zonisamide

zonisamide

 [zo-nis´ah-mīd″]

a sulfonamide that acts as an anticonvulsant , used as an adjunct in the treatment of partial seizures in adults; administered orally.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

zonisamide

Zonegran

Pharmacologic class: Sulfonamide

Therapeutic class: Anticonvulsant

Pregnancy risk category C

Action

Raises seizure threshold and reduces seizure duration, probably by stabilizing neuronal membranes through action on sodium and calcium channels

Availability

Capsules: 25 mg, 50 mg, 100 mg

Indications and dosages

➣ Adjunctive treatment of partial seizures

Adults and children older than age 16: Initially, 100 mg P.O. daily for 2 weeks, then, if required, increased to 200 mg P.O. daily for at least 2 weeks. May increase in 100-mg increments at 2-week intervals to 300 to 400 mg daily as required. Daily dosage ranges from 100 to 600 mg.

Dosage adjustment

• Hepatic or renal impairment

• Elderly patients

Off-label uses

• Infantile spasms

• Progressive myoclonic epilepsy

• Weight loss

Contraindications

• Hypersensitivity to drug or other sulfonamides

Precautions

Use cautiously in:

• hepatic or renal disease

• pregnant or breastfeeding patients

• children younger than age 16 (safety not established).

Administration

• Give with or without food.

Adverse reactions

CNS: drowsiness, fatigue, agitation, irritability, depression, dizziness, psychomotor slowing, psychosis, asthenia, abnormal gait, incoordination, tremor, ataxia, headache, confusion, impaired memory, hyperesthesia, paresthesia, seizures

EENT: diplopia, amblyopia, nystagmus, tinnitus, rhinitis, pharyngitis

GI: nausea, vomiting, diarrhea, dyspepsia, dry mouth, anorexia, pancreatitis

GU: renal calculi

Hematologic: anemia, leukopenia

Respiratory: cough

Skin: rash, pruritus, bruising, Stevens-Johnson syndrome

Other: abnormal taste, weight loss, allergic reactions, oligohidrosis and hyperthermia (in children), flulike symptoms, accidental injury

Interactions

Drug-drug. Carbamazepine, phenobarbital, phenytoin, valproic acid: decreased zonisamide blood level and effects

CYP450-3A4 inducers: decreased zonisamide half-life

CYP450-3A4 inhibitors: increased zonisamide blood level

Drug-diagnostic tests. Blood urea nitrogen, creatine kinase, creatinine: increased levels

Platelets, white blood cells: decreased counts

Patient monitoring

• Monitor CBC with white cell differential.

• Assess neurologic status; report significant adverse reactions.

• Monitor renal function tests. Watch for signs and symptoms of renal calculi.

☞ Monitor for rash, which may be first sign of Stevens-Johnson syndrome. If rash occurs, discontinue drug and notify prescriber immediately.

Patient teaching

• Explain therapy to patient. Instruct him to keep seizure diary and show it to prescriber.

• Instruct patient to swallow capsules whole. Advise him to drink 6 to 8 glasses of water daily to help prevent kidney stones.

☞ Warn patient that stopping drug abruptly may cause status epilepticus.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects him and until seizures are well controlled.

☞ Tell patient to immediately report rash, fever, sore throat, sudden back pain, depression, speech or language problems, or painful urination.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved