Download Anticonvulsants

Chapter 16
Anticonvulsants
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Epilepsy
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A group of functional disorders of the brain
characterized by recurrent single or
multiple seizures accompanied by motor
activity or changes in sensory or emotional
behavior
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Seizure Disorders
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About 10% of the population will have one or
more seizures at some point in life.
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1% to 3% of the population has a chronic seizure
disorder called epilepsy.
Most causes of epilepsy are idiopathic but other causes
include trauma to the head, neoplasm, drugs, and
congenital malformations.
Seizure disorders are classified as either general or
partial.
General seizures include generalized tonic-clonic
seizures and absence seizures.
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Drug Therapy of
Seizure Disorders
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The intent of drug therapy is to reduce the
frequency of seizures and reduce potential
adverse reactions.
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Ideally, the intent is to completely control all
seizures.
 A single drug at the lowest dose possible is
used first.
 If single drug therapy fails, then multiple drug
therapy at low doses is used.
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General Adverse Reactions to
Anticonvulsant Agents
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CNS depression is probably the most
common side effect of anticonvulsants.
CNS depressant effects include dizziness,
sedation, impaired learning and cognitive
abilities, and excitability.
Gastrointestinal adverse effects include
anorexia, nausea, vomiting, and GI upset.
Dermatologic adverse effects range from a
mild rash to Stevens-Johnson syndrome,
which is rare.
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Drug Interactions
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Many drug interactions can occur with
anticonvulsant drugs.
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These drugs increase or decrease the
metabolism of each other in the liver.
 The drug interactions that occur with each
other are more significant than other drugs
because of their narrow therapeutic indexes.
 Plasma monitoring of anticonvulsant drugs is
necessary.
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Dental Management of Patient
Taking Anticonvulsant Agents
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Carbamazepine
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Carbamazepine blocks sodium channels
which blocks the propagation of nerve
impulses.
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Adverse reactions unique to carbamazepine
• Hematologic
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Agranulocytosis has been reported with carbamazepine
therapy.
It usually occurs within 4 months of starting therapy or after
an increase in dose.
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Carbamazepine
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Adverse Reactions Unique to Carbamazepine
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Dry mouth, glossitis, and stomatitis can sometimes
occur.
The pediatric chewable dose form contains 63%
sugar.
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Dental Management of Patient
Taking Carbamazepine
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Valproate
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This drug may exert its anticonvulsant
effects by increasing the levels of GABA.
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This drug has been reported to cause
hypersalivation.
Hepatotoxicity has also been reported.
Valproate inhibits the second phase of platelet
aggregation. As a result, bleeding time may be
prolonged.
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Valproate
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Phenytoin
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Phenytoin is the most commonly used
anticonvulsant drug.
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Phenytoin has a very narrow therapeutic index.
Phenytoin demonstrates zero-order kinetics.
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Phenytoin
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Adverse Effects
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Phenytoin can cause hirsutism which can lead
to noncompliance in young women.
Some patients may experience vitamin D or
folate deficiency. Oral mucosal changes such
as ulcerations or glossitis are indicative of
folate deficiency.
Teratogenicity has also been reported.
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Phenytoin
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Adverse Effects
 Gingival Enlargement
• This occurs in 50% of all chronic users.
• It can appear in as little as a few weeks after
beginning therapy or after several years of
therapy.
• Its cause is unknown.
• The better the oral hygiene, the less likely it will
occur or the less severe the lesions will be.
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Phenytoin
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Adverse Effects
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Managing Gingival Enlargement
• Stop phenytoin and change to another drug.
• Improve and maintain meticulous oral hygiene.
• A gingivectomy may be necessary.
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Phenytoin
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Other Drugs
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Phenobarbital is used alone or in combination with
other antidepressants to treat generalized tonic-clonic
and partial seizures.
Its most common side effect is sedation.
Ethosuximide is the treatment of choice for absence
seizures.
Gingival enlargement and swelling of the tongue
have been reported with ethosuximide.
Benzodiazepines are often used to treat status
epilepticus. They are used as adjunct to treat other
seizures. Oral adverse effects include increased
salivation, coated tongue, dry mouth, and sore gums.
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Newer Anticonvulsants
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Gabapentin is unique in that it does not
appear to have any drug interactions.
Felbamate is limited to those that are
refractory to other anticonvulsants.
Felbamate has been associated with
aplastic anemia and acute hepatic failure.
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