Reader response: Clinical utility of therapeutic drug monitoring of antiepileptic drugs

I read with interest the systematic review of Al-Roubaie et al.¹ looking at clinical utility of therapeutic drug monitoring (TDM) in the management of patients with epilepsy. I personally have found TDM of limited utility in my patients. Even in the same patient, the drug levels may vary dramatically based on the time the blood sample is drawn relative to the time of ingestion of the antiepileptic drug (AED). Because monitoring is available, there is a tendency to adjust AED dosing based on the level rather than the actual seizure control itself. In a pregnant woman with epilepsy, monitoring needs to be balanced with the dose-dependent risk of major congenital malformations associated with AEDs. Like many things in medicine, TDM has gained acceptance as the standard of care without any scientific evidence to back that claim.