CNS 5 Flashcards
Second generation antiepileptic drugs
- gabapentin,
- lamotrigine,
- topiramate,
- levetiracetam,
- oxcarbazepine,
- zonisamide
Are most often used as an adjunctive therapy for myoclonic as well as for partial and generalized tonic-clonic seizures
Diazepam, and lorazepam
Has a shorter pharmacokinetic half-life but stays in the brain longer than diazepam.
Lorazepam
Is available for rectal administration to avoid or interrupt prolonged generalized tonic-clonic seizures or clusters.
Diazepam
Reduces the propagation of abnormal impulses in the brain by blocking sodium channels, thereby inhibiting the generation of repetitive action potentials in the epileptic focus and preventing their spread. Effective for treatment of partial seizures and secondarily generalized tonic-clonic seizures.
Carbamazepine
- 10,11-epoxide metabolite of the drug → implicated in causing blood
dyscrasias - A characteristic rash may develop early in therapy but may not require
a change in treatment. - Hyponatremia may be noted in some patients, especially the elderly →
could indicate a need for change of therapy. - SHOULD NOT BE PRESCRIBED FOR PATIENTS WITH ABSENCE SEIZURES BECAUSE IT MAY CAUSE AN INCREASE IN SEIZURES.
Carbamazepine
Is a combination of sodium valproate and valproic acid and is reduced to valproate when it reaches the gastrointestinal tract. It was developed to improve gastrointestinal tolerance of valproic acid.
Divalproex sodium
It is effective for the treatment of partial and primary generalized epilepsies
Divalproex
Is bound to albumin (greater than 90 percent), which can cause significant interactions with other highly protein bound drugs
Valproate
Teratogenicity is of great concern of this drug
Divalproex
- reduces propagation of abnormal electrical activity in the brain, most likely by inhibiting T-type calcium channels.
- It is effective in treating only primary generalized ABSENCE seizures.
- Use of this is limited because of this very narrow spectrum.
Ethosuximide
• has a broad spectrum of anticonvulsant action.
• The drug has multiple proposed mechanisms including:
1) blocking voltage-dependent sodium channels
2) competing with the glycine-coagonist binding site on the N-methyl-D-aspartate
(NMDA) glutamate receptor
3) blocking calcium channels
4) potentiation of GABA actions
• It is reserved for use in refractory epilepsies (particularly Lennox-Gastaut syndrome)
because of the RISK OF APLASTIC ANEMIA (about 1:4000) and HEPATIC FAILURE.
Felbamate
• An analog of GABA
• However, it does not act at GABA receptors nor enhance GABA
actions, nor is it converted to GABA.
• It is approved as adjunct therapy for partial seizures and for treatment of postherpetic neuralgia.
Gabapentin
Has been shown to be well tolerated by the elderly population with partial seizures due to the relatively mild adverse effects and a good choice due to limited or no reported
pharmacokinetic drug interactions.
Gabapentin
- Blocks sodium channels as well as high voltage dependent calcium channels.
- is effective in a wide variety of seizure disorders, including partial seizures, generalized seizures, typical absence seizures, and the Lennox-Gastaut syndrome.
- It is approved for use in bipolar disorder as well.
- The half-life of lamotrigine (24 to 35 hours) is decreased by enzyme-inducing drugs (for example, carbamazepine and phenytoin) and increased by greater than 50% with addition of valproate.
Lamotrigine