Anti-epileptic drugs Flashcards
When would rare, life-threatening ADRs occur in treatment for epilepsy? and what is this called/
first 1-8 weeks
Anticonvulsant hypersensitivity syndrome (fever, rash, liver involvement)
what is AHS?
Anticonvulsant hypersensitivity syndrome
most common in Han Chinese pop
Caused by aromatic amines (Phenobarb, Phenytoin, Carbamaz, Lamotrigine)
What proportion of patients will achieve full seizure response
2/3,
1/3 are refractory
If a patient fails to respond to TWO appropriate drugs then…
DEFINITELY REFRACTORY - REFER
Which are the MOST common intractable seizures
COMPLEX PARTIAL
What are some comorbidities?
- Depression
- Anxiety
- Suicide
AEDs… do they cure epilepsy?
NO, suppress temporarily
Most common ADRs for AEDs?
- Stomach upsets
- Sedation
POOR compliance…
with Epilepsy what is the standard for drug treatment?
MONOtherapy - NOT polypharmacy
What is the drug interaction for valproIc acid?
INCREASES blood levels of other drugs
What is the drug interaction for Phenobarb, Phenytoin, Carb
DECREASE blood levels of other drugs
Interaction between Phenytoin and Warfarin…
(Inducers of CYP 450) so warfarin levels LOWER
AEDs and OCPs…
Inducers- failed OCP
what can blood levels be used for
- check therapeutic range
- check for ADRs in liver, kidney, blood fox
- Check for non-compliance
What are the general withdrawal rules for AEDs?
- Withdraw over months - NOT quickly
- Rebound seizures, Status epilepticus may occur
- May lose license
Most women maintained on AED (1 only), which two are KNOWN Teratogens?
Phenytoin, Valproate
How do Phenytoin and Carbamazepine work?
- Partially Inhibit voltage-dependent Na channels (phenytoin, Carb), hold inactive state longer, lengthen refractory period
- Neuron fires at moderate rates, BUT NOT RAPID rates
How do the Barbiturates and Benzodiazepines work?
- Increase activation of GABA-A receptor
2. Enhance Cl- influx, decrease excitability
Problems with Barbiturates and Benzodiazepines work?
Sedating
Paradoxical irritatbility - can be serious in children
How does Ethosuximide work?
Inhibit T-type voltage-dependent calcium channels
Important in THALAMUS
(absence)
Which is the only drug used for Absence seizures?
Ethosuximide
t-type calcium inhibitor
once a day
Rare sidex - Photophobia, Hiccups
4 drugs used for tonic-clonic and complex partial seizures
- Phenobarb (increase GABA-A inhibition, very sedating)
- Phenytoin (VDSC, gingival hyperplasia, hirsutism, acne, CAN become zero-order and toxic, longer half life)
- Carbamazepine (VSDC, less sedating)
- Levetiracetam ( decreased SV2A release)
What is the toxic syndrome associated with Phenytoin increased half life and zero order metabolism?
Ataxia, Nystagmus
What are the four Broad-spectrum drugs (Tonic-clonic partial and absence treatments)
- Valproate (side eft tremor, hair loss, weight gain, bruising, bleeding, teratogenic, fear of hepatitis)
- Clobazam ( enhances gaba A, benzo, sedation, personality change, tolerance after 6 months)
- Lamotrigine (VDSC, rash/hypersensitivity syndrome)
- Topiramate (can cause sedation, and weight loss)
Which drug is associated with tolerance after 6 months?
CLOBAZAM
Which drugs are used ONLY for status epilepticus?
- IV Benzo (lorazepam, diazepam, midazolam)
- IV Phenytoin
- can use propafol, phenobarb, pentobarb
