Chapter 71: Seizures/Epilepsy Flashcards
What is the most common test used to diagnose epilepsy
EEG
Key drugs that can lower the seizure threshold
Bupropion Clozapine Theophylline Varenicline Carbapenems (esp. imipenem) Lithium Meperidine Penicillin Quinolones Tramadol
Where does a focal seizure start
One side of the brain, but can spread to the other side
Where does a generalized seizure start
Both sides of the brain
If a focal seizure results in no loss of consciousness, it is called
focal aware seizure
previously known as simple partial seizure
If a focal seizure results in loss of consciousness, it is called
focal seizure with impaired awareness
previously complex partial seizure
What are tonic symptoms
rigid or tense muscles
Generalized seizures with non-motor symptoms are called
absence seizures
“staring spells”
What is status epilepticus
A seizure that lasts beyond 5 minutes. It is a medical emergency
after 30 min, long-term damage occurs
What are the 3 phases of status epilepticus called and what are the time intervals for them
0-5 minutes = stabilization phase
5-20 minutes = initial treatment phase
20-40 minutes = second treatment phase
What should be done during the stabilization phase of SE
Time the seizure
Start EEG, oxygen may be needed
Check AED levels, electrolytes, if BG low - treat with D25-D50
What should be done during the initial treatment phase of SE
If seizure continues:
Give IV lorazepam (Ativan)
Alternatives if IV unavailable: IM midazolam (Versed) or rectal diazepam (Diastat)
What should be done during the second treatment phase (20-40 min) of SE
If seizure continues:
Give regular AED: IV fosphenytoin, valproic acid, levetiracetam (phenobarbital if others are unavailable)
Diastat AcuDial packages contain two rectal syringes prefilled with diazepam rectal gel. What doses does it come in
2.5, 10 and 20 mg
How do you use Diastat AcuDial
- Syringes must be dialed to the right dose and locked BEFORE DISPENSING
- Once locked, the green band should say “READY,” and the syringe cannot be unlocked
CBD brand name for seiures
Epidiolex
What kind of diet can be used in patients with refractory seizures
Ketogenic
What is the ratio of fats : protein and carbs combined in a ketogenic diet
4:1
What medication is used for absence seizures
ethosuximide
What is the MOA of benzodiazepines as AED
Increases GABA
What is the MOA of Valproic acid as AED
Increases GABA
What is the MOA of ethosuximide as AED
T-type Ca channel blocker - slows down or stops transmission or the electrical signal
What is the MOA of carbamazepine as AED
Na channel blocker - decr. neurons firing rate
What is the MOA of phenytoin/fosphenytoin as AED
Na channel blocker - decr. neurons firing rate
Which neurotransmitters are responsible for causing a seizure
Deficiency in GABA (inhibitory NT) Excess glutamate (excitatory)
Side effects of carbamazepine, oxcarbazepine, and eslicarbazepine
hyponatremia, rash, enzyme inducers
Side effects of gabapentin and pregabalin
Weight gain, peripheral edema, mild euphoria
Side effects of phenobarbital and primidone (prodrug of phenobarbital)
Sedation, dependence/tolerance/OD risk, enzyme inducers
Side effects of topiramate and zonisamide
Weight loss, metabolic acidosis
Nephrolithiasis and oligohydrosis/hyperthermia (in children)
All AEDs should be supplemented with
calcium and vitamin D
Women of childbearing age should supplement with ___ while on AEDs
folate
If taking valproic acid, what should you supplement with
possibly carnitine
If taking lamotrigine and valproic acid, what should you supplement with if alopecia develops
Supplement with selenium and zinc
Lamotrigine brand name
Lamictal
Lamotrigine dose for weeks 1 and 2
25 mg daily
Lamotrigine boxed warning
Serious skin reactions including SJS/TEN
Lamotrigine side effect
Alopecia (supplement selenium and zinc)
Lamictal starter kits are used to ensure correct dosing. Which color is the standard starting dose? When should you use it?
Orange
Use if no interacting medications
Lamictal starter kits are used to ensure correct dosing. Which color is a lower starting dose compared to the others? When should you use it?
Blue
Use if taking valproic acid (enzyme inhibitor)
Lamictal starter kits are used to ensure correct dosing. Which color is a higher starting dose compared to the others? When should you use it?
Green
Use if taking an enzyme inducer (e.g., carbamazepine, phenytoin, phenobarbital, primidone), and not taking valpoic acid
Lamotrigine drug interactions
Valproic acid increased lamotrigine concentrations more than two-fold. Use lower starting dose (blue box)
Inducers like carbamazepine, phenytoin, phenobarbital, & primidone decrease lamotrigine concentrations by 40%. Use the higher starting dose (green box)
Levetiracetam brand name
Keppra, Keppra XR
Keppra IV:PO ratio
1:1
Keppra warnings
psych reactions, including psychotic symptoms, somnolence, fatigue
T/F: Keppra does not have any significant drug interactions
True
Topiramate brand name
Topamax
Another use for topiramate
Migraine ppx
Topiramate warnings
Metabolic acidosis, oligohydrosis (reduced perspiration), nephrolithiasis (kidney stones), angle-closure glaucoma, hyperammonemia, fetal harm, visual problems
Topiramate side effects
Somnolence, difficulty with memory/concentration/attention, weight loss, anorexia
Topiramate monitoring
electrolytes (especially bicarbonate), intraocular pressure
Topiramate drug interaction
Can decrease OC effectiveness. Non-hormonal contraception is recommended
Depakene generic name
Valproic acid
Depakote, Depakote ER, Depakote Sprinkle generic name
Divalproex
Another use of divalproex
Bipolar and migraine ppx
Valproic acid therapeutic range
50-100 mcg/mL (total level)
alb < 3.5 must adjust with formula (phenytoin formula)
Valproic acid boxed warning
hepatic failure, fetal harm (neural tube defects and low IQ scores)
Valproic acid warnings
Hyperammonemia (treat with carnitine in symptomatic adults only), thrombocytopenia (increased bleeding risk)
Valproic acid side effects
Alopecia (supplement selenium and zinc), weight gain
Valproic acid monitoring
LFTs (baseline and frequently in the first 6 months), platelets
What is the drug interaction between valproic acid and lamotrigine
risk of serious rash
lower lamotrigine dose and titrate slowly
Tegretol generic name
Carbamazepine
Carbamazepine therapeutic range
4-12 mcg/mL
Carbamazepine boxed warnings
Serious skin reactions: patients of Asian descent should be tested for HLA-B*1502 allele prior to initiation
Aplastic anemia and agranulocytosis
Tegretol should be tested for ____ allele
HLA-B*1502
Carbamazepine contraindications
Myelosuppression
Carbamazepine warnings
hyponatremia (SIADH), fetal harm
Carbamazepine monitoring
CBC with diff and platelets, electrolytes (especially Na)
Carbamazepine drug interactions
Enzyme inducer, autoinducer - decreases levels of other drugs and itself
Which drugs can decrease levels of OCs and non-hormonal contraceptive is recommended
Topiramate, carbamazepine, oxcarbazepine, phenobarbital, primidone, phenytoin
PS PORCS + topiramate + primidone
Vimpat generic name
Lacosamide
What class of drug is Lacosamide
C-V
Lacosamide warnings
Prolongs PR interval and increases risk of arrhythmias
lacosamide DDIs
caution with 2C19, 2C9, and 3A4 inhibitors (can increase lacosamide levels)
Trileptal generic name
Oxcarbazepine
Oxcarbazepine warnings
Increased risk of serious skin reactions: consider screening patients of Asian descent for HLA-B*1502 prior to initiating therapy
Hyponatremia
Oxcarbazepine monitoring
Serum Na levels
Phenobarbital therapeutic range for adults
20-40 mcg/mL
Phenobarbital warnings
Habit forming, respiratory depression, fetal harm
Phenobarbital side effects
Physiological dependence, tolerance, hangover effect
Phenobarbital (and primidone) is a strong ____ of most enzymes
inducer
Dilantin generic name
Phenytoin
Cerebyx generic name
Fosphenytoin
Phenytoin IV:PO ratio
1:1
Phenytoin therapeutic range (total level and free level)
total level: 10-20 mcg/mL
free level: 1-2.5
Ten Y Two in = in range of 10 - 20
Phenytoin IV administration rate should not exceed ___ mg/min & fosphenytoin IV should not exceed ___ mg PE/min. If given faster than these rates ____ and ____ can occur
Phenytoin - 50 mg/min
fosphenytoin - 150 mg PE /min
if faster risk of hypotension and cardiac arrhythmias
Phenytoin can cause extravasation, which leads to ____
Purple glove syndrome, characterized by edema, pain and bluish discoloration of the skin which can sometimes lead to tissue necrosis
Phenytoin should be avoided in patients with a positive ____
HLA-B*1502
Can also cause fetal harm
Phenytoin dose-related (toxicity) side effects
Nystagmus, ataxia, diplopia/blurred vision
Phenytoin chronic side effects
Gingival hyperplasia, hair growth, hepatotoxicity
pheny to INCH - grows gingival hyperplasia, hair
Phenytoin monitoring
Serum phenytoin concentration, LFTs
IV: continuous cardiac and respiratory monitoring
Phenytoin and fosphenytoin are strong ____ of several enzymes
inducers
Phenytoin and fosphenytoin both have high ____
protein binding & can displace other highly protein-bound drugs or be displaced by other highly protein-bound drugs, causing an increase in levels that can lead to toxicity
Between Phenytoin and fosphenytoin, which has lower risk of purple glove syndrome
fosphenytoin
Between Phenytoin and fosphenytoin, which one requires a filter
Phenytoin
remember GAL PLAT
Phenytoin must be diluted in ___, is stable for ___ hours, and should not be ____
NS (DIAPACE)
4 hours
refrigerated (Dear Pharmacist, Being Frigid Makes Me Edgy)
Tube feeds (increase/decrease) phenytoin absorption
decrease
Hold feedings 1-2 hours before and after administration
Zarontin generic name
ethosuximide
Ethosuximide warnings
Serious skin rash (SJS/TEN), blood dyscrasias
Felbamate boxed warnings
Hepatic failure, aplastic anemia
Fenfluramine boxed warning & warnings
boxed warning: valvulr heart disease, pHTN
warning: decr. appetite, weight loss
Gabapentin brand name
Neurontin
Pregabalin brand name
Lyrica
Pregabalin drug schedule
C-V
What is the prodrug of phenobarbital
Primidone
Vigabatrin boxed warning
Causes permanent vision loss (≥ 30% patients)
Zonisamide contraindication
Hypersensitivity to sulfonamides
Zonisamide side effects
Similar to topiramate, including oligohidrosis/hypertheramia and risk of nephrolithiasis
All AEDs cause:
CNS depression (e.g, dizziness, confusion, sedation, and ataxia/coordination difficulties)
Which AEDs are enzyme inducers
Carbamazepine Oxcarbazepine Phenytoin Fosphenytoin Phenobarbital Primidone
PS PORCS
Which AED(s) are enzyme inhibitors
Valproic acid (increases lamotrigine levels)
Which AED has the highest teratogenic risk
Valproic acid
The levels of all AEDs (increase/decrease) during pregnancy and may require a dose (increase/decrease)
Decrease
Increase
Which two AEDs can cause reduced or lack of sweating in young children
Topiramate and zonisamide
Which AEDs come in formulations that are easy to swallow for children
Lamotrigine (ODT, chewable tablets)
Levetiracetam (ODT, oral solution)
A child who remains seizure free for ____ can often be tapered off AEDs
1-2 years
Formula to adjust phenytoin dose
phenytoin correction = total phenytoin measured/ [(0.2 x albumin) + 0.1]
