New Anticonvulsants

Question 1

What are the newer anticonvulsants?

Answer 1

Gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, tagabine, topiramate, vigabatrin

Question 2

What are the main toxicological featuers of newer anticonvulsants?

Answer 2

Generally much less toxic in overdose

Question 3

What symptoms do patients with new anticonvulsants in overdose present with?

Answer 3

Mild transient CNS symptoms within 2-24 hours. Coma/seizures are rare.

Question 4

In general, how do the newer anticonvulsants work?

Answer 4

Exert an anticonvulstant effect by potentiating GABA-neurotransmission (enhancing GABA release or inhibiting reuptake).

Question 5

How does lamotrigine work?

Answer 5

Exert an anticonvulstant effect by potentiating GABA-neurotransmission (enhancing GABA release or inhibiting reuptake) AND effects on voltage-gated sodium channels

Question 6

How does topiramate work?

Answer 6

Exert an anticonvulstant effect by potentiating GABA-neurotransmission (enhancing GABA release or inhibiting reuptake) AND inhibits carbonic anhydrase

Question 7

How does pregabalin work?

Answer 7

Decreases release of excitatory neurotransmitters, especially glutamate by blockade of calcium channels

Question 8

Which newer anticonvulsant follows saturable absorption, limiting toxicity after overdose?

Answer 8

Gabapentin

Question 9

Other than CNS symptoms, what newer anticonvulsants can cause other constitutional symptoms?

Answer 9

Gabapentin - hypotension/tachy, nausea/vomiting. Lamotrigine - intraventricular conduction delay. Topiramate - non-anion gap metabolic acidosis (not clinically significant)