Changes in unbound and total valproic acid concentrations after replacement of carbamazepine with oxcarbazepine.
Total and free valproic acid (VPA) concentrations were measured in patients switched from a combined VPA and carbamazepine (CBZ) to a combined VPA and oxcarbazepine (OXC) therapy, both administered in individualized daily doses. Four young epileptic patients (13-17 years old) were studied for a 12-week period, total and free VPA concentrations being analyzed just before and 4 h after the morning dose, at the end of VPA and CBZ therapy, and 2 and 10 weeks after CBZ was replaced by OXC. The expected increase in the level/dose (L/D) ratio of total VPA observed at the end of the study was preceded by a clear-cut increase in the L/D ratio of free VPA, which led to VPA-related side effects and required the retitration of VPA daily doses.
Battino
D
D
C. Besta Neurology Institute, Milan, Italy.
Croci
D
D
Granata
T
T
Bernardi
G
G
Monza
G
G
D000293:Adolescent; D000927:Anticonvulsants / Q000009:adverse effects / Q000494:pharmacology*; D002220:Carbamazepine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000097:blood / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D000078330:Oxcarbazepine; D014635:Valproic Acid / Q000009:adverse effects / Q000097:blood*
D000927:Anticonvulsants; D002220:Carbamazepine; D014635:Valproic Acid; D000078330:Oxcarbazepine