1. Phenytoin, topiramate, phenobarbitone, oxcarbazepine, carbamazepine and topiramate. All these anticonvulsants has an effect on the metabolism of oral contraceptives (the Pill) (Brand, 2021).

The anticonvulsants mentioned above are strong-inducers of the enzymes, cytochrome P450 enzyme and glucuronyl transferase enzymes and cause a reduction in oral contraceptive levels, which has a failure in birth-control as result (Katzung, 2018).

There are however anticonvulsants that does not affect the metabolism of oral contraceptives. These drugs are: levetiracetam, gabapentin, valproate, vigabatrin, lamotrigine (Brand, 2021; Katzung, 2018)).

2. Yes, these drugs can decrease the valproate and lamotrigine serum levels (Brand, 2021).
3. These drugs are mostly metabolized by 1st order metabolism in the liver. Neonates has slower metabolism than children, babies and adults, thus anticonvulsants will take longer to metabolize and lower doses should be given, to prevent toxicity. Adult’s have a slower  metabolism than children and babies, thus children and babies should receive higher doses than adults, to ensure therapeutic effectivity. Geriatric patients should be given lower doses anticonvulsants, because they have decreased liver- and kidney function and would not be able to metabolize the drugs as well as adults would, which could lead to toxicity if their doses are equal to adult’s doses (Brand, 2021).
4. It is important to do plasma blood level monitoring with the following cases, as a guide for dosing efficacy. These cases are: during pregnancy, when the patient experiences breakthrough seizures, with a change in drug formulation to help with dose adjustments, to assess adherence, to determine the individual’s therapeutic concentration range when in remission, when medication that interacts is removed or added to the regimen and to determine whether drug levels are related to adverse effects (Katzung, 2018).

Reference list

Brand, L. 2021. Anti-epileptic drugs. Study unit 4 [pdf]. Unpublished lecture notes on eFundi, FKLG312. Potchefstroom: NWU.

Katzung, B.G. 2018. Basic & Clinical Pharmacology. 14th ed. International: Mc Graw Hill Education.