case_images: PMC11780581_01
case_images: PMC11780581_02
case_images: PMC11780581_03
case_images: Concentrations of lamotrigine (green, dashed line), topiramate (red line) and valproic acid (blue line) and their temporal correlation with the administration of fosphenytoin (F), meropenem (M) and phenobarbital (P). A red cross indicates the occurrence of suspected seizures. The daily doses of lamotrigine, topiramate and valproic acid within a given time period are marked above. All antiepileptic medications were given orally with the exception of valproic acid on days 7-8 and 25-32 (intravenous treatment). *The daily doses of valproic acid varied, occasionally exceeding the stated dose.
case_images: bcr-18-1-g001.jpg
case_images: PMC11780581_03_bcr-18-1-g001.jpg
case_images: F1
case_images: Starting on the 11th day of hospitalisation, the plasma concentration of valproic acid and serum concentrations of lamotrigine and topiramate rapidly decreased and remained below therapeutic levels for over 1 month, despite continuous treatment (figure 1).
case_images: PMC11780581_04
case_images: Potential pharmacokinetic interactions between the patient's daily antiepileptic medication regimen (valproic acid, lamotrigine, topiramate and clobazam) and additional medications that the patient received during hospitalisation. The number of small, vertical arrows indicates the degree to which the concentration of a given medication is expected to be altered ( /  = minor,   /  = moderate,    /    = major).   A thick, solid arrow indicates that the interaction is presumed to partially explain the alterations in concentration levels illustrated in figure 1.   A thin, dashed arrow represents potential interactions in a general context. (): Prevailing data is inconsistent. * : Concurrent treatment did not occur. NB: Potential pharmacodynamic interactions are not included in this figure.
case_images: bcr-18-1-g002.jpg
case_images: PMC11780581_04_bcr-18-1-g002.jpg
case_images: F2
case_images: A thorough assessment for potential drug interactions was conducted by the local Department of Clinical Pharmacology, identifying fosphenytoin (day 11-18), meropenem (day 13-23) and phenobarbital (day 31-58) as agents likely to cause clinically significant interactions with valproic acid, lamotrigine and topiramate, potentially explaining the observed subtherapeutic levels (figure 2).
case_images: PMC11780581_05