Comparative study of bioavailability and clinical efficacy of carbamazepine in epileptic patients.
OBJECTIVE
To compare the bioavailability of three generic brands of carbamazepine tablets with that of a proprietary brand in adult patients with epilepsy.


METHODS
A double-blind, randomized, three-phase crossover study.


METHODS
A psychiatric facility.


METHODS
Eighteen patients with epilepsy who had taken carbamazepine at least 5 months before entering the study.


METHODS
Ten blood specimens from each patient were collected at steady-state. Plasma concentration of carbamazepine was analyzed for pharmacokinetic parameters such as maximum plasma concentration (Cmax), mean time to reach maximum concentration (tmax), and mean AUC.


RESULTS
There were no statistically significant differences in these parameters among four brands of carbamazepine. However, when comparing the 90% CI of AUC of three generic brands with that of the proprietary brand, the AUC of two generic brands lay within a range of 80% to 120%. The effects of gender and each brand of carbamazepine on these pharmacokinetic parameters were also analyzed. Breakthrough seizures occurred even though the plasma concentration of carbamazepine was therapeutic.


CONCLUSIONS
The bioavailability of two generic brands of carbamazepine tablets (Carmapine and Carzepine) and the proprietary brand (Tegretol) were equivalent in this sample of adult patients with epilepsy.
Silpakit
O
O
Division of Neurology, Srithanya Hospital, Nonthaburi, Thailand.
Amornpichetkoon
M
M
Kaojarern
S
S
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000927:Anticonvulsants / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D019540:Area Under Curve; D001682:Biological Availability; D002220:Carbamazepine / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004827:Epilepsy / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D013607:Tablets; D013810:Therapeutic Equivalency
D000927:Anticonvulsants; D013607:Tablets; D002220:Carbamazepine