Blog #7 (SU 4.3)

• 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?

1. Phenobarbitone
2. Phenytoin
3. Carbamazepine
4. Oxcarbazepine
5. Topiramate

These above listed drugs decrease the effectiveness of oral contraceptives. This increases the risk of a female patient using these drugs as therapy to fall pregnant even when she is taking oral contraceptives.

1. Valproate
2. Lamotrogine
3. Gabapentin
4. Leviteracetam
5. Vigabatrin

These above listed drugs do not affect oral contraceptives and can be used in combination.

 

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

Yes. Oral contraceptives decrease the serum levels of Lamotrogine and Valproate. Higher doses of this drug is thus needed to reach therapeutic serum levels to effectively treat the condition. If these drugs are taken in combination with oral contraceptives there is an increase in the risk of the patient experiencing seizures.

 

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

Neonates metabolise the drug slower, so a lower dose needs to be given as to not induce toxic serum levels. Babies and children metabolise the drug faster than adults and the dose should be higher to achieve therapeutic levels and get desired clinical outcomes. Geriatric patients a lower dose needs to be administered because often their liver and kidney function start to decline or are impaired thus affecting the metabolism (slower metabolism) of the drug.

 

• In which cases is plasma blood level monitoring indicated?

Plasma blood levels are indicated in patients that have impaired liver and kidney function if the drug they are using is metabolised in the impaired organ system.

 

Reference list

Brand, L. 2021. SU 4 Anti-Epileptic Drugs. https://efundi.nwu.ac.za/access/lessonbuilder/item/5613419/group/dd46f2da-d3be-402e-9ba7-2c5955cedd9d/English%20power%20point/English%20PP%202021/SU%204.pdf Date of access: 17 Mar. 2021.