Evaluation of Therapeutic Drug Monitoring of Valproate and Safety Evaluation of Prescribing in Acute Phase among Patients with Bipolar Disorder

Abstract

Objective: 1) To investigate the prescribing rate of therapeutic drug monitoring and the appropriate measurement of valproate level in blood and 2) to assess the order of laboratory test for safety monitoring of valproate use among bipolar disorder patients in the acute phase. Method: The study retrospectively collected the data by reviewing history of bipolar disorder patients in the acute phase who were treated with valproate between June 2017 and October 2018 at Prasrimahabhodi Psychiatric Hospital. The researchers assessed the percentage of patient with therapeutic drug monitoring, percentage of patients having valproate level within therapeutic range (50-100 mg/mL) and the time to valproate monitoring after starting the drug. For laboratory safety monitoring of valproate use, we evaluated the prescribing rate for the test of liver function, serum albumin and complete blood count. Results: There were              95 bipolar disorder patients in the acute phase eligible for the study according to the inclusion criteria. Forty three of patients received therapeutic drug monitoring for treatment evaluation. 62.8% of the patient had valproate levels within target therapeutic range, while 81.4% were monitored at ³ 5 days after valproate treatment. For laboratory test for safety monitoring, 66.3%, 50.5%, and 77.9% of patients received the test for liver function, serum albumin, and complete blood count, respectively. Among patients with therapeutic valproate monitoring, 28 were tested. Twenty-five percent of them had serum albumin < 4.0 g/dL. Conclusion: Only half of bipolar disorder patients receiving valproate were monitored drug level during acute phase of treatment. Most of them were monitored when drug level was at the steady state. In addition, the level of albumin in patients should be examined because albumin levels affect the concentration of free drug. A number of bipolar disorder patients in acute phase have a low level of albumin and are prone to adverse drug reactions.