Zonisamide add-on for drug-resistant partial epilepsy

Area of Science:

• Neurology
• Pharmacology

Background:

• Up to 30% of epilepsy patients develop drug-resistant epilepsy, particularly those with partial seizures.
• Zonisamide is an antiepileptic agent used as an add-on treatment.

Purpose of the Study:

• To evaluate the efficacy and tolerability of zonisamide as an add-on treatment for drug-resistant partial epilepsy.

Main Methods:

• Systematic review of randomized, placebo-controlled, add-on trials of zonisamide.
• Searched multiple databases including Cochrane, MEDLINE, SCOPUS, and ClinicalTrials.gov.
• Assessed risk of bias and quality of evidence using GRADE approach.

Main Results:

• Zonisamide (100-500 mg/day) significantly increased the likelihood of a 50% or greater seizure frequency reduction (RR 1.92, NNT 6).
• Treatment withdrawal was also increased (RR 1.47, NNT 21).
• Adverse effects like ataxia, somnolence, agitation, and anorexia were significantly associated with zonisamide.

Conclusions:

• Zonisamide demonstrates efficacy as an add-on treatment for drug-resistant partial epilepsy.
• Minimum effective and maximum tolerated doses were not identified.
• Results are limited to short-term effectiveness and cannot be extrapolated to monotherapy or other epilepsy types.