Zonisamide is a broad-spectrum antiepileptic structurally similar to sulphonamides.
Also known as: zonegran
DailyMed/FDA — Zonegran; EMC-UK — Zonisamide
DailyMed/FDA — Zonegran; EMC-UK
Two carbonic anhydrase inhibitors: increased risk of renal stones and metabolic acidosis.
Both inhibit carbonic anhydrase (isoenzymes II and IV). The combination multiplies the risk of hyperchloraemic metabolic acidosis (may reach 10-15% of patients), hypokalaemia, and nephrolithiasis. Avoid this combination. If unavoidable, monitor bicarbonate, electrolytes, and GFR fortnightly for the first 3 months, then monthly.
Two carbonic anhydrase inhibitors: significant risk of metabolic acidosis and renal stones.
Both inhibit carbonic anhydrase. The combination significantly increases the risk of metabolic acidosis, hypokalaemia, and nephrolithiasis.
Bicarbonate, electrolytes, GFR, renal ultrasound.
Severe metabolic acidosis, nephrolithiasis.
Avoid combination if possible. If necessary, monitor bicarbonate, electrolytes, and GFR fortnightly.
DailyMed/FDA; EMC-UK
No documented food or drink interactions.
No documented disease interactions.
CONTRAINDICATED in pregnancy. Animal studies show malformations and reproductive toxicity.
CONTRAINDICATED in all trimesters.
Avoid during breastfeeding.
Reliable contraception is mandatory.
DailyMed/FDA — Zonegran; EMC-UK
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Broad-spectrum antiepileptic activity. Na⁺ blockade and carbonic anhydrase inhibition.
Blockade of voltage-gated Na⁺ channels and T-type Ca²⁺ currents. Inhibits carbonic anhydrase (isoenzymes II and IV), contributing to adverse effects (renal stones, metabolic acidosis).
Complete and rapid oral absorption. Bioavailability: 100%. Peak: 2-6 h. Food does not affect absorption.
Metabolised by CYP3A4 (50%) and non-enzymatic reduction (25%). 35% excreted unchanged. Inactive metabolites.
50-70 h.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
