Q-Fit XR

The mechanism of action of Quetiapine, as with other drugs having efficacy in the treatment of schizophrenia and acute manic episodes associated with bipolar disorder, is unknown. However, it has been proposed that this drug’s efficacy in schizophrenia is mediated through a combination of dopamine type 2 (D2 ) and serotonin type 2 (5HT2) antagonism. Antagonism at receptors other than dopamine and 5HT 2 with similar receptor affinities may explain some of the other effects of Quetiapine. Quetiapine’s antagonism of histamine H1 receptors may explain the somnolence observed with this drug. Quetiapine’s antagonism of adrenergic α1 receptors may explain the orthostatic hypotension observed with this drug.

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.

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.

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.

• Suicide/suicidal thoughts or clinical worsening: Depression is associated with an increased risk of suicidal thoughts, self-harm and suicide (suicide-related events). This risk persists until significant remission occurs.
• Concomitant Illness: Quetiapine should be used with caution in patients with known cardiovascular disease, cerebrovascular disease, or other conditions predisposing to hypotension. Quetiapine may induce orthostatic hypotension especially during the initial dose-titration period.
• Seizures: As with other antipsychotics, caution is recommended when treating patients with a history of seizures.
• Tardive Dyskinesia and Extrapyramidal Symptoms (EPS): If signs and symptoms of tardive dyskinesia appear, dose reduction or discontinuation of Quetiapine should be considered.
• Neuroleptic Malignant Syndrome: This syndrome has been associated with antipsychotic treatment. Quetiapine should be discontinued and appropriate medical treatment given.
• QT Prolongation: As with other antipsychotics, caution should be exercised when Quetiapine is prescribed in patients with cardiovascular disease or family history of QT prolongation.
• Neutropenia: Severe neutropenia (<0.5×109/L) has been uncommonly reported in Quetiapine clinical trials. Most cases of severe neutropenia have occurred within the first two months of starting therapy with Quetiapine.
• Hyperglycemia & diabetes mellitus: Increases in blood glucose and hyperglycaemia, and occasional reports of diabetes, have been observed in clinical trials with Quetiapine.

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.

Children and Adolescents: Quetiapine is not indicated for use in children and adolescents below 18 years of age.

Atypical neuroleptic drugs

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 this medicine out of the sight and reach of children. Do not use this medicine after the expiry date which is stated on the blister pack and the carton. The expiry date refers to the last day of that month. Store in a cool and dry place away from light.