Guidelines for medical management of epileptic seizures Department of Pharmacy Department of Pharmacy Department of Pharmacy Department of Pharmacy Chia Chia Chia Chia- - -Yi Chang Gung Memorial Hospital Yi Chang Gung Memorial Hospital Yi Chang Gung Memorial Hospital Yi Chang Gung Memorial Hospital Ya Ya Ya Ya- - -Ju Ju Ju Ju, Ma , Ma , Ma , Ma 2017.01.11 2017.01.11 2017.01.11 2017.01.11
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Guidelines for medical management of epileptic seizures · • Commonly referred to as seizure disorder, epilepsy is a disorder comprising a collection of seizures that differ in
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Guidelines for medical management of epileptic
seizures
Department of Pharmacy Department of Pharmacy Department of Pharmacy Department of Pharmacy
ChiaChiaChiaChia----Yi Chang Gung Memorial HospitalYi Chang Gung Memorial HospitalYi Chang Gung Memorial HospitalYi Chang Gung Memorial Hospital
• Epilepsy is one of the most common neurological diseases.
• Seizures are assigned to one of two major categories: partial or generalized.
• Epilepsy cases can involve more than one type of seizure.
• Commonly referred to as seizure disorder, epilepsy is a disorder comprising a collection of seizures that differ in regard to cause, symptoms, severity, and treatment.
Introduction
• Drug therapy is based on type of seizure, age, gender, comorbidities, adverse-effect potential, drug interactions, and cost.
• In the last 20 years, the FDA has approved 15 new antiepileptic drugs (AEDs) , with many more currently in development.
• First-line treatment is the administration of AEDs .
• These are divided into first-, second-, and third-generation AEDs.
• About 60% of patients achieve adequate seizure control with monotherapy.
Diagnosis
• Electroencephalogram (EEG)• Computed tomography (CT)• Magnetic resonance imaging (MRI)
Pathophysiology
• Seizures occur when there is a disturbance in the balance of excitation and inhibition in the central nervous system (CNS) .
• These factors include changes in ion channel conduction, membrane receptor response, messenger systems, and gene transcription.
• Imbalances between excitatory (glutamate) and inhibitory (GABA) neurotransmitters, as well as excessive acetylcholine, norepinephrine, and serotonin levels, may also precipitate seizures.
ILAE Classification of Seizures
Unknown (4%)
Epileptic spasms
Seizures
Partial (60%) Generalized (36%)
Simple Partial
Complex Partial
Secondarily Generalized
Tonic-Clonic
Absence
Myoclonic
Clonic
Tonic
Atonic
Grand mal
Petit mal
Symptoms
• Depend on the type of seizure or epilepsy.
• Seizures involve abnormal electrical activity that can produce changes in consciousness, motor and sensory activity, and behavior.
• A number of patients can experience an aura or warning symptoms minutes to hours before partial seizures.
• Aura symptoms can differ significantly; examples include irritability, nausea, headache, and fear.
Symptoms
• Generalized seizures involve both hemispheres and typically include bilateral motor symptoms and loss of consciousness.
• The many different types of generalized seizures (tonic-clonic, absence, myoclonic, clonic, tonic, atonic) will vary in motor symptom characteristics.
Mechanisms
• Excitatory and inhibitory currents are primarily mediated by different channels including voltage- and ligand-gated channels.
• Voltage-gated channels include sodium and calcium channels.
• Ligand-gated channels include GABA and glutamate channels.
Vigabatrin 10.5 0 100 Not extensively metabolizedUrine excretion (95%)
Zonisamide 63 50 no significant effect
Liver metabolism (CYP450)Urine excretion (62%)
Treatment considerations
• Although most AEDs can cause common CNS side effects (dizziness and drowsiness)
• Impaired cognition is one major concern for many patients and family members.
• In general, newer agents like gabapentin and levetiracetam appear to have the least effects on cognition and may be better options.
Renal dysfunction
• Should have dosage adjustment performed for topiramate, oxcarbazepine,gabapentin, levetiracetam, pregabalin, vigabatrin andlacosamide to avoid accumulation of the drug or its metabolites.
Drug Clcr ( ml/min ) Dosage (mg)
Topiramate <70 50% of the usual adult dosage
Oxcarbazepine <30 300 QD
Lacosamide <30 or ESRD 300 mg/day
Gabapentin
Clcr ( ml/min ) Dosage (mg)
>60 400 tid
30~60 300 bid
15~30 300 qd
<15 300 qod
Levetiracetam
Clcr ( ml/min ) Dosage (mg)
>80 500~1500 Q12H
50~79 500~1000 Q12H
30~49 250~750 Q12H
<30 250~500 Q12H
End stage 500~1000 QD
Pregabalin
Clcr ( ml/min ) Dosage (mg)
30~60 75~300 bid~tid
15~30 25~150 qd
<15 25~75 qd
Vigabatrin
Clcr ( ml/min ) Dosage (mg)
50~80 ↓dose by 25%
30~50 ↓dose by 50%
10~30 ↓dose by 75%
Liver dysfunction
• A number of agents can affect the liver. Carbamazepine, phenytoin, and valproicacid can cause elevations in liver enzymes and thus should be avoided in patients with liver disease.
• Although these agents have also been known to cause hepatotoxicity, more severe liver problems are rare.
Dermatologic reactions
• Rare, fatal skin reactions like Stevens-Johnson syndrome (SJS) 、 toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms(DRESS) have been reported.
• More common with carbamazepine, valproic acid, phenytoin, phenobarbital, and lamotrigine.
Dermatologic reactions
• In Taiwan , it seems that aromatic AEDs is the main cause for SJS and TEN, and is a secondary reason for DRESS occurred.
• Among those AEDs, carbamazepine is the most common drug to cause SJS/TEN.
• DERSS usually caused by phenytoin.
• The study found that the AEDs (carbamazepine) caused of SJS / TEN and the Asians human leukocyte antigen gene Type HLA-B * 1502 has a strong correlation.
Adverse effects of new antiepileptic drugsAdverse events GBP TPM LTG LEV RFN VGB OXC PER LCM
• Many AEDs are metabolized through the CYP450 system in the liver and can be either enzyme inducers or enzyme inhibitors.
• Enzyme inducing AEDs- phenytoin, phenobarbital, carbamazepine, and primidone.
• Enzyme inhibiting AEDs- valproic acid.
Interactions
• Enzyme inducers can enhance the metabolism of warfarin, oral contraceptives, antibiotics, and antidepressants resulting, in decreased serum concentrations and effects.
• Valproic acid can decrease the metabolism of warfarin, statins, and tricyclic antidepressants, resulting in increased serum concentrations and effects.
Ref:US Pharmacist Published January 23, 2013Epilepsy: Treatment and Management
enzyme inhibitor
LTG+VPA:decrease LTG dose by 50%
TPM+enzy inducer:TPM clearance ↑2X
Preferable indications for the administration of new antiepileptic drugs
Entity Ponderable new AEDs
Background
History of rush, allergy LEV, GBP, TPM
Obesity TPM,LTG,LEV,OXC
Elderly group LEV,LTG,GBP
Comorbidity
Depression LTG,OXC
Cognitive impairment LTG,GBP
Brain tumor LEV,GBP
Migraine TPM
Neuropathic pain GBP,LTG,LCM
Hyperlipidemia no-enzyme inducing AEDs
Co-medications no-enzyme inducing AEDs
LEV,LTG,GBP,PGB,VGB
Therapeutic Drug Monitoring
Drug Target plasma concentration
Ethosuximide 40-100 ug/ml
Phenobarbital 15-40 ug/ml
Phenytoin 10-20 ug/ml
Primidone 5-12 ug/ml
Valproic acid 50-100 ug/ml
TDM is performed when a clear clinical problem occurs
• For the initial diagnosis of partial and major seizures –CBZ, PHT ,PB , OXC and VPA can be considered as the first line .partial seizure-CBZ and PHTgrand mal-CBZ、LTG、OXC、PB、PHT、TPM and VPA
,TPM, VPA and ZNS generalised epilepsy-LTG,LEV, Ethosuximide, VPA and
TPM
• The choice of drugs in combinationshould be matched to the patient's seizure type(s) and should, where possible, be limited to two or at most three AEDs.
• When the type of epileptic seizure is uncertain, or when a grand mal-Valproate,lamotrigine.
Diagonsis of epilepsyDiagonsis of epilepsy
MonotherapyBegin treatmentwith one AED
MonotherapyBegin treatmentwith one AED
Seizure free?Seizure free?
Intolerable side effects?
Intolerable side effects?
↓↓↓↓AED dose↓↓↓↓AED doseOptimal QOLOptimal QOL
Continue current treatment
Continue current treatment
Explore QOL issues?Explore QOL issues?
↑↑↑↑ AED dose↑↑↑↑ AED dose
↓↓↓↓dose of 1st AEDAdd 2nd AED↓↓↓↓dose of 1st AED
Add 2nd AED
Seizure free?Seizure free?
Consider removing 1st
Consider removing 1st
Intolerable side effects?
Intolerable side effects?
Yes
Yes
Yes
Yes
Yes
No
NoNo
No
No
Intolerable side effects?
Intolerable side effects?
Algorithm for the treatment of epilepsy.Algorithm for the treatment of epilepsy.
Ref:Pharmacotherapy: A Pathophysiologic Approach, 9e
Intolerable side effects?
Intolerable side effects?
↑↑↑↑Dose of 2nd AED check for DIC
↑↑↑↑Dose of 2nd AED check for DIC
Remove least effective AED add Another 2nd
AED
Remove least effective AED add Another 2nd
AED
Seizure free?Seizure free?
Continue current treatment
Continue current treatment
Reconfirm diagnosisConsider surgery
Reconfirm diagnosisConsider surgery
Yes
No
NoYes
Ref:Pharmacotherapy: A Pathophysiologic Approach, 9e
Summary
• Recommend initiating an AED in monotherapy who are at hight risk of recurrent seizures.
• If the first AED trial is unsuccessful,a second AED trial is recommended.
• Drug therapy is individualized.
• Each drugs have their advantages and disadvantages.
• Controlling seizures,avoiding treatment side effects,and maintaining or quality of life.