Valproic acid plasma concentration decreases in a dose-independent manner following administration of meropenem: a retrospective study.

Several case reports indicate that carbapenem antibiotics, especially meropenem, may decrease the plasma concentrations of valproic acid (VPA), thus decreasing its therapeutic activity. To investigate the onset, severity, and dose dependency of the interaction between meropenem and VPA, the authors carried out a retrospective evaluation of data collected during 24 months from patients hospitalized in a tertiary medical center. The analysis included 36 patients.