Venlafaxine

Venlafaxine is a drug from the class of antidepressants that belongs to the serotonin-norepinephrine reuptake inhibitors and is used to treat depression and anxiety disorders.

What is venlafaxine?

The active ingredient venlafaxine is used in the treatment of depression and anxiety disorders. Less often, a treating doctor prescribes venlafaxine for obsessive-compulsive disorders. Like many other antidepressants, venlafaxine is a serotonin-norepinephrine reuptake inhibitor.

However, the drug is not one of the first-choice agents used in the acute treatment of depressive illnesses. There is no treatment advantage compared to cheaper non-selective monoamine withdrawal inhibitors, so-called tricyclic and tetracyclic antidepressants, and selective serotonin withdrawal inhibitors. In addition, serious side effects may develop while taking venlafaxine and after stopping the drug.

Pharmacological effect

Venlafaxine is a so-called serotonin noradrenaline reuptake inhibitor (SSNRI). This relatively young group of antidepressants works in the central nervous system. In certain synapses in the brain, the active ingredient binds to substances that transport serotonin and noradrenaline. Serotonin is both a tissue hormone and a neurotransmitter. In the central nervous system, serotonin affects almost all brain functions. It has an effect on perception, sleep, the regulation of body temperature and mood.

By stimulating the cerebral cortex, serotonin leads to an inhibition of aggressiveness and impulsiveness. Because of its mood-enhancing effects, serotonin is often referred to as the happiness hormone. From a neurochemical point of view, depressive moods can often be traced back to a lack of serotonin.

Norepinephrine is also a neurotransmitter and a hormone at the same time. The neurotransmitter works both in the central nervous system and in the sympathetic nervous system. The effect in the central nervous system is similar to that of serotonin.

The drug venlafaxine inhibits the uptake of neurotransmitters from the synaptic gap into the cells. As a result, the active ingredient increases the transmitter concentration outside the cells, so that a signal amplification develops. As a result, venlafaxine has an antidepressant effect.

Medical application & use

Medicines containing venlafaxine are used to treat depression and anxiety disorders. These include generalized anxiety disorder, social anxiety disorder, and panic disorder. In generalized anxiety disorder, anxiety can be observed to become independent. Social anxiety disorder, on the other hand, is a phobic disorder. Those affected suffer from pronounced fears in social situations.

Venlafaxine is used to treat panic disorders with and without agoraphobia. In panic disorder, patients experience sudden attacks of anxiety that are not related to any real danger. Agoraphobia is popularly known as claustrophobia.

Venlafaxine is also indicated for maintenance therapy in depression and anxiety disorders and to prevent relapses, i.e. in the prevention of recurrences. It can show good results in previously unsuccessful attempts at therapy in the treatment of attention deficit hyperactivity disorder.

The active ingredient is also used to treat diabetic polyneuropathy. Diabetic polyneuropathy is a disease of the peripheral nervous system that occurs as part of diabetes mellitus. If venlafaxine is used for this purpose, it is an off-label use. This means that the drug is used outside of the use approved by the drug authority.

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Risks & side effects

Side effects mainly occur when you start taking venlafaxine. This leads to gastrointestinal complaints, increased restlessness and diffuse, indefinable fears. Psychotic reactions can also occur. In the case of psychosis, those affected suffer from an extensive loss of reference to reality. These psychotic states are believed to be the result of the dopaminergic effects of venlafaxine.

In addition to increases in blood pressure and heart problems, increased perspiration and increased night sweats can be observed. Nausea is another side effect that is very common. Around 10 percent of patients suffer from nausea and vomiting. In addition there are symptoms such as loss of appetite, dizziness, constipation, nervousness and tremors.

Teeth grinding and blurred vision are also common side effects. Some people feel tired or drowsy while taking venlafaxine. Disorders of the libido and loss of sexual functions are very common.

The evaluation of clinical studies from the USA also showed that venlafaxine can increase suicidality by a factor of 5 in users under the age of 25. However, these results could not be confirmed by a meta-study from 2012. Nevertheless, many experts advise against prescribing venlafaxine for the initial treatment of depression.

Another risk associated with the administration of venlafaxine is SSRI withdrawal syndrome. Venlafaxine should always be tapered off gradually and never stopped suddenly. Otherwise, withdrawal symptoms such as circulatory problems, dizziness, fear of heights, motor disorders, daytime sleepiness, diarrhea, constipation, mood swings and severe depression can occur. Withdrawal symptoms of this type can occur up to four weeks after stopping the drug.

Venlafaxine in combination with other serotonergic agents can lead to life-threatening serotonin syndrome. Therefore, the medicinal substance must not be used together with St. John's wort, lithium, triptans, serotonin reuptake inhibitors, sibutramine and tramadol. Simultaneous administration of MAOIs and CYP3A4 inhibitors is also contraindicated. It should also be noted that venlafaxine can increase the effects of haloperidol, metoprolol and risperidone.

Venlafaxine may only be prescribed during pregnancy in exceptional cases. Newborns whose mothers took venlafaxine in the last trimester of pregnancy may experience insomnia, seizures, shortness of breath, tremors, constant crying, and irritability. Whether mothers should breastfeed while taking venlafaxine is still controversial. In any case, strict observation of the child is necessary.