Zonisamide: Uses, Side Effects, Storage and Precautions

Zonisamide is an anticonvulsant medication primarily used to treat epilepsy. It is prescribed to reduce the frequency and severity of partial seizures in adults. Marketed under the brand name Zonegran, Zonisamide works as an adjunct therapy meaning it's used along with other seizure medications. Its effectiveness lies in its unique dual mechanism of action, offering added control for patients who don't fully respond to a single anticonvulsant.

What is Zonisamide?

Zonisamide is a sulfonamide derivative and a carbonic anhydrase inhibitor. It belongs to a class of drugs known as anticonvulsants. It is used in adults to manage partial-onset seizures and is available as oral capsules. Zonisamide alters the brain's electrical activity to help prevent seizures.

What are the Benefits and Uses of Zonisamide?

Zonisamide provides the following benefits:

• Reduces the frequency of partial seizures
• Works as an add-on therapy for epilepsy
• It may allow lower doses of other seizure drugs when used in combination

Conditions Zonisamide Treats

• Partial seizures in adults with epilepsy (when used with other seizure medications)

Secondary Uses of Zonisamide

While not officially approved, Zonisamide has been used off-label for:

• Migraine prevention
• Bipolar disorder
• Neuropathic pain
• Weight loss (due to its appetite-suppressing effects)

How Does Zonisamide Work?

Zonisamide works through multiple mechanisms:

• Blocks sodium and calcium channels in the brain to stabilize electrical activity and prevent seizure spread
• Inhibits carbonic anhydrase, which may contribute to its anticonvulsant effects
• Modifies neurotransmitter release, reducing excessive excitability in the nervous system

In simpler terms, Zonisamide helps to quiet abnormal brain activity that can lead to seizures.

Zonisamide Dosage

The dosage of Zonisamide varies based on individual needs and medical conditions, and it'should always be tailored and adjusted under the supervision of a healthcare professional.

• Usually taken 1 to 2 times daily by mouth, with or without food
• Start with a low dose, gradually increasing as directed by your doctor
• Drink plenty of fluids to reduce the risk of kidney stones

Note:

• Take it consistently at the same time each day
• Do not stop taking it abruptly-consult your doctor for a proper tapering schedule

What Should I Do If I Miss a Dose?

• Take the missed dose as soon as you remember
• If it's almost time for your next dose, skip the missed one
• Do not take a double dose to make up for the missed dose

What Happens in Case of an Overdose?

Overdose Symptoms:

• Severe drowsiness
• Confusion
• Trouble breathing
• Loss of consciousness

If you suspect an overdose, seek emergency medical attention immediately.

What are the Side Effects of Zonisamide?

Like all medications, Zonisamide may cause side effects ranging from mild to serious, and awareness of these can help in early identification and management.

Common Side Effects:

• Headache
• Nausea or vomiting
• Dizziness
• Abdominal pain
• Dry mouth
• Diarrhea or constipation
• Trouble sleeping
• Blurred or double vision
• Weight loss
• Fatigue
• Changes in taste
• Runny or stuffy nose
• Agitation or anxiety

Less Common but Serious Side Effects:

• Kidney stones
• Rash (can be severe or life-threatening, e.g., Stevens-Johnson syndrome)
• Depression, suicidal thoughts
• Cognitive issues (confusion, memory problems)
• Reduced sweating, leading to heatstroke (especially in hot weather or during physical activity)

Seek immediate medical attention for serious side effects or allergic reactions.

Precautions and Warnings

Before starting Zonisamide, it's essential to consider specific health risks and medical conditions to ensure safe and effective use.

Who Should Avoid Zonisamide?

• People with a known allergy to sulfonamides
• Pregnant or breastfeeding women (unless deemed necessary by a doctor)

Use with Caution If You Have:

• Kidney or liver problems
• Lung/breathing issues
• heatstroke
• History of depression or psychiatric disorders
• Metabolic acidosis
• On a ketogenic diet (may increase acid buildup)

Age Consideration:

• Use with caution in children and older adults due to increased side effect risk.

Are There Any Age Restrictions for Using Zonisamide?

Zonisamide is generally prescribed for adults, but it may be used cautiously in children over 16 years old for certain conditions under close medical supervision.

Alcohol or Food Interactions

• Avoid alcohol; it can increase dizziness, drowsiness, and the risk of seizures
• No significant food restrictions, but adequate hydration is essential to avoid kidney stones

Possible Interactions with Other Medications

Zonisamide can interact with various drugs, which may alter its effectiveness or increase the risk of side effects, so it's essential to review current medications with a healthcare provider.

Zonisamide may interact with:

• Other anticonvulsants (e.g., phenytoin, carbamazepine) - may affect drug levels
• Carbonic anhydrase inhibitors (e.g., acetazolamide) - increased risk of metabolic acidosis
• Orlistat - may affect absorption
• CNS depressants - increased drowsiness and cognitive impairment

Always inform your doctor about all prescription, over-the-counter, herbal, or supplement products you're taking.

How Should Zonisamide Be Stored?

Proper storage of Zonisamide helps maintain its effectiveness and safety, requiring specific conditions to prevent degradation.

• Store at room temperature (15°C to 30°C or 59°F to 86°F)
• Keep in a dry place, away from light and moisture
• Do not freeze
• Keep out of reach of children and pets

What Happens If Zonisamide Is Not Stored Properly?

• Exposure to heat, moisture, or light may reduce effectiveness
• Expired or improperly stored medication'should be disposed of safely

Zonisamide vs. Lacosamide:

References