Drug Class Description

Drug Description

Presentation

Indications

Adult Dosage

Initially two 5 ml spoonfuls daily and adjusted thereafter to the patient's needs; daily dosage should be increased by small increments, for example, by 5 ml every 4 to 7 days until control is achieved with minimal side effects. Although 20-30 ml daily in divided doses often produces control of seizures, higher doses up to 40 ml daily may occasionally be required.

Child Dosage

The initial dose is 5 ml daily which is adjusted by small increments until control is achieved with minimal side effects. The optimal dose for most children is 20mg/kg/day. This dose has given average plasma levels within the accepted therapeutic range of 40 to 100mg/l.

Contra Indications

Hypersensitivity to succinimides, ethosuximide or any of the components of this medication.

Zarontin Syrup contains sucrose. Patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.

Special Precautions

Suicidal ideation and behaviour have been reported in patients treated with anti-epileptic agents in several indications. A meta-analysis of randomised placebo controlled trials of anti-epileptic drugs has also shown a small increased risk of suicidal ideation and behaviour. The mechanism of this risk is not known and the available data do not exclude the possibility of an increased risk for ethosuximide.

Therefore patients should be monitored for signs of suicidal ideation and behaviours and appropriate treatment should be considered. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behaviour emerge.

Ethosuximide when used alone in mixed types of epilepsy, may increase the frequency of generalised tonic-clonic (grand mal) seizures in some patients.

As with other anticonvulsants, it is important to proceed slowly when increasing or decreasing dosage, as well as when adding or eliminating other medication. Abrupt withdrawal of anticonvulsant medication may precipitate absence (petit mal) seizures.

Haemopoietic Effect

Blood dyscrasias including some with fatal outcome have been reported to be associated with the use of ethosuximide; therefore, periodic blood count determinations should be performed. Should symptoms and/or signs of infection (e.g. sore throat, fever) develop, blood count determinations should be performed at that point.

Hepatic/Renal Impairment

Zarontin should be used with extreme caution in patients with impaired hepatic or renal function. Periodic urinalysis and liver function studies are advised for all patients receiving the drug. Ethosuximide is capable of producing morphological and functional changes in the animal liver. In humans, abnormal liver and renal function studies have been reported.

Autoimmune Disorders

Cases of systemic lupus erythematosus have been reported with the use of ethosuximide. The physician should be alert to this possibility. Additionally, lupus-like reactions have been reported in children given ethosuximide. They vary in severity from systemic immunological disorders, which include the nephrotic syndrome, to the asymptomatic presence of antinuclear antibodies. The nephrotic syndrome is rare and a complete recovery has usually been reported on drug withdrawal

Information for Patients

Patients taking taking ethosuximide should be advised of the importance of adhering strictly to the prescribed dosage regimen.

Patients should be instructed to promptly contact their physician if they develop signs and/or symptoms (eg., sore throat, fever) suggesting an infection (See Haemopoietic Effect above)

Interactions

Since ethosuximide may interact with concurrently administered antiepileptic drugs, periodic serum level determinations of these drugs may be necessary (e.g. ethosuximide may elevate phenytoin serum levels and valproic acid has been reported to both increase and decrease ethosuximide levels).

Adverse Reactions

Blood and lymphatic system disorders: Agranulocytosis, aplastic anaemia, eosinophilia, leucopenia and pancytopenia, with or without bone marrow suppression. In most cases of leucopenia, the blood picture has been restored to normal on reduction of the dosage or discontinuation of the drug. Where leucopenia has occurred with other drugs, the polymorph count has in some cases increased steadily after starting treatment with ethosuximide and discontinuing the previous medication. Monocytosis, leucocytosis and transitory mild eosinophilia have also been noted.

Immune system disorders: Allergic reaction, systemic lupus erythematosus.

Metabolism and nutrition disorders: Weight loss.

Psychiatric disorders: Psychiatric or psychological aberrations associated with ethosuximide administration have included aggressiveness, disturbances of sleep, inability to concentrate and night terrors. These effects may be noted particularly in patients who have previously exhibited psychological abnormalities. There have been rare reports of increased libido.

Nervous system disorders: Fatigue, headache. Neurologic and sensory reactions reported during therapy with ethosuximide have included ataxia, dizziness, drowsiness, euphoria, extrapyramidal side effects, hyperactivity, irritability and lethargy.

Eye disorders: Myopia.

Respiratory, thoracic and mediastinal disorders: Hiccups.

Gastrointestinal disorders: Abdominal pain, gastrointestinal symptoms occur frequently and include anorexia, cramps, diarrhoea, epigastric pain, nausea, vague gastric upset and vomiting. There have been reports of gum hypertrophy and swelling of the tongue.

Skin and subcutaneous tissue disorders: Pruritic erythematous rashes, Stevens-Johnson syndrome, urticaria.and alopecia

Renal and urnary disorders: Haematuria.

Reproductive system and breast disorders: Vaginal bleeding.

Manufacturer

Drug Availability

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