Quetiapine is indicated for the treatment of Acute and chronic psychoses, including schizophrenia, Bipolar Disorder including: treatment of manic episodes satisfying DSM-IV criteria for mania associated with bipolar disorder, treatment of depressive episodes associated with bipolar disorder, maintenance treatment of bipolar I disorder, in combination with a mood stabilizer, for the prevention of recurrence of manic, depressive or mixed episodes.
Atypical neuroleptic drugs
Quetiapine is an dibenzothiazepine atypical antipsychotic agent. Its clinical antipsychotic properties and low extrapyramidal side effect is mediated through a combination of D2 and 5-HT2 receptor antagonism. It has high affinity at histaminergic H1 and adrenergic α1 receptors, moderate affinity at adrenergic α2 receptors and moderate to high affinity at several antimuscarinic receptors.
Dosage & Administration
Acute and chronic psychoses, including schizophrenia: Quetiapine should be administered twice daily, with or without food. The total daily dose for the first four days of therapy is 50 mg (Day 1), 100 mg (Day 2), 200 mg (Day 3) and 300 mg (Day 4). From Day 4 onwards, the dose should be titrated to the usual effective dose range of 300-450 mg/day. However, this may be adjusted, depending on the clinical response and tolerability of the individual patient, within the range 150 to 750 mg/day.
Manic episodes associated with bipolar disorder: Quetiapine should be administered twice daily, with or without food. The total daily dose for the first four days of therapy is 100 mg (Day 1), 200 mg (Day 2), 300 mg (Day 3) and 400 mg (Day 4). Further dosage adjustments up to 800 mg/day by Day 6 should be in increments of no greater than 200 mg/day. The dose may be adjusted depending on clinical response & tolerability of the individual patient, within the range of 200 to 800 mg/day. The usual effective dose is in the range of 400 to 800 mg/day.
Depressive episodes associated with bipolar disorder: Quetiapine should be administered once daily at bedtime, with or without food. The usual dose is 300 mg/day. The daily dose for the first four days of therapy is 50 mg (Day 1), 100 mg (Day 2), 200 mg (Day 3) and 300 mg (Day 4). Quetiapine can be titrated to 400 mg on Day 5 and up to 600 mg by Day 8. Antidepressant efficacy was demonstrated with Quetiapine at 300 mg and 600 mg, however no additional benefit was seen in the 600 mg group during short term treatment. Maintenance treatment of bipolar I disorder in combination with mood stabilizers: Patients who have responded to Quetiapine in combination therapy with a mood stabiliser for acute treatment of bipolar disorder should continue on Quetiapine therapy at the same dose. Quetiapine dose can be re-adjusted depending on clinical response and tolerability of the individual patient. Efficacy was demonstrated with Quetiapine (administered twice daily totalling 400 mg to 800 mg a day) as combination therapy with a mood stabilizer.
Caution should be exercised when Quetiapine is used concomitantly with medicines known to cause electrolyte imbalance or to increase QT interval. Co-administration of Quetiapine and thioridazine or carbamazepine caused increases in the clearance of Quetiapine. Co-administration of Quetiapine with another microsomal enzyme inducer, phenytoin, also caused increases in the clearance of Quetiapine.
Quetiapine is contraindicated in patients who are hypersensitive to it.
The most commonly reported Adverse Drug Reactions (ADRs) with Quetiapine are somnolence, dizziness, dry mouth, withdrawal (discontinuation) symptoms, elevations in serum triglyceride levels, elevations in total cholesterol (predominantly LDL cholesterol), decreases in HDL cholesterol, weight gain, decreased haemoglobin and extrapyramidal symptoms.
Pregnancy & Lactation
The safety and efficacy of Quetiapine during human pregnancy have not been established. Therefore, Quetiapine should only be used during pregnancy if the benefits justify the potential risks and the administered dose and duration of treatment should be as low and as short as possible. The degree to which Quetiapine is excreted into human milk is unknown. Women who are breast-feeding should therefore be advised to avoid breast-feeding while taking Quetiapine.
Neuroleptic malignant syndrome, tardive dyskinesia. Hypotension and syncope, especially during the initial dose titration period. Conduct eye examinations prior to or shortly after starting Quetiapine and at 6-month intervals thereafter; discontinue the drug if clinically significant lens changes are observed. History of seizures. Hypothyroidism. Hyperprolactinemia. Antiemetic effect. Suicide. Use with great caution in moderate or severe hepatic impairments. Renal impairment, cardiovascular disease. Disruption of body temperature regulation. Hyperglycemia. Lactation (avoid breast-feeding).
In clinical trials, survival has been reported in acute overdoses of up to 30grams of Quetiapine. There is no specific antidote to Quetiapine. In cases of severe intoxication, the possibility of multiple drug involvement should be considered, and intensive care procedures are recommended, including establishing and maintaining a patent airway, ensuring adequate oxygenation and ventilation, and monitoring and support of the cardiovascular system. In cases of Quetiapine overdose, refractory hypotension should be treated with appropriate measures such as intravenous fluids and/or sympathomimetic agents (adrenaline and dopamine should be avoided, since beta stimulation may worsen hypotension in the setting of Quetiapine-induced alpha blockade). Close medical supervision and monitoring should be continued until the patient recovers.
Use in Special Population
Pediatric use: Quetiapine is not indicated for use in children and adolescents below 18 years of age.
Elderly: As with other antipsychotics, Quetiapine should be used with caution in the elderly, especially during the initial dosing period. The rate of dose titration may need to be slower, and the daily therapeutic dose lower, than that used in younger patients, depending on the clinical response and tolerability of the individual patient. The mean plasma clearance of Quetiapine was reduced by 30% to 50% in elderly subjects when compared with younger patients.
Store in a cool and dry place, protected from light.