Pharmacokinetics

The antipsychotic drugs are well absorbed when given orally, and because they are lipid soluble, they readily enter the central nervous system (CNS) and most other body tissues. Some metabolites are active. Many are bound extensively to plasma proteins. After oral administration showing increased absorption with food are ziprasidone and paliperidone. These drugs require metabolism by liver enzymes particularly by CYP2D6, CYP1A2, and CYP3A4 isoenzymes before elimination and have long plasma half-lives that permit once-daily dosing. In some cases, other drugs that inhibit cytochrome P450 enzymes can prolong the half-lives of antipsychotic agents.