Quetiapine Fumarate - (Seroquel)

Quetiapine Fumarate
(KWET-ee-uh-peen FYOO-muh-rayt)

Pharmacologic class: dibenzothiazepine derivative

Therapeutic class: antipsychotic

Pregnancy risk category: C

How supplied

Tablets: 25 mg, 100 mg, 200 mg

Pharmacokinetics

Absorption: rapid following oral administration; 100% bioavailable.

Distribution: widely distributed throughout body; 83% bound to plasma protein.

Metabolism: extensively metabolized by liver to inactive metabolites.

Excretion: about 73% is recovered in urine; 20% is recovered in feces. Halflife: 6 hours.

Route	Onset	Peak	Duration
P.O	Unknown	1.5 hr	Unknown

Pharmacodynamics

Chemical effect: exact mechanism of action is unknown, but drug is thought to exert antipsychotic activity through blocking dopamine D-2 receptors and serotonin 5-HT₂ receptors in the brain and may also act at histamine H₁ receptors and adrenergic alpha₁ receptors.

Therapeutic effect: improves symptoms associated with psychotic disorders.

Indications and dosages

Management of the manifestations of psychotic disorders. Adults: initially, 25 mg b.i.d , with increases in increments of 25 to 50 mg b.i.d. or t.i.d. on days 2 and 3, as tolerated. Target dose range of 300 to 400 mg daily, divided into two or three doses, by day 4. Further dosage adjustments, if indicated, should generally occur at intervals of not less than 2 days. Dosages can be increased or decreased by 25 to 50 mg b.i.d. Antipsychotic efficacy is generally in dose range of 150 to 750 mg/day. Safety of doses above 800 mg/day has not been evaluated.

Adverse reactions

CNS: asthenia, dizziness, headache, somnolence, hypertonia, dysarthria.

CV: postural hypotension, tachycardia, palpitations, peripheral edema.

EENT: pharyngitis, rhinitis, ear pain.

GI: dry mouth, dyspepsia, abdominal pain, constipation, anorexia.

Hematologic: leukopenia.

Metabolic: weight gain.

Respiratory: increased cough, dyspnea.

Skin: rash, sweating.

Other: back pain, fever, flulike syndrome.

Interactions

Drug-drug. Antihypertensive agents: increased effects. Monitor blood pressure. Carbamazepine, glucocorticoids, phenobarbital, phenytoin, rifampin: increased quetiapine clearance. Adjust dose as needed.

CNS depressants: increased CNS effects. Use cautiously.

Erythromycin, fluconazole, itraconazole, ketoconazole: decreased quetiapine clearance. Use cautiously.

Lorazepam: reduced clearance of lorazepam. Monitor patient.

Drug-lifestyle. Alcohol use: increased CNS effects. Use cautiously.

Contraindications and precautions

Contraindicated in patients hypersensitive to drug or its ingredients.
Use with caution in patients with CV or cerebrovascular disease or conditions that predispose them to hypotension; in those with history of seizures or conditions that lower seizure threshold; and in those who will be experiencing conditions in which core body temperature may be elevated.

NURSING CONSIDERATIONS

Assessment

Monitor patient for tardive dyskinesia. Condition may not appear until months or years after starting drug and may disappear spontaneously or persist for life, despite discontinuation of drug.
Monitor patient's vital signs carefully, especially during the 3- to 5-day period of initial dose titration, when re-initiating treatment, or when increasing dosages.
Assess patient's risk for physical injury due to drug's CNS side effects.
Be alert for adverse reactions and drug interactions.
Evaluate patient's and family's knowledge of drug therapy.

Nursing diagnoses

Risk for altered body temperature related to drug-induced hyperpyrexia.
Impaired physical mobility related to drug-induced CNS side effects.
Knowledge deficit related to drug therapy.

Planning and implementation

Know that elderly or debilitated patients or patients with hepatic impairment or predisposition to hypotensive reactions usually require lower initial doses and more gradual dosage titration.
Withhold drug and notify doctor if symptoms of neuroleptic malignant syndrome occur (hyperpyrexia, muscular rigidity, altered mental status, and autonomic instability).
Provide ice chips, dnnks, or sugarless hard candy to help relieve dry mouth.

Patient teaching

Advise patient of risk of orthostatic hypotension. Risk is greatest during 3- to 5-day period of initial dose titration, when re-initiating treatment, or when increasing dosages.
Tell patient to avoid becoming overheated or dehydrated during therapy.
Warn patient to avoid activities that require mental alertness such as driving a car or operating hazardous machinery until CNS effects of drug are known.
Remind patient to have initial eye examination before starting drug therapy and every 6 months during therapy to monitor for possibility of cataract formation.
Tell patient to notify doctor of other medications (prescription or OTC) he is taking or plans to take.
Tell female patient to notify doctor if she becomes pregnant or intends to become pregnant during drug therapy. Advise her not to breast-feed during therapy.
Advise patient to avoid alcohol during therapy.

Evaluation

Patient maintains normal body temperature.
Patient maintains physical mobility and does not experience extrapyramidal side effects of drug.
Patient and family state understanding of drug therapy.

FDA Public Health Advisory (April 2005)

The Food and Drug Administration has determined that the treatment of behavioral disorders in elderly patients with dementia with atypical (second generation) antipsychotic medications is associated with increased mortality. Of a total of seventeen placebo controlled trials performed with olanzapine (Zyprexa), aripiprazole (Abilify), risperidone (Risperdal), or quetiapine (Seroquel) in elderly demented patients with behavioral disorders, fifteen showed numerical increases in mortality in the drug-treated group compared to the placebo-treated patients. These studies enrolled a total of 5106 patients, and several analyses have demonstrated an approximately 1.6-1.7 fold increase in mortality in these studies. Examination of the specific causes of these deaths revealed that most were either due to heart related events (e.g., heart failure, sudden death) or infections (mostly pneumonia).

The atypical antipsychotics fall into three drug classes based on their chemical structure. Because the increase in mortality was seen with atypical antipsychotic medications in all three chemical classes, the Agency has concluded that the effect is probably related to the common pharmacologic effects of all atypical antipsychotic medications, including those that have not been systematically studied in the dementia population. In addition to the drugs that were studied, the atypical antipsychotic medications include clozapine (Clozaril) and ziprasidone (Geodon). All of tvhe atypical antipsychotics are approved for the treatment of schizophrenia. None, however, is approved for the treatment of behavioral disorders in patients with dementia. Because of these findings, the Agency will ask the manufacturers of these drugs to include a Boxed Warning in their labeling describing this risk and noting that these drugs are not approved for this indication. Symbyax, a combination product containing olanzapine and fluoxetine, approved for the treatment of depressive episodes associated with bipolar disorder, will also be included in the request.

The Agency is also considering adding a similar warning to the labeling for older antipsychotic medications because the limited data available suggest a similar increase in mortality for these drugs.

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Document last modified:01/20/08 05:21:24 AM