Antiepileptic Medications
during Pregnancy
주산기 전임의 안현숙
>Incidence of Seizure
>The most frequent major neurologic complication encountered in
pregnancy
>Approximately 1% of the general population . (Brodie and Dichter, 1996)
>Pathophysiology
>Paroxysmal dosorder of the CNS
>Abnormal neuronal discharge with or without loss of consciousness
>Two broad categories of epileptic syndrome:
-Partial seizure
-Generalized seizure
Introduction
<Partial seizure>
-15% of all seizure
-Trauma, abscess, tumor, or perinatal factors
1.Simple motor seizures
-Can affect sensory function of produce autonomic dysfunction or
psychological changes
-Consciousness is usually not lost, and recovery is rapid
2.Complex partial seizures
-Called temporal lobe or psychomotor seizures
-Involve clouding of consciousness
<Generalized Seizures>
-85% of seizure
-Involve both brain hemispheres spontaneously
-Preceded by an aura before an abrupt loss of consciousness
-Related with strong hereditary component
1.Grand mal seizure
-Status epilepticus
-With loss of consciousness
-Tonic contraction of the muscles
-Rigid posturing
-Clonic contraction of all extrimities
2.Petit mal seizures
-Absence seizures
-Involve a brief loss of consciousness without muscle activity
-Immediate recovery of consciousness and orientation
>Causes of Seizures:
-Trauma
-Alcohol- and other drug-induced withdrawals
-Brain tumors
-Biochemical abnormalities
-Arteriovenous malformation
>Prevalence of epilepsy in adults in 2005: approx. 1.65% (The Centers for Disease Control and Prevention, Kobau and colleagues, 2008)
>Incidence of pregnant women w/ epilepsy: 0.5% of all pregnancy
>Seizure disorders complicate 1 in 200 pregnancies (Brodie and Dichter, 1996)
>What are major pregnancy-related threats to women
with epilepsy?
- Increased seziures rates
- Risks for fetal malformation
Epilepsy during Pregnancy
>Increased seziures rates
-subtherapeutic anticonvulsant levels and lower seizures threshold
-Can be caused by nausea and vomiting
-Decreased gastrointestinal motilily and use of
antacids that diminish drug absorption
-Pregnancy hypervolemia offset by protein binding
-Induction of hepatic, plasma, and placental enzymes
that increase drug metabolism
-Increased glomerula filtration
-Discontinue medication
-Pregnancy-related sleep deprivation, hyperventilation and pain
during labor
>Risks for fetal malformation
-Untreated epilepsy is not associate with increased malformations.
-But the fetus of an epileptic mother who takes anticonvulsant
medications has an indisputably increased risk of congenital
malformation.
(Thomas and co-workers, 2008; Viinikainen and colleagues, 2006)
-Teratogenic effects of antiepileptic drugs
1)Pregnancy loss
2)Intrauterine growth retardation
3)Congenital malformation
4)Impaired postnatal development
5)Behavioural problems
6)Fetal anticonvulsant syndromes
>Carbamazepine
-Relatively slow absorption
-70~80% protein binding to albumin
-Main route of elimination : Hepatic metabolism
-Drug levels and bioavailability tend to be lower in pregnancy
-Carbamazepine-10,11-epoxide: increase during pregnancy
impaired conversion of carbamazepine
increased carbamazepine metabolism
Pregnancy-induced pharmacokinetic
changes of antiepileptic drugs
>Phenytoin
-Highly bind to protein(90~93%)
-Main route of elimination : Hepatic metabolism
-8-hydoxylation: substantial increased during
pregnancy increased clearance rate and
consequently decreased serum concentration
fall in total serum phenytoin concentration
cause lack of seizure control
>Phenobarbital
-Sedation and impaired cognitive function
-High oral bioavailability(90%), protein-bound(50%)
-Induced hepatic microsomal oxidative enzymes
-Main route of elimination : Hepatic metabolism
-Long elimination half life
>Valproic acid
-Rapidly absorption
-Highly protein-bound to plasma albumin(88~92%)
-Pharmacokinetics limitation by:
1)large fluctuation in the concentration–time profile
2)wide therapeutic index
3)concentration-dependent protein binding
-Dose adjustments during pregnancy
>New antiepileptic drug
:Topiramate, Felbamate, Oxcarbazepine, Gabapentin,
Vigabatrin, Lamotrigine
-no antifolate effects
-no arene oxide metabolites
-no effects on the cytochrome P-450
enzyme system
-Eliminated from the body through
renal clearance
There is little information
regarding their pharmacokinetics
and safety during pregnancy.
1. Some anticonvulsant medication form intermediate oxide metabolites that are known to be embryotoxic.
-Free active oxide radicals
bind to proteins and nucleic acids
interfere with DNA and RNA synthesis
-Critical amounts of free radicals may
increase the risk of perinatal death, intrauterine
growth retardation, and malformations
Mechanisms and clinical
implications of teratogenicity
2. Another mechanism that has been implicated in AED- mediated
teratogenicity is folate deficiency.
-Up to a 90% reduction of serum folate levels
(Ogawa Y, et al 1991)
3. Genetic predisposition
:Decreased epoxide hydrolase activity
Teratogenic effects of antiepileptic drugs Department of Clinical Neuroscience, KarolinskaInstitutet, Stockholm, Sweden
Rates of major congenital malformations in six different registries
Lancet Neurol 2012; 11: 803–13
Teratogenic effects of antiepileptic drugs Department of Clinical Neuroscience, KarolinskaInstitutet,
Stockholm, Sweden
Lancet Neurol 2012; 11: 803–13
>Major goal is seizure prevention
-Treatment for nausea and vomiting
-Prevention seizure-provoking stimuli
-Medication compliance
-Anticonvulsants should be maintained at the lowest dosage
associated with seizure control.
Management in Pregnancy
-Routinely monitor serum drug levels during pregnancy
-Specialized sonographic exam for identifying
anomalies at midpregnancy
>Monotherapy : low birth defect
-Increases the major malformation rate 2~ 3 fold
(therapy with phenytoin, phenobarbital,carbamazepine)
(Perucca, 2005; Thomas and associates, 2008)
-Valproate: increase the risk to as high as 4~8 fold (Eadie, 2008; Wyszynski and colleagues, 2005)
>Effect of antiepileptic drugs on vitamin K
Vitamin K deficiency
-Neonatal hemorrhage
-increased degradation of vitamin K
(enzyme–inducing AEDs such as carbamazepine,
phenytoin, phenobarbital, primidone)
The consensus guidelines:
Antenatal maternal vitamin K supplementation at
20mg orally throught the last 4 weeks of gestational
and 1mg of vitamin K parenterally to the neonate
immediately after deivery.
>Preeclampsia
>Postpartum hemorrhage
>Postpartum depression
>Increased cesarean section rate
>Nonproteinuric hypertension
>Increased incidence of labor induction
>Developing a seizure disorder of epileptic mother’s children
Pregnancy compication
>Adverse outcome of an epileptic women’s pregnancy depends on:
-AED-induced teratogenecity
-Patient’s genetic disposition
-Serverity of patient’s convulsive disorder
>Potential risk of increased seizure activity during pregnancy so as to
make sure that they do not avoid taking their medication.
>Should optimally begin at least 3 month before conception to allow
for adequate supplementation of folic acid
>Need to adequate patient education increased incidence of major
malformations possible adverse effects of AEDs to the fetal CNS
system
Preconceptional counseling
>Genetic counseling
>Quit smoking, maintain good nutrition, get enough sleep
>Gradual Drug discontinuation(over at least 3 months)
-Seizure-free for 2 or more years
>Cannot be avoided anticonvulsant medication:
-Should be achieved by the lowest effective dose of the single AED
-Folate supplementation at 5mg/day should start 3 months before
conception and continue until the end of the first trimester
>Proper seizure control is the primary goal in treating women with
epilepsy.
>Should understand the risks associated with uncontrolled seizures
>Should be used at the lowest effective dose: first-line drug
>Judicious preconceptional, antenatal and postpartum management for
favorable maternal and neonatal outcome
Conclusion
Thank you for your
attention