Hello friends. In this PPT I am talking about antiepileptic drugs. If you like it, please do let me know in the comments section. A single word of appreciation from you will encourage me to make more of such videos. Thanks. Enjoy and welcome to the beautiful world of pharmacology where pharmacology comes to life. This video is intended for MBBS, BDS, paramedical and any person who wishes to have a basic understanding of the subject in the simplest way.
2. Definitions
• Seizure (from the Latin sacire, “to take
possession of ”) is a transient occurrence of signs or
symptoms due to abnormal excessive or
synchronous neuronal activity in the brain
• Epilepsy Condition in which a person has a risk
of recurrent seizures due to a chronic, underlying
process. Clinical phenomenon rather than a single
disease entity.
3. Types of seizures
• Focal seizures Originate within networks limited
to one brain region (partial seizures NO longer
used)
• Generalized seizures Arise within and rapidly
engage networks distributed
4. Classification of seizures (2017 ILAE)
1. Focal Onset (having intact or impaired awareness,
motor or nonmotor onset, or evolve from focal to
bilateral tonic clonic)
2. Generalized Onset
a. Motor Tonic-clonic, Other motor (e.g., atonic,
myoclonic)
b. Nonmotor (absence)
3. Unknown Onset
a. Motor, nonmotor, or unclassified
11. Approach to the patient
• History and examination
• 1st goal Determine whether the event was truly
a seizure
• In-depth history is essential, because in many cases
the diagnosis of a seizure is based solely on clinical
grounds—the examination and laboratory studies
are often normal
14. PNES or PNEE
• Pseudoseizures, psychogenic seizures, and
hysterical seizures are older terms
• Clinically resemble epileptic seizures but occur
without the excessive synchronous cortical
electroencephalographic activity that defines
epileptic seizures
• These terms reinforce the idea that the events are
not epileptic seizures and are of psychiatric origin
15. Phenytoin
• MOA Prevents repetitive detonation of normal
brain cells (↑ inact. state of VGSC)
• Also,
1. ↓ presynaptic release of glutamate
2. ↑ GABA release
3. ↓ Ca2+ influx
16. Adverse effects-PHENYTOIN
• Plasma level monitoring needed (0 order k.)
• Hypertrophy of gums
• Enzyme induction
• Neutropenia and other hypersensitivity reactions
• Young girls beware ! Causes hirsutism, coarsening
of facial features and acne
• Teratogenic
• Osteomalacia
17. • Interference with folate absorption leads to
megaloblastic anemia
• Neurological manifestations at higher doses
Ataxia, vertigo, nystagmus, diplopia
18. Uses
• Used only when better tolerated newer drugs
cannot be used
• Trigeminal neuralgia 2nd choice drug to
Carbamazepine
19. Interactions
1. Phenobarbitone competitively inhibits phenytoin
metabolism, while by enzyme induction both
enhance each other’s degradation—
unpredictable overall interaction
2. Carbamazepine and phenytoin induce each
other’s metabolism
3. Valproate displaces protein bound phenytoin and
decreases its metabolism Plasma level of
unbound phenytoin increases
20. 4. Chloramphenicol, Isoniazid, Cimetidine and
Warfarin inhibit phenytoin metabolism Can
precipitate its toxicity
5. Phenytoin induces microsomal enzymes and
increases degradation of steroids (failure of oral
contraceptives), Doxycycline, Theophylline
21. Fosphenytoin
• Water soluble prodrug of Phenytoin has been
introduced to overcome the difficulties in i.v.
administration of Phenytoin, which it has replaced
for use in status epilepticus.
• On i.v. injection it is less damaging to the intima
• While Phenytoin cannot be injected in a drip of
glucose solution (because it gets precipitated),
fosphenytoin can be injected with both saline and
glucose
22. Carbamazepine
• 1st line AED for focal seizures and trigeminal
neuralgia (MOA ↑ inact. state of VGSC)
• Manic depressive illness and acute mania As an
alternative to Lithium
• Carbamazepine produces dose-related
neurotoxicity sedation, dizziness, vertigo,
diplopia and ataxia
• Hypersensitivity Rashes, photosensitivity,
hepatitis, lupus like syndrome and rarely
agranulocytosis, aplastic anemia
23. Lupus like syndrome
• Autoimmune disorder caused by a reaction to
certain medications
• Symptoms are muscle and joint pain sometimes
with swelling;flu-like symptoms of fatigue and fever
• SHIP drugs are responsible
1. Sulfonamides incl. dapsone and PAS
2. Hydralazine
3. Isoniazid
4. Procainamide
24.
25. Interactions
• Carbamazepine is an enzyme inducer; can reduce
efficacy of Haloperidol, oral contraceptives
• Metabolism of Carbamazepine is induced by
Phenobarbitone, Phenytoin, Valproate and vice
versa
• Erythromycin, Fluoxetine, Isoniazid inhibit
metabolism of carbamazepine
26. Oxcarbazepine
• Newer congener of carbamazepine
• Toxic effects due to the epoxide metabolite are
avoided
• Drug interactions and auto induction of own
metabolism are less marked, because it is a weak
enzyme inducer
• Risk of hepatotoxicity is estimated to be lower than
carbamazepine; but that of hyponatremia is more
• Indications are the same as for carbamazepine, but
it may be better tolerated
• Dose to dose it is 1½ times less potent
27. Eslicarbazepine
• Prodrug
• Rapidly converted in liver to the same active
metabolite as is oxcarbazepine
• Same range of therapeutic and toxic effects
• Once daily dosing
• Add-on drug for focal seizure with or without
generalization only in adults
28. Valproic acid (Sodium valproate)
• Valproate appears to act by multiple mechanisms:
1. A phenytoin-like frequency-dependent
prolongation of Na+ channel inactivation.
2. Weak attenuation of Ca2+ mediated ‘T’ current
(Ethosuximide like)
3. Augmentation of release of inhibitory transmitter
GABA by inhibiting its degradation (by GABA-
transaminase)
4. Blockade of excitatory NMDA type of glutamate
receptor
29. Uses
• Drug of choice for
1. Generalised tonic clonic seizures
2. Absence seizures
3. Myoclonic seizures
4. Atonic seizures
• Alternative/adjuvant drug for focal seizures
• Mania and bipolar illness As alternative to
Lithium
31. • E (dEntist) Dentist may face excess bleeding
while executing a dental procedure as Valproate
causes increased bleeding tendency
• E Epigastric pain
32. Interactions
1. ↑ plasma levels of Phenobarbitone and Lamotrigine
2. Displaces Phenytoin from protein binding site
3. Inhibits hydrolysis of active epoxide metabolite of
Carbamazepine
4. Concurrent administration of Clonazepam and
valproate is C/I (absence status may be pptd.)
5. Foetal abnormalities are more common if Valproate
and Carbamazepine are given concurrently
33. Divalproex (Semisodium
valproate)
• Coordination compound of valproic acid with
sodium valproate (1:1)
• Oral absorption is slower, but bioavailability is the
same
• Gastric tolerance may be better
• Primarily used in mania and bipolar illness
• May be used like Valproate
34. Lamotrigine
• Blocks voltage sensitive Na+ channels
• Broad-spectrum antiepileptic
• S/E Sleepiness, dizziness, diplopia, ataxia and
vomiting. Rash may be a severe reaction,
particularly in children, requiring withdrawal
• Dose of lamotrigine should be reduced to half in
patients taking Valproate
35. Uses
• Drug of choice for
1. Generalised tonic clonic seizures
2. Absence seizures
3. Myoclonic seizures
4. Atonic seizures
5. Focal seizures
36. Gabapentin
• Enhances GABA release, but does not act as agonist
at GABAA receptor
• Adjunctive therapy in focal seizures
• 1st line drug for neuralgic pain due to diabetic
neuropathy and postherpetic neuralgia
• Prophylactic effect in migraine
• Alternative drug for phobic states
• S/E Sedation, tiredness, dizziness, tremors &
unsteadiness
37. Pregabalin
• Similar to gabapentin
• Used for
1. Neuropathic pain (diabetic neuropathy,
postherpetic neuralgia, complex regional pain
syndrome (CRPS)
2. Chronic pain
S/E Poor concentration, rashes and allergic
reactions have been complained
38. Levetiracetam
• 1st line drug Focal seizures
• 2nd line drug GTCS and typical absence seizures
• MOA Binds selectively to a synaptic vesicular
protein ‘SV2A’, and this may alter release of
glutamate and/or GABA across the synapse,
thereby exerting anti-seizure effect
• S/E Sleepiness, dizziness, weakness
39. Topiramate
• 1st line drug in atypical absence, myoclonic and
atonic seizures
• 2nd line drug in GTCS and focal seizures
• Broad spectrum anticonvulsant drug acting by :-
1. Prolongation of Na+ channel inactivation
2. Suppression of repetitive neuronal firing
3. GABA potentiation
4. Antagonism of certain glutamate receptors
5. Neuronal hyperpolarization through K+ channels
40. • A/E Impairment of attention, sedation, ataxia,
word finding difficulties, poor memory, weight loss,
paresthesias and renal stones.
• Other uses
• Approved for prophylaxis of migraine (when β
blockers/other prophylactics are C/I or ineffective)
41. Zonisamide
• Adjunctive therapy in GTCS and focal seizures
• MOA Prolongation of Na+ channel inactivation
• S/E Somnolence, dizziness, headache, irritability
and anorexia.
• Metabolic acidosis and renal stones can occur.
• C/I In patients sensitive to Sulfonamides
42. Lacosamide
• Adjunctive therapy in focal seizures
• MOA ↑ Na+ channel inactivation and suppresses
repetitive firing of neurons
• A/E Ataxia, vertigo, diplopia, tremor, depression
and cardiac arrhythmia
43. Treatment of epilepsies
• Antiepileptic drugs suppress seizures, but do not
cure the disorder
• Aim Control and prevent all seizure activity at an
acceptable level of side effects
• Cause of epilepsy should be searched; if found and
treatable, an attempt to remove it should be made
• Some general principles of symptomatic treatment
with antiepileptic drugs are
44. 1. Start with one 1st line drug
2. Initiate treatment early
3. Start at a low dose; gradually ↑ until
1. Effective control of seizures is achieved OR
2. Side-effects develop
4. Optimise adherence (use minimum number of
doses per day)
5. If 1st drug fails start second 1st line drug, followed
if possible by gradual withdrawal of 1st
6. If 2nd drug fails, start 2nd line drug in combination
with the preferred baseline drug at maximum
tolerated dose (beware interactions)
45. 7. If this combination fails, replace 2nd line drug with
alternative second-line drug
8. If this combination fails, check adherence and
reconsider diagnosis (Are events seizures? Occult
lesion? Treatment adherence/alcohol/drugs
confounding response?)
9. Consider alternative, non-drug treatments (e.g.
epilepsy surgery, vagal nerve stimulation)
10. Use minimum number of drugs in combination at
any one time
46. Epilepsy in pregnancy
1. Pre-conception counselling Best; start folic
acid (5 mg daily for 2 months) before conception
to reduce the risk of fetal malformations.
2. Risk of fetal malformation is minimised if a single
drug is used. Carbamazepine and Lamotrigine
have the lowest incidence of major fetal
malformations
3. Prophylactic folic acid supplementation in 2, 3 tri.
4. Vit. K in the last month of pregnancy
47. Dental implications
1. Dentists have to recognize and manage Phenytoin
induced gum hypertrophy
2. In an epileptic patient, dental procedure should
be carried out only after ensuring that the patient
is under adequate anticonvulsant drug cover and
has taken his/her medication
3. In the event of a patient developing an attack of
GTCS during dental procedure, the first priority is
to prevent injuries due to biting or fall. Ensure
that the patient is secure on the flat dental chair
or floor
48. • Any denture or instrument should be immediately
removed from the mouth
• The head should be turned to the side to prevent
the tongue from falling back and obstructing the
airway
• Give oxygen through a face mask to support
respiration if any sign of cyanosis is seen
• Do not attempt to stop convulsive movements by
restraining the patient
• In case the seizures do not stop or recur within 10-
20 minutes, management is as for status epilepticus
49. Status epilepticus
• Continuous seizures or repetitive, discrete seizures
with impaired consciousness in the interictal period
1. GCSE (e.g., persistent, generalized electrographic
seizures, coma, and tonic-clonic movements)
2. Nonconvulsive status epilepticus (e.g., persistent
absence seizures or focal seizures with confusion
or partially impaired consciousness, and minimal
motor abnormalities)
• Practical def. Duration of seizures prompts the
acute use of anticonvulsant therapy
• In GCSE When seizures last beyond 5 min.
50.
51.
52. Febrile convulsions
• Some children (<5 yrs.) develop convulsions during
fever
• Attempt should be made to see that they do not
develop fever, but when they do, temperature
should not be allowed to rise by using paracetamol
and external cooling
• DOC Rectal diazepam 0.5 mg/kg
• In recurrent cases or those at particular risk of
developing epilepsy Intermittent prophylaxis
with diazepam (oral or rectal)
53. Infantile spasms (hypsarrhythmia)
• Therapy of this condition is unsatisfactory
• antiepileptic drugs are generally useless
• Corticosteroids afford symptomatic relief but
cannot be used for long-term due to A/E
• Clonazepam, Valproate and Vigabatrin may afford
some relief
Hinweis der Redaktion
existing or occurring at the same time. be a sign or warning that (something, especially something momentous or calamitous) is likely to happen. something (such as an interesting fact or event) that can be observed and studied and that typically is unusual or difficult to understand or explain fully. natural phenomena like lightning and earthquakes.
International League Against Epilepsy
Tonic-clonic seizures involve both tonic (stiffening) and clonic (twitching or jerking) phases of muscle activity
Secondary generalized seizures begin in one part of the brain, but then spread to both sides of the brain. In other words, the person first has a focal seizure, followed by a generalized seizure.
Primary generalized, or absence, epilepsy is characterized by repeated lapses of consciousness that generally last less than 15 seconds each and usually occur many times a day.
These words are used to describe generalized seizures:
Tonic: Muscles in the body become stiff.
Atonic: Muscles in the body relax.
Myoclonic: Short jerking in parts of the body.
Clonic: Periods of shaking or jerking parts on the body.
Myoclonic seizures These are typically brief, jerking movements, predominating in the arms.
Most of the cases of epilepsy are primary
(idiopathic
γ-Aminobutyric acid (GABA) transporter (GAT)-1
Mechanism of action of antiepileptic drugs (AEDs). A, Excitatory synapse. (1) Phenytoin, carbamazepine, valproic acid, and others inhibit voltage-gated Na+ channels, thereby inhibiting action potentials at excitatory synapse. (2) Levetiracetam and brivaracetam bind to the vesicle transporter SV2A, decreasing amount of NT in vesicles. (3) Topirimate, perampel, and valproic acid inhibit the activation of AMPA and kainate glutamate receptors, decreasing excitation. Topirimate and valproic have other actions as well. (4)Felbamate inhibits activation of NMDA glutamate receptors decreasing excitation. (5) Pregabalin and gabapentin inhibit the L-type Ca+2 channel, decreasing Ca+2 inflow and exocytosis of vesicles and NT release.In the central nervous system, fast excitatory glutamatergic neurotransmission is mediated by ligand-gated or ionotropic glutamate receptors (iGluRs), predominantly the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)
(6) Vigabatrin is an irreversible inhibitor of GABA transaminase (GABA-T), the enzyme responsible for the breakdown of GABA, increasing levels of GABA. (7) Tiagabine binds to the GABA reuptake transporter (GAT-1), permitting greater levels of GABA in the synapse and more neuronal inhibition. (8) Ezogabine activates K+ ion channels, leading to inward flow of ions and hyperpolarization of neurons. (9) Diazepam, clobazam, and other benzodiazepines coactivate GABAA receptors with GABA, leading to inhibition of neuronal activity. (10) Barbiturates like phenobarbital activate GABAA receptors and increase inhibition. (11) Topirimate and ezogabine augment the activation of the GABAA receptor by GABA.
(12) Gabapentin increases the release of GABA from inhibitory neurons. Not shown is the mechanism of action of ethosuximide and valproate, which block T-type (low-threshold) calcium channels that are located in thalamic
neurons and underlie the propagation of generalized absence seizures.
What is syncope? Syncope (SINK-a-pee) is another word for fainting or passing out
Fainting or a sudden temporary loss of consciousness. A brief stroke-like attack that, despite resolving within minutes to hours, still requires immediate medical attention to distinguish from an actual stroke.
Typical Absence Seizures Typical absence seizures are characterized by sudden, brief lapses of consciousness without loss of postural control. The seizure usually lasts for only seconds, consciousness returns as suddenly as it was lost, and there is no postictal confusion. electrophysiologic hallmark of typical absence seizures is a burst of generalized, symmetric, 3-Hz, spike-and-slow-wave discharges that begins and ends suddenly, superimposed on a normal EEG background.
Atypical Absence Seizures Atypical absence seizures have features that deviate both clinically and electrophysiologically from typical absence seizures. For example, the lapse of consciousness is usually of longer duration and less abrupt in onset and cessation, and the seizure is accompanied by more obvious motor signs that may include focal or lateralizing features. The EEG shows a generalized, slow spikeand-slow-wave pattern with a frequency of ≤2.5 per second, as well as
other abnormal activity. Atypical absence seizures are usually associated with diffuse or multifocal structural abnormalities of the brain and therefore may accompany other signs of neurologic dysfunction such as mental retardation. Furthermore, the seizures are less responsive to anticonvulsants compared to typical absence seizures
by prolonging the inactivated state of voltage sensitive neuronal Na+ channel
An involuntary eye movement which may cause the eye to rapidly move from side to side, up and down or in a circle, and may slightly blur vision
Megaloblastic anemia is a condition in which the bone marrow produces unusually large, structurally abnormal, immature red blood cells (megaloblasts)
NMDA receptors (NMDARs) are glutamate-gated cation channels with high calcium permeability that play important roles in many aspects of the biology of higher organisms
an abnormal sensation, typically tingling or pricking (‘pins and needles’), caused chiefly by pressure on or damage to peripheral nerves.
Adjuvant therapy, also known as adjunct therapy, adjuvant care, or augmentation therapy, is a therapy that is given in addition to the primary or initial therapy to maximize its effectiveness. Excess sleepiness
cause surprise or confusion in (someone)
to minimise neural tube defects and bleeding disorder respectively in the neonate
Individually separate and distinct. between seizures; generalized convulsive status Epilepticus; Duration of seizure activity sufficient to meet the definition of status epilepticus has traditionally been specified as 15–30 min.