• Which of the anti-epileptic drugs affect the metabolism of the Pill (oral contraceptive) and what are the implications of this? Which drugs are safe to use in combination with the Pill? 

Drugs that affect metabolism of the Pill: Perampenel (decreases levonorgestrel-containing contraceptives) and Phenobarbitone, phenytoin , carbamazepine and oxcarbazepine all decrease the effectiveness of the oral contraceptive pill leading to increased pregnancies and the possibility of teratogenic effects in these pregnancies.

Drugs that are safe to use in combination is Valproate, Lamotrigine, Gabapentin, Levetiracetam and Vigabatrin.

• Can oral contraceptives also affect the effectivity of the anti-epileptic drugs?

Yes, oral contraceptives can decrease serum levels of drugs such as Lamotrigine and Valproate.

• How does age affect the kinetics of these drugs (from neonates to old age)?

Neonates have a slower metabolism and should therefore receive lower dosages. Babies and children have a faster metabolism than adults and should receive higher dosages. For geriatric patient’s lower dosages are required due to slower metabolism and decreased renal function.

• In which cases is plasma blood level monitoring indicated?

Where protein binding takes place and in certain diseases that may affect protein binding, these cases are with chronic kidney failure, liver diseases, hypoalbuminemia, burns, pregnancy, malnutrition, age and where displacement drugs are involved. In these instances, plasma blood level monitoring is required.

Brand, L. 2021. Antiepileptic drugs. Study unit 4 [PowerPoint Presentation]. Unpublished lecture notes on eFundi, FKLG312. Potchefstroom: NWU