Venlafaxine is an antidepressant drug that belongs to the group of serotonin-norepinephrine reuptake inhibitors (SNRIs). Therefore, it works by increasing the amount of these neurotransmitters in the intersynaptic space. Venlafaxine was also shown to have a weak dopamine reuptake inhibitory effect at higher doses. SNRIs are one of the first choice groups and thus one of the most frequently used groups for the treatment of depression.

Venlafaxine: indications

Venlafaxine is the first-line treatment for both the treatment and prevention of major depressive episodes, which are characterized by the following clinical features:

  • apathy,
  • lack of motivation,
  • depression with pain,
  • social withdrawal,
  • the occurrence of intrusive thoughts.

As a drug of first choice, it is also used in the treatment of generalized anxiety disorders and anxiety related to post-traumatic stress. It is also used in the treatment of social phobia, anxiety disorders with panic attacks and in the case of obsessive-compulsive disorders. In these cases, it is treated as a second-line treatment.

Venlafaxine: dosage

The recommended daily doses range from 75 mg to a maximum dose of 375 mg, and their values ​​for individual patients depend on the indication for use and on individual response to treatment and the risk of side effects.

Stable concentration of venlafaxine in the blood is achieved after 3 days of use, and drugs should be used at least 6 months after achieving the state of improvement in well-being, i.e. disease remission.

  • Major Depressive Episodes:75 - 375 mg / day
  • Generalized Anxiety Disorder:75 - 225 mg / day
  • Social phobia:75 mg (no evidence of dose escalation being effective) - up to 225 mg / day
  • Panic disorder:37.5 mg / day for 7 days and then increasing to 75 mg - further increasing the dose to a maximum of 225 mg / day.

In any case, doses should be increased gradually and following clinical judgment (4 days to 2 weeks between dose adjustments). Discontinuation of venlafaxine therapy should be carried out graduallydose reduction. Sudden discontinuation or accidental missed dose may cause unwanted withdrawal symptoms, such as:

  • dizziness and headache,
  • sleep disorders,
  • anxiety,
  • nausea,
  • vomiting.

Venlafaxine: contraindications

Venlafaxine is not suitable for use in children and adolescents. Caution should be exercised when used by the elderly and in people with renal insufficiency (this substance is excreted from the body mainly through the kidneys).

Concomitant use of venlafaxine with MAO inhibitors (iproniazid, phenelzine, isocarboxazid, moclobemide, linezolid) may lead to the occurrence of serotonin syndrome, which manifests itself in:

  • arousal,
  • hallucinations,
  • coma,
  • tachycardia,
  • unstable blood pressure,
  • hyperthermia,
  • digestive symptoms.

You can start taking venlafaxine only 14 days after completing your MAOI treatment. In contrast, iMAOs can be started 7 days after the end of treatment with venlafaxine.

Due to the increased risk of cardiac arrhythmias (prolongation of the QT interval on the ECG), it is not recommended to use venlafaxine with other drugs that prolong the QT interval, for example: macrolide antibiotics (erythromycin), some antiarrhythmic drugs (quinidine, amiodarone) , sotalol, dofetilide), some antipsychotics (e.g. thioridazine) or some antihistamines.

Due to the possibility of increased intraocular pressure, special care should be taken in patients with glaucoma.

Venlafaxine and pregnancy

Venlafaxine has a C category in the classification of drugs used in pregnant women. the indication for the use of venlafaxine in pregnant women.

Venlafaxine: side effects

The side effects associated with the use of venlafaxine mentioned in the literature include:

  • nausea,
  • vomiting,
  • sweating,
  • constipation,
  • sleepiness,
  • dry mouth,
  • dizziness,
  • accommodation disorders,
  • insomnia,
  • decreased appetite,
  • asthenia,
  • nervousness,
  • ejaculation / orgasm disorders,
  • erectile dysfunction.

May increase the risk of hyponatraemia in elderly patients.

Veryrarely seen in patients using venlafaxine, weight gain, sedation or orthostatic hypotension.

If symptoms such as drowsiness or dizziness do not occur, there are no contraindications for driving or operating machinery. The patient should therefore first assess whether these effects will not occur.

Venlafaxine is considered an active substance that is well tolerated by patients and has a high safety profile and a low potential for clinically relevant interactions with other medicinal substances.

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