Pine Fumarate

quetiapine fumarate (kwe tie' ah peen) Seroquel Pregnancy Category C Drug classes

Dibenzothiazepine Antipsychotic Therapeutic actions

Mechanism of action not fully understood: Blocks dopamine and serotonin receptors in the brain; also acts as a receptor antagonist at histamine and adrenergic receptor sites (which may contribute to the adverse effects of orthostatic hypotension and somnolence). Indications

• • •

Treatment of schizophrenia in patients > 18 yr Adjunct or monotherapy for the treatment of manic episodes associated with bipolar disorders Short-term treatment of acute manic episodes associated with bipolar I disorder, as monotherapy or in combination with lithium or divalproex

Contraindications and cautions

• •

Contraindicated with coma or severe CNS depression, allergy to quetiapine, lactation. Use cautiously with CV disease, hypotension, hepatic dysfunction, seizures, exposure to extreme heat, autonomic instability, tardive dyskinesia, dehydration, thyroid disease, pregnancy.

Available forms

Tablets—25, 100, 200, 300 mg Dosages ADULTS

• •

Schizophrenia: 25 mg PO bid. Increase in increments of 25–50 mg bid–tid on days 2 and 3; dosage range by day 4: 300–400 mg/day in 2–3 divided doses. Further increases can be made at 2-day intervals. Maximum dose, 800 mg/day. Manic episodes: 100 mg/day PO divided bid on day 1; increase to 400 mg/day PO in bid divided doses by day 4 using 100-mg/day increments. Range, 400– 800 mg/day given in divided doses.

PEDIATRIC PATIENTS

Not recommended for patients < 18 yr old. GERIATRIC OR DEBILITATED PATIENTS OR PATIENTS WITH HEPATIC IMPAIRMENT

Use lower doses and increase dosage more gradually than in other patients.

Pharmacokinetics Route Oral

Onset Slow

Peak 1.5 hr

Duration Unknown

Metabolism: Hepatic; T1/2: 6 hr Distribution: Crosses placenta; enters breast milk Excretion: Urine and feces Adverse effects

• • • • •

Autonomic: Dry mouth, salivation, nasal congestion, nausea, vomiting, anorexia, fever, pallor, flushed facies, sweating, constipation CNS: Drowsiness, insomnia, vertigo, headache, weakness, tremor, tardive dyskinesias, neuroleptic malignant syndrome CV: Hypotension, orthostatic hypotension, syncope Hematologic: Increased ALT, total cholesterol and triglycerides Other: Risk of development of diabetes mellitus

Interactions

Drug-drug • CNS effects potentiated by alcohol, CNS depressants • Effects decreased with phenytoin, thioridazine, carbamazepine, phenobarbital, rifampin, glucocorticoids; monitor patient closely and adjust dosages appropriately when these drugs are added to or discontinued from regimen • Increased effects of antihypertensives, lorazepam • Decreased effects of levodopa, dopamine antagonists • Potential for heatstroke and intolerance with drugs that affect temperature regulation (anticholinergics); use extreme caution and monitor patient closely Nursing considerations Assessment

•

•

History: Coma or severe CNS depression; allergy to quetiapine, lactation, pregnancy, CV disease, hypotension, hepatic dysfunction, seizures, exposure to extreme heat, autonomic instability, tardive dyskinesia, dehydration, thyroid disease, suicidal tendencies Physical: Body weight, T; reflexes, orientation, IOP; P, BP, orthostatic BP; R, adventitious sounds; CBC, urinalysis, thyroid, liver, and kidney function tests

Interventions

• • • • •

Administer small quantity to any patient with suicidal ideation. Monitor elderly patients for dehydration and institute remedial measures promptly; sedation and decreased sensation of thirst related to CNS effects of drug can lead to severe dehydration. Monitor patient closely in any setting that would promote overheating. Regularly monitor patient for signs and symptoms of diabetes mellitus. Consult physician about dosage reduction and use of anticholinergic antiparkinsonians (controversial) if extrapyramidal effects occur.

Teaching points

• • • • •

Take this drug exactly as prescribed. This drug should not be used during pregnancy; using barrier contraceptives is advised. Maintain fluid intake and use precautions against heat stroke in hot weather. These side effects may occur: Dizziness, drowsiness, fainting (avoid driving or engaging in other dangerous activities); dry mouth, nausea, loss of appetite (use frequent mouth care, eat frequent small meals, and increase fluid intake). Report sore throat, fever, unusual bleeding or bruising, rash, weakness, tremors, dark-colored urine, pale stools, yellowing of the skin or eyes.

Adverse effects in Italic are most common; those in Bold are life-threatening.