What is the typical dosage and usage of Zonogran (zonisamide)?

Zonisamide (Zonegran) Dosage and Usage

Zonisamide is typically administered at an initial dose of 100 mg daily, gradually titrated to 200-400 mg daily for most indications, with dosing adjustments needed for patients with renal or hepatic impairment. 1

Standard Dosing for Epilepsy (FDA-Approved Indication)

• Initial dose: 100 mg once daily 1
• After two weeks, increase to 200 mg daily and maintain for at least two weeks 1
• Can be further increased to 300 mg daily and then 400 mg daily, with each dose maintained for at least two weeks to achieve steady state 1
• Effective dose range: 100-600 mg daily, with no additional benefit typically seen above 400 mg daily 1
• Can be administered once or twice daily, with or without food; capsules should be swallowed whole 1

Dosing Considerations

• Long half-life (~60 hours) allows for once-daily dosing in most patients 2
• Slow titration is recommended to minimize side effects, particularly for doses above 300 mg daily 1
• Therapeutic levels can be achieved more rapidly with loading doses of 600-900 mg given as divided doses over 6-12 hours in monitored settings, though this is not the FDA-approved approach 3

Special Populations

• Renal or Hepatic Impairment: Patients require slower titration and more frequent monitoring as zonisamide is metabolized in the liver and excreted by the kidneys 1
• Pediatric Patients: Safety and efficacy not established in patients under 16 years of age 1

Off-Label Uses

Cyclic Vomiting Syndrome

• Starting dose: 100 mg daily 4
• Goal dosage: 200-400 mg daily 4
• Common side effects: Irritability, confusion, depression 4
• Titration: Increase by 100 mg daily every 2 weeks to goal dose 4
• Monitoring: Check electrolytes and renal function twice annually 4

Weight Loss (Off-Label)

• Zonisamide has demonstrated efficacy for weight loss in obese adults when combined with a hypocaloric diet 5
• In clinical trials, doses of 400-600 mg daily resulted in significant weight loss compared to placebo 5
• Not FDA-approved for weight management, though it has pharmacologic properties similar to topiramate, which is used in combination products for obesity 4

Common Adverse Effects

• Central nervous system effects: Somnolence, dizziness, cognitive dysfunction, irritability, confusion, depression 4, 2
• Gastrointestinal effects: Anorexia, nausea 2
• Metabolic effects: Weight loss (may be advantageous in some patients) 4, 5
• Renal effects: Increased risk of kidney stones 4

Monitoring Recommendations

• Monitor serum electrolytes and renal function twice annually 4
• Assess for cognitive side effects, particularly at higher doses 2
• Monitor for weight changes, which may be desirable or undesirable depending on the indication 5

Clinical Pearls

• Zonisamide has multiple mechanisms of action, including inhibition of sodium channels and reduction of T-type calcium currents 2
• Has a low potential for drug interactions compared to many other antiepileptic medications 2
• Demonstrated favorable long-term retention rates in epilepsy studies, suggesting good overall effectiveness and tolerability 2
• Avoid use in patients with history of kidney stones due to increased risk 4