ABSTRACT
INTRODUCTION: This study assesses the utilization of antipsychotic therapeutic drug monitoring (TDM) and describes characteristics of appropriate and inappropriate TDM at a state psychiatric hospital. METHODS: A retrospective, descriptive review was conducted for antipsychotic TDM completed between December 1, 2009, and June 30, 2011, at a 65-bed adult inpatient extended-care and forensic state psychiatric hospital. RESULTS: One hundred thirty-three (n = 133) antipsychotic serum levels were collected from 44 patients during the study period. Sixty-nine percent (69%) of the TDM were deemed inappropriate, 28% were appropriate, and 3% could not be designated appropriate or inappropriate owing to the lack of information regarding steady-state conditions. The primary reason for inappropriate TDM was lack of documentation with regard to the indication for TDM (n = 79, 59.3%), the intervention following laboratory analysis (n = 88, 66%), or both. Appropriate TDM was associated with a lower laboratory cost for antipsychotic serum level ($48.98 ± $53.49 versus $72.06 ± $51.02, P < .05), lower daily cost of scheduled psychiatric medications ($17.72 ± $23.03 versus $32.26 ± $31.05, P < .05), lower daily cost of total medications ($19.28 ± $24.91 versus $33.82 ± $31.03, P < .05), fewer scheduled psychiatric medications (2.95 ± 1.90 versus 4.04 ± 2.19, P < .01), and fewer total scheduled medications (5.95 ± 3.60 versus 7.60 ± 3.29, P < .05). Inappropriate TDM led to approximately $6,753 in avoidable laboratory costs over a 20-month period. DISCUSSION: Therapeutic drug monitoring is a complex process with many points at which errors may occur. The majority of antipsychotic levels at this state psychiatric hospital were not documented in a way that was clinically useful. Inappropriate TDM was associated with increased laboratory and medication costs.
ABSTRACT
Paliperidone extended-release tablet (paliperidone ER; INVEGA()) is an oral antipsychotic for the treatment of schizophrenia. The recommended dose range is 3-12 mg per day. Paliperidone ER utilizes the OROS((R)) delivery system, which allows for once-daily dosing. Its pharmacokinetic profile results in a more stable serum concentration. Paliperidone is 9-hydroxyrisperidone, the chief active metabolite of risperidone. It undergoes limited hepatic metabolism, thereby minimizing the risks of hepatic drug-drug and drug-disease interactions. Three 6-week trials in patients with acute schizophrenia reported that paliperidone ER was effective, well tolerated, and produced clinically meaningful improvements in personal and social functioning compared with placebo. Post-hoc analysis of these trials in various populations, including recently diagnosed, elderly and more severely ill patients, those with sleep disturbances and those with predominant negative symptoms demonstrated improvement as well. Paliperidone ER was also significantly better than placebo in the prevention of symptom recurrence in a 6-month maintenance study. The most common clinically relevant adverse events associated with paliperidone ER were extrapyramidal symptoms, tachycardia and somnolence. The incidence of Parkinsonism, akathisia and use of anticholinergic medications increased in a dose-related manner. Further, modest QTc interval prolongation was observed but did not produce clinical symptoms. Similar to risperidone, paliperidone ER is associated with increases in serum prolactin levels. Overall, paliperidone ER was effective, well tolerated and provides a new treatment option for patients with schizophrenia.
