Products
Zonisamide is commercially available in the form of capsules (Zonegran). It has been approved in many countries since 2006.
Structure and properties
Zonisamide (C8H8N2O3S, Mr = 212.2 g/mol) is a benzisoxazole derivative and a sulfonamide. It exists as a white powder that is soluble in water.
Effects
Zonisamide (ATC N03AX15) has anticonvulsant and antiepileptic properties. The effects are due to interaction with voltage-gated sodium and calium channels. Zonisamide has a long half-life of 60 hours. Zonisamide additionally inhibits the enzyme carbonic anhydrase, which may cause adverse effects.
Indications
For the treatment of focal seizures with or without secondary generalization in patients with epilepsy.
Dosage
According to the SmPC. Capsules are taken once or twice daily, independent of meals. Therapy initiation is gradual.
Contraindications
- Hypersensitivity, including to sulfonamides.
- Renal dysfunction
- Liver dysfunction
- Taking carbonic anhydrase inhibitors
Full precautions can be found in the drug label.
Interactions
Zonisamide is a substrate of CYP3A4.
Adverse effects
The most common potential adverse effects include decreased bicarbonate levels, headache, poor appetite, and weight loss. Sulfonamides can cause hypersensitivity reactions, some of which are severe.
