[The clinical relevance of serial determinations of plasma concentrations of carbamazepine and sodium valproate].
BACKGROUND
Serum concentrations of valproate (VPA) and carbamazepine (CBZ) were monitored in 66 epileptic out patients to determine then pharmacokinetic profiles.


METHODS
Thirty-eight patients were receiving monotherapy, 17 with CBZ and 28 with VPA, and 28 patients were receiving VPA and CBZ. All were receiving standard (not controlled-release) CBZ or VPA preparations. Blood samples were obtained 2, 4, and 6 hours after the last dose. Serum concentrations were determined by gas chromatography.


RESULTS
Mean serum concentrations of patients receiving CBZ were 8.2, 7.3 and 6.4 micrograms/ml for the 2, 4 and 6 hours samples, respectively. Mean serum concentrations of CBZ in the group receiving CBZ + VAP were 7.8, 8.4 and 7.8 micrograms/ml, respectively. Patients receiving VPA had mean serum concentrations of 92.8, 97.8 micrograms/ml, respectively. Those receiving CBZ + VPA had serum concentrations of 69.1, 70.6 and 55.8 micrograms/ml, respectively. Mean variation in the CBZ serum concentrations was 45% (range 7-91%) in patients receiving monotherapy and 31% (range 8-93%) in patients receiving CBZ + VPA. Mean variation in VPA serum levels of the patients receiving CBZ + VPA (56%) was greater than those of patients receiving CPA alone (38%). Subtherapeutic serum levels of either drug were detected in 35% of the patients.


CONCLUSIONS
The large inter- and intraindividual variability of serum concentrations showed that a single measurement does not reflect the reality or CBZ and VPA clinical kinetics. The results confirm that three samples collected at 2, 4, and 6 hours after the last dose determine a clinically useful kinetic profile.
Hernández-Fustes
O J
OJ
Servicio de Neurología, Hospital Universitário Cajuru da Pontificia, Universidade Católica de Paraná, Brasil. ottojhf@milenio.com.br
Marcourakis
T
T
de Bittencourt
P R
PR
D000927:Anticonvulsants / Q000097:blood* / Q000627:therapeutic use; D002220:Carbamazepine / Q000097:blood* / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000188:drug therapy; D006801:Humans; D014635:Valproic Acid / Q000097:blood* / Q000627:therapeutic use
D000927:Anticonvulsants; D002220:Carbamazepine; D014635:Valproic Acid
Relevancia clínica de las determinaciones seriadas de concentraciones séricas de carbamacepina y valproato sódico.