The Pharmacokinetics of Second-Generation Long-Acting Injectable Antipsychotics: Limitations of Monograph Values

Product monographs (also known by terms such as Summary of Product Characteristics and Highlights of Prescribing Information, depending on the jurisdiction) provide essential information to ensure the safe and effective use of a drug. Medical practitioners often rely on these monographs for guidance on matters related to pharmacokinetics as well as indications, contraindications, clinical pharmacology, and adverse reactions. The clinical and scientific information found within these documents, forming the basis for decision making, are presumed to be derived from well-designed studies. The objective of this review is to examine the source and validity of the pharmacokinetic data used in establishing the half-lives and times to steady-state reported in the product monographs of second-generation long-acting injectable antipsychotics. Thus, we have critically evaluated the clinical trials from which the pharmacokinetic parameters listed in the product monographs were determined. In many cases, the pharmacokinetic information presented in product monographs is of limited use to clinicians wishing to optimize the effectiveness and tolerability of second-generation long-acting injectable antipsychotics. Under such circumstances, off-label prescribing practices may actually produce better clinical outcomes than if decisions were made based on the product monographs alone.