DICLOFENAC 50 TABLET ( Diclofenac 50mg)

Indications

• Schizophrenia
• Bipolar disorder (manic and depressive episodes)
• Major depressive disorder (as adjunctive therapy)

Dosage

Children: Refer to the BNF for Children for appropriate pediatric dosing information.

Adults: Refer to the BNF for specific dosage guidelines, which may vary based on the condition being treated and patient characteristics.

Mechanism of action

Quetiapine exerts its antipsychotic effects through antagonism of dopamine D2 receptors and serotonin 5-HT2A receptors. This dual action helps in modulating the neurotransmitter balance in the brain, which is often disrupted in psychiatric conditions. Additionally, quetiapine has effects on adrenergic and histaminergic receptors, contributing to its overall pharmacological profile.

Pharmacodynamics

Quetiapine demonstrates a dose-dependent relationship in its efficacy and side effect profile. At lower doses, it may have sedative effects due to its antihistaminergic properties, while higher doses are more effective for treating psychotic symptoms. The medication also has a relatively low risk of extrapyramidal side effects compared to typical antipsychotics.

Pharmacokinetics

Quetiapine is well-absorbed after oral administration, with peak plasma concentrations occurring approximately 1 to 2 hours post-dose. It undergoes extensive hepatic metabolism primarily via CYP3A4, resulting in the formation of active metabolites. The elimination half-life ranges from 6 to 7 hours for the immediate-release formulation, and it is primarily excreted in urine. Factors such as age, liver function, and concomitant medications can influence its pharmacokinetics.

Contra-indications

• Hypersensitivity to quetiapine or any of the excipients
• Severe central nervous system depression
• Coma
• Concomitant use of monoamine oxidase inhibitors (MAOIs)

Adverse effects

• Sedation
• Dizziness
• Orthostatic hypotension
• Weight gain
• Metabolic syndrome
• Extrapyramidal symptoms
• Tardive dyskinesia
• Neuroleptic malignant syndrome
• Increased cholesterol and triglycerides
• Hyperglycemia

Interactions

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) may increase quetiapine levels
• CYP3A4 inducers (e.g., rifampicin, carbamazepine) may decrease quetiapine levels
• CNS depressants (e.g., alcohol, benzodiazepines) can enhance sedative effects
• Antihypertensives may have additive hypotensive effects

Precautions

• Monitor for signs of metabolic syndrome
• Caution in patients with a history of seizures
• Use with caution in elderly patients
• Monitor for symptoms of tardive dyskinesia
• Assess risk of neuroleptic malignant syndrome
• Consider risk of orthostatic hypotension in susceptible patients

Pregnancy

Quetiapine should only be used during pregnancy if the benefits outweigh the risks. Limited data on safety.

Breast-feeding

Quetiapine is excreted in breast milk. Caution is advised when used during breastfeeding.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Tablets
• Extended-release tablets