Paliperidone palmitate: Adjusting dosing intervals and measuring serum concentrations

Would monitoring a patient’s paliperidone serum concentrations be useful? Currently, measuring an individual’s paliperidone serum concentration is generally considered unwarranted.^3,4 One of the major reasons is a lack of appropriately designed studies to determine a therapeutic range.⁵ Flexible dose designs, commonly used in registration studies, cloud the relationships between concentration, time, response, and adverse effects. There are additional problems that are the result of diagnostic heterogeneity and placebo responders. A well-designed study to determine the therapeutic range would have ≥1 fixed dose groups and be diagnostically homogeneous. There are currently only a limited number of clinical laboratories that have implemented suitable assays.

Given the lack of knowledge of a therapeutic range, assured knowledge of nonadherence to LAIs, and the absence of significant drug interactions for paliperidone, there remain a few reasonable justifications for obtaining a patient’s paliperidone serum concentration (Table). If the patient had a good response with mild adverse effects, there is no reason to obtain a paliperidone serum concentration or make any change in the medication or dose. However, if the patient had a good response accompanied by moderate or severe adverse effects, or the patient has a poor response, then obtaining the paliperidone serum concentration could help determine an appropriate course of action.

CASE CONTINUED

After the second dose at the increased frequency on Day 252, the paliperidone serum concentration was maintained above 40 ng/mL. Mr. B continued to tolerate the LAI well and no longer reported any breakthrough hallucinations.

Related Resources

• ARUP Laboratories. Paliperidone, serum or plasma. https://ltd.aruplab.com/tests/pub/2007949.
• LabCorp. Paliperidone Paliperidone (as 9-hydroxyrisperidone), serum or plasma. https://www.labcorp.com/test-menu/38351/paliperidone-as-9-hydroxyrisperidone-serum-or-plasma.
• Janssen Scientific Affairs. Educational dose illustrator. https://www.educationaldoseillustrator.com.

Drug Brand Names

Paliperidone palmitate • Invega Sustenna
Risperidone • Risperdal