• 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? 

Anti-epileptic drugs that affect metabolism of the Pill

Phenobarbitone, Carbamazepine, Phenytoin, Oxcarbazepine, topiramate. The implication of this is that in case a person is on epileptic drugs it could increase pregnancy risk because it decreases the pill’s effectiveness. The Concentration of the pill needs to be increased to maintain effective levels.

Pills that do not interfere with the metabolism of the pill.

Valproate, Lamotrigine, Gabapentin, Levetiracetam. Normal dose of pill can be used.

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

No. I could be wrong, but didn’t find anything on Google.

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

Babies and children metabolise Epileptic drugs faster than adults. Neonates metabolise slower. It is important to have be careful with some epileptic drugs because they have a narrow therapeutic window and there is more chance for toxicity then if metabolism rates is not taken into consideration. Especially for phenytoin.

• In which cases is plasma blood level monitoring indicated?

Definitely for Phenytoin, because Phenytoin starts off with 1^st order kinetics and then zero order kinetics once the plasma concentration of phenytoin is > 10 ug/ml. The drug can then accumulate and then reach a toxicity level which is very dangerous. Its also important when enzyme inducers are used. Lamotrigine can be used with Carbamazepine. Carbamazepine induce liver enzymes and the enzymes can break lamotrigine down.