Trade Names: Velaxin ER, Efectin ER, Symfaxin ER, Faxolet ER, Prefaxine, Oriven, Venlectine, Alventa, Velafax, Axyven
Venlafaxine: An Antidepressant with a Strong Impact on the Brain and Body
Venlafaxine is one of the most well-researched antidepressants, belonging to the group of selective serotonin and norepinephrine reuptake inhibitors (SNRIs). Considered the gold standard of this group, it is actively used to treat various depressive and anxiety disorders. Its unique effects make it effective not only for classic depression but also for psychosomatic disorders, addictions, and even chronic pain. However, to fully benefit from venlafaxine, it is important to understand how it works and its specific properties.
Mechanism of Action: How Does Venlafaxine Help the Brain?
The primary action of venlafaxine involves inhibiting the reuptake of monoamines: serotonin, norepinephrine, and at higher doses, dopamine. This means it prevents these substances from leaving the synapses (contact points between nerve cells), prolonging their action. The effect depends on the dosage:
- Low doses (up to 150 mg/day): Primarily affect serotonin levels, helping to reduce anxiety and improve mood.
- Moderate doses (150-225 mg/day): Affect both serotonin and norepinephrine, increasing energy, motivation, and vitality.
- High doses (above 225 mg/day): Also impact dopamine, which can improve motor function, motivation, and productivity.
This makes venlafaxine unique: instead of switching medications to enhance the effect, the dose can simply be increased to achieve a stronger impact on the brain.
Rapid Absorption and Extended Release
Venlafaxine dissolves quickly in water and is rapidly absorbed into the bloodstream. This can be both an advantage and a drawback, as sudden spikes in concentration often lead to side effects like nausea. However, modern extended-release forms of venlafaxine, such as delayed-release capsules, solve this problem. These forms ensure gradual, sustained action without sudden peaks and drops, reducing the risk of side effects.
Extended-release forms also reduce the frequency of intake from three times a day to once or twice daily. The half-life of the regular form is about 4-5 hours, while the extended-release form lasts up to 15 hours.
Multifunctional Impact on Symptoms
- Antidepressant Effect: Venlafaxine is particularly effective in cases of depression with apathy and fatigue. It helps patients return to active life, reduces feelings of emotional emptiness, and increases interest in the world around them. It works especially well for asthenic and apathetic depression, where the patient feels overwhelmed and unable to find the energy to do anything.
- Anti-Anxiety Effect: At low doses, venlafaxine effectively reduces anxiety, phobias, and obsessive thoughts. However, at doses above 150 mg, the anti-anxiety effect may turn into stimulation, which should be considered when adjusting the dosage.
- Pain Relief: Although venlafaxine is not the primary drug for neuropathic pain, it can enhance the effectiveness of opioids and reduce the need for high doses. It is added to combination therapy when there is a need to raise the pain threshold and minimize the side effects of opioids.
Side Effects
In the initial stages of taking venlafaxine, serotonin-related side effects such as nausea, vomiting, and constipation are common. These symptoms usually subside within the first few weeks as the body adjusts to the medication.
- Moderate doses: May cause noradrenergic side effects such as excessive sweating, increased heart rate, and elevated blood pressure.
- High doses: May cause dopaminergic effects, which sometimes lead to agitation or sleep disturbances.
Example: One patient reported that after increasing the dose, they became overly active and had difficulty sleeping. The problem was resolved by switching to morning intake.
How to Start Treatment and Increase the Dose
Treatment should begin with a minimal dose of 37.5-75 mg per day. If the medication is well-tolerated, the dose can be gradually increased.
It is important to note that low doses, such as 37.5 or even 75 mg, do not provide significant antidepressant effects. These are starting doses necessary for the body’s gradual adaptation.
Standard therapeutic doses:
- 150-225 mg/day for moderate depression.
- Up to 375 mg/day for severe depression.
When increasing the dose, it is essential to monitor side effects and adjust treatment if necessary. For example, beta-blockers may be prescribed for headaches or increased blood pressure.
Withdrawal Syndrome
Venlafaxine has a short half-life (about 4-5 hours for the regular form and 15 hours for the extended-release form), meaning its concentration in the blood can drop quickly if a dose is missed or if treatment is abruptly stopped. This can cause withdrawal symptoms such as headaches, nausea, dizziness, “electric shock” sensations (brain zaps), irritability, and sleep disturbances.
To minimize the risk of these symptoms, the venlafaxine dose should be gradually reduced by 37.5-75 mg every one to two weeks. In some cases, the dose is reduced even more slowly if withdrawal symptoms persist.
If withdrawal symptoms occur, doctors may prescribe temporary medications to ease the transition. For example, drugs with a gentler effect on the serotonin system may be used.
Interactions with Other Medications
Due to its low plasma protein binding level (27%), venlafaxine works well in combination with other medications. For example, it can be combined with antipsychotics (e.g., risperidone) for severe depression or psychosis. However, combining it with other SNRIs or SSRIs should be avoided to prevent serotonin syndrome.
Conclusion
Venlafaxine is a powerful treatment option for depression, anxiety disorders, and even pain. Its flexible dosing allows for personalized treatment based on specific symptoms, and extended-release forms help reduce the risk of side effects. However, it is crucial to follow a doctor’s recommendations, as improper use can lead to unwanted reactions or withdrawal symptoms. With patience and the right approach, venlafaxine can be the key to returning to a full and active life.
If you want to understand what’s happening with your condition or discuss appropriate treatment, visit the Plexus center in Warsaw — we have a psychiatrist who speaks Polish and Russian, who will help you find a solution that suits you best.