Clinical utility of therapeutic drug monitoring of antiepileptic drugs

Zanab Al-Roubaie, Elena Guadagno, Agnihotram V. Ramanakumar, Afsheen Q. Khan, Kenneth A. Myers.  Clinical utility of therapeutic drug monitoring of antiepileptic drugs. Systematic review. Neurol Clin Pract Aug 2020, 10 (4) 344-355; DOI: 10.1212/CPJ.0000000000000722

Abstract

Objective To systematically review and evaluate the available evidence supporting or refuting clinical use of therapeutic drug monitoring (TDM) of antiepileptic drugs (AEDs) in patients with epilepsy. 

Methods We searched MEDLINE, Embase, BIOSIS, Cochrane, PubMed, Africa-Wide Information, Web of Science, and grey literature. Randomized controlled studies and observational studies that compared the clinical outcomes of TDM vs non-TDM were included. Two reviewers independently extracted the data. The primary outcome was seizure control; adverse effects were considered as secondary outcomes. The PROSPERO ID of this systematic review's protocol is CRD42018089925. 

Results Sixteen studies were identified meeting eligibility requirements. Four randomized controlled trials (RCTs), 1 meta-analysis, and 11 quasiexperimental (QE) studies were included in the systematic review. Results from the analysis of RCTs showed no significant positive effect of TDM on seizure outcome (only 25% positive effect of phenytoin). However, some of the QE studies found that TDM was associated with better seizure control or lower rates of adverse effects. The existing evidence from various designs has shown various methodological implications, which warrants inconclusive results and highlights the requirement of more number of studies in this line. 

Conclusions If optimally implemented, TDM may enhance clinical care, particularly for phenytoin and other AEDs with complex pharmacokinetics. However, the ideal method for implementation is unclear, and serum drug levels should be considered in context with patient-reported clinical data regarding seizure control and adverse events.