Effects of short-term lamotrigine treatment on pharmacokinetics of carbamazepine

Aim and method: The effects of short-term treatment with lamotrigine (LTG) (100 mg twice daily for one week) on single dose pharmacokinetics of carbamazepine (CBZ, 200 mg) were investigated in a randomized, double-blinded, placebo-controlled cross-over study with 10 healthy volunteers. Results: Pharmacokinetic parameters for CBZ or for CBZ-10,11-epoxide, the main metabolite of CBZ, were not significantly affected by LTG pretreatment. The mean (± SEM) elimination half-life of CBZ was 33.0 ± 1.8 h after pretreatment with placebo and 30.1 ± 2.0 h after a one-week-pretreatment with LTG (NS). The area under the serum concentration curve to infinity (AUC) of CBZ was 638 ± 45 μmol/l after placebo and 624 ± 53 μmol/l after LTG (NS). Changes in the peak serum concentration, from 9.0 ± 0.3 μmol/l to 9.2 ± 0.4 μmol/l (LTG), and in the time to peak serum concentration, from 9.3 ± 1.1 h to 9.1 ± 1.2 h (LTG), were also not significant. Conclusion: These data support the earlier findings that LTG does not significantly affect the rate or extent of absorption, or elimination of CBZ.