anti epilepsy Flashcards
what are seizures
• About 10% of the population will have at least one seizure in their lifetime.
• Sudden, excessive, and synchronous discharge of cerebral neurons.
• This abnormal electrical activity may result in a variety of events, including
loss of consciousness, abnormal movements, atypical or odd behavior, and
• distorted perceptions that are of limited duration but recur if untreated.
• The site of origin of the abnormal neuronal firing determines the
symptoms that are produced. For example:
o if the motor cortex is involved, the patient may experience abnormal
movements or a generalized convulsion.
o Seizures originating in the parietal or occipital lobe may include visual,
auditory, or olfactory hallucinations.
o It is expected that seizures can be controlled completely in approximately
70-80% of patients with one medication and
o 10-15% will require more than one drug.
what are partial/focal seizures
• Involve only a portion of the brain, typically part of one lobe of one
hemisphere.
1) Simple partial: the electrical discharge does not spread, and the patient
does not lose consciousness.
• Abnormal activity of a single limb or muscle group that is controlled by the
region of the brain experiencing the disturbance.
• The patient may also show sensory distortions تشويه .
2) Complex partial: complex sensory hallucinations, mental distortion, and
loss of consciousness.
• Motor dysfunction may involve chewing movements, diarrhea, and/or
urination.
• Simple partial seizure activity may spread and become complex and then
spread to become a secondarily generalized convulsion
what are partial/focal seizures
• Involve only a portion of the brain, typically part of one lobe of one
hemisphere.
1) Simple partial: the electrical discharge does not spread, and the patient
does not lose consciousness.
• Abnormal activity of a single limb or muscle group that is controlled by the
region of the brain experiencing the disturbance.
• The patient may also show sensory distortions تشويه .
2) Complex partial: complex sensory hallucinations, mental distortion, and
loss of consciousness.
• Motor dysfunction may involve chewing movements, diarrhea, and/or
urination.
• Simple partial seizure activity may spread and become complex and then
spread to become a secondarily generalized convulsion
what are generalized seizures
Generalized seizures may begin locally and then progress to include abnormal
electrical discharges throughout both hemispheres of the brain. Primary
generalized seizures may be convulsive or nonconvulsive, and the patient
usually has an immediate loss of consciousness.
• 1) Tonic-clonic seizure: loss of consciousness, followed by tonic (continuous
contraction) and clonic (rapid contraction and relaxation) phases.
• The seizure may be followed by a period of confusion and exhaustion due to
the depletion of glucose and energy stores.
• 2) Absence seizure: These seizures involve a brief, abrupt, and self-limiting
loss of consciousness.
• The patient stares and exhibits rapid eye-blinking, which lasts for 3 to 5
seconds.
• 3) Myoclonic: These seizures consist of short episodes of
muscle contractions that may reoccur for several minutes.
They exhibit as brief jerks of the limbs.
• Myoclonic seizures occur at any age but usually begin around
puberty or early adulthood.
• 4) Clonic: These seizures consist of short episodes of muscle
contractions that may closely resemble myoclonic seizures.
• Consciousness is more impaired with clonic seizures as
compared to myoclonic.
• 5) Tonic: These seizures involve increased tone in the
extension muscles and are generally less than 60 seconds
long.
• 6) Atonic: These seizures are also known as
drop attacks and are characterized by a
sudden loss of muscle tone.
• 7) Febrile seizures: in young children with
illness accompanied by high fever. Consist of
generalized tonic-clonic convulsions
• 8) Status epilepticus: lasts for ≥ 20 min.
• In status epilepticus, two or more seizures occur without
recovery of full consciousness in between episodes. These
may be focal or primary generalized, convulsive or
nonconvulsive.
• Status epilepticus is life threatening and requires
emergency treatment usually consisting of administration
of a fast-acting medication such as a benzodiazepine,
followed by a slower-acting medication such as phenytoin
what are generalized seizures
Generalized seizures may begin locally and then progress to include abnormal
electrical discharges throughout both hemispheres of the brain. Primary
generalized seizures may be convulsive or nonconvulsive, and the patient
usually has an immediate loss of consciousness.
• 1) Tonic-clonic seizure: loss of consciousness, followed by tonic (continuous
contraction) and clonic (rapid contraction and relaxation) phases.
• The seizure may be followed by a period of confusion and exhaustion due to
the depletion of glucose and energy stores.
• 2) Absence seizure: These seizures involve a brief, abrupt, and self-limiting
loss of consciousness.
• The patient stares and exhibits rapid eye-blinking, which lasts for 3 to 5
seconds.
• 3) Myoclonic: These seizures consist of short episodes of
muscle contractions that may reoccur for several minutes.
They exhibit as brief jerks of the limbs.
• Myoclonic seizures occur at any age but usually begin around
puberty or early adulthood.
• 4) Clonic: These seizures consist of short episodes of muscle
contractions that may closely resemble myoclonic seizures.
• Consciousness is more impaired with clonic seizures as
compared to myoclonic.
• 5) Tonic: These seizures involve increased tone in the
extension muscles and are generally less than 60 seconds
long.
• 6) Atonic: These seizures are also known as
drop attacks and are characterized by a
sudden loss of muscle tone.
• 7) Febrile seizures: in young children with
illness accompanied by high fever. Consist of
generalized tonic-clonic convulsions
• 8) Status epilepticus: lasts for ≥ 20 min.
• In status epilepticus, two or more seizures occur without
recovery of full consciousness in between episodes. These
may be focal or primary generalized, convulsive or
nonconvulsive.
• Status epilepticus is life threatening and requires
emergency treatment usually consisting of administration
of a fast-acting medication such as a benzodiazepine,
followed by a slower-acting medication such as phenytoin
how do we choose drugs for the treatment of seizures
• Choice of drug treatment is
based on the classification of
the seizures, patient-specific
variables (for example, age,
comorbid medical conditions,
lifestyle, and personal
preference), and
characteristics of the
• drug (such as cost and drug
interactions).
• Monotherapy is preferred.
• If not controlled
monotherapy with an
alternate drug, or vagal nerve
stimulation should be
considered.
what is the mechanism of action of antiepileptic drugs
Blockade of voltage-gated channels (Na+ or
Ca2+), enhancement of inhibitory GABAergic
impulses, or interference with excitatory
glutamate transmission. Some antiepileptic
drugs appear to have multiple targets within
the CNS, whereas the mechanism of action for
some agents is poorly defined
what are the old antiepileptic drugs
phenobarbital, primidone, phenytoin, carbamazepine,
ethosuximide, divalproex, valproic acid, diazepam, and
lorazepam.
The newer agents have advantages in terms of
Pharmacokinetics
Tolerability
Lesser risk for drug-drug interactions when compared with the older
agents
The newer agents have advantages in terms of
Pharmacokinetics
Tolerability
Lesser risk for drug-drug interactions when compared with the older
agents
What are the usages of BDZs in epilepsy
• Benzodiazepines bind to GABA inhibitory receptors to reduce firing rate of
the neuron.
• Most are reserved for emergency or acute seizure treatment due to
tolerance. However, clonazepam and clobazam may be prescribed as
adjunctive therapy for particular types of seizures.
• Diazepam is also available for rectal administration to avoid or interrupt
prolonged generalized tonic–clonic seizures or clusters when oral
administration is not possible
what is carbamazepine
• MOA: Blocks sodium channels thereby inhibiting the generation of repetitive
action potentials.
• Indications:
• 1. partial onset seizures and generalized tonic-clonic seizures. 2. trigeminal
neuralgia 3. bipolar disease.
• Absorbed erratically following oral administration and may vary from generic
to generic. It induces its own drug metabolism and has an active metabolite.
• Hepatic enzyme inducer, liver enzymes should be checked
periodically.
• A/E: N/V, headache, hepatotoxicity, somnolence, weight gain,
and Stevens-Jonson syndrome.
• It is not as well tolerated by the elderly as other available
antiseizure medications, and causes hyponatremia.
• Carbamazepine should not be prescribed for patients with
absence seizures because it may cause an increase in seizures.
• The use of carbamazepine and valproic acid for tonic clonic
seizure is increasing on the expense of phenytoin and
phenobarbital because the formers are equally effective to the
latters and their adverse effects are less.
what is carbamazepine
• MOA: Blocks sodium channels thereby inhibiting the generation of repetitive
action potentials.
• Indications:
• 1. partial onset seizures and generalized tonic-clonic seizures. 2. trigeminal
neuralgia 3. bipolar disease.
• Absorbed erratically following oral administration and may vary from generic
to generic. It induces its own drug metabolism and has an active metabolite.
• Hepatic enzyme inducer, liver enzymes should be checked
periodically.
• A/E: N/V, headache, hepatotoxicity, somnolence, weight gain,
and Stevens-Jonson syndrome.
• It is not as well tolerated by the elderly as other available
antiseizure medications, and causes hyponatremia.
• Carbamazepine should not be prescribed for patients with
absence seizures because it may cause an increase in seizures.
• The use of carbamazepine and valproic acid for tonic clonic
seizure is increasing on the expense of phenytoin and
phenobarbital because the formers are equally effective to the
latters and their adverse effects are less.
what is Ethosuximide
• It reduces propagation of abnormal electrical activity in the brain, by
inhibiting T-type calcium channels.
• Only for absence seizures.
• Safe.
what is felbamate
• It has a broad spectrum of anticonvulsant action with multiple proposed
mechanisms including
• 1) blocking voltage-dependent sodium channels
• 2) competing with the glycine-coagonist binding site on the NMDA glutamate
receptor
• 3) blocking calcium channels and
• 4) potentiating of GABA action
• Reserved for use in refractory epilepsies (particularly Lennox-Gastaut syndrome)
because of the risk of hepatic failure and aplastic anemia (about 1:4000)
