Risk factors for carbamazepine elevation and toxicity following epilepsy surgery.
A proportion of patients undergoing epilepsy surgery, and receiving carbamazepine (CBZ), experience significant elevations in CBZ plasma concentrations, some with associated CBZ toxicity. The objective of this study was to identify significant risk factors for elevations (>12 microg/ml) in CBZ concentrations and CBZ-induced toxicity following epilepsy surgery.


METHODS
We retrospectively examined charts of 74 inpatients (31 children and 43 adults) chronically receiving CBZ and undergoing epilepsy surgery between January 1996 and June 2000. Patient demographics, medications, type of surgery, seizure history, adverse events, CBZ doses and concentrations were evaluated.


RESULTS
51.2% of adults and 51.6% of pediatric patients had drug elevations. In the pediatric group, 12.9% had symptoms of toxicity compared to 9.3% in the adult group. Five risk factors-pre-operative CBZ dose, fentanyl dose, surgery day CBZ concentration, body weight, and blood loss-were related to post-operative CBZ concentrations. Three risk factors: age <18 years, pre-operative CBZ dose, and the surgery day CBZ (immediate pre-operative) concentration, were significantly related to the outcome measure of abnormal CBZ concentration (>12 microg/ml). Two variables significantly related to toxicity were average post-operative CBZ dose and the surgery day CBZ concentration. Increases in concentrations occurred at a mean 33+/-13.7 h (range: 11-74 h) after surgery.


CONCLUSIONS
Based upon our results in patients with one or more risk factors, we suggest that reduction of post-operative CBZ doses be considered.
Hiremath
Girish K
GK
Department of Neurosurgery, The Cleveland Clinic Foundation, 9500 Euclid Avenue, S-80 Cleveland, OH 44195, USA. hiremag@ccf.org
Kotagal
Prakash
P
Bingaman
William
W
Hovinga
Collin
C
Wyllie
Elaine
E
Morris
Harold
H
Nelson
David
D
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000927:Anticonvulsants / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D001835:Body Weight; D002220:Carbamazepine / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D062787:Drug Overdose; D004827:Epilepsy / Q000097:blood* / Q000188:drug therapy / Q000601:surgery; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors
D000927:Anticonvulsants; D002220:Carbamazepine