Comparing the pharmacology and pharmacokinetics of antipsychotics: Choosing an antipsychotic and dosing a long-acting injectable.

In this paper, we will discuss the pharmacologic properties of antipsychotics, including those that are the same in structure and those that differentiate one from another. We will bring to you how differential pharmacologic properties can explain differential efficacy and differential tolerability. We will review how to use plasma drug levels and long-acting injectables to enhance compliance early in the illness, and to manage both forms of treatment resistance (pharmacokinetic and pharmacodynamic failures). Through inadequate pharmacokinetic processes (poor absorption, rapid metabolism, enzymatic polymorphisms, etc.), antipsychotic plasma levels do not reach sufficient concentration. Pharmacodynamic treatment failure (receptor binding and sensitivity, post-receptor effects, etc.) is the inability to provide a significant effect on psychotic symptoms despite therapeutic plasma levels. Long-Acting Injectable (LAI) antipsychotics employ technology that can provide a useful treatment tool in the armamentarium of a modern psychopharmacologist. The pharmacologic properties of antipsychotics differentiate one from another and can help explain differences in efficacy and tolerability. Utilizing plasma drug levels can enhance understanding of treatment failures and lead to specific patient management strategies for best outcomes. This kind of personalized approach to antipsychotic dosage would mean a big shift in the treatment of psychiatric patients.