pharm 3 - seizure rx

Phenytoin Adverse Effects

P-450 Inducer

Hirsutism (excess hair)

Enlarged Gums (gingival hyperplasia)

Nystagmus

Yellow-browning of skin (hepatotoxicity)

Teratogenicity

Osteomalacia

Interference with B12 Metabolism

Neuropathies

"enzyme eraser"

Phenytoin is contraindicated in patients with

HLA-B*1502 (SJS)

Phenytoin follows non-linear pharmacokinetics meaning

Small dose = short half-life

High dose = prolonged half-life

Saturation Kinetics

the higher does = increases at an exponential rate and lasts longer in the body

Na channel blocker

Carbamazepine (Tegretol) ADEs

Diplopia, hyponatremia, hepatotoxicity (LFTs), agranulocytosis/leukopenia (CBC)

Carbamazepine (Tegretol) contraindications & drug interactions

"double trouble"

CI: HLA-B*1502 (SJS), liver disease, hyponatremia

DI: P450 auto-inducer

-increases the metabolism of itself AND lowers levels of other drugs

Na channel blocker

Oxcarbazepine (Trileptal) ADEs & contraindications

"carb's cuzz"

ADEs:

-Hyponatremia, osteoporosis

CI: HLA-B*1502 (SJS) – patients experiencing a rash on CMZ have a 25-30% risk of cross-sensitivity with OXZ

*Na channel blocker*

Eslicarbazepine (Aptiom) ADEs

"carb junior" bc it has all the same ADEs as Carbamezapine

Diplopia, hyponatremia, hepatotoxicity, agranulocytosis/leukopenia

Na channel blocker

Lamotrigine (Lamictal) ADEs and drug interactions

"rash queen"

ADEs:

-Rash, including SJS

DI: birth control DECREASES lamotrigine clearance = increased risk of rashes due to staying in the body longer

Na channel blocker

Zonisamide (Zonegran) ADEs and contraindications

"space cadet"

-cognitive impairment and 'space rocks' (kidney stones)

ADEs:

-Cognitive impairment (somnolence, nervousness), kidney stones (d/t renal calculi)

CI: Sulfa hypersensitivity (sulfa rash)

*Na channel blocker*

Lacosamide (Vimpat) ADEs

"pulling on the heart strings"

Prolong PR interval, nystagmus

*Na channel blocker*

Rufinamide (Banzel) ADEs

"short circuit"

Shortened QT interval

Na channel blocker

Ethosuximide (Zarontin) ADEs

"Absent Ethan"

GI complaints (N/V), CNS effects (drowsiness), SJS

-Major caution in liver disease

Ca channel blocker

Drug of choice for absence seizures

Ethosuximide (Zarontin)

Ca channel blocker

Pregabalin (Lyrica) ADEs

"Puffy Peggy"

Dry mouth, peripheral edema, weight gain, cognitive difficulties

-Caution in pregnancy

Ca channel blocker

Valproic acid (Depakote) ADEs

"heavy hitter"

Weight gain, pancreatitis (BBW), hepatotoxicity (BBW), thrombocytopenia

TERATOGENIC

*enhance GABA*

Phenobarbital ADEs

"sleepy barb"

Cognitive difficulties (sedation), depression, anemia, physical dependence

*enhance GABA*

Gabapentin (Neurontin) ADEs

"Gaba the goldfish"

Peripheral edema, weight gain, cognitive difficulties

enhance GABA

Tiagabine (Gabitril) ADEs

"tongue tied tia"

Cognitive difficulties, depression, aphasia

*enhance GABA*

Vigabatrin (Sabril) ADEs

"tunnel vision vinny"

Visual field constriction (BBW) - eye exams required during therapy, weight gain

enhance GABA

Benzodiazepines ADES

"benz blanket"

One of most sedating AEDs, hypotension, loss of appetite, decrease in thinking speed

-*Must taper off slowly, tolerance may develop

*enhance GABA*

drug names:

clobazam, lorazepam, clonazepam, diazepam, midazolam

When should benzodiazepine reversal NOT be used

if the pt is taking the benzo for seizure indication

drug name:

flumazenil

Levetiracetam (Keppra) ADEs

"levvy rage"

Mood/behavioral changes – irritability, aggression, anxiety

Brivaracetam (Briviact) ADEs

"Bri Bone Marrow Bully"

Neutropenia

Topiramate (Topamax) ADEs

"Dopamax"

Brain fog (concentration difficulty, word retrieval), weight loss, kidney stones

Felbamate (Felbatol) is only recommended for what patients

only for patients whose epilepsy is so severe that a substantial risk of aplastic anemia or liver failure is considered acceptable. Requires informed consent.

"Felony Fel"

Medications that Decrease Hormonal Contraceptives

Carbamazepine

Oxcarbazepine

Phenytoin

Phenobarbital

Eslicarbazepine

Rufinamide

Topiramate

Lamotrigine effectiveness is decreased BY

hormonal contraceptives

Avoid valproic acid in _____________

Pregnancy

-due to possibility of birth defects - 1-2% risk of neural tube defects or lack of spinal cord closure

CYP Inducers

Phenobarbital

Phenytoin

Carbamazepine

Also Check Vitamin D levels

Drugs contraindicated in patients with HLA-B*1502

Carbamazepine, oxcarbazepine, phenytoin

-associated with risk of developing SJS and TEN

Higher frequency of this allele in Asian populations

What is the medication of choice for a patient who is seizing NOW

Benzodiazepines!

-Diazepam IV

-lorazepam IV

-midazolam IM

-Diazepam also comes in a rectal suppository formulation

Alternative Options: Phenobarbital IV, levetiracetam IV, fosphenytoin IV, valproate IV