Side effects of venlafaxine
Antidepressants as well as venlafaxine are known to cause a variety of side effects. These occur more frequently, especially at the beginning of treatment. Most of the time, however, the side effects disappear after taking the drug for a long time.
However, the group of selective serotonin reuptake inhibitors (SSRIs) has better tolerability compared to the tricyclic antidepressants that were used more often in the past. Very often (in more than 1 in 10 patients) headaches and nausea occur during the course of treatment. Patients also very often report severe dizziness, dry mouth and increased sweating (including night sweats).
In addition, weight changes are often caused by a change in appetite. Depending on the patient, both weight gain and weight loss are possible. Another common side effect of treatment with venlafaxine is loss of libido (sexual desire).
Irregular menstruation in women and ejaculation disorders in men are possible. Finally, side effects in the gastrointestinal tract are also frequently observed, with patients complaining of diarrhea and constipation. Further side effects can be found in the package insert.
Interactions
Venlafaxine is absorbed as a tablet and activated in the liver by specific enzymes. This can lead to numerous interactions with other drugs, which are also metabolized by the same enzyme. In addition, venlafaxine should not be combined with MAO inhibitors (including selegiline, tranylcypromine). Due to a mutually reinforcing effect, there is a risk of massively increased serotonin levels in the central nervous system, which causes the serotonin syndrome (symptoms of which are heart palpitations, seizures, clouding of consciousness, nausea, etc. ).For this reason, the simultaneous intake of venlafaxine with other serotonin-level increasing drugs (serotonergic drugs, such as other antidepressants) should be avoided as far as possible.
Dosage
In case of depression the usual starting dose is 75 mg a day. This dose can be continuously increased during the course of therapy if the effect is absent or weak up to a maximum of 375 mg. An increase in dosage must always be carried out by the treating physician. Abrupt discontinuation of the drug therapy should be avoided, as this can lead to typical discontinuation symptoms (dizziness, sleep disorders, nausea, vomiting, trembling, etc.).
For the treatment of generalized and social anxiety disorders, the procedure is the same as for the treatment of depression. However, the maximum dosage here is 225 mg per day. In panic disorders, one starts with a lower dosage (37.5 mg a day) before slowly increasing to 225 mg. Due to the metabolism in the liver and excretion via the kidney, liver and kidney dysfunction can lead to considerable changes in the levels of the active substance in the blood. For this reason, the dose in these patients should be adjusted by the treating physician.
