Seroquel (quetiapine)
Seroquel (quetiapine)

How does it work?

Seroquel tablets and Seroquel XL prolonged-release tablets both contain the active ingredient quetiapine, which is a type of medicine known as an atypical antipsychotic.

Quetiapine works in the brain, where it affects various neurotransmitters, in particular serotonin (5HT) and dopamine. Neurotransmitters are chemicals that are stored in nerve cells and are involved in transmitting messages between the nerve cells.

Dopamine and serotonin are neurotransmitters known to be involved in regulating mood and behaviour, amongst other things. Psychotic illness is considered to be caused by disturbances in the activity of neurotransmitters (mainly dopamine) in the brain. Schizophrenia is known to be associated with an overactivity of dopamine in the brain, and this may be associated with the delusions and hallucinations that are a feature of this disease.

Quetiapine works by blocking the receptors in the brain that dopamine acts on. This prevents the excessive activity of dopamine and helps to control schizophrenia.

Schizophrenic patients may experience 'positive symptoms' (such as hallucinations, disturbances of thought, hostility) and/or 'negative symptoms' (such as lack of emotion and social isolation). Quetiapine is effective in relieving both positive and negative symptoms of schizophrenia, whereas the conventional antipsychotics are usually less effective against the negative symptoms.

Quetiapine is also used by specialists to treat episodes of mania in people with the psychiatric illness, bipolar affective disorder (manic depression).

Seroquel tablets are standard release tablets that are taken twice a day. They can be taken with or without food.

Seroquel XL prolonged-release tablets should be taken once a day without food. These tablets are designed to release the quetiapine slowly and continuously over 24 hours to help provide steady blood levels of the medicine throughout the day. Seroquel XL tablets should be swallowed whole and not broken, crushed or chewed, as this would damage the prolonged-release action.
What is it used for?

* Schizophrenia.
* Manic episodes of manic depression (bipolar affective disorder).

Warning!

* Seroquel XL tablets should be taken without food, at least one hour before a meal. These tablets should be swallowed whole and not broken, crushed or chewed.
* It is recommended that you avoid drinking grapefruit juice while taking this medicine, as it could affect the level of quetiapine in your blood.
* This medicine may make you feel sleepy, particularly when you first start treatment. This generally gets better after the first couple of weeks. If affected you should not drive or operate machinery. Alcohol should be avoided.
* This medicine can occasionally cause your blood pressure to drop when you move from a lying down or sitting position to sitting or standing, especially when you first start taking the medicine. This may make you feel dizzy or unsteady and could make you faint. To avoid this try getting up slowly. If you do feel dizzy, sit or lie down until the symptoms pass.
* This medicine can cause some people to put on weight, usually during the early weeks of treatment. Talk to your doctor about this before you start treatment so that you can discuss strategies, such as diet and exercise, for minimising any weight gain.
* Unless your doctor tells you otherwise, you should not suddenly stop taking this medicine, even if you feel better and think you don't need it any more. This is because the medicine controls the symptoms of the illness but doesn't actually cure it. This means that if you suddenly stop treatment your symptoms could come back. Stopping the medicine suddenly may also rarely cause withdrawal symptoms such as nausea, vomiting, difficulty sleeping or abnormal involuntary muscle movements. When treatment with this medicine is stopped, it should be done gradually, following the instructions given by your doctor.
* Consult your doctor immediately if you experience abnormal movements, particularly of the face, lips, jaw and tongue, while taking this medicine. These symptoms may be indicative of a very rare side effect known as tardive dyskinesia, and your doctor may ask you to stop taking this medicine, or decrease your dose.
* Consult your doctor immediately if you experience the following symptoms while taking this medicine: high fever, sweating, muscle stiffness, faster breathing and drowsiness or sleepiness. These symptoms may be due to a rare side effect known as the neuroleptic malignant syndrome, and your treatment may need to be stopped.
* You should also consult your doctor immediately if you experience any of the following side effects while taking this medicine: persistent sore throat or mouth ulcers, fever, or other signs of infections (this may indicate a problem with your blood cells); fits or seizures; allergic reactions such as a blistering skin rash, or swelling of the face, lips, throat or tongue; yellowing of the skin and whites of the eyes (jaundice); or a long-lasting and painful erection (priapism). These side effects are rare, but may be serious and may require urgent medical attention.

Use with caution in

* Elderly people.
* Decreased kidney function.
* Decreased liver function.
* Disease of the blood vessels in and around the brain (cerebrovascular disease).
* People with risk factors for having a stroke, for example a history of stroke or mini-stroke (TIA), smoking, diabetes, high blood pressure, or a type of irregular heartbeat called atrial fibrillation.
* Disease involving the heart and blood vessels (cardiovascular disease).
* Low blood pressure (hypotension).
* People with heart failure or an enlarged heart.
* People with a personal or family history of an abnormal heart rhythm seen on a heart monitoring trace (ECG) as a 'prolonged QT interval'.
* People taking medicines that can cause a 'prolonged QT interval' (your doctor will know, but see end of this factsheet for some examples).
* People with low levels of magnesium or potassium in their blood.
* People with low numbers of white blood cells in their blood (leucopenia).
* People with a history of a drop in their white blood cells (leucopenia) caused by a medicine.
* People with diabetes or who are at risk of developing diabetes.
* History of seizures, eg epilepsy.

Not to be used in

* Breastfeeding.
* Seroquel and Seroquel XL tablets are not recommended for children and adolescents under 18 years of age, as the manufacturer has not studied the medicine in this age group. However, Seroquel tablets may sometimes be prescribed by specialists to treat schizophrenia in children aged 12 to 18 years. This is an unlicensed use of the medicine.
* This medicine is not licensed or recommended for treating behavioural problems or psychosis in elderly people with dementia, as antipsychotic medicines such as this one have been shown to increase the risk of stroke in this group of patients.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

* The safety of this medicine for use during pregnancy has not been established. It should therefore be used with caution during pregnancy, and only if the benefits to the mother outweigh any potential risks to the developing baby. When this medicine has been used during pregnancy some withdrawal effects have been seen in the baby after birth. Seek further medical advice from your doctor.
* It is not known if this medicine passes into breast milk. The manufacturer recommends that mothers who need to take this medicine should not breastfeed their infants. Seek medical advice from your doctor.

Label warnings

* This medication may cause drowsiness. If affected do not drive or operate machinery. Avoid alcoholic drink.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.
Very common (affect more than 1 in 10 people)

* Sleepiness.
* Dizziness.
* Headache.
* Dry mouth.

Common (affect between 1 in 10 and 1 in 100 people)

* Weakness or loss of strength (asthenia).
* Constipation.
* Indigestion (dyspepsia).
* Faster than normal heart beat (tachycardia).
* A drop in blood pressure that occurs when moving from a lying down or sitting position to sitting or standing, which may cause dizziness or fainting (postural hypotension - see warning section above).
* Decrease in the number of white blood cells in the blood (see warning section above).
* Swelling of the legs and ankles due to excess fluid retention (peripheral oedema).
* Weight gain (see warning section above).
* Inflammation of the lining of the nose (rhinitis) causing a blocked or runny nose.
* Alteration in results of liver function tests.
* Raised blood sugar levels (hyperglycaemia).

Uncommon (affect between 1 in 100 and 1 in 1000 people)

* Raised levels of cholesterol and triglycerides in the blood.
* Seizures.
* Restless legs syndrome.

Rare (affect between 1 in 1000 and 1 in 10,000 people)

* Persistent painful erection of the penis (priapism).
* Yellowing of the skin and whites of the eyes (jaundice).
* Neuroleptic malignant syndrome (see warning section above).

Very rare (affect less than 1 in 10,000 people)

* Inflammation of the liver (hepatitis).
* Diabetes.
* Tardive dyskinesia (see warning section above).
* Severe allergic blistering skin reaction (Stevens-Johnson syndrome).
* Allergic reaction involving swelling of the face, throat, lips or tongue (angioedema).

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

There may be an increased risk of drowsiness if this medicine is taken with any of the following (which can also cause drowsiness):

* alcohol
* barbiturates, eg amobarbital, phenobarbital
* benzodiazepines, eg diazepam, temazepam
* MAOI antidepressants, eg phenelzine
* sedating antihistamines, eg chlorphenamine, hydroxyzine
* sleeping tablets, eg zopiclone
* strong opioid painkillers, eg morphine, codeine, dihydrocodeine
* tricyclic antidepressants, eg amitriptyline.

This medicine may enhance the blood pressure-lowering effects of certain medicines used to treat high blood pressure (antihypertensives). If you are taking medicines for high blood pressure you should tell your doctor if you feel dizzy or faint after starting treatment with this medicine, as your blood pressure medicines may need adjusting.

The following medicines may increase the breakdown of quetiapine by the liver, which could make it less effective. If you are taking any of these medicines, your doctor may need to switch you onto an alternative that doesn't affect quetiapine, or prescribe you a bigger dose of quetiapine:

* barbiturates such as amobarbital and phenobarbital
* carbamazepine
* phenytoin
* rifampicin
* thioridazine.

The following medicines may decrease the breakdown of quetiapine by the liver and so could increase the risk of its side effects. If you are prescribed any of these medicines while taking quetiapine your doctor may need to decrease your quetiapine dose:

* azole antifungal medicines such as itraconazole, ketoconazole, fluconazole
* macrolide antibiotics such as erythromycin, clarithromycin
* protease inhibitors for HIV infection such as ritonavir.

There may be an increased risk of abnormal heart rhythms (prolonged QT interval on a heart monitoring trace or ECG) if the following medicines are taken in combination with quetiapine:

* antiarrhythmics (medicines to treat abnormal heart beats), eg amiodarone, procainamide, disopyramide, sotalol
* the antihistamines astemizole, mizolastine or terfenadine
* atomoxetine
* certain antidepressants, eg amitriptyline, imipramine, maprotiline
* certain antimalarials, eg halofantrine, chloroquine, quinine, mefloquine, Riamet
* certain other antipsychotics, eg thioridazine, chlorpromazine, sertindole, haloperidol
* cisapride
* intravenous erythromycin or pentamidine
* moxifloxacin
* medicines that can alter the levels of salts such as potassium or magnesium in your blood, eg diuretics such as furosemide.

Quetiapine may oppose the effect of medicines for Parkinson's disease that work by stimulating dopamine receptors in the brain, for example levodopa, ropinirole, pergolide, bromocriptine.

Quetiapine may oppose the effect of anticonvulsant medicines used to treat epilepsy.
Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain quetiapine as the active ingredient.

Last updated 24.03.2009