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Zonisamide information from DrugsUpdate  

See Available Brands of Zonisamide in India

P - Caution when used during pregnancy
L - Contraindicated in lactation

Zonisamide is a sulfonamide anticonvulsant approved for use as an adjunctive therapy in adults with partial-onset seizures for adults; infantile spasm, mixed seizure types of Lennox-Gastaut syndrome, myoclonic, and generalized tonic clonic seizure.

Pharmacodynamics

Pharmacokinetics

Zonisamide is a benzisoxazole derivative anticonvulsant containing sulfonamide. It may act on voltage sensitive sodium and calcium channels, thereby affecting neuronal firing and therefore reducing the spread of seizure discharges. It may modulate GABA mediated neuronal inhibition.

Absorption
Absorbed from GI tract; peak plasma concentration: 2-6 hours. Bioavailability: High. Food delays time to peak concentration.

Distribution
Widely distributed. Crosses placenta and distributed into breast milk. Protein binding: 40-50%; extensively bound to erythrocytes.

Metabolism
Undergoes hepatic metabolism via cytochrome P450 isoenzyme CYP3A4 to metabolites.

Excretion
Excreted mainly via urine as metabolites and unchanged drug (15-30%). Plasma elimination half life: 63 hours.

Zonisamide Indications / Zonisamide Uses

Information Not Available

Zonisamide Adverse Reactions / Zonisamide Side Effects

Abdominal pain, anorexia, diarrhoea, nausea, headache, dizziness, ataxia, nystagmus, paraesthesia, confusion, difficulty concentrating, impaired memory, mental slowing, speech abnormalities, difficulty in verbal expression, agitation and/or irritability, depression, insomnia, schizophrenic behaviour, somnolence, fatigue, ecchymosis, weight loss, rash, diplopia, decreased sweating, renal stones, pancreatitis, rhabdomyolysis.

Potentially Fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis, blood dyscrasias.

Precautions

Information Not Available

Special Precautions

Pregnancy. Child. Renal or hepatic impairment. Patient at risk of nephrolithiasis; ensure adequate hydration to prevent renal stones. Discontinue use if unexplained rash develops; otherwise, frequent observation is necessary. Withdraw gradually and reduce dosage slowly. Avoid driving and operating machinery. Monitor serum creatine phosphokinase and aldolase levels if patient develops severe muscle pain or weakness; withdraw if levels are raised. Monitor pancreatic lipase and amylase levels in patients who develop pancreatitis and withdraw zonisamide if needed. Consider drug withdrawl in patients with severe weight loss. Monitor renal function periodically.

Other Drug Interactions

Small decrease in zonisamide levels with phenytoin, phenobarbital, carbamazepine. Zonisamide has variable effects on carbamazepine levels. Increased zonisamide levels with lamotrigine.

Other Interactions

Information Not Available

Dosage

Oral
Partial seizures
Adult: Initially, 50 mg daily in 2 divided doses, may increase to 100 mg daily after 1 week. Thereafter, may further increase dose at weekly intervals in steps of up to 100 mg. Usual dose: 300-500 mg daily, although some patients may respond to lower doses.

Renal impairment: Dose reduction and slower titration may be needed.
Hepatic impairment: Mild to moderate: Slower titration may be needed. Severe: Not recommended.

Food(before/after)

May be taken with or without food

List of Contraindications

Zonisamide and Pregnancy

Caution when used during pregnancy

Zonisamide and Lactation

Contraindicated in lactation

Zonisamide and Children

Safety and efficacy in children younger than 16 years not established.

Zonisamide and Geriatic

Select dose with caution, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and comorbidity.

Zonisamide and Other Contraindications

Known hypersensitivity to sulfonamide. Lactation.

Storage

Oral
Store below 30°C.

Lab interference

Oral
Store below 30°C.

Zonisamide brands in India:

Zonegran Zonicare Zonimid Zonisep Zonit Zopicon

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