Anticonvulsants Flashcards
Convulsion
Sudden attack of involuntary muscular contractions and relaxations
Seizure
Abnormal central nervous system electrical activity
Epilepsy
A group of recurrent disorders of cerebral function characterized by both seizures and convulsions
Causes of Epilepsy
- Genetic (autosomal dominant)
- congenital defects
- Severe head trauma
- Ischemic injury, tumor
- Drug abuse
- UNKNOWN
Glutamate
-Excitatory (tells the neuron to fire)
GABA
-Inhibitory (dampens the neuron firing rate)
Partial (focal) seizure
-Excessive electrical activity in one cerebral hemisphere
-Affects only part of the body
-SIMPLE PARTIAL- Person may experience a range of strange or unusual sensations
-Motor
-Sensory
-Autonomic
KEY: PRESERVATION OF CONSCIOUSNESS
COMPLEX PARTIAL:
- LOSS OF AWARNESS AT SEIZURE ONSET- person seems dazed or confused
- typically originate in frontal or temporal lobes
Generalized Seizures
- Excessive electrical activity in both cerebral hemispheres
- Originate in thalamus or brainstem
- AFFECTS THE WHOLE BODY
- LOSS O FCONSCIOUSNESS IS COMMON
Generalized Seizures
- Myoclonic: brief shock like muscle jerks restricted to part of one extremity
- Atonic: sudden loss o muscles tone
- TONIC SEIZURES: sudden stiffening of the body, arms, or legs
- Clonic Seizures: rhythmic jerking movements of the arms and legs without a tonic component
- TONIC CLONIC (GRAND MAL) Tonic phase followed by clonic phase 25% of all seizures
Status Epillepticus
- A seizure lasting longer than 30 minutes or 3 seizures without a normal period in between
- May be fatal
- Emergency intervention required
Seizure facts
- Seizures ar not usually life threatening
- the brain almost always stops the seizure on its own
- Breathing may cease for a few seconds, and the patient may turn blue
- People don’t feel pain during a seizure, muscles may be sore afterward
- person may be different for a while after the seizure
Treatment
- try to find cause (fever,; head trauma, drug abuse)
- Recurrent seizures that cannot be attributed to any cause are seen in patients with epilepsy
- Therapy is control NO CURE
- Type of seizure determines the choice of drug
- More than 80% can have seizures controlled with medications
Therapeutics
- Inhibition of Na+ channels to slow neuron firing
- Enhancement o the inhibitory effects of the neurotransmitter GABA
- Inhibition of calcium channels
Na+ Channel Drugs
- Phenytoin (Dilantin, phenytek)- MOST USED**
- Cabamazepine (Tegretol, carbatrol)
- Valproic Acid (Depakote, Depakane)
- Lamotrigine (Lamictal)
- Topiramate (Topamax)
- Zonisamide (Zonegran)
- Lidocaine
Phenytoin (Dilantin)
- Most widely used
- NA+ Channel blocker
- First choice for partial and generalized tonic clonic seizures
- Decreased blood levels of medications
- Increases blood levels of PHENOBARBITOL AND COUMADIN (interacts with P450 enzyme)
- Adverse effects- Hirsutism , acne, GINIGIVAL HYPERPLASIA
Lamotrigine (lamictal)
-may inhibit release of glutamate
-Simple and complex partial seizures (ages 2 and up)
-generalized seizures of Lennox-Gastaut Syndrome
-Adults -simple and complex partial seizures
Contraindications:
-MAY MAKE MYOCLONIC SEIZURES WORSE
-Adverse: rash (10%) rare progression to serious systemic illness
-Black Box : can lead to aseptic meningitis
GABA Drugs
- Barbiturates
- Benzodiazepines
- Tiagabine (Gabitril)
- **VALPRIC ACID(Depakote)
- Topiramate (Topamax)
- Zonisamide (Zonegran)
Phenobarbital (Luminal)
- Barbiturate
- 2nd choice for partial and generalized tonic clonic seizures
- status epilepticus
- Contraindications: Absence seizures
Benzodiazepine
Inhibit GABA
First line treatment of status epilecticus
-Lorazapam
-Diazapam ( painful to inject)
Contraindicated: use in children <9, narrow angle glaucoma
Ca Channel Drugs
- Ethosuximade (Zarontin)
- Valproic Acid (Depakote)
- Zonisamide (Zonegran)
- Gabepentin (Neurontin)
- Pregabalin (lyrica)
- Levetiracetam (Keppra)
Ethosuximide (Zarontin)
- Reduces Ca2 currents in the thalamic neurons
- First line for absence seizures
- Contraindications: may exacerbate partial and tonic clonic seizures
- half life is 60hrs in adults, 30hrs in children
Gabepentin (Neurontin)
usually adjunct therapy
used in neuropathy
Pregabalin (lyrica)
-adjunct therapy for partial and secondarily generalized seizures
-no effect on absence, myoclonic, or primary generalized tonic clonic seizures
-fibromyalgia, neuropathic pain
-
other MOA
- magnesium chloride -used for mag deficiency seizures
- Paraldehyde - alcohol withdrawal seizures ( inhibits ethanol pathway
