<qa>  What is the primary objective to determine the difference in dopamine D2 occupancy of ziprasiThe primary objective to determine the difference in dopamine D2 occupancy of ziprasidone at expected peak plasma levels 6 hours and 12 and 24 hours postdose. The secondary objectives are to compare ED50 the plasma levels of ziprasidone resulting in 50 maximal receptor occupancy 24 hours postdose with those 6 and 12 hours postdose. 