Paroxetine

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Benjamin 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.

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Paroxetine is one of the antidepressants of the selective serotonin reuptake inhibitor type. It is used to treat depression, obsessive-compulsive disorder, anxiety disorders, social phobias, and post-traumatic stress disorder. It is usually taken in the form of tablets. Here you can read everything you need to know about the effects and use of paroxetine, side effects and interactions.

This is how paroxetine works

The nerve cells in the brain communicate with each other via chemical messengers, so-called neurotransmitters. These are released from one cell and "perceived" by the next via certain docking points (receptors). Then the messenger substances are taken up again by the first cell, whereby their effect ends.

In this way, the neurotransmitter serotonin conveys feelings such as good mood, happiness and a positive mood. A relative deficiency in serotonin, on the other hand, leads to anxiety, depression and impulsive aggression.

In such cases, selective serotonin reuptake inhibitors (SSRIs) such as paroxetine can help: These antidepressants prevent the reuptake of serotonin into the cell of origin. Once released, the serotonin can act longer on the target cell - symptoms of a serotonin deficiency such as depression and anxiety improve.

Uptake, breakdown and excretion

The antidepressant is well absorbed in the intestine after ingestion by mouth (orally) and is then partially metabolized in the liver with the help of the enzyme CYP2D6.

The resulting metabolic products show no antidepressant effect and are quickly excreted. Elimination is very individual, about one third occurs with the stool and two thirds with the urine. After one day, about half of the absorbed active ingredient has disappeared from the body.

When is paroxetine used?

Paroxetine is used to treat:

• Depressive illness
• Obsessive-compulsive disorder
• Panic disorder
• Social anxiety disorder (social phobia)
• Generalized anxiety disorder
• Post traumatic stress disorder

In general, the therapy takes place over a longer period of time, whereby the benefit of the therapy should be checked regularly.

This is how paroxetine is used

Most often, paroxetine is given in the form of tablets. For patients with swallowing disorders or a feeding tube, there are liquid preparations such as drops or an oral suspension.

The therapy is started with a low dosage, which is then increased gradually (up to a maximum of 60 milligrams per day). Once the desired effect has been achieved, the corresponding dose is retained for the remainder of the therapy. The daily dose is taken once a day in the morning.

It usually takes two to six weeks, depending on the area of ​​application, until the desired effect is achieved.

In order to end the therapy, it is discussed with the doctor how to discontinue the paroxetine. Sudden discontinuation is not recommended because it can cause severe side effects and withdrawal symptoms. Instead, the active ingredient is only reduced very slowly (gradually), which is known as "tapering off" therapy.

What are the side effects of paroxetine?

When taking the antidepressant, nausea and sexual dysfunction are very common (more than one in ten people treated).

Side effects such as drowsiness, insomnia, tremors, headache, blurred vision, yawning, sweating, weakness and dizziness occur frequently (in every tenth to one hundredth person treated). These side effects can also be seen if paroxetine is discontinued too quickly.

Weight gain, constipation, diarrhea, and vomiting are other common side effects.

What should be considered when taking paroxetine?

Contraindications

Paroxetine must not be taken if:

• simultaneous use of monoamine oxidase inhibitors (MAOIs) - also antidepressants
• simultaneous use of thioridazine and / or pimozide (antipsychotics) - anti-psychotic agents

Interactions

Since paroxetine affects serotonin levels, other active ingredients that act on the release of the hormone may have an increased effect. In particular, caution should be exercised when taking L-tryptophan (for depression and sleep disorders), triptans (anti-migraine drugs), tramadol, pethidine and fentanyl (all pain relievers), linezolid (antibiotics), MAO inhibitors (antidepressants) and other SSRIs.

Various active ingredients can inhibit or increase the breakdown of paroxetine via the liver. These include pimozide (antipsychotic), fosamprenavir and ritonavir (HIV drugs), procyclidine (anti-Parkinson drugs), phenprocoumon (anticoagulants) and acetylsalicylic acid (pain relievers and anticoagulants).

Paroxetine is metabolized in the liver via the enzyme CYP2D6 and is also an inhibitor of this enzyme. For this reason, it can interact with various substances that are also broken down by this enzyme. For example:

• Agents against cardiac arrhythmias (e.g. propafenone, flecainide)
• Beta blockers (cardiovascular drugs)
• Insulin (diabetes drug)
• Epilepsy drugs (e.g. carbamazepine, phenobarbital, phenytoin)
• Parkinson's disease agents (e.g. levodopa, amantadine)
• Antipsychotics (e.g. risperidone, thioridazine)
• other antidepressants (e.g. tricyclic antidepressants and selective serotonin reuptake inhibitors)
• Tamoxifen (medicine for breast cancer)
• Tramadol (pain reliever)

Experts recommend avoiding alcohol during treatment with paroxetine. Otherwise it can lead to an increased effect of alcohol up to severe nausea and malaise.

Age restriction

A therapeutic benefit of paroxetine in children and adolescents under 18 years of age has not been proven. Therefore, the active ingredient should only be used from the age of 18 years.

Elderly patients may experience slower excretion of the antidepressant, which is why it may have to be dosed lower. The same applies to patients with kidney or liver dysfunction.

pregnancy and breast feeding period

Several thousand documented pregnancy courses under treatment with SSRIs such as paroxetine have mostly not provided any clear indications of an increased rate of malformations. However, some studies suggest a link between congenital malformations and paroxetine use during the first trimester of pregnancy.

For this reason, paroxetine should only be taken during pregnancy if absolutely necessary. If possible, better researched substances (e.g. citalopram, sertraline) should be used.

Small amounts of paroxetine pass into breast milk. So far, no abnormalities have been observed in breastfed children when the mother took the antidepressant. Paroxetine is therefore one of the SSRIs of choice during breastfeeding - alongside citalopram and sertraline.

How to get medication with paroxetine

Paroxetine requires a prescription in Germany, Austria and Switzerland in every dosage and dosage form and is only available in pharmacies.

How long has paroxetine been known?

Paroxetine was launched in the United States in 1992. Since the original manufacturer's patent expired in 2003, numerous generics with the active ingredient have been on the market.

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