Charting and Handling Therapeutic Drug Monitoring Results: How they Differ From Most Laboratory Results

How Loading Dose Strategies for Depot Paliperidone Can Go Wrong

This column presents a real-life case of a patient who developed severe and prolonged Parkinsonism secondary to the loading dose strategy recommended in the prescribing information (package insert) for paliperidone palmitate (Invega Sustenna). This column presents 2 major points. First, the case illustrates what the practitioner must do before following the general guidelines for a loading dose approach to the administration of paliperidone palmitate as outlined in the package insert to decrease the likelihood of a serious and potentially fatal consequence. Second, the case illustrates how therapeutic drug monitoring can be useful in assessing and managing patients who develop an untoward reaction. In this case, therapeutic drug monitoring was done using serum prolactin levels because the available laboratory could not measure the level of the drug itself in plasma, and the case highlights some limitations to keep in mind when using plasma prolactin levels to do such monitoring. To put this case in context, a review of the literature was conducted which identified 3 related cases. The author also refers readers to previous articles on therapeutic drug monitoring and pharmacokinetic considerations that arise when using depot (long-acting injectable) antipsychotics.