ziprasidone hydrochloride

Action

Unknown. Thought to antagonize dopamine₂ and serotonin₂ receptors.

Availability

Capsules: 20 mg, 40 mg, 60 mg, 80 mg

Injection (powder, lyophilized for solution): 20 mg/ml

Indications and dosages

➣ Schizophrenia

Adults: Initially, 20 mg P.O. b.i.d. with food; may increase q 2 days up to 80 mg b.i.d. Usual maintenance dosage is 20 to 80 mg P.O. b.i.d.; maximum recommended dosage is 80 mg b.i.d. For prompt control of acute agitation, 10 to 20 mg I.M. as a single dose; depending on patient's response, may repeat 10-mg I.M. dose q 2 hours or 20-mg I.M. dose q 4 hours to a maximum daily dosage of 40 mg.

➣ Acute treatment as monotherapy of manic or mixed episodes associated with bipolar I disorder

Adults: Initially, 40 mg P.O. b.i.d. with food; may increase to 60 or 80 mg P.O. b.i.d. on second day of treatment and subsequently adjust on basis of tolerance and efficacy within range of 40 to 80 mg P.O. b.i.d. For maintenance (as an adjunct to lithium or valproate), continue treatment at same dosage on which patient was initially stabilized, within range of 40 to 80 mg P.O. b.i.d. with food; also continue periodic assessments to determine need for maintenance treatment.

Contraindications

• Hypersensitivity to drug

• History of arrhythmias, prolonged QT interval

• Recent myocardial infarction

• Uncompensated heart failure

• Concomitant use of arsenic trioxide, chlorpromazine, class IA or III anti-arrhythmics, or other drugs that prolong the QT interval

Precautions

Use cautiously in:

• renal impairment, cerebrovascular disease, history of seizures or with conditions that lower seizure threshold, cardiovascular disorders, dysphagia, hyperprolactinemia

• bradycardia, hypokalemia, or hypomagnesemia (avoid use)

• adverse reactions with previous use of atypical antipsychotics (such as risperidone or clozapine)

• pregnant patients

• breastfeeding patients (use not recommended)

• children (safety and efficacy not established).

Administration

• Give with food.

• Know that P.O. therapy should replace I.M. therapy as soon as possible.

See Don't give with drugs that prolong the QT interval.

Adverse reactions

CNS: dizziness, drowsiness, dystonia, hypertonia, asthenia, akathisia, extra-pyramidal reactions, agitation, headache, insomnia, personality disorder, paresthesia, speech disorder, neuroleptic malignant syndrome, seizures, suicide attempt

CV: orthostatic hypotension, hypertension, tachycardia, arrhythmias (from prolonged QT interval)

EENT: abnormal vision, rhinitis

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

GU: dysmenorrhea, priapism

Metabolic: hypomagnesemia (rare), hypokalemia, hyperglycemia

Musculoskeletal: myalgia

Respiratory: cough, cold symptoms

Skin: urticaria, rash, fungal dermatitis, diaphoresis, photosensitivity

Other: accidental injury, pain at I.M. injection site

Interactions

Drug-drug. Antihypertensives: additive hypotension

Carbamazepine: decreased ziprasidone blood level

Centrally acting drugs: additive CNS effects

Dopamine agonists, levodopa: antagonism of these drugs' effects

Drugs that decrease potassium or magnesium level (such as diuretics) or prolong QT interval (such as dofetilide, moxifloxacin, pimozide, quinidine, sotalol, sparfloxacin, thioridazine): increased risk of arrhythmias

Ketoconazole: increased ziprasidone blood level

Drug-diagnostic tests. Glucose, magnesium, potassium: decreased levels

Drug-food. Any food: increased drug absorption

Drug-herbs. Chamomile, hops, kava, skullcap, valerian: increased CNS depression

Patient monitoring

See Monitor ECG before and during therapy. Stay alert for prolonged QT interval. Know that dizziness, syncope, or palpitations may signify life-threatening arrhythmias caused by prolonged QT interval.

See Obtain baseline serum potassium and magnesium levels in patients at risk for significant electrolyte disturbances. Replace potassium and magnesium as appropriate before proceeding with therapy. Periodically monitor serum potassium and magnesium levels in patients on concurrent diuretics. Discontinue drug in patients with persistent QTc measurements greater than 500 msec.

• In patients with preexisting low white blood cell count (WBC) or history of leukopenia or neutropenia, determine WBC count frequently during first few months of therapy; discontinue drug at first sign of WBC decrease in the absence of other causative factors.

• Monitor patients with risk factors for diabetes mellitus for signs and symptoms of hyperglycemia, including polydipsia, polyuria, polyphagia, and weakness, and perform glucose testing before and during treatment.

• Assess blood pressure for hypertension and orthostatic hypotension.

See Monitor neurologic status, especially for neuroleptic malignant syndrome and tardive dyskinesia. Immediately discontinue drug and provide appropriate treatment if these conditions develop. However, some patients who develop tardive dyskinesia may require this drug despite the presence of the syndrome.

See Be aware that patient with bradycardia, hypokalemia, or hypomagnesemia is at greater risk for torsades de pointes and sudden death.

See Closely supervise patients at high risk for suicide.

See Discontinue drug in patients who develop a rash without an identified cause.

Patient teaching

• Tell patient to take with food.

• Explain therapy and need for follow-up laboratory testing.

See Advise patient to promptly report suicidal thoughts or actions, extra-pyramidal reactions (such as repetitive, involuntary, purposeless movements), severe thirst or other signs of hyperglycemia, rash, fainting, seizures, high fever, sweating, unstable blood pressure, stupor, muscle rigidity, or suspected infection.

• Instruct patient to consult prescriber before taking over-the-counter preparations.

• Caution patient to avoid driving and other hazardous activities until drug effects are known.

• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure drop.

• Advise patient to avoid sun exposure and to wear sunscreen and protective clothing when going outdoors.

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