Antiepileptic drugs (flashcards)
what is status epilepticus?
Multiple seizures occur that last 5 minutes or longer of continuous or electrographic seizure activity or recurrent seizure activity without recovery between seizures
Result: hypotension, hypoxia, brain damage, and possibly death
what drug is used for status epilepticus?
diazepam
Serum concentrations of what drugs correlate better with seizure control and toxicity? PPPC
phenytoin, phenobarbital, carbamazepine, and primidone correlate better with seizure control and toxicity
whats the pharmacological effects of the drugs?
Pharmacological effects:
Reduce nerve’s ability to be stimulated
Suppress transmission of impulses from one nerve to the next
Decrease speed of nerve impulse conduction within a neuron
Antiepileptic drug indications?
Prevention or control of seizure activity
Long-term maintenance therapy for chronic, recurring seizures
Acute treatment of convulsions and status epilepticus
what should you do if adverse effects occur in antiepileptic drugs?
Adverse effects often necessitate a change in medication.
Antiepileptic Drugs: Contraindications
Drug allergy
Pregnancy
Sometime, prescribers weigh the fetal versus mother risk of maternal epilepsy and look to newer generation of drugs
Dilantin has shown congenital spinal malformations such as spina bifida
what interacts with carbamazepine?
acetominophen
what interacts with phenytoin?
increased free warfarin levels (bleeding )
what interacts with valporic acid?
aspirin
Many drugs have narrow therapeutic index so require lab drug monitoring such as? PPVC
phenytoin, valproic acid, phenobarbital, carbamazepine
phenobarbital and primidone therapeutic effect levels?
serum drug levels of 15 to 40 mcg/mL
adverse ffects of primidone and phenobarbital?
cardiovascular, central nervous system (CNS), gastrointestinal (GI), and dermatological reactions
whats the therapeutic drug levels of phenytoin?
Therapeutic drug levels are usually 10 to 20 mcg/mL.
whats the long term therapy adverse effects of phenytoin?
Long-term therapy adverse effects: lethargy, ataxia, mental confusion, gingival hyperplasia, acne, hirsutism, Dilantin facies, and osteoporosis (long term)
how to administer phenytoin?
- Use NS, filter must be used.
carbamazepine what is it?
Second most commonly prescribed antiepileptic drug in Canada after phenytoin
Autoinduction of hepatic enzymes
ethosuximide what is it, adverse effects, contraindications and interactions?
Used in the treatment of uncomplicated absence seizures
Not effective for secondary generalized tonic-clonic seizures
Contraindication: known allergy
Adverse effects: GI and CNS effects
Drug interactions: hepatic enzyme–inducing drugs
Gabapentin what is it, contraindications, adverse effects?
Believed to work by increasing the synthesis and synaptic accumulation of GABA between neurons
Contraindication: known drug allergy
Adverse effects: CNS and GI symptoms
Oral use only
lamotrigine what is it, contraindications, adverse effects?
Also used for the treatment of bipolar disorder
Contraindications: drug allergy
Common adverse effects: relatively minor CNS and GI symptoms and possible Stevens-Johnson syndrome
Oral use only
Valporic acid what is it, contraindications, adverse effects?
Also used for absence and myoclonic seizures
Contraindications: drug allergy, liver impairment
Common adverse effects: weight gain, hair loss
Interacts with aspirin to create toxic levels of valproic acid
levetiracetam what is it, contraindications, adverse effects?
Adjunct therapy for focal seizures with and without secondary generalization
Contraindication: known drug allergy
Mechanism of action: unknown
Adverse effects: generally well tolerated, CNS effects
No drug interactions
Oral and injectable forms
pregabalin what is it, contraindications, adverse effects?
Structurally related to GABA
Indication: focal seizures
Most common uses: adjunct therapy for neuropathic pain, postherpetic neuralgia
Contraindication: known drug allergy
Adverse drug reactions: primarily CNS related
Oral use only
no grapefruit juice with what drug?
Carbamazepine
