Epilepsy prevalence

Active epilepsy affects around 6.4 per 1000 persons

Enzyme inducing anti-epileptic drugs

• Carbamazepine

• Phenytoin

• Topiramate

Non-enzyme inducing anti-epileptic drugs

• Clobazam

• Lamotrigine (anti-epileptic efficacy of lamotrigine is reduced by combined oral contraceptive pill)

• Sodium valproate

• Levetiracetam

TERATOGENICITY

Higher risk of teratogenicity (5-10%): sodium valproate (neural tube defects, cardiac malformations), carbamazepine (cardiac malformations).

Lower risk of teratogenicity (<3%): levetiracetam (cardiac malformations, neural tube defects), lamotrigine (cardiac malformations, oro-facial clefts).

Women taking anti-epileptic drugs, who are planning for pregnancy, are recommended to take high-dose daily folic acid 5mg from preconception until the end of the first trimester.

CONTRACEPTIVE EFFICACY

Enzyme inducing anti-epileptic drugs such as carbamazepine, phenytoin, and topiramate can reduce the efficacy of hormonal contraceptives.

LNG-IUS, Cu-IUD, DMPA (all LARCS except IMP) are unaffected by enzyme inducing anti-epileptic drugs, and therefore appropriate contraceptive choices.

Contraceptive efficacy of CHC (pill, patch or vaginal ring), POP, IMP drugs are reduced.

The efficacy of CHC can be improved by:

• increasing the oestrogen dose (50 ug-70 ug)

• tri-cycling (taking three packets back to back without a pill free interval)

• reducing the pill free interval to four days.

Advise women taking anti-epileptic drugs who wish to use IMP, CHC, POP, to take additional contraceptive precautions (condoms or a vaginal diaphragm)

Non-enzyme inducing anti-epileptic drugs do not affect hormonal contraceptive efficacy.Women on these medications can choose any contraceptive and emergency contraceptive method.

Lamotrigine, a non-enzyme inducing anti-epileptic drug, has minimal effects on the efficacy of CHC.
However, CHC pills reduce blood concentrations of lamotrigine by 40%–60%, which can result in poor seizure control.
If CHC pills are chosen, the dose of lamotrigine may need to be increased to maintain anti-epileptic efficacy.

EMERGENCY CONTRACEPTION

UPSI <5d : Cu-IUD
UPSI <3d: 3 mg dose of levonorgestrel (LNG-EC)
Ulipristal acetate (UPA-EC) is not recommended in patients on enzyme inducing anti-epileptic drugs