Qtasim

Generic composition: Quetiapine Fumarate

General description

Quetiapine is a second-generation dibenzothiazepine atypical antipsychotic used in schizophrenia, major depression, and bipolar disorder. Quetiapine demonstrates a high level of therapeutic efficacy and low risk of adverse effects during long-term treatment. It is well-tolerated and a suitable option for some patients with high sensitivity to other drugs, such as clozapine and olanzapine.

Therapeutic category

• Atypical Anti-psychotics

Dosage forms

• QTASIM 25mg Tablets
• QTASIM 50mg Tablets
• QTASIM 100mg Tablets

Indications

• Schizophrenia
• Bipolar Disorder
• Major Depressive Disorder

 Dose

• 25mg or 50 mg two or three times a day.
• Dose reduction in elderly and hepatic impairment: initial 25 mg followed by daily increments of 25-50 mg, according to response.

 Mechanism of action:

It is Dopamine (D₁ and D₂), Serotonin (5-HT₂), Histamine (H₁), and Adrenergic receptor antagonist. It has been

proposed that the efficacy of Quetiapine in schizophrenia and its mood-stabilizing properties in bipolar

depression and mania are mediated through a combination of D₂ and 5-HT₂ antagonisms.

Pharmacokinetics     

Absorption: Well absorbed after oral doses, 83% plasma Protein Binding), 1.5 hrs peak plasma concentration

Distribution: distributes throughout body tissues, apparent volume of distribution of this drug is about 10±4 L/kg.

Metabolism: Metabolized in liver by CYP3A4 (sulfoxidation and oxidation).

Elimination: Eliminated primarily via urine (73%) and minor via feces (20%),

Half-life: 6-7 hours

Precautions

Caution in patients receiving antihypertensive, gradual withdrawal is recommended, because of risk of withdrawal symptoms.

Side effects

Common: Somnolence, headache, dizziness, weight gain, particularly during early treatment, rises in plasma-TG and total cholesterol concentration, constipation, dry mouth, dyspepsia, increased appetite, peripheral edema, anxiety.

Rare: Orthostatic hypotension associated with dizziness, tachycardia and syncope, Hyperglycaemia and exacerbation of pre-existing diabetes. Monitoring in such case required.

 Drug Interactions:

• Central effects of CNS Depressants, including alcohol, are increased.
• CYP inhibitors like erythromycin, fluconazole, ketoconazole increases plasma concentration. Hence, dose reduction recommended.
• CYP inducers like carbamazepine, phenytoin decreases concentration. Hence, higher dose recommended.

References

• Rxlist
• Drug bank