Ch 14 - Anticonvulsants - DONE Flashcards
What are the toxic effect of Lamotrigine?
- dizziness
- blurred vision
- rarely life-threatning skin disorders such as Stevens-Johnson syndrome and toxic epidermal necrolysis
What is the route of administration of Valproic acid?
- well absorbed orally; 90% is bound to plasma proteins
How does Topiramate work?
Topiramate has several sites of action.
- It blocks glutamate receptors and Na+ channels.
- It also potentiates the action of GABA
Is phenytoin teratogenic?
Yes.
- It produces fetal hydantoin syndrome, which is characterized by prenatal growth deficiency and mental deficiencies .
- There is also an increase in incidence of congenital malformations, such as cleft palate and heart malformations.
Describe the Tonic phase of a grand mal seizure:
loss of consciousness, rigidity, loss of bowel and bladder control
How is Valproic acid metabolized?
- This drug is extensively metabolized in the liver by cytochrome P-450 system.
- However it does not induce the enzymes of this system, as do carbamazepine and phenytoin
How toxic is topiramate?
- mild side effects
- fatigue
- ataxia
- dizziness
- renal stones
How do the Valproic acid work?
- Valproic acid prolongs the inactive state of Na+ channels
- It may also increase the GABA concentration in the brain
What is the mechanism of action of Gabapentin?
Gabapentin has been found to promote the release of GABA
What is the therapeutic use of carbamazepine?
- It is the drug of choice for treating partial and tonic-clonic seizures.
- It is also the drug of choice for treating trigeminal neuroalgia
How is phenobarbital absorbed and metabolized?
- The drug is well absorbed orally; 75% of it is metabolized in the liver.
- It is a potent inducer of the cytochrome P-450 system.
- Th metabolic by-products are excreted in the urine.
Name one drug that is well known to decrease the plasma concentration of Phenytoin:
Carbamazepine
What is the therapeutic uses of Benzodiazepines?
- IV diazepam is the drug of choice for initiating treatment of status epilepticus
What part of the brain is involved in a generalized tonic-clonic (grand mal) seizure?
The entire cerebral cortex
Describe the absorption and metabolism of Phenytoin:
- Oral absorption is slow
- Phenytoin undergoes hydroxylation by the hepatic cytochrome P450 system.
- At high doses, the hydroxylation system becomes saturated; it is therefore important to watch for toxicity.
How does the Lamotrigine compare to Zonisamide?
Zonisamide can also cause renal stones
What can Clorazepate be used for?
Benzodiazepines
Clorazepate may be used for partial seizures in combination with other drugs
What happens in a complex partial seizure?
- The initial focus of abnormal discharge spreads, so that the patient experiences loss of consciousness and postictal (postseizure) confusion.
- Symptoms can include coordinated motor activity, mental distortion, and sensory hallucinations
Can a partial seizure progress into a grand mal seizure?
Yes. This is known as partial seizure with secondary generation.
When should topiramate be prescribed?
As an adjuvant in the treatment of partial or generalized tonic-clonic seizures.
How is primidone metabolized?
Primidone is converted to phenylethyl-malonamide (PEMA) and to phenobarbital in the liver.
What is the mechanism of action of phenobarbital?
Potentiation of GABA-mediated synaptic inhibition. The mechanism of action is not completely clear, but it is thought to prolong the opening of Cl- channels.
What is the site of metabolism of Lamotrigine?
Lamotrigine is metbolized in the liver
When is primidone used?
Primidone is an alternative drug of choice for adults who have partial seizures (both simple and complex) and generalized tonic-clonic seizures.
When would you use Levetiracetam?
- As an adjuvant for partial seizure
- does not interact with other seizure medications
What is the metabolism of Gabapentin?
it is excreted unchanged in the urine
List the different types of seizures:
- Partial (simple and complex)
- Generalized tonic-clonic
- Status epilepticus
- Absence
- Febrile
- Myoclonic
How does Tiagabine work?
Tiagabine increases GABA concentration in the synapse bly blocking GABA reuptake
What is a seizure?
an abnormal, synchronized electrical depolarization of neurons in the CNS
How does oxcarbazepine differ from carbamazepine
- Oxcarbazepine has a slightly different chemical structure than carbamazepine, which helps minimize its side effect.
- Oxcarbazepine also does not induce the cytochrome P-450 systemas much as carbamazepine.
- It does, however, have mechanism of action and antiepileptic activity similar to those of carbamazepine.
What percentage of the population is affected by epilepsy?
About 1%