Anticonvulsants Flashcards
Anticonvulsants/ AEDs are used for what?
1) long term management of chronic epilepsy
2) management of seizures not caused by epilepsy
What is off-label use of anticonvulsants? Hint: 4
1) anxiety
2) bipolar disorder
3) chronic pain
4) migraines
What will happen if a pt abruptly stops taking their anticonvulsant?
It can trigger recurrence of seizures
What are the mechanisms of action of anticonvulsants?
1) sodium channel blockers
2) calcium channel blockers
3) GABA enhancers
4) glutamate blockers
Mechanisms of actions:
Sodium channel blockers
Prevent the rapid firing of neurons
prevent return of channel to active state – stabilizes them – inactive state
Mechanisms of action:
Calcium channel blockers
Slow down the flow of calcium into cells, limiting the development of action potentials
Mechanisms of action:
GABA enhancers
Enhances inhibitory effects, making neurons less likely to fire
Mechanisms of action:
Glutamate blockers
Prevent excitatory signaling by blocking glutamate
How do we select which medication is used for Tx of seizures?
By the classification of the seizure and epilepsy
What type of seizures are broad spectrum meds used for?
Effective for Tx of focal & generalized seizures
What type of seizures are narrow spectrum meds used for?
Used primarily for focal-onset seizures (including focal which evolve to B/L convulsive seizures)
List 9 things to base selection of meds for seizure Tx off of
1) efficacy
2) tolerability
3) presence of comorbidities
4) pharmacokinetic profile
5) potential drug-drug interactions
6) ease of use
7) cost
8) age
9) gender
List 10 AEDs thats mechanism of action is Na+ channel blockers
1) carbamazepine
2) oxcarbazepine (trileptal)
3) eslicarbazepine
4) felbamate
5) lamotrigine
6) lacosamide (vimpat)
7) phenytoin (fosphenytoin (IV))
8) topiramate
9) valproate
10) rufinamide
List 6 AEDs thats mechanism of action is glutamate blockers
1) topiramate
2) zonisamide (zonegran)
3) perampanel
4) felbate
5) levetiracetam
6) Brivaracetam (PO, IV only > 16 yrs)
List 6 AEDs thats mechanism of action is calcium channel blockers
1) ethosuxmide
2) gabapentin
3) lamotrigine (lamictal)
4) pregabalin
5) valproic acid
6) zonisamide
List 6 AEDs thats mechanism of action is GABA enhancers
1) benzodiazepines
2) barbiturates
3) valproic acid (depakote)
4) gabapentin
5) pregabalin
6) ethosuximide
How do AEDs that act as Ca channel blockers work?
Ca going in during cells resting state facilitates development of an action potential; however these meds slow the flow of Ca++ into the cell
What do AEDs that act as Ca channel blockers inhibit?
Slow depolarization which is needed for spike-wave bursts
help “lock the channel”
How do AEDs that act as GABA enhancers work?
May enhance Cl- influx which makes cell more negative & harder for cell to generate AP
some ↓ metabolism of GABA so more is available
How do AEDs that act as glutamate blockers work?
Bind glutamate (excitatory neurotransmitter)
Glutamate has 5 binding sites
What do many AEDs require?
Drug monitoring
List 3 patient education tips when using AEDs
1) take as prescribed
2) NEVER stop taking on own
3) side effect management
How does Phenytoin (Dilantin) work?
Na+ channel blocker
Works to stabilize neurons from becoming too excited
Stops spread of seizure activity in motor cortex
Which AED is highly (90%) protein-bound drug?
Phenytoin (Dilantin)
List 3 indications for giving Phenytoin
1) tonic-clonic seizures
2) status epilepticus
3) prophylaxis for surgery
What is the therapeutic range of Phenytoin?
10-20 mcg/ mL
very narrow; monitor drug levels
Routes of admin for Phenytoin
PO, IM, or IV
If Phenytoin is administered IV how should it be given?
Normal saline
Over 30-60 min b/c it can be very irritating to veins
Important precautions with tube feeds when using Phenytoin
Need to STOP feeds for 2 hrs before & after administration
List 7 neuro side effects of Phenytoin
1) drowsiness
2) ataxia
3) irritability
4) visual problems
5) peripheral neuropathy
6) N/V
7) headache
List 2 CV side effects of Phenytoin
1) hypotension
2) arrhythmias
List 3 other side effects of Phenytoin
1) suicidal thoughts
2) skin rash (Steven Johnsons)
3) Gingival hyperplasia
Phenobarbital (solfoton, luminal) is classified as a ____
Barbiturate
How does Phenobarbital work?
Inactivates fast Na channels leading to enhanced GABA effects & decreased glutamate release
Describe the half-life on Phenobarbital
Long half-life
List 6 side effects of phenobarbital
1) sedation
2) diplopia
3) cognitive skill impairment
4) respiratory depression
5) hypotension
6) hyperactivity & inattention in children
Phenobarbital can lead to ____ ____
physical dependence (habit forming)
Carbamazepine (tegretol) works similar to what other AED?
Phenytoin
Carbamazepine is the drug of choice for what types of seizures?
Partial & generalized tonic-clonic seizures
Carbamazepine (tegretol) inhibits
Spread of seizure activity
Where should carbamazepine be kept?
DRY location (not a bathroom)
List 2 off-label uses for carbamazepines
1) trigeminal neuralgia
2) bipolar disorder
Carbamazepine can interact with what & cause reduction in effectiveness
Oral contraceptives
What types of seizures should carbamazepines NOT be used for?
Absence & myoclonic seizures (can make them worse)
What is therapeutic range of carbamazepine?
4-12 mcg/ mL
List 5 neuro side effects of carbamazepines
1) headache
2) diplopia
3) ataxia
4) drowsiness
5) sedation
List 5 other side effects of carbamazepines
1) N/V
2) hyponatremia
3) ↓ blood counts (neutropenia/ thrombocytopenia)
4) rashes (including steven-johnsons)
5) increase suicidal thoughts
What should carbamazepines be taken with?
Food
What labs should be monitored for someone taking Carbamazepines? Hint: 4
1) sodium
2) CBC
3) LFTs
4) BUN/ Cr (esp. in those w/ renal impairment)
What AED has the same efficacy as Carbamazepine but is better tolerated?
Oxycarbazepine (trileptal)
When is Oxycarbazepine used?
As adjunctive therapy or monotherapy for partial seizures in children & adults
Oxycarbazepine can make what two types of seizures worse?
1) absence
2) myoclonic
Oxycarbazepines can reduce effectiveness of ____ ____ & increase risk of _____ thoughts
Oral contraceptives; suicidal thoughts
How does Valproic acid/ Valproate (Depakote) work?
Inactivation of fast Na+ channels; GABA enhancer
List 5 indications for giving Valproic acid/ Valproate
1) absence seizures
2) myoclonic seizures
3) tonic-clonic seizures
4) partial seizures
5) neonatal seizures
Off-label use of Valproic acid/ Valproate
Used to control Sx of acute mania in bipolar disorder
What other AED can Valproic acid be given with?
Phenytoin
Is Valproic acid/ Valproate considered broad or narrow spectrum?
Broad spectrum
List 6 side effects of Valproic acid/ Valproate
1) N/V
2) sedation/ dizziness
3) pancreatitis
4) increased ammonia levels
5) thrombocytopenia
6) suicidal thoughts
Valproic acid/ Valproate can cause ____ toxicity
liver toxicity (hepatotoxicity)
Narrow therapeutic range of Valproic acid/ Valproate
50-100 mcg/ mL
List 3 labs you need to monitor in a patient taking Valproic acid/ Valproate
1) LFTs
2) CBC
3) ammonia levels
Routes of administration for Valproic acid/ Valproate
Oral or IV
What is important to keep in mind when giving Valproic acid/ Valproate IV?
Must be diluted w/ at least 50 mL NSS or D5W
Give over an hr (no more than 20 mg/ min)
What should Valproic acid/ Valproate be given with?
Food
How does Gabapentin (Neurontin) work?
Thought to act on the Ca channels to ↓ glutamate & ↑ GABA in the brain
Indications for giving Gabapentin
1) Partial seizures
2) New onset of epilepsy
What type of seizure can become worse if Gabapentin is used for Tx?
Myoclonic seizures
List 6 off-label uses for Gabapentin
1) Chronic neuropathic pain
2) Anxiety
3) Hot flashes/ night sweats
4) Headaches
5) Hiccups
6) Alcohol withdrawal
What type of dose range does Gabapentin have?
Wide dose range (no monitoring needed)
List 9 side effects of Gabapentin
1) Fatigue
2) mental cloudiness
3) leukopenia
4) edema
5) weight gain
6) emotional lability (mood changes)
7) tremors
8) GI side effects
9) suicidal thoughts
Cautions for using Gabapentin Hint: 2
1) Use reduced dose in renal pts
2) Cautious use in those with an addiction Hx
What do doses of Gabapentin look like when used for pain control?
Doses will be very high
