zonisamide

Seizures are caused by abnormal electrical activity in the brain and partial or focal seizure is a type in which it is confined to a limited area of the brain. Zonisamide is also used off-label for binge-eating disorder, along with cognitive behavioral therapy, because it appears to suppress the appetite in the brain.

Zonisamide reduces the duration of focal seizures, prevents seizure spread to other regions of the brain, and increases the threshold for generalized seizures. It is more effective for the tonic phase than the clonic phase of seizures. Zonisamide stabilizes the membranes of neurons and suppresses neuronal hypersynchronization by reducing sodium and calcium currents and the action potential. Zonisamide has no effect on the neurotransmitters gamma-aminobutyric acid (GABA) or glutamate.

Warnings

• Do not use in patients with hypersensitivity to sulfonamides, zonisamide, or any of its components. Rare, fatal drug reactions have occurred. Reactions have included life-threatening skin reactions, multiorgan reactions, and blood disorders. Monitor the patient and discontinue zonisamide if hypersensitivity symptoms develop.
• Zonisamide can reduce sweating and dangerously increase body temperature in pediatric patients. Zonisamide is not approved for use in children under 16 years.
• Antiepileptic drugs, including zonisamide, can increase the risk of suicidal thoughts and behavior. Patients, their family, and caregivers should be cautioned.
• Abrupt discontinuation of zonisamide may increase seizure frequency or precipitate status epilepticus, a state of prolonged seizure lasting longer than 5 minutes.
• Zonisamide causes fetal harm. Women of reproductive potential should use effective contraception.
• May cause metabolic acidosis in certain patients. Risk factors include kidney disease, severe respiratory disease, diarrhea, status epilepticus, ketogenic diet, and some drugs.
• Zonisamide can cause central nervous system (CNS) effects including psychiatric symptoms, fatigue, and drowsiness. Patients should avoid tasks that require mental alertness.
• Zonisamide can increase ammonia level, which is neurotoxic and may damage the brain. The risk is higher in patients with inborn metabolic errors.
• Can cause kidney stones. Advise patients to increase water intake.
• Can affect kidney function and increase creatinine levels and blood urea nitrogen (BUN).
• Use zonisamide with caution in patients with impaired liver or kidney function.
• Reports of ophthalmic effects including acute myopia, angle closure glaucoma, ocular pain, and reduced visual acuity.

What are the side effects of zonisamide?

Common side effects of zonisamide include:

• Drowsiness
• Dizziness
• Headache
• Agitation
• Irritability
• Nausea
• Loss of appetite
• Abdominal pain
• Diarrhea
• Indigestion
• Constipation
• Vomiting
• Taste disorder
• Dry mouth
• Weight loss
• Fatigue
• Tiredness
• Confusion
• Depression
• Anxiety
• Nervousness
• Difficulty concentrating
• Memory impairment
• Insomnia
• Mental slowing
• Difficulty with language
• Speech disorder
• Schizophrenic/schizophreniform behavior
• Impaired coordination, balance, and speech
• Abnormal gait
• Weakness
• Numbness and tingling
• Excessive sensitivity of skin
• High temperature
• Low muscle tone
• Tremor
• Seizure
• Status epilepticus
• Repetitive uncontrolled eye movements
• Lazy eye
• Double vision
• Ringing in the ears
• Excessive acidity of body fluids
• Flu-like syndrome
• Accidental injury
• Increased cough
• Throat inflammation
• Nasal inflammation
• Kidney stones
• Facial swelling
• Skin reactions

Less common side effects of zonisamide include:

• Chest pain
• Flank pain
• Feeling unwell
• Allergic reaction
• Neck rigidity
• Gas
• Gum inflammation
• Gum overgrowth
• Gum hemorrhage
• Gastrointestinal inflammation
• Oral and tongue inflammation
• Ulcerative stomatitis
• Gallstone
• Black, tarry stools
• Rectal hemorrhage
• Gastro-duodenal ulcer
• Swallowing difficulty
• Shortness of breath
• Palpitation
• Rapid or slow heart rate
• Vascular insufficiency
• Low or high blood pressure
• Inflammation with blood clot in the vein
• Cerebrovascular accident
• Fainting
• Peripheral edema
• Weight gain
• Thirst
• Dehydration
• Low blood count of leukocyte immune cells
• Low red blood cell count
• Immunodeficiency
• Lymph node swelling
• Leg cramps
• Muscle pain
• Muscle weakness
• Joint pain
• Joint inflammation
• Inflammation of conjunctiva
• Visual field defect
• Glaucoma
• Deafness
• Loss of smell
• High muscle tone
• Twitching
• Vertigo
• Excessive movement and restlessness
• Movement disorder
• Abnormal dreams
• Euphoria
• Increased reflexes
• Nerve damage
• Peripheral nerve inflammation
• Decreased libido
• Impotence
• Absence of menstruation
• Urinary frequency
• Urinary incontinence
• Urinary urgency
• Excessive urination
• Frequent nighttime urination
• Painful urination
• Blood in urine
• Urinary retention
• Dry skin
• Acne
• Hives
• Eczema
• Eruptive skin rashes
• Hair loss
• Abnormal male pattern hair growth in women

Rare side effects of zonisamide include:

• Lupus erythematosus
• Rapid and irregular atrial rhythm
• Extra beats in the ventricles
• Heart failure
• Blood clot in lungs
• Inflammation of the gall bladder or bile ducts
• Jaundice from impaired bile flow
• Blood in vomit
• Esophagus, duodenum, or colon inflammation
• Acute pancreas inflammation
• Fecal incontinence
• Anemia due to red cells being smaller than normal
• Low count of platelets
• Low blood sugar levels
• Low sodium levels
• Increase in lactic dehydrogenase (LDH) enzyme
• Increase in liver enzymes SGOT and SGPT
• Pause in breathing
• Coughing up blood
• Suicidal thoughts and behavior
• Numbness and tingling around the mouth
• Facial paralysis
• Eye muscle spasm
• Light sensitivity
• Inflammation of the iris
• Acute shortsightedness and secondary angle closure glaucoma
• Excessive albumin in urine
• Bladder pain
• Bladder stone
• Breast tissue growth in males
• Breast inflammation
• Excessive menstrual bleeding
• Breakdown of muscle cells
• Increase in creatine phosphokinase
• Drug reaction with eosinophilia and systemic symptoms
• High ammonia levels in the blood and brain damage

Call your doctor immediately if you experience any of the following symptoms or serious side effects while using this drug:

• Serious heart symptoms include fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness;
• Severe headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
• Severe nervous system reaction with very stiff muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, and feeling like you might pass out; or
• Serious eye symptoms include blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights.

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.