Quetiapine is a second generation antipsychotic approved for the treatment of schizophrenia, bipolar disorder and as adjunct treatment of major depressive disorder.
Dibenzothiazepine; Antipsychotic
Quetiapine Fumarate is an atypical psychotropic agent belonging to a chemical class, the Dibenzothiazepine derivatives. Quetiapine is an antagonist at multiple neurotransmitter receptors in the brain: Serotonin 5HT1A and 5HT2, dopamine D1 and D2, histamine H1, and adrenergic α1 and α2 receptors. Quetiapine has no appreciable anity at cholinergic, muscarinic and benzodiazepine receptors. The mechanism of action of Quetiapine is unknown. However, it has been proposed that this drug's ecacy in schizophrenia is mediated through a combination of dopamine D2 and serotonin 5HT2 antagonism. Quetiapine's antagonism of histamine H1 receptors may explain the somnolence and that of adrenergic α1 receptors may explain the orthostatic hypotension observed with this drug.
ORAL Schizophrenia: Adult: Initially, 25 mg bid on day 1, increased to 50 mg bid on day 2, 100 mg bid on day 3 & 150 mg bid on day 4. Usual dose range: 300-450 mg daily. Max: 750 mg/day. Elderly: Initially, 25 mg daily, increased in steps of 25-50 mg daily according to response. Bipolar disorder: Adult: Manic phase: 50 mg bid on day 1, 100mg bid on day 2, 150 mg bid on day 3 & 200 mg bid on day 4. Usual range: 400-800 mgI day; adjust dose according to response. Dosage increments should be 200 mgi day. Depressive phase: Initially, 50 mg at bedtime on day 1; 100mg on day 2,200 mg on day 3, & 300 mg on day 4. May increase to 400 mg on day 5 & 600 mg on day 8, if needed. Elderly: Initially, 25 mg daily, increased in steps of 25-50 mg daily according to response.
May enhance the eects of other centrally acting drugs, certain antihypertensive agents, may antagonize the eects of dopamine agonists and levodopa. Increased clearance of Quetiapine by phenytoin, barbiturates, rifampin, carbamazepine. Increased concentrations of Quetiapine with azole antifungals and macrolide antibiotics.
Angle-closure glaucoma; lactation. IM: History of CVS disease, heart surgery. Impaired renal, hepatic, CV function; prostatic hypertrophy; paralytic ileus; DM; parkinsonism; pregnancy. History of blood dyscrasias, myelosuppression, seizures; dementia; dyslipidaemia.
Postural hypotension; constipation; dizziness: wt gain; agitation; insomnia; akathisia; tremor; personality disorders; oedema; somnolence; increased appetite; antimuscarinic effects; speech difficulty; exacerbation of Parkinson’s disease; hallucinations; asthenia; increased body tern perature; bradycardia; hyperprolactinaemia; QT prolongation (uncommon); asymptomatic elevations of hepatic transaminases. Exacerbation of preexisting diabetes sometimes leading to ketoacidosis. Neuroleptic malignant syndrome.
Limited published human data have reported no major malformations associated with use during pregnancy. There are no controlled data in human pregnancy. Neonates exposed to antipsychotic drugs during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery. Excretion Into Breast Milk and Safe Breastfeeding Strategy.
In clinical trials, survival has been reported in acute overdoses of up to 30 grams 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.
Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.
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