A Study of the Dose Proportionality of Extended Release Paliperidone

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 volunteers will receive a single oral 1.5 or 3 mg dose of study drug; and end of study evaluations upon completion of all the study procedures in Period 2. All volunteers will receive each of the following 2 treatments in random order: Treatment A: One tablet of 1.5 mg paliperidone ER to-be-marketed formulation in the fasted state; Treatment B: One tablet of 3 mg paliperidone ER Phase 3 formulation in the fasted state. Successive study drug administrations will be separated by a washout period of at least 9 days and no more than 21 days. A 1.5-mg dose of paliperidone ER was selected to be studied as the availability of a 1.5-mg tablet would make dose-adjustments across the existing range of doses of paliperidone ER easier in patients with reduced renal function or tolerability issues. Safety and tolerability of the 1.5- and 3 mg tablets of paliperidone ER in healthy men will be monitored throughout the study. A single oral doses of 1.5 mg and 3 mg paliperidone ER