CONTRACEPTIVES AND LAMOTRIGINE
One study suggests that lamotrigine does not alter the contraceptive efficacy or plasma levels of combined oral contraceptives. Another study found a slight reduction in levonorgestrel levels but no evidence of ovulation. Hormonal contraceptives may reduce the levels of lamotrigine, which can lead to a decrease in seizure control.
The manufacturers suggest that reduced contraceptive efficacy cannot be ruled out, and recommend the use of non-hormonal contraceptives. However, the FFPRHC has found no evidence of reduced contraceptive efficacy and so they suggest that there is no good evidence that non-hormonal methods of contracep- tion are preferable. Lamotrigine can be started as normal in patients already taking hormonal contraceptives. For women already taking lamotrigine and carbamaze- pine or phenytoin no lamotrigine dosage adjustment is necessary when hormonal contraceptives are started, but in the absence of these other antiepileptics the maintenance dose of lamotrigine may need to be increased by as much as twofold, according to clinical response. Patients should also be advised that an increase in seizure frequency may occur when the combined oral contraceptive is started.
The manufacturers suggest that reduced contraceptive efficacy cannot be ruled out, and recommend the use of non-hormonal contraceptives. However, the FFPRHC has found no evidence of reduced contraceptive efficacy and so they suggest that there is no good evidence that non-hormonal methods of contracep- tion are preferable. Lamotrigine can be started as normal in patients already taking hormonal contraceptives. For women already taking lamotrigine and carbamaze- pine or phenytoin no lamotrigine dosage adjustment is necessary when hormonal contraceptives are started, but in the absence of these other antiepileptics the maintenance dose of lamotrigine may need to be increased by as much as twofold, according to clinical response. Patients should also be advised that an increase in seizure frequency may occur when the combined oral contraceptive is started.