Quetiapine
Updated onBenjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.
More about the experts All content is checked by medical journalists.The active ingredient quetiapine is one of the atypical antipsychotics - a group of drugs used to treat schizophrenia and bipolar disorders. As a second-generation antipsychotic, quetiapine has fewer serious side effects than those of the first generation. Here you can read everything you need to know about the effects and use of quetiapine, side effects and interactions.
This is how quetiapine works
Quetiapine has antipsychotic, antidepressant and central depressant properties by interacting with the receptors of various neurotransmitters in the brain.
One of these messenger substances is dopamine: it is released by a nerve cell to transmit signals, then binds to specific receptors in another nerve cell and is thus effective: Among other things, dopamine conveys a feeling of motivation and joy and is involved in memory performance and targeted movements (fine motor skills).
Too much dopamine results, for example, in excessive, manic pleasure up to schizophrenia and a loss of reality. To get this excessive dopamine effect under control, antipsychotic drugs such as quetiapine are used:
Quetiapine binds to dopamine receptors in the brain, but does not activate them. It simply blocks them for the high concentration of dopamine. This regulates the dopamine effect down to normal levels.
Uptake, breakdown and excretion
After being absorbed in the intestine, quetiapine is extensively metabolized in the liver. The resulting breakdown products also have an antipsychotic effect. After about seven hours, half of the active ingredient (after twelve hours half of the active breakdown product) is excreted - three quarters with the urine and one fourth with the stool.
When is quetiapine used?
The active ingredient is used to treat schizophrenia and bipolar disorder. In the latter, quetiapine is used in particular to treat manic and depressive episodes in the course of the disease. If it proves effective, it can also be used to prevent relapse into such episodes.
Quetiapine is also approved as an add-on therapy for depression.
This is how quetiapine is used
The active ingredient quetiapine is mainly used in the form of tablets. In order to avoid multiple dosing at higher doses, which is important for constant blood levels, tablets with delayed release of active ingredients (retard tablets) are on the market.
There are different dosage regimens depending on the area of application. What they all have in common is that for the initial treatment of acute psychological complaints, the active ingredient is "crept in" over a few days - treatment is started with a small dose, which is then increased over the course of several days until the desired quetiapine effect is achieved is.
For maintenance therapy, the amount of active ingredient is then reduced to the lowest effective dose.
The active ingredient is taken once or twice a day, regardless of meals, according to the doctor's instructions.
What are the side effects of quetiapine?
The most common side effects (affecting more than one in ten people) are drowsiness, dizziness, dry mouth, headache, withdrawal symptoms (when stopping treatment), increased blood lipid levels, increased total cholesterol (mostly LDL cholesterol), decreased HDL cholesterol, weight gain and so-called extrapyramidal symptoms (Parkinson-like symptoms).
In addition, every hundredth to tenth person treated has side effects such as changes in thyroid hormone levels, high blood sugar levels, increased appetite, abnormal dreams and nightmares, suicidal thoughts, blurred vision, rapid heartbeat, shortness of breath and indigestion.
What should be considered when taking quetiapine?
Quetiapine works primarily in the central nervous system, which is why the intake of other centrally active active ingredients should be clarified beforehand and only with caution. The same applies to the consumption of alcohol.
Elimination from the body is slowed in the elderly. This is why the quetiapine dose is often reduced - this is to prevent the active substance from building up in the body. The same applies to patients with impaired liver function.
Contraindications
Quetiapine is contraindicated in:
- Hypersensitivity to the active ingredient
- simultaneous use of strong inhibitors of the enzyme CYP3A4 (important for the breakdown of quetiapine)
Interactions
The active ingredient is mainly broken down by the so-called CYP enzyme system in the liver, which also breaks down many other drugs in the body. In particular, the enzyme CYP3A4, which metabolizes quetiapine, also breaks down many other active substances.
If taken at the same time, there may be interactions:
Some drugs are then broken down primarily by CYP3A4, so that quetiapine accumulates - its effects and side effects increase. Examples of such so-called CYP3A4 inhibitors are clarithromycin (antibiotic), ketoconazole (antifungal agent) and indinavir (HIV drug).
Conversely, there are also drugs that accelerate (induce) the breakdown of quetiapine via CYP3A4 and thus reduce its effectiveness. These CYP3A4 inducers include rifampicin (an antibiotic) and some anti-epileptic drugs such as carbamazepine and phenytoin.
Some foods, such as grapefruit juice, can also interact with CYP3A4.
pregnancy and breast feeding period
Various studies with more than 4500 evaluated pregnancies have not provided any indication of an increased risk of malformations due to the maternal intake of quetiapine. If it is necessary to take this active ingredient, pregnancy is not an obstacle.
Quetiapine is acceptable during breastfeeding with monotherapy and careful observation of the child.
Children and adolescents
The use of quetiapine in children and adolescents under 18 years of age is not recommended as no data are available.
How to get quetiapine medication
In Germany, Austria and Switzerland, quetiapine is only available on prescription in any dosage and is only available at the pharmacy upon presentation of a prescription.
How long has quetiapine been known?
The active ingredient was discovered and researched by a British pharmaceutical company between 1992 and 1996 as a further development of the first generation of antipsychotics (the typical neuroleptics). Quetiapine received approval in the United States in 1997. After the patent expired in 2012, numerous generics with the active ingredient quetiapine came onto the market.
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