Premium
Pharmacokinetic interaction on valproic acid and recurrence of epileptic seizures during chemotherapy in an epileptic patient
Author(s) -
Ikeda Hiroaki,
Murakami Teruo,
Takano Mikihisa,
Usui Tsuguru,
Kihira Kenji
Publication year - 2005
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.2005.02339.x
Subject(s) - valproic acid , phenytoin , chemotherapy , pharmacokinetics , anticonvulsant , medicine , epilepsy , pharmacology , cisplatin , serum concentration , drug interaction , anesthesia , gastroenterology , psychiatry
Aims To report a pharmacokinetic interaction between valproic acid (VPA) and anticancer agents observed in an epileptic patient. Methods A 34‐year old male epileptic patient receiving VPA underwent cisplatin‐based chemotherapy for the treatment of a testicular tumour. The first chemotherapeutic cycle decreased the serum VPA concentration and caused severe generalized tonic‐clonic seizures. Thus, thereafter, the serum VPA concentration was monitored along with the chemotherapy. Results In a patient receiving VPA daily, severe seizures were observed 7 weeks after the first chemotherapeutic cycle, at which the serum VPA concentration was found to be reduced by approximately 50% of the initial level (90–100 µg ml −1 ). The following cycles (six cycles over a 7‐month period) also caused seizures in association with decreased serum VPA concentrations. In contrast, the serum concentration of phenytoin, which was given daily after the second chemotherapeutic cycle, remained at a therapeutic concentration (10–20 µg ml −1 ). After the completion of chemotherapy, the serum concentration of a tumour marker, hCGβ, decreased to 1.2 ng ml −1 from more than 120 ng ml −1 prior to the chemotherapy in this patient. Conclusions Careful monitoring of VPA concentrations are necessary during cisplatin‐based chemotherapy because anticancer agents can reduce the serum concentration and antiepileptic activity of VPA.