Seizure Medications Flashcards
Sketchy Pharm
Subclassifications of focal seizures
Aware or impaired awareness
Motor or nonmotor
[2]
Subclassifications of generalized seizures
Motor (tonic-clonic: stiffening and jerking, and myoclonic: shock-like) or nonmotor
[3]
Valproic acid is effective in treating:
Focal and generalized seizures [4]
Biopolar disorder
What is the physiological function of valproate/ valproic acid?
Blocks Na+ channels [4a] and T-type calcium channels [4b]- extends the inactivation of voltage-gated Na+ channels, preventing propagation of action potential
Enhances GABA release [4c] through presynaptic effect on GABA-B receptors
No effects on GABA A
Inhibits GABA-transaminase increasing presynaptic GABA
Increased synthesis of GABA through activation of glutamic acid decarboxylase
Side effects of Valproic acid include (in order of most common to least):
- GI disturbances [4d]- take with food
- Weight gain [4e]
- Fine tremor [4f]
- Hepatotoxicity- rare but potentially fatal [4g]- rash, fever, abdominal pain
- Hyperammonimia [4h]
- Acute pancreatitis [4i]
- Fetal malformations: neural tube defects, limb defects, oral facial cleft defects [4j]
What broad-spectrum antiepileptic is teratogenic?
Valproic acid [4i]
Topiramate is used to treat:
All generalized and focal seizures including absence seizures, but not as effective as valproic acid for absence seizures [5] (guy with a toupee)
Can also be used as migraine prophylaxis
Can be used for weight loss
What are the physiologic functions of topiramate?
Inactivating sodium channels [5a]- blocking neuron firing
Increases inhibitory effects of GABA through binding of allosteric site of GABA-A receptor [5b]
What are the side effects of Topiramate?
Somnolence, fatigue, confusion, impaired concentration, weight loss [5c]
Urolithiasis (kidney stones) [5d]
Acute myopia, angle closure glaucoma [5e] (stop immediately if any symptoms occur)
What is Lamotrigine used to treat?
Focal, generalized, and potentially absence seizures [6]
What are the physiological functions of lamotrigine?
Blocked voltage-gated sodium channels [6a]
What are the side effects of lamotrigine?
Diplopia, blurred vision [6b]
Skin rash (10%) or Stevens Johnsons Syndrome [6c]
DRESS
How do lamotrigine and valproic acid interact?
Valproic acid inhibits metabolism and elimination of lamotrigine
Should decrease amount of lamotrigine used with valproic acid to decrease lamotrigine side effects
Brivaracetam is used to treat:
Focal-onset seizures [8]
Added to other antiepileptics
What are the physiologic functions of brivaracetam?
Binds to synaptic vesicle glycoprotein 2A [8]
Levetiracetam is used to treat:
Focal and generalized seizures [7]
Added to other antiepileptics
What is the physiologic function of levetiracetam?
Binds synaptic vesicle glycoprotein 2A [7]
What are side effects of levetiracetam and brivaracetam?
Dizziness, drowsiness, nausea [7a] [8a]
What are side effects specific to levetiracetam?
depression, hostility, aggression, agitation [7a]
What broad-spectrum antiepileptic is metabolized by CYP450?
Brivaracetam [8b]
Dont use with antiepileptics that induce CYP450 because serum drug concentrations will decrease
What drug only treats absence seizures?
Ethosuximide [1] [2]
Ethosuximide treats:
Absence seizures [1] [2]
Some characteristics of absence seizures:
Sudden momentary lapse in awareness
Staring
Blinking
Clonic jerks [3]
10seconds
up to 100s of times a day
What is a characteristic EEG finding in absence seizures?
3 Hz spike wave complex [5a]
With normal background EEG
What is the physiologic function of Ethosuximide?
Blocks T-type calcium channels in thalamic neurons [6] [6a]
Blocks sustained rhythmical bursts in this region
The most common dose-related side effect of ethosuximide:
GI distress- pain, nausea, vomiting [7]
Lethargy or fatigue [8]
What other drugs may be beneficial in treating absence seizures?
Valproic acid [9]
Lamotrigine [10]
Gabapentin and Pregabalin treat:
Adjunctive treatment for refractory focal seizures with or without secondary generalization
Treat neuropathic pain [4]
Diabetic neuropathy [5]
Fibromyalgia [6]
Post herpetic neuralgia/ VZV reactivation- often causing allodynia or pain with light touch [7]
What is the physiologic function of gabapentin and pregabalin?
Block voltage-gated Ca++ channels [2]
What are the side effects of gabapentin and pregabalin?
Ataxia, dizziness, sedation [8]
More common in elderly patients
What do narrow spectrum anti-epileptics typically treat?
Focal seizures and focal seizures with secondary generalizations [2]
May also treat generalized tonic-clonic seizures
Avoid in JME
What are some examples of narrow spectrum antiepileptics?
Carbamazepine [3]
Oxcarbazepine [4]
Phenytoin [5]
Tiagabine
Vigabatrin
What is carbamezapine ineffective in treating?
Absence seizures
Should be avoided in generalized seizures such as JME
What are the physiologic actions of carbamezapine?
Binds voltage- and use- dependent Na+ gated channels [3a]
Extends inactivated phase of neurons
Blocks sustained high frequency firing of neurons
What is carbamezapine a first line treatment for?
Trigeminal neuralgia [3b]
Sudden pain in the CNV1/2 regions unilaterally triggered by stimulus to these regions
Why is oxcarbazepine sometimes preferred in the treatment of trigeminal neuralgia?
Increased tolerance
Fewer drug-drug interactions
What are some side effects of carbamezapine?
Diplopia [3d]- often occurs first
Ataxia [3c]
Excess free water retention due to inappropriate ADH secretion (siADH)- causes a dose-dependent hyponatremia [3e]
Leukopenia
Aplastic anemia
Agranulocytosis [3f]
WBC counts <3000/uL
When is carbamezapine contraindicated?
Patients with bone marrow suppression [3f]
What are the most significant drug-drug interactions of carbamezapine?
Carbamazepine induces CYP450 [3g]
Causing a decrease in serum levels of other drugs that are metabolized by CYP450 including:
- warfarin
- antiepileptics (brivaracetam)
- BCP due to CYP3A4 induction [3k]
DRESS [3h]- fever, facial edema, eosinophilia, lymphadenopathy, diffuse skin rash, hepatic or renal failure
Fetal malformations [3i] [3j]
Steven Johnson Syndrome [3l]
What allele causes and in likelihood of getting stevens johnson syndrome?
HLAB1502
Occurs almost exclusively in persons of Asian ancestry
Oxcarbaepine is used to treat:
Focal and secondarily generalized tonic clonic seizures in children and adults [4]
What is the physiologic function of oxcarbazepine?
Blocking voltage dependent Na+ channels [4a]
Increases inactivation
What side effects are reduced in oxcarbazepine vs carbamazepine?
Lower CNS side effects [4b]
Fewer drug interactions [4c] tinted glass to reduce interactions
What are common side effects of oxcarbazepine?
Like Carbamazepine:
Diplopia
Ataxia
SJS
Blood dyscrasias
DRESS
Fetal malformations: cardiac and oral clefts [4d]
What is phenytoin ineffective in treating?
Absence seizures and JME
What is the physiologic function of phenytoin?
Blocking of voltage dependent Na+ channels leading to prolonged inactivation [5a]
What are common side effects of phenytoin?
Ataxia [5b]
Diplopia [5c]
Nystagmus
Gingival hyperplasia [5d] due to increased expression of platelet derived growth factor
Hirsutism [5e]
DRESS [5f]
Rash or SJS or TEN [5g]
Fetal malformations [5h]
CYP450 induction- reduces serum levels of drugs metabolized by CYP450 [5i]
CYP3A4 induction- reduces efficacy of BCP [5j]
Decreased bone density [5k]- supplement with Vitamin D, especially elderly
What antiepileptics are associated with drug-induced lupus syndrome?
Carbamazepine
Oxcarbazepine
Phenytoin
[6]
Define status epilepticus.
Seizures lasting longer than 5 minutes [7]
How do you treat status epilepticus?
IV Benzodiazapines [7a]
- diazepam
- lorazepam
Maintenance with IV phenytoin [7b]
What do you treat a patient with if they do not respond to benzodiazapines or phenytoin?
IV Phenobarbital [7c]- barbituate
What are some side effects of barbituates such as phenobarbital?
Sedation
Reduction of blood pressure
Reduced respiration
What narrow spectrum antiepileptics increase GABA levels?
Vigabatrin [8]
Tiagabine [8]
What is the physiologic function of Vigabatrin?
Irreversibly inhibits GABA transaminase [8a]- transmission
Decreases GABA breakdown [8a]- repairmen prevent the cabs breakdown
Increases GABA in synapse
Tonic inhibition
What is the physiologic function of Tiagabine?
Inhibits GABA uptake [8b]
Prolonging action of GABA in synapse
Adjunct treatment for focal seizures
What antiepileptics induce CYP450?
Carbamazepine
Oxcarbazepine
Phenytoin
Phenobarbital
Explain phenytoin’s interaction with CYP450
Phenytoin is metabolized by CYP450
At high drug levels, CYP450 enzymes are saturated and clearance rates decrease leading to an exponential increase in phenytoin serum levels, causing phenytoin toxicity
