Venlafaxine is a drug in the antidepressant drug class that belongs to the serotonin–norepinephrine reuptake inhibitors and is used to treat depression and anxiety disorders.
What is venlafaxine?
Venlafaxine is a drug used to treat depression and anxiety disorders. The active ingredient venlafaxine is used to treat depression and anxiety disorders. Less commonly, a treating doctor will also prescribe venlafaxine for obsessive-compulsive disorder. Like many other antidepressants, venlafaxine belongs to the serotonin–norepinephrine reuptake inhibitors. However, the drug is not among the first-line agents used in the acute treatment of depressive disorders. It shows no treatment advantage over less expensive nonselective monoamine reuptake inhibitors, so-called tri- and tetracyclic antidepressants, and selective serotonin reuptake inhibitors. In addition, severe side effects may develop while taking venlafaxine and after discontinuation of each drug.
Pharmacologic effects
Venlafaxine is a so-called serotonin-norepinephrine reuptake inhibitor (SSNRI). This relatively new group of antidepressants exerts its effects in the central nervous system. In certain synapses of the brain, the active substance binds to substances that transport serotonin and norepinephrine. Serotonin is both a tissue hormone and a neurotransmitter. In the central nervous system, serotonin influences almost all brain functions. It has an effect on perception, sleep, regulation of body temperature and mood. Via stimulation of the cerebral cortex, serotonin leads to inhibition of aggressiveness and impulsivity. Due to its mood-lifting effect, serotonin is often referred to as the happiness hormone. From a neurochemical point of view, depressive moods can often be traced back to a serotonin deficiency. Norepinephrine is also a neurotransmitter and hormone at the same time. The neurotransmitter exerts its effect both in the central nervous system and in the sympathetic nervous system. The effect in the central nervous system is similar to the effect of serotonin. The drug venlafaxine inhibits the reuptake of neurotransmitters from the synaptic cleft into the cells. As a result, the drug increases the transmitter concentration outside the cells, so that signal amplification develops. As a result, venlafaxine mediates an antidepressant effect.
Medical application and 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 becomes independent. Social anxiety disorder, on the other hand, belongs to the phobic disorders. Those affected suffer from pronounced anxiety in social situations. Venlafaxine is used to treat panic disorder with and without agoraphobia. In panic disorder, patients experience sudden anxiety attacks that have no connection to real dangers. Agoraphobia is popularly known as claustrophobia. Venlafaxine is further indicated for maintenance therapy in depression and anxiety disorders and to prevent relapse, i.e., in relapse prevention. It can show good results in previously failed therapy attempts in the treatment of attention deficit hyperactivity disorder. Furthermore, the drug is also used in the treatment of diabetic polyneuropathy. Diabetic polyneuropathy is a disease of the peripheral nervous system that occurs in the context of diabetes mellitus. When venlafaxine is used for this purpose, it is an off-label use. This means that the drug is being used outside of the use approved by the drug regulatory agency.
Risks and side effects
Side effects occur mainly at the beginning of taking venlafaxine. Thus, gastrointestinal discomfort, increased restlessness, and diffuse, indefinable anxiety occur. Psychotic reactions can also occur. In psychosis, those affected suffer from an extensive loss of reference to reality. These psychotic states are probably the result of the dopaminergic effect of venlafaxine. In addition to increases in blood pressure and heart complaints, increased sweating and night sweats may be observed.Nausea is another side effect that occurs very frequently. Around 10 percent of patients suffer from nausea and vomiting. In addition, there are symptoms such as loss of appetite, dizziness, constipation, nervousness and tremor. Teeth grinding and visual disturbances are also among the common side effects. Some patients suffer from fatigue and drowsiness while taking venlafaxine. Libido disturbances and loss of sexual function 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 findings could not be confirmed by a 2012 meta-study. Nevertheless, many experts advise against prescribing venlafaxine for the initial treatment of depression. Another risk associated with venlafaxine administration is SSRI discontinuation syndrome. Venlafaxine should always be gradually phased out and never abruptly discontinued. Otherwise, withdrawal symptoms such as circulatory problems, dizziness, anxiety about heights, motor disturbances, daytime sleepiness, diarrhea, constipation, mood swings, and severe depression may occur. Withdrawal symptoms of this type may occur for up to four weeks after discontinuation of the drug. Venlafaxine in combination with other serotonergic agents can lead to life-threatening serotonin syndrome. Therefore, the drug must not be used together with St. John’s wort, lithium, triptans, serotonin reuptake inhibitors, sibutramine, and tramadol. Simultaneous administration of MAO inhibitors and CYP3A4 inhibitors is also contraindicated. It should also be noted that venlafaxine may potentiate the effects of haloperidol, metoprolol, and risperidone. During pregnancy, venlafaxine should be prescribed only in exceptional circumstances. Newborns whose mothers took venlafaxine during the last trimester of pregnancy may suffer from sleep disturbances, seizures, shortness of breath, tremors, constant crying, and irritability. Whether mothers should breastfeed while taking venlafaxine is currently controversial. In any case, close observation of the child is necessary.
