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Pharmacology of Epilepsy - Coggle Diagram
Pharmacology of Epilepsy
Goals of Therapy
Reduce seizure frequency and severity, improve function, enhance quality of life, and promote coping, prevent premature death
Monitoring
Do not lower ASM dose unless clinically toxic
Focus on Potentent Adverse effects
Enzyme inducers
Enzyme inducers: (Carbamazepine, Phenytoin, Phenobarbital, Primidone, Oxcarbazepine) Monitor CBC, LFTs, monitor for Na
Phenytoin -> Perpheral neuropathy, cerebellar atrophy, gingival PBC
Valpoic Acid -> Tremors, weight gain, osteopenia
LAC, Levetiracetam dont need monitoring, unless in pregnancy
Mechanism of Action
Na Channel Blocker: Carbamazepine, Phenytoin, Oxcarbazepine, Lamatrigine, Lacosomide
GABAergic: Barbiturates, Benzodiazepines, VIgabatrin
Synaptic Vesicle Protein: Levetiracetam, brivaracetam
AMPA Receptor antagonist: Perampanel
Ca Channel Blcoker: Gabapentin, Pregabalin
Ca Channel Blocker: Gabapentin, Pregabalin
Carbonic Anhydrase Inhibitor: Acetazolamide
Multiple Actions: Valproic Acid, Zonisamide, Cenobamate
Phenytoin
Pharmacokinetics
Elimination is dose dependent
Drug Interactions
IV Rapid Infusions, Fosphenytoin
Absorption highly dependent on formulation, highly protien bound, liver metabolism
Other Components
P-450 Pony Tails, Hirsutism, Enlarged GUms, Nystagmus, Yellow-browning of the skin, Teratogenic, Osteomalacia, Interferes with folate metabolism, Neuropathies
Levetiracetam
Broad-spectrum, antimyclonic, Binds with affinity to SV2A
Adverse Effects
Anxiety, irritability, depression, aggression, suicidal ideation
Selecting an Antipsychotic
Efficacy
Few are known to be more efficacious than another for a given indication
Selection Criteria
According to age, S/E profile, comorbid conditions, Drug interaction, ease of use, cost, Clinician familitary
Partial Epilepsy
Lamotrigine better tolerated that Carbamazepine, topiramate, gabapentin
Carbamazepine achieves better 1 year remission than gabapentin
Generalized/Unclassifiable
Valproic better than topiramate, and better 1-year remission than lamotrigine
Absence Trial
Ethosuximide and Valproic Acid more effective, ethosuximide assoicated wtih fewer side effects
Pt Wants weight loss
Topiramate, Zonisamide
Pt Has disabling migraines
Topiramate, Gabapentin
Mood Issues
Avoid levetiracetam, perampanel, topiramate, Benzos, brivaracetam
Mood and Anxiety
Gabapentin, pregabalin, Clobazam
Overall Guidelines
Start with Broad Spectrum (Valproic Acid, Levetiracetam, Lamotrigine, Topiramage, Phenobarbital, Perampanel, Primidone)
Valproic Acid for generalized epilepsy, or Levetiracetam in women of Child Bearing
Valproic Acid or ETX for absence epilepsy
Pharmacoresitsent epilepsy (consider referral to EMU for presurgical workup)
Psuedoresistance
Wrong DIagnosis: Syncope, cardiac arrhythmia
Wrong drug: Inappropriate for seizure type
Wrong Dose: Too low
Lifestyle issues
Rational Polytherapy
Match for seizure semiology, avoid combinations causing similar side effects, complementary and similar mechanisms, use lowest effective doses
Status Epilepticus
Consulsive
Benzodiazepine -> Phenytoin, Valproic Acid, Levetiracetam -> Phenobarbital, Midazolam, Propofol
Non-Convulsive
Tailor ASM , and continuous EEG monitoring