AED Flashcards
Difference between seizure and epilepsy?
Seizure - rapid, synchronized, and uncontrolled spread of electrical activity in the brain (may result in loss of consiousness, involuntary movements, abnormal sensory phenomena, increased autonomic activity, and a variety of psychic disturbances)
Epilepsy - individual has a tendency toward recurrent seizures
A seizure is not necessarily epilepsy: may be isolated: either high/low sodium/glucose or alcohol withdrawal
Classifications:
- What is a simple partial seizure?
- What is a complex partial seizure?
- What is a partial seizure with secondary generalization?
Classifications:
- Simple partial - no alteration in consciousness
- Complex partial - alteration in consciousness
- Partial with secondary - spread from one focal area to multiple brain regions resulting in loss of consciousness and possibly a tonic-clonic seizure
Classifications:
Primary generalized:
- What is a tonic clonic seizure?
- What is an absence seizure? EEG pattern?
- What is a myoclonic seizure?
Classifications:
Primary generalized:
- Tonic clonic - abrupt loss of consciousness without warning, followed by tonic contraction of all muscle groups (arched back/estensor posturing) followed by rhythmic jerk of arms and legs
- Absence - brief lapses of attention w/o loss of consiousness or town. 3-Hz spike and wave EEG
- Myoclonic - brief contraction of muscles, no loss of con.
Classifications:
Status epilepticus:
- What is a tonic clonic status?
- What is an absence status?
Classifications:
Status epilepticus:
- Tonic clonic - continuous or recurrent without the individual regaining consciousness between seizures
- Absence - prolonged or continuous lapses of consciousness associated with continuous 3Hz spike an wave activity in the EEG
2 strategies for AED therapy?
2 strategies for AED therapy:
a. Decrease discharge at seizure focus
b. Decrease discharge spread
Partial seizure:
- Results from?
- Targets of AEDs?
Partial seizure:
- Results from rapid, uncontrolled neuronal firing and loss of surround inhibition
- GABA, Na+ channels, HVA Ca++ channels, and glutamate receptors
Absence seizure:
- Cause?
- Drugs target?
Absence seizure:
- Caused by a self-sustaining cycle of activity generated between thalamic and cortical cells
- Drugs target GABAa in reticular thalamic nucleus and T-type Ca++ channels
AEDs facilitate GABA how? (4)
AEDs and GABA:
a. Bind directly to GABA-A receptors
b. Blocking presynaptic GABA uptake
c. Inhibiting metabolism by GABA transaminase
d. Increasing the synthesis of GABA
Drugs that are general hepatic inducers?
General hepatic inducers:
a. Carbamazapine
b. Phenytoin
c. Phenobarbital
d. Primidone
Drugs that are CYP3A inducers? (3)
CYP3A inducers:
a. felbamate
b. Topiramate
c. Oxcarbazine
AEDs with NO CYP effect? (6)
NO CYP effect:
a. Gabapentin
b. Lamotrigine
c. Pregabalin
d. Tiagabine
e. Levetiracetam
f. Zonisamide
Calcium channel blockers:
T type vs HVA inhibitors? And examples?
Calcium Channel Blockers:
T-Type: “pacemakers” of normal rhythmic brain activity, especially in the Thalamus (and in regards to absence seizures); Ethosuximide and valproate
HVA (high-voltage-activated) - Control entry of calcium into presynaptic terminal; Gabapentin
Sodium channel blockers:
- Blockade causes?
- Should not be used when?
Sodium Channel Blockers:
- Blockade causes stabilization of neuronal membranes, prevents posttetanic potentiation, limits development of maximal seizure activity, and reduces the spread of seizures
- Should NOT be used for absence seizures - makes the worse
Sodium channel blockers:
Drugs? (9)
Sodium channel blockers:
a. Carbamazepine, Oxcarbazepine, and Eslicarbazepine
b. Phenytoin
c. Lamotrigine
d. Zonisamide
e. Lacosamide
f. Rufinamide
g. Primidone
Carbamazepine:
- First line therapy for?
- Other uses?
- Drug of choice for?
Carbamazepine:
- First line: focal seizures w/ or w/o secondary generalization and generalized tonic-clonic seizures (DOC)
- Other - BPD, ADD, ADHD, schizophrenia, phantom limb, and paroxysmal extreme pain disorder
- DOC - trigeminal neuralgia
Carbamazepine:
- Primary MOA?
- Also decreases? Blocks what receptors? And blocks reuptake of?
- Action results in action potential ____ AND?
Carbamazepine:
- Stabilize voltage-gated axonal Na+ channels in the inactivated conformation (increases refractory period)
- Also decreases voltage gated Ca++ channels; blocks adenosine receptors; and blocks reuptake of NE
- Action potential propagation AND increased seizure threshold
Carbamazepine:
- Given IV, IM, or subcutaneously for?
- Role in CYP450 enzymes?
Carbamazepine:
- IV/IM/SQ - for status epilepticus
- POTENT INDUCER OF CYP450
Carbamazepine:
- Potent inducer increasing metabolism of?
Carbamazepine:
- Inducer: increasing its own metabolism (autoinduction) as well as other AEDs (met in the liver), oral contraceptives, warfarin, theophylline, and protease inhibitors
Carbamazepine:
Side effects:
- CNS? Due to?
- Systemic?
Carbamazepine:
Side effects:
- CNS - _nystagmus, blurred vision, diplopia, ataxia, lethargy, _drowsiness and HA; due to hyponatremia
- Systemic - N/V, diarrhea, rash, pruritis, and fluid retention
Carbamazepine:
Rare side effects?
Carbamazepine:
Rare SE:
a. BM suppression: agranulocytosis, leukopenia, aplastic anemia, and thrombocytopenia
b. Steven johnson - esp with HLA-B allele and asian
c. Teratogenic - NT tube defects (abnormal facial features, spina bifida etc)
Carbamazepine:
- Contraindications?
- Increases metabolism of?
- What decreases its metabolism? This results in?
Carbamazepine:
- Contraindications - hypersensitivity
- Increase met: AEDs, oral contraceptives, warfarin
- Macrolides, cimetidine, and Ca++ channel blockers decrease its metabolism leading to raised carbamazepine levels
Carbamazepine:
- Can increase toxicity of?
- Monitor what levels?
Carbamazepine:
- Increase toxicity of lithium
- Monitor renal, hepatic, and hematologic levels
Oxcarbazepine (OXC):
- First line monotherapy for?
- May aggravate?
Oxcarbazepine (OXC):
- First line: partial and generalized seizures
- May aggravate: myoclonic and absence seizures
Oxcarbazepine (OXC):
- OXC does not produce the ____ metabolite, which is largely responsible for what with carbamazepine?
- Common side effects?
Oxcarbazepine (OXC):
- Doesnt produce epoxide metabolite responsible for SE with carbamazepine
- SE: sedation, HA, dizziness, vertigo, ataxia, diplopia, rash, hyponatremia, wt gain, GI disturbances, and alopecia
Oxcarbazepine (OXC):
- Severe side effects?
- Interactions?
- Contraindications?
Oxcarbazepine (OXC):
- Severe SE: Stevens-Johnson
- Reduces the effectiveness of hormonal contraceptives
- NOT to be used in combination with eslicarbazepine (active metabolite of OXC)
Eslicarbazepine:
- Use?
- MOA?
- SE?
- Contraindications?
Eslicarbazepine:
- Focal onset seizures
- MOA: active metabolite of OXC - blocks Na+ channels in rapidly firing neurons
- SE: dizziness, sedation, HA, vertigo, ataxia, blurred vision, and tremor
- Contraindications: OXC or patients with severe liver impairment
Phenytoin:
- First line monotherapy/adjunctive for?
- Also used for?
Phenytoin:
- First line: focal and generalized seizures
- Also: Lennox-Gastaut syndrome, status epilepticus, and childhood syndromes
Phenytoin:
- What is Lennox-Gastaut syndrome?
- Contraindicated for?
- No longer used for what kind of seizures?
Phenytoin:
- LG = frequent seizures of different types accompanied by retardation and behavioral problems seen in children
- Contra - absence seizures
- No longer used for alcohol withdrawal or toxin induced seizures
Phenytoin:
MOA:
- Primary MOA?
- Also inhibits? Limits fluctuation of neuronal ___ gradients via?
- Effects on ___ and other ___ ___ systems.
- Action results in? Does NOT?
Phenytoin:
MOA:
- Primary - Na+ blocker in inactivated conformation
- Also inhibits voltage-gated Ca++ channels; limits fluctuation of ionic gradients via Na+/K+ ATPase
- Effects on calmodulin and other 2nd messenger systems
- Action results in decreased AP propagation (size and spread) but DOES NOT increase seizure threshold
Phenytoin:
- Kinetics?
- Protein binding?
- Strong _____ of hepatic enzymes.
Phenytoin:
- Dose-dependent zero order kinetics (smaller change in dose leads to BIG change in [plasma])
- Highly bound (90%) but free is active
- Strong inducer of hepatic enzymes
Phenytoin:
- Induction of hepatic enzymes results in?
- Common CNS side effects?
- Systemic side effects? ___ ____ can reduce incidence of?
Phenytoin:
- Induction results in increased metabolism of other liver metabolized AEDs, oral contraceptives, warfarin, theophylline, and protease inhibitors
- CNS: horizontal gaze nystagmus, loss of smooth pursuit eye movements, diplopia, confusion, ataxia, slurred speech, neuropathy
- Systemic: gingival hyperplasia and hirsutism; Folic acid can reduce the gingival hyperplasia
Phenytoin:
Serious side effects?
Phenytoin:
Serious side effects: osteomalacia, bleeding problems, megaloblastic anemia, teratogen, seizures, drug-induced lupus, steven-johnson syndrome, toxic epidermal necrolysis, rash and severe allergic reactions
Phenytoin:
- Osteomalacia due to?
- Bleeding problems due to?
- Megaloblastic anemia due to?
Phenytoin:
- Osteomalacia: interference with Vit D metabolism –> bone softening
- Bleeding - interference with Vit K
- Megaloblastic anemia - due to reduction in folic acid
Phenytoin:
- Teratogenic result? Resembles?
- What occurs with parenteral administration? Why? How to avoid?
- Has one of the most problematic ____ _____ profiles.
Phenytoin:
- Teratogen: craniofacial anomalies, cardiac defects, and mild retardation; resembles Fetal Alcohol Syndrome
- Parenteral: skin necrosis and cardiac arrhythmias because the drug is VERY insoluble in H2O and the dilutant is toxic; avoid by administering fosphenytoin
- Most problematic drug interaction profiles
Phenytoin:
- Increased phenytoin metabolism by?
- Decreased metabolism of phenytoin by?
Phenytoin:
- Increased phenytoin MET by carbamazepine and phenobarbital
- Decreased phenytoin met by cimetidine