Effect of lamotrigine on carbamazepine epoxide/carbamazepine serum concentration ratios in adult patients with epilepsy.
Although lamotrigine (LTG) appears to have a low propensity to cause pharmacokinetic interactions with other medications, it has been suggested that LTG may interfere with the elimination of carbamazepine 10,11-epoxide (CBZE), the active metabolite of carbamazepine (CBZ). Evidence for this pharmacokinetic interaction is inconclusive and conflicting, however. We evaluated CBZ apparent oral clearance and the steady-state CBZE/CBZ serum concentration ratios in nine patients (30.8 +/- 7.7 years) with epilepsy prior to and following the initiation of adjunctive treatment with LTG. Overall, CBZ oral clearance was unchanged following the introduction of LTG (5.58 +/- 1.60 vs. 5.81 +/- 1.74 1/h, P = 0.630). Likewise, CBZE to CBZ serum concentration ratios were not significantly different (0.241 +/- 0.082 vs. 0.232 +/- 0.082, P = 0.782). These observations suggest that the addition of LTG did not result in a significant pharmacokinetic interaction involving either CBZ or CBZE.
Gidal
B E
BE
School of Pharmacy, University of Wisconsin-Madison 53706, USA.
Rutecki
P
P
Shaw
R
R
Maly
M M
MM
Collins
D M
DM
Pitterle
M E
ME
D000284:Administration, Oral; D000328:Adult; D000927:Anticonvulsants / Q000627:therapeutic use*; D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000097:blood*; D004827:Epilepsy / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D008297:Male; D008657:Metabolic Clearance Rate; D014227:Triazines / Q000627:therapeutic use*
D000927:Anticonvulsants; D014227:Triazines; D002220:Carbamazepine; C012227:carbamazepine epoxide; D000077213:Lamotrigine