Seroquel^® (Tablets) Instructions for Use

ATC Code

N05AH04 (Quetiapine)

Active Substance

Quetiapine (Rec.INN registered by WHO)

Clinical-Pharmacological Group

Antipsychotic drug (neuroleptic)

Pharmacotherapeutic Group

Psycholeptics; antipsychotics; diazepines, oxazepines, thiazepines and oxepines

Pharmacological Action

Antipsychotic agent (neuroleptic). It exhibits a higher affinity for serotonin 5HT₂ receptors compared to dopamine D₁ and D₂ receptors in the brain. It also has a high affinity for histaminic and α₁-receptors and a less pronounced one for α₂-receptors. It has no affinity for m-cholinergic receptors and benzodiazepine receptors.

Quetiapine, at a dose that effectively blocks dopamine D₂ receptors, causes only weak catalepsy. It selectively reduces the activity of mesolimbic A₁₀ dopamine neurons compared to A₉ nigrostriatal neurons involved in motor function.

It does not cause a prolonged increase in prolactin levels.

According to positron emission tomography results, the effect of quetiapine on serotonin 5HT₂ and dopamine D₂ receptors lasts up to 12 hours.

Pharmacokinetics

After oral administration, it is well absorbed from the gastrointestinal tract. Food intake does not significantly affect the bioavailability of quetiapine.

The pharmacokinetics of quetiapine are linear.

Plasma protein binding is about 83%.

It undergoes intensive metabolism. In vitro studies have established that the key enzyme for quetiapine metabolism is CYP3A4. The main metabolites detected in blood plasma do not have significant pharmacological activity.

T_1/2 is about 7 hours. Less than 5% of quetiapine is excreted unchanged by the kidneys or through the intestines. Approximately 73% of metabolites are excreted by the kidneys and 21% through the intestines. The average clearance of quetiapine in elderly patients is 30-50% lower than that observed in patients aged 18 to 65 years.

The average plasma clearance of quetiapine was approximately 25% lower in patients with severe renal impairment (creatinine clearance less than 30 ml/min/1.73 m²) and in patients with liver damage (compensated alcoholic cirrhosis), but individual clearance levels were within the range corresponding to healthy individuals.

Indications

Acute and chronic psychoses (including schizophrenia).

ICD codes

Dosage Regimen

Tablets

When used in adults, the initial dose is 50 mg/day, for elderly patients – 25 mg/day. Then the dose is gradually increased according to the scheme. Depending on the clinical effect and individual sensitivity, the effective therapeutic dose can be 150-750 mg/day.

In patients with impaired liver and/or kidney function, the initial dose is 25 mg/day. The daily dose increase should be 25-50 mg until the optimal effect is achieved.

Adverse Reactions

From the central nervous system headache, drowsiness, dizziness, anxiety; rarely – neuroleptic malignant syndrome.

From the cardiovascular system orthostatic hypotension, tachycardia, arterial hypertension.

From the digestive system constipation, dry mouth, dyspepsia, diarrhea, transient increase in the activity of liver enzymes (ALT, AST, GGT), abdominal pain.

From the hematopoietic organs asymptomatic leukopenia and/or neutropenia; rarely – eosinophilia.

From the musculoskeletal system myalgia.

From the respiratory system rhinitis.

Dermatological reactions skin rash, dry skin.

From the hearing organ ear pain.

From the genitourinary system urinary tract infections.

From the side of metabolism slight increase in blood cholesterol and triglyceride levels.

From the endocrine system slight dose-dependent reversible decrease in thyroid hormone levels (in particular total and free T₄).

Other asthenia, back pain, weight gain, fever, chest pain.

Contraindications

Hypersensitivity to quetiapine.

Use in Pregnancy and Lactation

During pregnancy and lactation, use is possible in cases where the expected benefit to the mother outweighs the potential risk to the fetus. It is not known whether Quetiapine is excreted in breast milk. If it is necessary to use during lactation, breastfeeding should be discontinued.

In experimental studies on animals, no mutagenic or clastogenic effects of quetiapine were detected. No effect of quetiapine on fertility was detected (decreased male fertility, pseudopregnancy, increased interval between two estrous cycles, increased precoital interval and decreased pregnancy rate), however, these data cannot be directly extrapolated to humans, as there are specific differences in the hormonal control of reproduction.

Use in Hepatic Impairment

Quetiapine undergoes active metabolism in the liver. In patients with impaired liver function, the clearance of quetiapine is reduced by approximately 25%. Therefore, Quetiapine should be used with caution in patients with impaired liver function.

Use in Renal Impairment

In patients with impaired renal function, the clearance of quetiapine is reduced by approximately 25%. Therefore, Quetiapine should be used with caution in patients with impaired renal function.

Geriatric Use

Use with caution in elderly individuals, especially when taken concomitantly with drugs that prolong the QT interval.

Special Precautions

Use with caution in patients with cardiovascular diseases and other conditions associated with the risk of arterial hypotension, especially at the beginning of treatment and in elderly individuals; with a history of seizures.

Quetiapine undergoes active metabolism in the liver. In patients with impaired liver and kidney function, the clearance of quetiapine is reduced by approximately 25%. Therefore, Quetiapine should be used with caution in patients with impaired liver and/or kidney function.

Use with caution concomitantly with drugs that prolong the QT interval (especially in elderly individuals); with drugs that have a depressant effect on the central nervous system, as well as with ethanol; with potential inhibitors of the CYP3A4 isoenzyme (including ketoconazole, erythromycin).

If neuroleptic malignant syndrome develops during treatment, Quetiapine should be discontinued and appropriate treatment initiated.

With long-term use, there is a possibility of developing tardive dyskinesia. In such cases, it is necessary to reduce the dose of quetiapine or discontinue it.

Use with caution in combination with other drugs that affect the activity of the central nervous system, as well as with ethanol.

In experimental studies on carcinogenicity of quetiapine, an increased incidence of mammary gland adenocarcinomas was noted in rats (at doses of 20, 75 and 250 mg/kg/day), which is associated with prolonged hyperprolactinemia.

In male rats (250 mg/kg/day) and mice (250 and 750 mg/kg/day), an increased incidence of benign adenomas of thyroid follicular cells was noted, which was associated with a known, rodent-specific mechanism of increased hepatic clearance of thyroxine.

Effect on ability to drive vehicles and operate machinery

Quetiapine may cause drowsiness, therefore patients are not recommended to perform work requiring concentration and high speed of psychomotor reactions (including driving vehicles).

Drug Interactions

When used concomitantly with ketoconazole, erythromycin, a theoretical possibility exists of an increase in quetiapine plasma concentration and the development of side effects.

When used concomitantly with phenytoin, carbamazepine, barbiturates, rifampicin, the clearance of quetiapine increases, and its plasma concentration decreases.

When used concomitantly with thioridazine, an increase in the clearance of quetiapine is possible.

Storage Conditions

Store at 2°C (36°F) to 30°C (86°F). Keep in original packaging, protected from light. Keep out of reach of children.

Dispensing Status

Rx Only

Important Safety Information

This information is for educational purposes only and does not replace professional medical advice. Always consult your doctor before use. Dosage and side effects may vary. Use only as prescribed.