Elevated Serum Concentrations of Lacosamide and Perampanel in a Pediatric Patient Following Coadministration of Clarithromycin for Mycoplasma pneumoniae Pneumonia.

Lacosamide (LCM) and perampanel (PER) are antiepileptic drugs eliminated, in part, by cytochrome P450 (CYP) 3A4. However, clinical reports of their interactions are limited. Here, we report the case of a 12-year-old girl with a history of infantile epileptic spasms syndrome, treated with LCM, PER, valproic acid (VPA), and levetiracetam (LEV), who was diagnosed with Mycoplasma pneumoniae pneumonia and prescribed clarithromycin (CAM). Owing to impaired consciousness, serum drug concentrations were measured on multiple occasions during hospitalization. Markedly elevated serum concentrations of LCM (2.3 × baseline) and PER (4.4 × baseline) were observed after initiation of CAM. These concentrations were normalized after CAM was discontinued. Serum concentrations of LEV and VPA remained unchanged. According to the Drug Interaction Probability Scale, interaction was considered probable, with a total score of 5. Clarithromycin likely induced a pharmacokinetic interaction via CYP3A4 inhibition, leading to increased serum concentrations of LCM and PER. Although the concomitant use of CAM with these agents is not contraindicated, the findings of this case suggest caution is warranted. When macrolide therapy is necessary, alternative agents with weaker CYP3A4 inhibition, such as azithromycin, may be preferable.