RxPrep: Ch. 53 - Epilepsy
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RxPrep: Ch. 53 - Epilepsy
RxPrep NAPLEX pharmacy pharmacist epilepsy
Chapter 53 in RxPrep
Which AEDs decrease effectiveness of oral contraceptives?
Topiramate (Notes)? or Felbamate (RXP)?
Which AEDs are pregnancy category D?
an like watching
Which AEDs are pregnancy category C?
(prob safer than others)
What AEDs give modest weight loss?
In general, what is the most common side effect of AEDs?
CNS side effects, like dizziness, ataxia, somnolence, blurry vision, diplopia
ezogabine, gabapentin, phenytoin, pregabalin, topiramate, valproate, zonisamide
clonazepam, levetiracetam, zonisamide
Atypical absence, myoclonic, atonic
clonazepam, felbamate, topiramate, zonisamide
carbamazepine, oxcarbazepine, phenytoin, topiramate, zonisamide
What can you mix phenytoin IV in? Max rate of infusion? What happens when you exceed this rate?
Severe bradycardia, hypotension
Phenytoin (and Fosphenytoin)
Dilantin (and Cerebyx - pro-drug, IV/IM)
100 mg TID, up to 600 mg TID
: 10-20 mcg/mL
What kind of kinetics does phenytoin have?
Michaelis-Menten kinetics (small increase in dose, big increase in serum level)
What happens if the albumin is low? How do you correct phenytoin levels?
If alb is <3.5, true phenytoin level may be higher than it appears
PHTcorr = PHT meas/[(0.2xalb) + 0.1]
How do tube feedings interact with phenytoin?
Decrease PHT absorption; must separate - hold tube feedings 2 hrs before or 2 hrs after
What is the IV-to-PO ratio of phenytoin? Also compare ER caps to susp/chewable.
ER caps have 8% less drug
What can you mix Cerebyx in? What is the max rate of infusion? What is the ratio between Cerebyx (PE)-to-Phenytoin?
NS or D5W
150 mg/min - can push drug in faster
1 mg PE = 1 mg PHT
Is PHT an inducer or inhibitor?
otent inducer, purple glove
nlarged gums (brush and floss!), SLE
ukky blood dyscrasias, yukky purple skin color/damage if drug extravasates
nterference w/folic acid absorption (anemia)
What are the major side effects of PHT?
Sedation, cognitive impairment
Blurred vision, diplopia
Lethargy, drowsiness, HA
Ataxia, slurred speech
Nystagmus (wobbly eyes)
*These sxts are
*SLuG HOPpin', defnitely
Skin thickening of face
VitD, Ca2+ deficiency
What are some serious AEs of PHT?
What should you supplement with PHT?
Folic acid, vitD, Ca2+
Tegretol, Tegretol XR, Carbatrol, Epitol
: 100-200 mg BID, or daily if XR; Maintenance: 400-1600 mg/d
: 4-12 mcg/mL
What are the major side effects of carbamazepine (Tegretol)?
Nausea, dizziness, drowsiness
: hepatotoxicity, SIADH/low Na+
What are Tegretol's BBW?
SJS and TEN, esp. if Asian
If Asian, need HLA-B*1502 test done
: aplastic anemia, agranulocytosis
What is another indication of Tegretol? Is it an inducer or inhibitor?
Inducer and autoinducer
300-600 mg BID
If CrCl<30, start at 300 mg daily
What are Trileptal's major side effects?
Similar to Tegretol's:
GI upset, sedation, ataxia, diplopia
SJS and TEN
: 20-30% cross rxtivity with Tegretol
Valproate, valproic acid
: soln, liq-filled caps
: ext-rel, sprinkle-filled caps
: 125-250 mg BID; Maintenance: 15-45 mg/kg/d
: 50-100 mcg/mL
Is valproic acid an inducer or inhibitor?
Can you substitute Depakote ER for Depakote DR tabs?
No; must increase ER by 8-20%
What are the major side effects of valproate?
(tx w/selenium, Zn)
GI upset, sedation, tremor
What are the 3 BBWs of valproate?
Lamictal, Lamictal ODT, Lamictal CD (chewable), Lamictal XR
: 50 mg/d
: 100 mg/d
: 200 mg/d
: may increase 100 mg/d every 1-2 wks, max: 400 mg/d
Divide BID, daily if XR
What are the side effects of Lamictal?
N/V, HA, sedation, ataxia, diplopia
What is Lamictal's BBW?
SJS, TEN - that's why we have titration schedule
: increased risk of aseptic meningitis
: 25 mg BID
: 50 mg BID
: 75 mg BID
: 100 mg BID
: 150 mg BID
: 200 mg BID
Sprinkle caps 15 and 25 mg
What are the major side effects of topiramate?
emory problems, concentration diff., paresthesias
ephrolithiasis (keep hydrated!)
ligohydrosis, hyperthermia (limit sun expo., drink H2O!)
*I like my
What is the intxt b/t valproate and Topamax?
What schedule is clonazepam (Klonopin) in?
What are the side effects of Klonopin?
Sedation, dizziness, ataxia, depression, mood changes, psychological dependence, tolerance
Do not d/c abruptly! --> seizures
Keppra, Keppra XR
500-1500 mg BID
What are the side effects if Keppra?
Nothing major - sedation, dizziness
If you have a sulfa allergy, which AED must you avoid?
What are the major side effects of Zonegran?
SJS and TEN
Oligohydrosis/hyperthermia (in kids) (limit sun! Drink H2O!)
Nephrolithiasis (drink H2O!)
What schedule is phenobarb in?
What is Primidone (Mysoline)?
Pro-drug of phenobarbital (Luminal, Barbital)
Is phenobarb an inducer or inhibitor?
What is the t1/2 of phenobarb?
What are the major side effects of phenobarb?
Somnolence (major!), cognitive impairment, dependence, tolerance, SJS and TEN
What is the schedule of lacosamide (Vimpat) and pregabalin (Lyrica)?
What is another indication of Lyrica?
75 mg BID, up to 300 mg/d
Decrease dose if CrCl<60
What are the side effects of Lyrica?
Slight euphoria (why it's CV)
Peripheral edema/wt gain, dizziness, somnolence, blurred vision
Vigabatrin (Sabril) is only available through what program?
SHARE (Support, Help, and Resources for Epilepsy)
What is the major side effect of vigabatrin (Sabril)?
Vision loss (thus, vision testing at BL and every 3 mon)
What is the AED used for Lennox-Gastaut seizures?
What is status epilepticus?
Seizure lasting more than 5 minutes or 2+ seizures with incomplete recovery of consciousness between
What are favorable factors for withdrawal of AEDs?
Seizure-free for 2-4 yrs
Complete seizure control within 1 yr of onset
An onset of seizures after age of 2 and before age 35
Why should you be cautious with the combo valproate-lamotrigine?
May cause rash (valproate is inhibitor --> increase levels of Lamictal --> rash)
Can you take Tegretol with grapefruit?
Which AEDs are inducers?
Which AED is an inhibitor?
Which AED does not have any significant drug intxts?
What program should women enroll to if they become pregnant while taking a teratogenic AED?
NAAED - North American Antiepileptic Drug Pregnancy Registry
Which AEDs have the FDA BBW for hepatotoxicity?
Which AEDs require caution in hepatic dysfunction?
Which AEDs require caution in renal failure?
Which AEDs are associated with significant cognitive impairment?
Which AED has the FDA BBW of pancreatitis?
Which AEDs have the FDA BBW of aplastic anemia?
Which AEDs are known for causing SJS?
*PLZ Visit a COP named Steven*
What AEDs causes oligohydrosis (inability to sweat) in kids and nephrolithiasis?
Which AED causes wt gain?
Which AEDs cause weight loss?
What AED increases the risk of aseptic meningitis?
What is one risk that all anticonvulsants have that we must counsel?
Can we abruptly d/c AEDs?
No - must taper
Can we take AEDs with CNS depressants?
No - avoid if possible
What are 2 OTCs we must avoid with AEDs?
St. John's Wort
Evening primrose oil
What drugs can decrease the seizure threshold?
Meperidine (w/poor renal function)
Beta lactams (w/poor renal function)
Which AEDs are FDA approved for migraine prophylaxis?