Zonisamide

Generic Name: zonisamide

Anti-epileptic Agent [EPC]Over-the-Counter (OTC)

Brand Names:

Zonisamide

DESCRIPTION Zonisamide, USP is an antiseizure drug chemically classified as a sulfonamide and unrelated to other antiseizure agents. The active ingredient is zonisamide, USP, 1,2-benzisoxazole-3-methanesulfonamide. The empirical formula is C 8 H 8 N 2 O 3 S with a molecular weight of 212.23 g/mol. Zonisamide, USP is a white powder, pK a = 10.2, and is moderately soluble in water (0.80 mg/mL) and 0.1 N HCl (0.50 mg/mL).

Overview

DESCRIPTION Zonisamide, USP is an antiseizure drug chemically classified as a sulfonamide and unrelated to other antiseizure agents. The active ingredient is zonisamide, USP, 1,2-benzisoxazole-3-methanesulfonamide. The empirical formula is C 8 H 8 N 2 O 3 S with a molecular weight of 212.23 g/mol. Zonisamide, USP is a white powder, pK a = 10.2, and is moderately soluble in water (0.80 mg/mL) and 0.1 N HCl (0.50 mg/mL).

Uses

INDICATIONS AND USAGE Zonisamide capsules are indicated as adjunctive therapy in the treatment of partial seizures in adults with epilepsy.

Dosage

DOSAGE AND ADMINISTRATION Zonisamide capsules USP are recommended as adjunctive therapy for the treatment of partial seizures in adults. Safety and efficacy in pediatric patients below the age of 16 have not been established. Zonisamide capsules USP should be administered once or twice daily, using 25 mg or 100 mg capsules. Zonisamide capsules USP are given orally and can be taken with or without food. Capsules should be swallowed whole. Adults over Age 16: The prescriber should be aware that, because of the long half-life of zonisamide, up to two weeks may be required to achieve steady state levels upon reaching a stable dose or following dosage adjustment.

Side Effects

ADVERSE REACTIONS The most common adverse reactions with zonisamide (an incidence at least 4% greater than placebo) in controlled clinical trials and shown in descending order of frequency were somnolence, anorexia, dizziness, ataxia, agitation/irritability, and difficulty with memory and/or concentration. In controlled clinical trials, 12% of patients receiving zonisamide as adjunctive therapy discontinued due to an adverse reaction compared to 6% receiving placebo. Approximately 21% of the 1,336 patients with epilepsy who received zonisamide in clinical studies discontinued treatment because of an adverse reaction.

Interactions

Drug Interactions with CNS Depressants: Concomitant administration of zonisamide and alcohol or other CNS depressant drugs has not been evaluated in clinical studies. Because of the potential of zonisamide to cause CNS depression, as well as other cognitive and/or neuropsychiatric adverse events, zonisamide should be used with caution if used in combination with alcohol or other CNS depressants. Other Carbonic Anhydrase Inhibitors: Concomitant use of zonisamide, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor (e.g. topiramate, acetazolamide or dichlorphenamide), may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation or the risk of hyperammonemia.

Warnings

WARNINGS Potentially Fatal Reactions to Sulfonamides: Fatalities have occurred, although rarely, as a result of severe reactions to sulfonamides (zonisamide is a sulfonamide) including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Such reactions may occur when a sulfonamide is readministered irrespective of the route of administration. If signs of hypersensitivity or other serious reactions occur, discontinue zonisamide immediately. Specific experience with sulfonamide-type adverse reaction to zonisamide is described below. Serious Skin Reactions: Consideration should be given to discontinuing zonisamide in patients who develop an otherwise unexplained rash. CONTRAINDICATIONS Zonisamide capsules are contraindicated in patients who have demonstrated hypersensitivity to sulfonamides or zonisamide.

Pregnancy

Pregnancy: (see subsection): Zonisamide may cause serious adverse fetal effects, based on clinical and nonclinical data. Zonisamide was teratogenic in multiple animal species. Zonisamide treatment causes metabolic acidosis in humans. The effect of zonisamide-induced metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) may be associated with decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the fetus’s ability to tolerate labor.

Storage

Store at 25°C (77°F), excursions permitted to 15° C to 30°C (59°F to 86°F). [see USP Controlled Room Temperature]. Store in a dry place and protect from light. Medication Guide available at www.glenmarkpharma-us.com/medguides-bluepoint

Frequently Asked Questions

What is Zonisamide used for?

INDICATIONS AND USAGE Zonisamide capsules are indicated as adjunctive therapy in the treatment of partial seizures in adults with epilepsy.

What are the side effects of Zonisamide?

ADVERSE REACTIONS The most common adverse reactions with zonisamide (an incidence at least 4% greater than placebo) in controlled clinical trials and shown in descending order of frequency were somnolence, anorexia, dizziness, ataxia, agitation/irritability, and difficulty with memory and/or concentration. In controlled clinical trials, 12% of patients receiving zonisamide as adjunctive therapy discontinued due to an adverse reaction compared to 6% receiving placebo. Approximately 21% of the 1,336 patients with epilepsy who received zonisamide in clinical studies discontinued treatment because of an adverse reaction.

Can I take Zonisamide during pregnancy?

Pregnancy: (see subsection): Zonisamide may cause serious adverse fetal effects, based on clinical and nonclinical data. Zonisamide was teratogenic in multiple animal species. Zonisamide treatment causes metabolic acidosis in humans. The effect of zonisamide-induced metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) may be associated with decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the fetus’s ability to tolerate labor.

What are the important warnings for Zonisamide?

WARNINGS Potentially Fatal Reactions to Sulfonamides: Fatalities have occurred, although rarely, as a result of severe reactions to sulfonamides (zonisamide is a sulfonamide) including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Such reactions may occur when a sulfonamide is readministered irrespective of the route of administration. If signs of hypersensitivity or other serious reactions occur, discontinue zonisamide immediately. Specific experience with sulfonamide-type adverse reaction to zonisamide is described below. Serious Skin Reactions: Consideration should be given to discontinuing zonisamide in patients who develop an otherwise unexplained rash. CONTRAINDICATIONS Zonisamide capsules are contraindicated in patients who have demonstrated hypersensitivity to sulfonamides or zonisamide.

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Medical Disclaimer

This drug information is for educational purposes only and should not replace professional medical advice. Drug information is sourced from the FDA National Drug Code Directory and Structured Product Labeling. Always consult with a healthcare provider before starting, stopping, or changing any medication.