EXAM #3: ANTICONVULSANTS Flashcards
What causes a seizure?
Abnormally excessive, synchronous, and rhythmic firing of populations of hyper-excitable neurons
What is epilepsy?
Chronic neurological disorder characterized by recurrent seizures
What is the general feature of partial seizures?
Only part of the brain is involved i.e. seizure stars in one region and remain there
What is the general feature of a generalized seizure?
Involvement of the entire brain with global EEG changes
What are the three subtypes of partial seizures?
1) Simple Partial
2) Complex Partial
3) Partial becoming generalized
What is a Simple Partial Seizure?
- Seizure with no loss of consciousness and only focal involvement
- Characterized by minimal spread of abnormal neuronal discharge
What is a Complex Partial Seizure?
- Seizure with altered consciousness and potential automatisms
- Focus originates in a small brain area and quickly spreads to other areas
What is a partial seizure becoming generalized?
Partial seizure that spreads throughout the brain and progresses to a generalizes seizure
What is the most common type of partial seizure?
Complex partial
What is an automatism?
Lip smacking
Fumbling
Swallowing
What is an Absence or Petit Mal seizure?
- Brief LOC with some motor signs/ automatisms
- Typically seen in children
What is a Tonic-Clonic or Grand Mal seizure?
Prototypical seizure with tonic spasms and major convulsions with LOC
What are the stages of seizures?
1) Aura
2) Tonic phase–rigidity
3) Clonic phase–convulsions
4) Stuporous state/sleep
What is Status Epilepticus?
- Continuous or very rapidly recurring seizures (tonic-clonic)
- Medical EMERGENCY
What is an atonic seizure?
Sudden loss of muscle/ postural tone
What are the three stages of epileptic seizure generation?
1) Initiation i.e. lowered threshold of activation
2) Synchronization of surrounding tissue
3) Propagation and recruitment of normal neurons
What is an EPSP?
Excitatory Postsynaptic Potential
What is the molecular basis for EPSPs?
Na+ influx
Ca++ currents
Paroxysmal Deplarization
What is the goal of antiepileptic medications?
Restoration of normal patterns of electrical activity
What are the three drugs that are best to treat partial seizures?
Carbamazepine
Phenytoin
Valrpoate
What are the drugs that are best to treat tonic clonic seizures?
Carbamazepine
Phenytoin
Valrpoate
What drugs are best for treating absence/petite mal seizures? What ion channel do these drugs block?
Ethosiximide
Valproate
Ca++*
What drugs are best for treating myoclonic seizures?
Clonazepam
Valproate
What drugs are best for treating status epilepticus?
Diazepam
Lorazepam
Phenytoin
Fosphenytoin
What is the general mechanism of action of anticonvulsant drugs?
Inhibit firing of hyperexctiable cerebral neurons
How do anticonvulsants inhibit firing of hyperexcitable neurons?
1) Decrease excitatory effects of glutamate by blocking voltage-gated Na+ channels
2) Increase inhibitory effects of GABA
3) Alter neuronal activation by altering Ca++ currents i.e. block voltage gated Ca++ channels (T-type)
What do Na+ blockers do in treating seizures?
Bind to the Na+ channel in inactive state and prevent conversion back to resting state
**This decreases sustained, high frequency, and repetitive discharge*
What is the effect of reducing Ca++ influx in the pre-synaptic neuron?
Decreased NT release
What type of seizures are Ca++ blockers best at treating?
Petit mal
What are the side effects of anticonvulsant drugs?
- Sedation
- Diplopia
- Nystagmus
- Ataxia
- GI upset
What can happen with the abrupt withdrawal of anticonvulsants?
Increased potential for seizures
What are the special considerations regarding anticonvulsants and women?
1) Decreases efficacy of oral contraceptives
2) Teratrogenic
What anticonvulsant is considered to be the safest in pregnancy?
Phenobarbital
