Zonisamide

Anti-epileptic · Benzisoxazole derivative

Indications

Monotherapy for partial seizures with or without secondary generalisation in adults with newly diagnosed epilepsy. Adjunctive therapy for partial seizures with or without secondary generalisation.

Dosage

Monotherapy: Adults: > 18 yrs: Initially, 100 mg once daily for 2 wks, Titrate by 100 mg at 2 wks interval; maintenance, 300 mg once daily; Max, 500 mg daily. Adjuctive Therapy: Adults: >18 yrs: Initially 50 mg daily in 2 divided doses; Titrate after 7 days to 100 mg daily in 2 divided doses; then increased by 100 mg every 7 days; maintenance, 300-500 mg daily in 1-2 divided doses. Children: 6-18 yrs: Initially 1 mg/kg once daily for 7 days, Titrate by 1 mg/kg every 7 days; maintenance, body-weight 20-55 kg, 6-8 mg/kg once daily (max.500 mg once daily), body- weight over 55 kg, 300-500 mg once daily.

Adverse Effects

Headache, anorexia, depression, anxiety, speech disorders, tremors, GI upset, alopecia, fatigue, flu like symptoms, raised creatinine and LFTs, stevens-johnson syndrome, reports of blood dyscrasias, dizziness, agitation, confusion, emotional lability, insomnia, psychosis, ataxia, memory impairment, tinnitus, rhinitis, nystagmus, paraesthesia, diplopia, echymosis, rash, pruritus, decreased bicarbonate, nephrolithiasis, fatigue, peripheral oedema, weight loss. Acute myopia with secondary angle-closure glaucoma, blood dyscrasias, Stevens-Johnson syndrome.

Risk Factor (Pregnancy/Lactation)

Contraindications: Underweight or anorexia in children, hypersensitivity to sulfonamides, severe renal or hepatic impairment, ensure contraception till the use of medicine, do not breastfeed during and after 1 month of stopping treatment. Precautions: Hypercalciuria or risk of nephrolithiasis, risk of heat stroke, pancreatitis, substantial weight loss, metabolic acidosis, rhabdomyolysis, mild to moderate renal or hepatic impairment, monitor patient if suicidal thoughts or mood changes developed, monitor weight and serum bicarbonate in children; if children weight is less than 20 kg than withdraw gradually. Elderly.

Interactions

Anticholinergics, glucoronic acid, digoxin, carbonic anhydrase inhibitors, inducers of urolithiasis, inducers and inhibitors of CYP3A4, N-acetyl transferase or glucuronic acid. Digoxin, St John’s wort, clarithromycin, erythromycin, diltiazem, ritonavir, other P-gp substrates.

Pharmacokinetics

Absorption: Oral: Rapid and complete. Metabolism: Hepatic. Half-life elimination: Plasma: Approx. 63 hrs. Time to peak: 2-6 hrs. Excretion: Urine (62%). Faeces (3%).

Compiled by Healify Pharmacy from published drug references. How we compile it →

Always consult a pharmacist or doctor.