Therapeutic drug monitoring in epilepsy clinic: a multi-disciplinary approach

Epilepsy is a common public health problem and needs multi-disciplinary treatment. Therapeutic drug monitoring (TDM) is one of step of the multi-disciplinary treatment in epilepsy at Epilepsy clinic, Khon Kaen University (Thailand). The TDM service has been established since 2008. Here, we aimed to study the roles of TDM order and epilepsy control. This is a prospective descriptive study in which data collection was done from January 1 to December 31, 2010, the period when pharmacists took part in assessing the appropriateness in measurement and interpretation of TDM in order to provide suggestions for physicians. The 112 patients under study had an average age of 38.21±15.36 years; 254 samples were collected for therapeutic drug monitoring; phenytoin was submitted mostly for drug monitoring at 46.46%; 44.49% of submissions for drug level monitoring were made owing to a suspected sub-therapeutic level. Associations were found between reasons of sending samples for drug level monitoring and the measured drug levels, i.e., 66.67% of drug levels found was so low that they were undetectable in sample for patients' compliance investigation and 38.94% of the drug levels were found to be sub-therapeutic as for the case where submission of samples was done because of suspected sub-therapeutic level, 40% of the cases were found to be in toxicity range in the cases with suspected over-therapeutic levels and monitoring levels, 58.25% were found to be within the therapeutic range. Pharmacists used the interpreted results in patients' care by recommending physicians to monitor therapeutic drug closely, to adjust the dosage of drugs, and to recommend checking patients' compliance in their use of drugs at 56.5, 38.9, and 4.3%, respectively. Physicians' responses were found to be absolute follow, partial follow and not follow at 77.95, 11.03, and 7.48%, respectively. In conclusion, associations were found between reasons of TDM order and measured drug level. Therapeutic drug monitoring services at the Epilepsy Clinic was useful in supporting clinical information queries. Pharmacists could make use of interpreted drug level information by recommending physicians to monitor drug levels and adjust individual dosage regimen accordingly. It should be noted that physicians accepted pharmacists' recommendation, denoting multi-disciplinary care team that would lead to greater efficiency.