Neurologic Drugs Flashcards
Name two changes in neurotransmitter levels that favor a reduction in seizure threshold
Excess glutamate (excitatory), deficiency of GABA (inhibitory)
List risk factors for seizure (eight possible)
Trauma, surgery, electrolyte disturbances (hyponatremia), drug toxicity/withdrawal, stroke, infection, fever, genetics, idiopathic
Which electrolyte disturbance causes the greatest risk for seizures?
Hyponatremia
Describe goals of epilepsy treatment
Reduce seizure frequency, avoid medicine related adverse effects
List two drug agents that have a wide spectrum effects against several types of seizure
VPA (valproic acid) and Lamotrigine
How many antiepileptics do most patients take to control symptoms?
Most achieve control with monotherapy (one drug)
When are drug levels in the blood checked?
Checked as trough right before dose
Name an antiepileptic agent reserved for refractory generalized seizures due to highly sedating effects
Phenobarbital
How are eclampsia seizures treated?
Magnesium sulfate
Describe the use of BDZ’s and antiepileptics in seizure control
Benzos terminate seizures, antiepileptics are maintenance drugs
List three drugs given to status epilepticus patients
Lorazepam (short half-life) diazepam (long half-life) fosphenytoin
How does Phenytoin (Dilantin) work to treat seizures?
Promotes sodium efflux from neurons to stabilize cell and reduce hyperexcitability
Name dose related adverse affects of phenytoin
Nystagmus (sign of toxicity) Headache, nausea, rash, confusion
Name non-dose related adverse effects of phenytoin
Gingival hyperplasia, acne, coarsening of facial features
Which two drugs studied so far cause gingival hyperplasia?
Phenytoin and nifedipine
Name two interactions of phenytoin
Vitamin D (increases metabolism to cause osteomalacia), folate wasting
Why is Fosphenytoin preferred to IV phenytoin?
IV phenytoin is unstable, must be combined with propylene glycol, and risks hypotension
How often must fosphenytoin be taken and what is the therapeutic level?
TID or QID
10–20 mcg/mL
When would a free phenytoin level test be ordered?
When hypoalbuminemia is suspected (drug is highly ppb)
What pregnancy category is phenytoin and why?
Category D: Folate wasting causes neural tube defects
Define seizure
Excessive neuronal activity in cerebral cortex with disrupted or lost consciousness, possible confusion and hallucinations
How does valproic acid work to treat seizure?
Increases bioavailability of GABA, enhances activity of GABA, or mimics action of GABA at receptor sites
List three other indications of valproic acid
Migraines, bipolar disorder, agitation
What is the benefit of using valproic acid (rather than the usual benzo or narcotic) to treat agitation?
Valproic acid won’t cause respiratory depression
List adverse affects of valproic acid (six possible)
Hepatotoxicity, pancreatitis, thrombocytopenia, drowsiness, alopecia, weight gain
List some dosage forms of valproic acid
Sprinkle caps, tablets, capsules, delayed release, extended release, syrup, injection
What is the therapeutic level for valproic acid?
50-100 mcg/ml
What pregnancy category is valproic acid?
Category D
What type of drug is carbamazepine (Tegretol) related to?
TCA
How is the overdose of Tegretol and TCA treated?
Bicarb
How does carbamazepine work to treat seizures?
Reduces post synaptic transmission and response
Three other indications for carbamazepine?
Trigeminal neuralgia, bipolar, migraine prophylaxis
What is the therapeutic level of carbamazepine?
4 – 12 mcg/mL
List adverse affects of carbamazepine
Stevens Johnson syndrome, SIADH, hepatotoxicity
What is an autoinducer?
Revs up own metabolism over time causing increased dose requirements after several weeks
What is the analog of carbamazepine with fewer hepatic adverse effects called?
Oxycarbazepine (Trileptal)
What is the pregnancy category of carbamazepine and why?
Category D – causes folate wasting and spina bifida
What is gabapentin used for?
Neuropathy (in HIV, diabetics, spinal cord, slipped discs)
What is gabapentin the precursor to? How do these drugs differ?
Pregabalin (Lyrica): has greater addictive potential therefore C5 controlled substance
How is gabapentin eliminated?
Renally (extremely hydrophilic)
How does topiramate work to prevent seizures?
Block sodium channels, enhances GABA activity, weak carbonic anhydrase inhibitor
Name an off label use of topiramate
Weight loss
List adverse effects of topiramate
Anorexia, nephrolithiasis, psychomotor slowing (Topa makes you a dope-a)
What pregnancy category is Topiramate?
Category C
Which two antiepileptic drugs cause Stevens-Johnson syndrome?
Carbamazepine and Lamotrigine
List adverse affects of Levitracetam (keppra)
Somnolence (behavior changes)
Which two antiepileptics cause somnolence?
Levetiracetam (Keppra) and carbamazepine
List two cautions of all antiepileptics
Suicide risk (second generation) Avoid generic substitution
List the three first-generation AED’s
Carbamazepine, phenytoin, valproic acid
