 3 phases: a screening phase beginning within 21 days before the first study drug administration; an open label treatment phase consisting of 2 treatment periods (Period 1 and Period 2), during which patients will receive 2 single doses of 3 mg paliperidone ER; and end of study evaluations upon completion of all the study procedures in Period 2 or at early withdrawal. All volunteers will receive each of the following 2 treatments in random order: Treatment A: 1 tablet of 3 mg paliperidone ER in the fasted state; Treatment B: one 20 mg paroxetine tablet once a day from Day 1 to Day 13 and 1 tablet of 3 mg paliperidone ER on Day 10 in the fasted state. Successive paliperidone ER administrations will be separated by a washout period of at least 14 days and no more than 28 days. Paroxetine is a potent and selective CYP2D6 inhibitor. Inhibitors of CYP2D6 such as paroxetine have been reported to increase the plasma concentrations of antipsychotics such as perphenazine, clozapine, and risperidone. Because paliperidone ER and paroxetine could potentially be used in combination in schizophrenic patients, the potential for a drug-drug interaction between paroxetine and paliperidone ER needs to be explored.The safety and tolerability of the 3 mg tablet of paliperidone ER administered with and without paroxetine to healthy men will be monitored. Two single oral doses of paliperidone ER 3-mg; 20-mg paroxetine orally once a day for 13 days