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Anticonvulsants
L.O. 16
chapter 16, pg.213
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Epilepsy
Group of disorders characterized by recurrent episodes termed seizures.
These are due to abnormal electrical discharges in the brain, recorded on EEG.
Seizures may be accompanied by involuntary motor activity (convulsions) or other neurologic changes (sensory or emotional)
Treated with anticonvulsant medication, usually for life
Adjuvant medication: benzodiazepines, phenobarbital
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Epilepsy
Causes:
Idiopathic (majority)
genetic
cancers
trauma
infections
toxicity to exogenous agents
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Epilepsy
Classification:
Partial seizures (activity only in one part of the brain):
simple seizures (without loss of consciousness)
complex seizures (loss of consciousness)
Generalized seizures:
absence seizures = petit mal (usually partial loss of consciousness)
tonic-clonic seizures = grand mal (complete loss of conscious.)
Miscellaneous seizures
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Absence seizures
Begins in childhood and disappear in middle age.
Patient usually unaware of the occurrence of seizure,
body tone is not lost, patient quickly returns to normal activity (few seconds).
Treatment: valproic acid, ethosuximide
Risk for the dental team: drug interactions and adverse reactions
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6. Tonic-clonic seizures (grand mal)
Longer periods of loss of consciouness
Major motor activity of large muscles
tonic rigidity of the muscles followed by
clonic jerking of the face, limbs and body
Patient falls to the floor
Might bite lips, tongue. Injury to self
Finally becomes limp and comatose
Consciousness returns gradually, followed by confusion, headache, drowsiness
Treatment: valproic acid, phenytoin, phenobarbital, carbamazepine
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Partial seizures
Last several minutes
Abnormal activity in only one part of the brain, with symptoms different according to location of activity
Simple (elementary) attack: conscious
Complex (psychomotor, temporal-lobe seizure): unconscious, may have an aura, consciouness is slow to return.
Treatment: carbamazepine, phenytoin, phenobarbital, primidone
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8. Anticonvulsant agents
Are CNS depressants that attempt to prevent seizures without causing excessive drowsiness.
Prevent the spread of abnormal electric discharges in the brain. Mechanism of action not completely known.
Single or combination
Narrow therapeutic index
Usually taken for life; chronic toxicity
Complete control of seizures (difficult to achieve), or just reduce frequency
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Adverse reactions
CNS depression:
Impaired learning.
Behavior alteration: hyperactivity or sedation
exacerbation of a seizure type that is not being treated.
Additive with other CNS depressants; opioids, reduce opioid dose.
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Adverse reactions
GI tract:
Anorexia, nausea, vomiting
Minimize these effects by taking the drug with food
Avoid other agents with similar GI effects; NSAIAs and opioids
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Adverse reactions
Dermatological effects:
rash, exfoliate dermatitis, erythematic multiform, Stevens-Johnson syndrome(target lesions)
drug induced systemic lupus erythematous
Hematologic effects:
anemia from folic acid and B12 vitamine deficiency
bleeding because of platelet aggregation inhibition
Teratogenic
Withdrawal: abrupt discontinuation of medication will precipitate seizures
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12. Oral adverse reactions
Gingival enlargement; phenytoin, ethosuximide
Dry mouth: carbamazepine
Glossitis, stomatitis, ulcerations for phenitoin (due to folate deficiency), carbamazepine (dry mouth)
Mucositis; gabapentin(newer anticonvulsant)
Caries in children using chewable carbamazepine due to high content of sugar (63%)
Increased bleeding times: valproates inhibit platelet aggregations
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Gingival enlargement
Cause is unknown
Affects ~50% of chronic users
In about 30% of affected patients is severe enough to require surgical removal
Symptoms appear after few weeks of –few years of treatment
Most affected areas: anterior region, buccal side
Influenced by OH
Younger patients are more affected
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Gingival enlargement
Management: in consultation with patient’s physician
Switch to another effective antiepileptic drug
Substitute ethotoin for phenytoin if possible
Discontinue phenytoin; decrease in gingival enlargement over a 1-year period. Wait with surgical intervention for at least 18 month after therapy is discontinued.
Improve OH
Gingivectomy; regrowth of gingiva with continuation of drug therapy
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Drug interactions
Stimulation of hepatic enzymes, resulting in reduced blood levels of some drugs that are metabolized by the liver
Interactions with other anticonvulsant medications
Narrow therapeutic index, so if level of anticonvulsant medication is altered by drug interaction, either toxicity or loss of seizure control will result.
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Phenytoin (Dilantin)
Treatment of tonic-clonic and partial seizures
Was used to treat trigeminal neuralgia
Has quinidine-like antiarrhythmic properties
Adverse reactions: narrow therapeutic index
Associated with gingival enlargement
Nausea,
confusion, insomnia,
vit.D and folate deficiency: oral ulcers, glossitis
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17. Management of patients taking phenytoin (Dilantin)
If nausea is present, avoid drugs that are gastric irritants
Monitor for gingival enlargement
Administer folic acid if necessary
Provide extensive OHI
Schedule more frequent oral prophylaxis appointments
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18. Carbamazepine (Tegretol)
Related structurally to tricyclic antidepressants
Treat of epilepsy, bipolar depression, trigeminal neuralgia
Side effects; CNS(confusion, fatigue, headache), GI(nausea, vomiting), hematologic (blood dyscrasias, can be serious: anemia, agranulocytosis, thrombocytopenia, leukopenia. Lab tests. Observe oral cavity for petechiae or infections)
Oral side effects; xerostomia, caries for children on chewable tablets
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19. Management of patients taking carbamazepine (Tegretol)
Check for xerostomia, glossitis, stomatits
Avoid drugs that can alter coagulation: additive bleeding
Look for symptoms of blood dyscrasia
Drug interactions: doxycycline has reduced effect, erythromycin increases carbamazepine’s effect
OHI and F as necessary for child on chewable carbamazepine tablets
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Valproic acid
Adverse reactions:
nausea and vomiting
Sedation and drowsiness
Hepatotoxicity, can be serious. Test hepatic function
Bleeding; inhibits platelet aggregation. Caution with other drugs that promote bleeding
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21. Management of patients taking valproic acid (Depakote)
Caution in using other drugs that can alter coagulation; additive bleeding
Look for signs of hepatotoxicity
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22. Management of patients with epilepsy
Education of entire dental team
Detailed seizure history
Treatment planning for low stress, patient not to miss medication
If tonic-clonic seizure occurs:
Place patient on the floor if possible. Or dental chair to horizontal.
Tilt head to prevent aspiration
Remove objects from mouth before seizure to prevent tooth fracture
Do not use tongue blade, as can split and produce oral trauma
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23. Non-seizure uses of anticonvulsants
Neurologic pain:
Carbamazepine for trigeminal neuralgia and atypical facial pain
Phenytoin was use for trigeminal neuralgia
Valproic acid for migraine headache prophylaxis
Psychiatric use:
Carbamazepine, valproic acid, clonazepam, gabapentin as mood stabilizers for bipolar disorder.
A patient on anticonvulsant medication does not necessarily have a seizure disorder, but a neurologic or psychiatric diagnostic
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