Seizures Flashcards
(23 cards)
What are 3 drug classes that can cause seizures?
Analgesics
- opioids (esp tramadol, meperidine)
Anti-infectives
- quinolones
- carbapenems
- cephalosporins
- penicillins
- mefloquine
Psychiatric medications
- bupropion
- antipsychotics (esp. clozapine)
- lithium
- tricyclic antidepressants
What are the 3 main types of seizure classifications?
Seizures are classified based on where the seizure starts in the brain
- focal seizures - start on one side of the brain but can spread to the other side
- focal aware seizure: the pt experiences no loss of consciousness
- focal seizure w/ impaired awareness: pt experiences loss of consciousness - generalized seizures - start on both sides of the brain
- these pts always experience a loss of consciousness - unknown onset - unwitnessed seizure or occurs during the night and the initial symptom presentation is not known
What is the definition of status epilepticus? What is the treatment algorithm for SE?
status epilepticus - a seizure that lasts 5 minutes or more
- after 30 minutes, long-term damage can occur
- this is a medical emergency. Emergency treatment should start with any seizure lasting longer than 5 minutes
Treatment:
1. Stabilization phase (0-5 minutes)
- stabilize circulation, airway, and breathing
- time the seizure, start ECG
- check antiseizure med levels and ECG
- if BG is low, treat with glucose
- Initial treatment phase (5-20 minutes)
- if seizures continue: give IV lorazepam, IM midazolam, or IV diazepam
- alternatives: rectal diazepam, intranasal or buccal midazolam - Second treatment phase (20-40 minutes)
- if seizures continue: give nonbenzodiazepine antiseizure meds; IV fospheytoin, valproic acid or levetiracetam
- alternative: IV phenobarbital - Thirst treatment phase (refractory)
- no clear evidence to guide therapy
- repeat second-line therapy or midazolam, pentobarbital, or propofol
How must Diastat Acudial (rectal diazepam) be dispensed? How is the dose locked?
Dispensing:
- each package must contain two rectal syringes prefilled with diazepam rectal gel
- each syringe must be dialed to the right dose and locked before dispensing
Locking in the dose:
1. hold barrel of the syringe w/ cap facing down and the dose window visible
2. use the other hand to grab the cap firmly and turn to adjust dose
3. confirm correct dose. Hold the locking ring at the bottom of the syringe barrel and push upward on both sides of the ring. Once locked, the green band should say “ready” and the syringe cannot be unlocked
4. Repeat these steps and double check the doses are locked when counseling the patient
What are 4 adjuvant treatments that may help with chronic seizure management?
- medical marijuana (Epidiolex, or CBD)
- ketogenic diet (high fats, normal protein, and low carbs)
- vagal nerve stimulation
- surgical intervention
What is the difference between broad spectrum and narrow-spectrum antiseizure meds (ASMs)? What supplements should pts take while on ASMs?
Broad spectrum ASMs treat both focal and generalized seizures. Narrow spectrum ASMs primarily treat focal seizures. A few ASMs are used for isolated conditions (ex. ethosuximide for absence seizures)
Supplements:
- All ASMs: calcium and vit D (inc. bone loss and fracture risk)
- women of childbearing age: folate
- valproic acid: possible carnitine
- lamotrigine and valproic acid: if alopecia develops, supplement biotin, selenium, and zinc
What is the MOA of benzodiazepines/phenobarbital, valproate, levetriacetam, carbamazepine/phenytoin/fosphenytoin/topiramte, lamotrigene, and ethosuximide?
BZDs & phenobarbital: enhance GABA effect
valproate: blocks sodium channels AND increases GABA
levetiracetam: inhibits vesicle fusion by binding SV2A proteins
carbamazepine, phenytoin/fosphenytoin & topiramate: blocks sodium channels
lamotrigine: blocks sodium channels AND decreases glutamate
ethosuximide: blocks T-type Ca channels
What are the broad ASMs? (4)
What are the narrow ASMs? (5)
broad: lamotrigine, levetiracetam, topiramate, valproate
narrow: lacosamide, carbamazepine, oxcarbazepine, phenytoin/fosphenytoin, phenobarbital
Lamotrigine - initial dosing? 1 boxed warning, 1 warning, 1 side effect, 1 d/c dosing note?
Initial dosing: weeks 1 and 2 -> 25mg (titration)
Boxed warning: serious skin reactions (including SJS)
Warning: multiorgan hypersensitivity reaction (DRESS)
Side effects: alopecia (supplement biotin, selenium, and zinc)
Note
- if discontinued for over 5 half lives (≥ 6 days), restart initial dosing titration
What are the different lamictal starter kits? When would you use each one?
Blue: lower starting dose
- use if taking valproic acid (enzyme inhibitor, increases concentrations of lamotrigine at least 2x)
Orange: standard starting dose
- use if no interacting meds
Green: higher starting dose
- use if taking an enzyme inducer (ex. carbamazepine, phenytoin, phenobarbital, primidone) AND not taking valproic acid
Levetiracetam: What is the IV: PO ratio? What is 1 warning? Does this have any significant drug interactions? At what CrCl should the dose be decreased?
IV: PO ratio is 1:1
Warning: psychiatric reactions (psychotic symptoms, somnolence, fatigue)
No significant drug interactions!!
Decrease dose if CrCl ≤ 80 mL/min
Topiramate: what are 7 warnings, 4 side effects, and 2 monitoring parameters? 1 drug interaction?
Warnings
- metabolic acidosis
- oligohidrosis (reduced perspiration)
- nephrolithiasis
- angle-closure glaucoma
- hyperammonemia
- visual problems
- fetal harm
Side effects
- somnolence
- difficulty with memory, concentration, and attention
- weight loss
- anorexia
Monitoring
- electrolytes (esp. bicarb)
- intraocular pressure
Drug interaction:
- can decrease effectiveness of oral contraceptives, non-hormonal contraception is recommended
valproate: goal therapeutic range? 3 boxed warnings? 2 warnings? 5 side effects? 2 monitoring parameters?
Goal therapeutic range: 50-100mcg/mL (total)
Boxed warnings:
- hepatic failure
- fetal harm (neural tube defects and dec. IQ)
- pancreatitis
Warnings:
- hyperammonemia (treat with carnitine in symptomatic adults)
- dose-related thrombocytopenia
Side effects:
- alopecia (supplement biotin, selenium, zinc)
- N/V
- weight changes
- somnolence
- tremor
Monitoring:
- LFTs
- CBC
lacosamide: what schedule? 2 warnings? max dose if CrCl <30mL/min?
Schedule: C-V
Warnings
- prolongs PR interval (inc. risk of arrhythmias)
- DRESS
CrCl <30mL/min - max dose 300mg/day (in normal renal fx usually 400mg/day)
carbamezapine: goal therapeutic range? 2 boxed warnings? 1 contraindication? 2 warnings? Drug interactions?
Therapeutic range: 4-12mcg/mL
Boxed warnings
- serious skin reactions, including SJS: HLA-B*1502 allele testing is requirest in Asian descent
- alpastic anemia and agranulocytosis
Contraindication: myelosuppression
Warnings: hyponatremia (SIADH), fetal harm
Carbamezapine is an auto inducer. Strong inducer of CYP3A4, and many others.
oxcarbazepine: brand name? 2 warnings? Drug interactions
oxcarbazepine (Trileptal)
Warning:
- SJS/TEN, consider screening for HLA-B*1502 in pts of Asian descent
- hyponatremia
Drugs interactions:
- weak CYP3A4 inducer, but not autoinducer
- would recommend non-hormonal contraception
phenytoin/fosphenytoin: brand names? phenytoin therapeutic range (total and free)? IV:PO ratio? 2 boxed warnings? 3 warnings? toxicity side effects? 2 chronic side effects? What to monitor?
Phenytoin (Dilantin, Dilantin Infatabs)
- therapeutic range: 10-20mcg/mL (total), 1-2mcg/mL (free)
- 1:1 IV:PO ratio
Fosphenytoin (Cerebyx)
Boxed warnings
- Phenytoin IV: administration rate not to exceed 50mg/min (due to cardiac arrhythmias)
- fosphenytoin IV: administration rate no to exceed 150mg PE/min or 2mg/PE/kg/min (due to cardiac arrhythmias)
Warnings
- extravasation (leading to purple glove syndrome)
- avoid if HLA-B*1502 tests and if previous severe skin rash to carbamazepine
- fetal harm
Toxicity side effects: nystagmus, ataxia, diplopia (double vision)
Chronic side effects: gingival hyperplasia, hepatotoxicity
Monitoring:
- serum phenytoin concentration, LFTs
- IV: cardiac and respiratory function
What are important notes for the administration of IV phenytoin (4), NG phenytoin (2), and IV fosphenytoin (3)
IV phenytoin:
- do not exceed 50mg/min
- monitor BP, respiratory function, and ECG
- requires a filter
- dilute in NS, stable for 4 hours, do not refrigerate
NG phenytoin:
- enteral feedings decrease phenytoin absorption
- hold feeding 1-2 hours before and after administration
IV fosphenytoin:
- do not exceed 150mg PE/min
- monitor BP, respiratory function, and ECG
- lower risk of purple glove syndrome than phenytoin
What is important to keep in mind when adjusting phenytoin doses? What is the phenytoin correction equation?
- metabolism of phenytoin is saturable (Michaelis-Menten kinetics)
- if enzymes become saturated, a small increase in dose can cause a large increase in drug level
- use phenytoin correction if albumin is low (< 3.5mg/dL) and CrCl > 10mL/min
- free levels do not require correction
Phenytoin correction = total phenytoin measured / [(0.2 x albumin) + 0.1]
Phenobarbital: what schedule? Therapeutic range? 2 warnings? 3 side effects?
Schedule: C-IV
Therapeutic range: 20-40mcg/mL in adults
Warnings
- respiratory depression
- fetal harm
Side effects
- physiological dependence
- tolerance
- residual sedation
What is the brand name of ethosuximide? What type of seizure is it used for? What are 2 warnings?
Ethosuximide (Zarontin)
Used for absence seizures
Warnings
- SJS/TEN
- blood dyscrasias
Which ASMs are enzyme inducers (6)? Which is an enzyme inhibitor (1)?
Inducer
- carbamazepine
- oxcarbazepine
- phenytoin
- fosphenytoin
- phenobarbital
- primidone
Inhibitor
- valproic acid
