Ethotoin
Pronouncation: (ETH-oh-toyn)
Class: Hydantoin
Trade Names:
Peganone
- Tablets 250 mg
Mechanism of Action
Pharmacology
May act at motor cortex to inhibit spread of seizure activity. Possibly works by promoting sodium efflux from neurons, thereby stabilizing threshold against hyperexcitability. Also, decreases posttetanic potentiation at synapse.
Pharmacokinetics
Absorption
Fairly rapidly absorbed.
Metabolism
Major metabolites are to N-deethyl and p-hydroxyl-ethotoin.
Elimination
Elimination t ½ ranges from 3 to 9 h.
Indications and Usage
Control of tonic-clonic (grand mal) and complex partial (psychomotor) seizures.
Contraindications
Patients with hepatic abnormalities or hematologic disorders.
Dosage and Administration
Adults
PO Start with 1 g/day or less (in 4 to 6 divided doses daily), with subsequent gradual dosage increases over a period of several days. Optimum dosage is based on individual response. Usual maintenance dose is 2 to 3 g/day. Doses less than 2 g have not been found to be effective in most adults.
Children
PO Dose depends on age and weight of patient. Do not start with more than 750 mg/day. Usual maintenance dose ranges from 500 mg to 1 g; although occasionally 2 g or, rarely, 3 g may be necessary.
Storage/Stability
Store tablets at controlled room temperature (below 77°F).
Drug Interactions
Coumarin anticoagulants
Anticoagulant effect may be decreased.
Drugs known to adversely affect the hematopoietic system
Avoid coadministration.
Laboratory Test Interactions
None well documented.
Adverse Reactions
CNS
Ataxia; dizziness; headache; insomnia; fatigue.
Dermatologic
Skin rash.
EENT
Nystagmus; diplopia.
GI
Gingival hyperplasia; vomiting, nausea; diarrhea.
Lymphatic
Lymphadenopathy.
Miscellaneous
Systemic lupus erythematosus; chest pain; fever; numbness.
Precautions
Monitor
Infection
Monitor patient for skin rash, fever, or other signs of infection; sores in the mouth; unusual bruising or bleeding; petechiae. Notify health care provider immediately if noted.
Urinalysis/CBC
Ensure that urinalysis and CBC with differential are performed before starting therapy and at monthly intervals for several months during therapy.
Response to treatment
Frequently assess patient for response to treatment. Notify health care provider if seizures do not improve or appear to worsen.
Review therapy
Ensure that therapy is periodically reviewed to determine if it needs to be continued without change or if a dose change (eg, increase, decrease, discontinuation) is indicated.
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Pregnancy
Category C .
Lactation
Excreted in breast milk.
Blood dyscrasias
May occur. In addition, there is some evidence that hydantoin-like compounds may interfere with folic acid metabolism, precipitating megaloblastic anemia. Ensure that folic acid levels are periodically evaluated during prolonged therapy. Be prepared to supplement folic acid to prevent megaloblastic anemia.
Hepatic function impairment
Ensure that medication is discontinued in patients who develop hepatic function impairment, marked depression of blood count, or lymphadenopathy.
Withdrawal
Avoid sudden discontinuation of therapy if possible. Attempt to gradually reduce dose over a period of several weeks if decision to discontinue medication is made.
Overdosage
Symptoms
Drowsiness, visual disturbances, nausea, ataxia, coma.
Patient Information
- Instruct patient to continue to take other antiepileptic medications as prescribed by health care provider.
- Advise patient to read the patient information leaflet before starting therapy and with each refill.
- Instruct patient to take exactly as prescribed and to not change the dose or discontinue unless advised by health care provider.
- Advise patient that dose is gradually increased as tolerated until max benefit has been obtained.
- Advise patient that each dose should be taken after food.
- Advise patient that if a dose is missed to take it as soon as remembered but if several hours have passed, or it is nearing the time for the next scheduled dose, to skip that dose and take the next dose at the regularly scheduled time. Caution patient to never double the dose to catch up.
- Advise patient that if medication needs to be discontinued it will be slowly withdrawn over a period of several weeks unless safety concerns (eg, rash) require a more rapid withdrawal.
- Caution patient that drug may cause dizziness and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.
- Advise women of childbearing potential to use effective contraception during treatment with ethotoin.
- Instruct patient to contact health care provider immediately if skin rash, fever, sore throat or other signs of infection, yellowing of skin or eyes, easy or unusual bruising, bleeding, or swollen lymph glands develop.
- Instruct patient to inform health care provider if seizures get worse or if new types of seizures occur.
- Advise patient to carry medical identification (eg, card, bracelet) indicating epilepsy and medication use.
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