Introduction to An Overview on Anti-epileptic Drugs, Introduction to Epilepsy, Types of Seizures, Classification, Mechanism of Action, Pharmacokinetics, Uses, Adverse Effects, Contraindications, New Drugs Presented by A. Harsha Vardan Naidu Department of Pharmacology

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K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 1
A seminar as a part of curricular requirement
for I year M. Pharm I semester
Presented by
A. Harsha Vardan Naidu (20L81S0107)
M. Pharmacy
Department of Pharmacology
Under the guidance of
Mr. A. Sudheer kumar, M. Pharm.
Associate Professor, Department of Pharmacology.

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AUTONOMOUS
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Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 2
• Introduction to Epilepsy
• Types of Seizures
• Classification
• Mechanism of Action
• Pharmacokinetics
• Uses
• Adverse Effects
• Contraindications
• New Drugs
• References
Contents

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• Convulsion is a condition in which muscles contract and relax quickly
and cause uncontrolled shaking of the body.
• Seizure is a change in electrical activity between neurons that causes
temporary abnormalities in muscle tone or movements (stiffness,
twitching), behaviours, sensations or states of awareness.
• Epilepsy is a neurological disorder in which brain activity becomes
abnormal, causing seizures or periods of unusual behaviour, sensations,
and sometimes loss of awareness.
• A seizure is a single occurrence, whereas epilepsy is a neurological
condition characterized by two or more unprovoked seizures.
Introduction

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• Brain conditions including stroke or a tumour
• Genetical problem
• Head trauma, from a vehicle accident
• Drug abuse or alcohol misuse
• Infectious diseases like viral encephalitis
• Lack of oxygen during birth
• Prenatal injury- brain damage that occurs before child birth
• COVID-19 infection
• Blood vessel malformations
Causes of Epilepsy:

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Stages of seizures

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• Partial seizures - Simple partial seizure
- Complex partial seizure
- Partial with secondarily generalised seizure
• Generalized seizures - Tonic clonic/ grandmal seizure
- Clonic seizure
- Tonic seizure
- Atonic seizure
- Myoclonic seizure
- Absence/ Petit mal seizure
• Non epileptic seizure- not related to epilepsy, occurs due to diabetes/ high fever.
• Status epilepticus- condition where seizure lasts for more than 5 mins.
Types of seizures

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Managing seizures

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1. Hydantoins: Phenytoin, Mephentoin
2. Barbiturates: Phenobarbitone, Mephobarbitone
3. Deoxy barbiturate: Primidone
4. Benzodiazepines: Diazepam, Clonazepam, Lorazepam
5. Iminostilbenes: Carbamazepine
6. Succinimides: Ethosuximide
7. GABA transaminase inhibitors: Valproic acid, Vigabatrin
8. GABA analogs: Gabapentin, Pregabalin
9. Others: Lamotrigine, Levetiracetam
Classification

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Conduction of nerve impulse

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Mechanism of action

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Phenytoin
• First line drug for partial seizures.
• Inhibits Na+ channels.
• Prodrug- Fosphenytoin for IM/IV administration. High plasma
protein binding.
• Adverse effects: CNS sedation ( drowsiness, ataxia, confusion,
insomnia, nystagmus), gum hyperplasia, hirsutism.
Carbamazepine
• First line drug for partial seizures.
• Inhibits Na+ channels.
• Adverse effects- CNS sedation, agranulocytosis and aplastic anaemia
in elderly patients, leukopenia.

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Phenobarbital
• Used for partial seizures, effective in neonates.
• Second line drug in adults due to severe CNS sedation.
• Allosteric modulator of GABA-A receptor (increase open time).
• Adverse effects- CNS sedation but produces excitation in some
patients. Skin rashes if allergic. Tolerance and dependence may be
possible.
Primidone
• Used for partial seizures.
• Allosteric modulator of GABA-A receptor (increase open time).
• Not highly bound to plasma.
• Adverse effects- CNS sedation.

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Benzodiazepines
• Eg- Diazepam, Clonazepam.
• Used to treat status epilepticus.
• Allosteric modulators of GABA-A receptor- increase frequency.
• Adverse effects- CNS sedation, paradoxical hyper excitability in
children, tolerance and dependence.
Valproate
• Used for partial seizures, first line drug for generalized seizures.
• Enhance GABA transmission, block Na+ channels, activates K+
channels.
• Adverse effects- CNS depression, anorexia, nausea, vomiting, hair
loss, weight gain, may cause birth defects.

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Ethosuximide
• Used for absence seizures.
• Blocks T-type Ca++ currents in thalamus.
• Adverese effects- gastric distress, pain, nausea, vomiting.
• Less CNS side effects than other anti-epileptic drugs, transient
fatigue, dizziness, headache.
Oxcarbamazepine
• Approved for add-on therapy, monotherapy for partial seizures, that
are refractory to other antiepileptic drugs.
• Activity dependent blockade of Na+ channels, also open K+
channels.
• Similar to carbamazepine, it causes CNS sedation, but may be less
toxic.

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Gabapentin
• Add-on therapy for partial seizures.
• Also effective as monotherapy.
• Interfere with GABA uptake.
• Adverse effects- less CNS sedative than other classic anti-epileptic
drugs.
Lamotrigine
• Add-on therapy and monotherapy for refractive partial seizures.
• Effective against generalized seizures.
• Inhibition of Na+ channels, inhibition of glutamate release, may
inhibit Ca++ channels.
• Less CNS sedative than other anti-epileptic drugs, dermatitis.

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Tiagabine
• Add- on therapy for partial seizures.
• Interferes with GABA reuptake.
• CNS sedative
• Minimal drug interaction.
Zonisamide
• Add- on therapy for partial and generalized seizures.
• Blocks Na+ channels and T- type Ca++ channels.
• Causes CNS sedation.

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Felbamate
• Third-line drug for refractory partial seizures.
• Frequency dependent- inhibition of Na+ channels, modulation of
NMDA receptors.
• Aplastic anaemia and severe hepatits reduces its use.
Levetiracitam
• Add- on therapy for partial seizures.
• Binds to synaptical vessicle protein SV2A, may regulate
neurotransmitter release.
• Causes CNS ddepression.

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• Good absorption from gut, with a bioavailability of 80- 100%.
• They show minimal plasma protein binding( except phenytoin,
valproic acid).
• Half life is usually 12- 24 hours and it increases upto 60 hours
when plasma concentration of drug increases.
• Metabolised in liver by non-CYP450 isoenzymes.
• Enzyme inducers- Phenytoin, Phenobarbital.
• Enzyme inhibitors- Valproate, Topiramate.
• Primarily cleared renally.
Pharmacokinetic profile

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• Used to treat partial, generalized and mixed seizures.
• Used to treat Status epilepticus
• Used as prophylaxis in case of tumours in brain.
• Manic depressive illness and acute mania
• Phenytoin is a group 1B anti-arrhythmic agent.
• Several drugs, especially carbamazepine and lamotrigine, are
useful for bipolar disorder.
• Many drugs are useful in migraine, e.g., phenytoin, gabapentin,
topiramate.
Uses of Antiepileptic Drugs

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• Hypersensitivity reactions like rashes, photosensitivity, hepatitis
• Vomiting, diarrhoea, weight loss, tremors
• At high plasma levels- ataxia, vertigo, nystagmus, drowsiness
• Gum hypertrophy
• Aplastic anaemia
• Foetal hydantoin syndrome
• Osteoporosis
• Teratogenesis
• Neuropathy, coma
• Epigastric pain, hypotension, arrythmias
Adverse effects

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Contraindications
• Cardiac patients
• Pregnant women
• Patients with livers disorder
• People with lung infections etc
Latest discovery
• Levitiracitam
• Brivaracetam
• Cannabidiol
• Stiripentol

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1. Padmaja Udaykumar. Pharmacology for Dental and Allied Health
Sciences. 2017; 4th edition.
2. Tripathi, K. D. Essentials of Medical Pharmacology. 2013. JP
Medical Ltd.
3. Christopher Melinosky. Epilepsy drugs used to treat seizures.
WebMD. 2020.
4. Marketa Mavanova. Pharmacokinetic characteristics of
antiepileptic drugs. NCBI. 2016; 6(1): 8-20.
References

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