Drug dosing in patients with chronic kidney disease can be a challenging task, especially for those drugs in which neither a physiological readout (blood pressure) nor laboratory data (blood glucose) are available. Peritoneal dialysis is a rather infrequently used dialysis modality. According to the 2012 USRDS report (
http://www.usrds.org) less than 30,000 patients in the US undergo peritoneal dialysis as compared to 400,000 patients on hemodialysis, which is below the global rate of 12% [
3]. Choice of dialysis modality is however very heterogenous and influenced by multiple factors which explains extremes such as a peritoneal dialysis rate of 0% in Luxemburg and a rate of 49% in New Zealand among patients on maintenance dialysis [
3]. In general, the quantity of drugs removed during peritoneal dialysis is substantially lower than that during hemodialysis, and thus, the supplemental administration of drugs, even when they are efficiently removed during hemodialysis, is not necessary in patients receiving continuous ambulatory peritoneal dialysis (CAPD) [
4]. There are only limited data on how newer antiepileptic drugs are handled by the kidney and especially how the different modes and intensities affect those drugs [
5]. In a situation like this even a single case like ours can enhance the quality of pharmacokinetic information available to clinicians, as recently asked for by a KDIGO working group [
6]. Antiepileptic drugs are frequently used in patients with renal impairment. Safe and effective treatment requires attention to changes in pharmacokinetics and knowledge about the effect of extracorporeal treatment methods in terms of elimination of these drugs. Therapeutic drug monitoring can be a valuable aid [
7]. For levetiracetam most individuals display optimal response to treatment with trough serum levels 12 to 46 mg/l. Some individuals may respond well outside of this range, or may display toxicity within the therapeutic range, thus interpretation should include clinical evaluation [
8]. Toxic levels have not been well established but anecdotal reports show that overdose is facilitated if chronic kidney disease is present [
9]. For patients in CKD 5 D, i.e. patient undergoing dialysis PubMed (
http://www.ncbi.nlm.nih.gov/pubmed) does not list a single pharmacokinetic study. The package insert such as reference books and online resources recommend a dose of 250–500 mg bid and an additional dose of 250–500 mg after “dialysis”.
Our data from a peritoneal dialysis patient suggest that a dose as low as 500 mg bid has the potential of causing severe side effects. As dosing guidelines for patients on thrice weekly hemodialysis should not be simply transferred to patients undergoing daily peritoneal dialysis it is also not understandable how some online-resources advice to reduce the dose of levetiracetam in pediatric peritoneal dialysis patients by 50%. Our case illustrates that therapeutic drug monitoring should be used in this patient population whenever possible. This opportunity was missed in the reported case and could probably have avoided the severe side effects of the levetiracepam overdose.