Epilepsies Flashcards
(35 cards)
What are the 4 drugs that belong to the voltage-gated sodium channel stabilizers?
- Phenytoin
- Carbamazepine
- Oxcarbamazepine
- Lamotrigine
What is the mechanism of the voltage-gated sodium channel stabilizers?
A little redundant but, they stabilize the inactive conformation of sodium channels!
What are the primary therapeutic uses of carbamazepine and oxcarbamazepine?
- They are more effective for complex partial seizures than primary generalized.
- bipolar disorder
- neuropathic pain.
What is pheytoin effective at treating? Less effective at treating?
- Tonic-clonics of primary generalized epilepsy
- Partial onset
- Secondarily generalized seizures
- Less Effective: Absence (particularly pediatric), myoclonic, atonic seizures
What conditions is Lamotrigine used to treat?
- Primary and Secondary Generalized Epilepsy
- Partial complex
- Absence seizures
- Bipolar disorder
- Neuropathic pain
A neurologist wants to prescribe a Na channel stabilizer for a pediatric patient who has absence seizures. What drug would be the best choice?
Lamotrigine
What are the side effects of phenytoin?
Rash
- Gingival hyperplasia
- Hirsutism
- Lupus-like reaction
- Contraceptive failure
What are the side effects of carbamazepine and oxcarbamazepine?
- Rash (rarely Stevens-Johnson syndrome)
- Mild myelosuppresion
- Mild increase in LFTs
- Contraceptive failure
For which sodium channel stabilizer is slow initial titration important? What are the side effects of this drug?
Lamotrigine
- Rash (Rarely Stevens-Johnson syndrome)
- Contraceptive failure
A patient has been taking a sodium channel stabilizer for years and is experiencing cerebellar degeneration, peripheral neuropathy and osteoporosis. What drug has he been on?
Phenytoin
What limits the IV infusion of phenytoin?
Hypotension; It is a hepatic enzyme inducer
Rank the Sodium channel stabilizers from most protein bound to least protein bound
Phenytoin ~ Carbamazepine > Oxcarbamazepine > Lamotrigine
Which sodium channel stabilizers cause hepatic enzyme induction?
All of them!
Which sodium channel blocker may exacerbate myoclonic seizures and competes with valproic acid for excretion?
Lamotrigine
What are the benefits of oxcarbamazepine over carbamazepine?
- Bypasses carbamazepine epoxide
- Less protein-bound
- Less auto-induction
- Fewer interactions
- Less toxic
- Longer half-life
- Carbamazepine doses need to be increased every 1-2 weeks due to autoinduction
How does Valproate work?
MECHANISM UNKNOWN (but it likely affects Na-gated channels and GABA system)
Valproate is great because it can be used therapeutically for many conditions. What conditions is it used for?
- Absence
- Myoclonic
- Tonic-clonic
- Primary generalized
- Partial onset
- Secondary generalize seizures
- IV for Status Epilepticus
- Bipolar disorder
- Migraine
- Long-term cluster headache prophylaxis
What is the plethora of side effects that come with Valproate use?
Weight gain
- Hair turnover
- Hyperammonemia (which can be mitigated with oral carnitine)
- Teratogenicity
- Blood dyscrasias
- Pancreatitis
What are the three GABAergic anti-epileptic drugs? What are their mechanisms, respectively?
Vigabatrin, Tigabine, Benzos; GABA transaminase binder (slows down intracellular breakdown of GABA), GABA reuptake inhibitor, binds GABA-A
I need a GABAergic anti-epileptic that won’t cause sedation, STAT! What two drugs could I use?
Vigabatrin or Tigabine
Now I need a GABAergic anti-epileptic for Status Epilepticus (refactory) that causes sedation, STAT! Wow, I’m needy! What do you got? I want to use this med long term. What are your thoughts?
Benzos; Don’t do it! Patients can become tolerant to long-term benzo use!
What is the class, mechanism and therapeutic uses of Gabapentin and Pregabalin?
- GABA analog
- Block presynaptic influx of Ca
- Adjunct for partial complex epilepsy, neuropathic pain.
My GABA analog is taking FOREVER to absorb into my patient! But I know that it has very few side effects (besides sedation) and therefore I used it. What drug am I using? Why is it taking so long to absorb? Why does its use result in minimal side effects?
- Gabapentin
- Its absorption is limited by the AA transporter
- It has limited protein binding, no metabolism and no drug interactions in humans!
What are my two Glutamate Receptor Blockers? How are their mechanisms different? Same?
- Topiramate: Partial AMPA, Kainate Ca receptor blocker
- Felbamate: NMDA receptor blocker
- Both: Secondary effect at voltage-gated Na channel, GABA system
