Ch 14 - Anticonvulsants - DONE Flashcards
1
Q
What are the toxic effect of Lamotrigine?
A
- dizziness
- blurred vision
- rarely life-threatning skin disorders such as Stevens-Johnson syndrome and toxic epidermal necrolysis
2
Q
What is the route of administration of Valproic acid?
A
- well absorbed orally; 90% is bound to plasma proteins
3
Q
How does Topiramate work?
A
Topiramate has several sites of action.
- It blocks glutamate receptors and Na+ channels.
- It also potentiates the action of GABA
4
Q
Is phenytoin teratogenic?
A
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.
5
Q
Describe the Tonic phase of a grand mal seizure:
A
loss of consciousness, rigidity, loss of bowel and bladder control
6
Q
How is Valproic acid metabolized?
A
- 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
7
Q
How toxic is topiramate?
A
- mild side effects
- fatigue
- ataxia
- dizziness
- renal stones
8
Q
How do the Valproic acid work?
A
- Valproic acid prolongs the inactive state of Na+ channels
- It may also increase the GABA concentration in the brain
9
Q
What is the mechanism of action of Gabapentin?
A
Gabapentin has been found to promote the release of GABA
10
Q
What is the therapeutic use of carbamazepine?
A
- It is the drug of choice for treating partial and tonic-clonic seizures.
- It is also the drug of choice for treating trigeminal neuroalgia
11
Q
How is phenobarbital absorbed and metabolized?
A
- 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.
12
Q
Name one drug that is well known to decrease the plasma concentration of Phenytoin:
A
Carbamazepine
13
Q
What is the therapeutic uses of Benzodiazepines?
A
- IV diazepam is the drug of choice for initiating treatment of status epilepticus
14
Q
What part of the brain is involved in a generalized tonic-clonic (grand mal) seizure?
A
The entire cerebral cortex
15
Q
Describe the absorption and metabolism of Phenytoin:
A
- 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.
16
Q
How does the Lamotrigine compare to Zonisamide?
A
Zonisamide can also cause renal stones
17
Q
What can Clorazepate be used for?
Benzodiazepines
A
Clorazepate may be used for partial seizures in combination with other drugs
18
Q
What happens in a complex partial seizure?
A
- 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
19
Q
Can a partial seizure progress into a grand mal seizure?
A
Yes. This is known as partial seizure with secondary generation.
20
Q
When should topiramate be prescribed?
A
As an adjuvant in the treatment of partial or generalized tonic-clonic seizures.
21
Q
How is primidone metabolized?
A
Primidone is converted to phenylethyl-malonamide (PEMA) and to phenobarbital in the liver.
22
Q
What is the mechanism of action of phenobarbital?
A
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.
23
Q
What is the site of metabolism of Lamotrigine?
A
Lamotrigine is metbolized in the liver
24
Q
When is primidone used?
A
Primidone is an alternative drug of choice for adults who have partial seizures (both simple and complex) and generalized tonic-clonic seizures.
25
When would you use Levetiracetam?
- As an adjuvant for partial seizure
| - does not interact with other seizure medications
26
What is the metabolism of Gabapentin?
it is excreted unchanged in the urine
27
List the different types of seizures:
- Partial (simple and complex)
- Generalized tonic-clonic
- Status epilepticus
- Absence
- Febrile
- Myoclonic
28
How does Tiagabine work?
Tiagabine increases GABA concentration in the synapse bly blocking GABA reuptake
29
What is a seizure?
an abnormal, synchronized electrical depolarization of neurons in the CNS
30
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.
31
What percentage of the population is affected by epilepsy?
About 1%
32
Which drugs inhibit the metabolism of carbamezapine?
- Erythromycin
- Isoniazid
- Propoxyphene
- Verapamil
- Cimetidine
33
What is Ethosuximide used for?
Ethosuximide si the drug of choice when treating absence seizures.
34
Valproic acid AE:
- Hepatotoxicity
- GI distress: nausea and vomiting
- Sedation
- Tremor
35
Name the typical phases of a grand mal seizure:
- Tonic phase
| - Clonic phase
36
How is Ethosuximide absrobed?
- orally
37
Benzodiazepines AE:
- when it is used correctly there are minor side effects
- you should watch for:
* drowsiness
* respiratory depression
* cardiac depression
38
Should pregnant women use topimarate?
No! Because of it teratogenic effects
39
What are the characteristics of myoclonic seizures?
- They are sudden, short episodes of either local or generalised muscle contraction.
- They can occur at any age
- They are associated with variety of rare hereditary neurodegenerative disorders.
40
Levetiracetam AE:
most common ones:
- drowsiness
- asthenia
- dizziness
41
What are the therapeutic uses of phenytoin?
Phenytoin is effective in the treating tonic clonic seizures and partial seizures but not absence seizures.
It is also used in the treatment of status epilepticus after the preliminary administration of diazepam
42
What are the indications of Valproic acid?
- Valproic acid is the most effective agent for treating myoclonic seizures.
- It is also used in the treatment of absence seizures.
43
How does Zonisande work?
| seizure medication
It blocks voltage gated Na+ channels and T-type calcium currents
44
What is the therapeutic role of Lamotrigine?
Lamotrigine is used to treat:
- partial seizures
- generalized toxic-clonic seizures
- absence seizures
45
What are the therapeutic uses of phenobarbital?
1. It is the drug of choice when treating febril seizures.
- it is also used to treat grand mal seizures in children.
2. It is good for treating partial seizures and tonic-clonic seizures
- However its sedative effects have reduced its use as a primary agent.
46
What is status epilepticus?
- Continuous seizures not separated by any periods of regained consciousness.
- This condition is a medical emergency.
47
What are the toxic effects of Zonisande?
most common:
- somnolence
- ataxia
- headache
rarely:
- renal stones
48
What is the mechanism of action of Ethosuximide?
Ethosuximide inhibits Ca2+ influx through T-type channels in the thalamic neurons
49
Phenobarbital AE:
- sedation
- nystagmus
- psychotic reactions
- hypersensitivity reactions - Stevens-Johnson syndrome
50
What is a partial (focal) seizure?
- A seizure in which abnormal discharges occur from a focal area within the brain.
- There are two types of partial seizures:
* simple
* complex
51
What are the absorption and metabolism of this drug?
Carbamezapine is absorbed slowly when given orally and is metabolized by the P450 system
52
How is Ethosuximide metabolized?
The majority of the drug is metabolized by the cytochrome P450 system in the liver. It does not induce the P-450 enzyme synthesis
53
What is the mechanism of action of Lamotrigine?
Lamotrigine blocks sustained repetitive firing by blocking voltage-dependent Na+ channels
54
What are the characteristics of simple partial seizure?
- A simple partial seizure involves a focal neyrological symptoms that can be sensory (for examples visual or auditory hallucinations), motor, or psychomotor.
- Consciousness is always retained
55
Primidone AE:
- sedation
- ataxia
- nausea
- vomiting
- drowsiness
56
What are the characteristic febrile seizures?
- They occur in children.
- They usually lasts less than 10 min.
- The child has a fever, but there is no apparent infection or other defined cause of the seizure.
57
What is the classification of phenobarbital?
it is a barbiturate
58
What are the characteristics of absence (petit mal) seizures?
- They usually occur in children 2-12 yrs of age.
- They are characterized by a very brief second loss of consciousness. The child will stop whatever he or she is doing and stare or have some facial twiching.
- Following the attack, the child immediately becomes alert and is seldom even aware that it has occurred.
59
Should pregnant women be given Valproic acid?
No! The incidence of neural tube defects is very high i the drugs are taken while pregnant.
60
What is the mechanism of action of Phenytoin?
Phenytoin binds to Na+ channels and prolongs their inactivated state.
61
Carbamazepine AE:
- Acute intoxication can lead to respiratory depression, stupor, or coma.
- Severe liver toxicity. Patients need frequent liver tests while receiving this drug
- Aplastic anemia
- Patient frequently complain of drowsiness, ataxia, nystagmus, and vomiting.
62
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Blood dyscrasias (may occur in extremely sensitive patients):
(Ethosuximide AE)
```
- leukopenia
- aplastic anemia
- thrombocytopenia
63
What is the mechanism of action of carbamazepine?
It prolongs the inactivated state of Na+ channels
64
What drug is primidone structurally releated to?
It i related to phenobarbital and it works the same way as phenobarbital.
65
Where do complex partial seizure originate?
the majority occur in the temporal lobe
66
Gabapentin toxic effect:
- ataxia
- somnolence
- headache
67
State the therapeutic use of Gabapentin?
Gabapentin is used to treat partial seizures with and without secondary generalization.
- it is used in combination with other antiseizure drugs
- been found useful in the treatment of neurpathic pain
68
Name 5 major causes of seizures:
1. Idiopathic
2. CNS infection
3. Fever
4. Metabolic effect
5. Cerebral trauma
69
Tiagabine AE:
- dizziness
- GI upset
- tremor
70
Ethosuximide AE:
- Dizziness
- Agitation
- GI distress
- Confusion
- Blood dyscrasias
- Skin reactions such as Stevens Johnson syndrome
71
Define epilepsy:
Epilepsy is a group of chronic syndromes characterised by a recurrent seizures with periods of consciousness.
72
Give examples of Benzodiazepines:
- Diazepam
- Clonazepam
- Clorazepate
73
What are the major pharmacological treatment options for seizures?
- Phenytoin
- Carbamazepine/oxcarbazepine
- Phenobarbital
- Primidone
- Valproic acid
- Topiramate
- Ethosuximide
- Benzodiazepine
- Tiagabine
- Vigabatrin
- Gabapentin
- Lamotrigine
- Zonisamide
74
Describe the Clonic phase of a grand mal seizure:
jerking movement of the entire body
75
Name three drugs that increase the plasma concentration of phenytoin:
- Chloramphenicol
- Isoniazid
- Cimetidine
76
What are the toxic effects of Phenytoin?
- Gingival hyperplasia
- Diplopia nystagmus
- Megaloblastic anemia secondary to interference with folate metabolism
- Hirsutism
- Diminished deep tendon reflexes in the extremeties
- CNS depression
- Endocrine disturbances - diabetes insipidus, hyperglycemia, glycosuria, osteomalacia
77
When do we prescribe Zonisande?
Zonisande is used as an adjacement drug in the therapy of partial seizures and generalized seizures
78
What can Clonazepam be used for?
| Benzodiazepines
Clonazepam can be used for treating myoclonic or absence seizures in children
79
When do we use Tiagabine?
Tiagabine is used for the treatment of partial seizures with or without secondary generalization
