Epilepsy Pharm Flashcards
What is epilepsy
Enduring predisposition to generate epileptic seizures and associated cognitive , psychological and social consequences.
Abnormal excessive or synchronous electric discharges in the brain
Provoked vs Unprovoked Seizures
Provoked: Ex: take drugs which cause patient to have seizure , reversible risk factors
Unprovoked: no acutely reversible risk factor for the seizure ( structural or functional problem)
If you have 2 seizures within more than 24hrs then this means what
Patient is more likely to have more seizures later in life , think epilepsy
Can 1 seizure cause epilepsy ?
Yes
What is Resolution Epilepsy
If it’s an age dependent syndrome and patient has grown out of it
What is drug refractory epilepsy
Pharmacoresistant epilepsy
Considerations taken in when prescribing Anti-seizure Medication ( ASM ) for patient ?
1- Type ( focal/generalized ) 2- Spectrum or efficacy 3- Comorbidities ( migraine , bipolar ) 4- Tolerability ( compliance) 5- pharmacokinetics and dynamics 6- Speed of titration 7- Cost, blood tests , frequency of administration
What is the goal for medication for epilepsy patients
Patient to be seizure free without adverse effects
Classification of Seizure
1- Focal Onset - Aware / impaired awareness - motor onset - non motor onset - focal to bilateral tonic-clonic 2- Generalized onset - motor : tonic-clonic / the motor - non motor( absence ) 3- Unknown onset - tonic-clonic / other motor - non motor
What is a focal onset seizure ?
Seizure that starts in one area of the brain
Symptoms of focal onset seizure in Limbic region
- Changes in taste , smell
- funny feeling in epigastrium
- memory disturbance
- psychiatric dysfunction ( extreme fear / goosebumps )
What is a Generalized Onset Seizure
Seizure that has a widespread disturbance of brain function
If patient has seizure in the inferior frontal lobe, what symptoms will they present with
Speech disturbance
What cell stages are targeted by anti-epileptic medications
1- Sodium channels on presynaptic area that release neurotransmitters
2- GABAa receptors : GABA causes CL- to rush in , inactivating neurone
3- NMDA/AMPA receptors that block glutamate from binging to receptors and causing excitation
4-
What is the key excitatory and inhibitory neurotransmitter for neuronal transmission
Excitatory : glutamate
Inhibitory : GABA
Which Anti-seizure medications promote inhibition
1- Topiramate
2- Benzodiazepines
3- Valproate
Which Anti-seizure medications reduce excitation
1- Phenytoin 2- Carbamazepine 3- Lamotrigine 4- Valproate 5- Topiramate 6- Levetiracetam
Which Anti-seizure medications are the sodium channel blocking drugs
Carbamazepine and Phenytoin
Which seizures should Carbamazepine and Phenytoin not be used for
Absence and Myoclonic
If someone presents with focal or generalized seizures which medication will be chosen and why ?
Drugs with least interactions , side affects and with priority to comorbidities. Could be used for all seizure types
Lamotrigine or Levetiracetam
Which ASM is most affective for generalised seizures, but why is it not the one always used
Sodium Valproate but it’s side effects , especially for women make it not possible to prescribe sometimes
Explain Carbamazepine , MOA , side effects , interactions
MOA : sodium channel blocker
Hepatically metabolized
Interactions: Strong hepatic enzyme inducer ( CYP3A4 ) - messes up a lot of medications
- auto-induction of liver enzymes : liver gets better at metabolizing carbamazepine the more it’s used = need to increase dose later
- bone health , can metabolize vitamin D more rapidly
- Abnormal lipid function & CVS risk
Side effect :
- reduces liver function
- dizziness, headaches, double vision
- fatigue , nausea , GI disturbance
- Hyponatraemia through SIAH mechanism
- Idiosyncratic : bone marrow suppression , hypersensitivity , hepatic derangement , rash
Explain Phenytoin , MOA , side effects , interactions
MOA: Sodium channel blockers
Side effects :
Acute : dizziness, ataxia , fatigue , diplopia , nystagmus, rash , sedation
Chronic: gum hyperplasia, coarse face, hirsutism, osteopenia, enhanced Vitamin D metabolism , low folate, peripheral neuropathy
Idiosyncratic: fever, rash , lymphadenopathy, teratogenic
Interactions : Hepatic enzyme induced = reacts with most drugs
Which contraceptive is not effective while on Carbamazepine
Progesterone
Which contraceptive is not effective while on Carbamazepine
Progesterone only
Can sodium channel blocker ASM be combined
Better to combine drugs with other MOA. There could be compounding side effects
What is the therapeutic range of Phenytoin
10-20ug/ml
How can Phenytoin be dangerous
Has First order kinetics at first and the zero order kinetics. Can suddenly become toxic since there will be a high saturation of it and the liver will not accommodate to metabolize it
What ASM can displace and inhibit the metabolism of Phenytoin and what is the effect
Sodium Valproate.
Effect: increases free phenytoin and toxicity
Explain Sodium Valproate, MOA , side effects , interactions
MOA = multiple
- Sodium/calcium blocker
- CABA & glutamate receptor actions
Hepatic metabolism
Side effect : - Extremely Teratogenetic ( have to do legal paper work if prescribing to women ) V ( nemonic VALPROATE) - A ppetite increase/gain weight - L iver failure - p ancreatitis - R eversible hair loss - O edema - A taxia - T eratogenicity , tremor , thrombocytopenia - E ncephalopathy
Interactions :
- Lamotrigine ( very effective combination therapy for epilepsy )
Which ASM can double the dose of Lamotrigine if interact together
Sodium Valproate
Explain Levetiracetam , MOA , side effects , interactions
MOA : SV2A ligand , blocks synaptic vesicle release
Few side effects :
- irritability , anxiety , anger , fatigue , dizziness, behavioural changes, rare psychosis
- highly rare hepatic failure
No significant interactions : Doesn’t effect liver enzymes
Not teratogenic
Really excreted
If patient comes after being prescribed ASM with behavioural changes , which ASM were they most likely prescribed
Levetiracetam
Explain Lamotrigine, MOA , side effects , interactions
MOA: Sodium channel modulators
Pregnancy Safe
Side effects
KEY: Rash/ Stevens-Johnson syndrome = could cause death
- insomnia
- mood stabilizing drug ( good if person has depression )
Interactions
- OCP ( combined pill ) could cause drop in lamotrigine levels
- other AEDs especially Valproate could increase concentration
Explain Topiramate , MOA , side effects , interactions
MOA : multiple
- Sodium/calcium blocker
- GABA / Glutamte affects
Interactions :
- enzyme inducer and inhibitor
Side effects : - sedation - anorexia - weight loss ( big one ) - psychiatric - word finding difficulties Rare: kidney stones, acute angle closure glaucoma - Teratogenic
Topiramate is also used for
Migraines
Is lamotrigine or Levetiracetam more first line prescribed
lamotrigine but needs slower titration
Which ASM can cause weight gain
Valproate , Carbamazepine , Gabapentin
If trying to promote weight loss what ASM could be prescribed
Topiramate
What Is often prescribed with Carbamazepine for bone health
Vitamin D
Which ASM should not be given in those with mental health issues
Levetiracetam
Are there interactions with ASM and antidepressants ? will they be prescribed
Yes there is but antidepressants are still prescribed , rarely to affect the seizures
For neuropathic pain which ASM could be used
Carbamazepine, Gabapentin / pregablin
For Bipolar disorder which ASM could be used
Carbamazepine , lamotrigine and Valproic acid
For migraine which ASM could be used
Topiramate
For Trigeminal neuralgia which ASM could be used
Carbamazepine
For obesity which ASM could be used
Topiramate and zonisamide
For anxiety which ASM could be used
Clobazam and prcegablin
What are the ASMs of choice in pregnancy
Lamotrigine and Levetiracetam
