IRFANA PARVEEN
By Irfana Parveen

B.Sc (Psychiatry Ward)

25 April 2022
Medically reviewed by
Sumayya Salam
Pharm D
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Table of Contents

Venlafaxine sold under the brand name Effexor is an antidepressant medication used to treat medical conditions such as major depressive disorder, Anxiety, and panic disorder. 

Venlafaxine is not available over the counter. Buy Venlafaxine online from a certified online pharmacy, but it is essential to consult your health care before consuming it.

It is categorized under the group of drugs called selective serotonin and norepinephrine reuptake inhibitors (SSNRIs).
Venlafaxine is available in two formulations, namely

What Is Venlafaxine?

Venlafaxine was initially synthesized in the early 1980s at Wyeth Pharmaceuticals. Wyeth scientists recognized Venlafaxine as an important antidepressant agent, and they launched Venlafaxine to treat depression in the United States in early 1994 under the trade name Effexor.

The medicine was initially launched as an immediate-release formulation. The FDA approved the extended-release (XR) formulation in 1997. The advantage of the XR formulation, besides once-daily dosing, is a slightly lower rate of nausea during the beginning of therapy. Generic formulations of venlafaxine immediate-release entered the market in 2007.

Venlafaxine Mechanism of Action

Venlafaxine (Effexor) is an SSRI antidepressant that blocks the transporters responsible for the reuptake of serotonin and norepinephrine and potentiates the neurotransmitter action in the central nervous system. Venlafaxine works without the various cardiovascular, anticholinergic, and sedative effects seen in other drugs in this class.

The two main signs that indicate the working of Venlafaxine include a decrease or lack of thoughts of self-harm. Later, a patient will be more tolerant, every little thing will not irritate them anymore, and they will enjoy it more.

If the recommended dosage of Venlafaxine is correct, the patient should feel improvement in mood, energy levels, and interest in daily living. Feeling of fear, Anxiety, panic attacks, or undesired thoughts should be less. It should be noted that the treatment should not be ceased even if the depression symptoms improve.

How Long Does Venlafaxine Stay In Your System?

Venlafaxine comes in two forms: immediate-release pills and extended-release tablets. The drug's half-life varies based on the drug's formulation. 

The half-life of immediate-release pills is roughly 5 hours, whereas extended-release tablets have an 11-hour half-life.
It takes around a day for the medicine to be eliminated on average. It may take approximately 16.5 hours, while some patients may take a day and a half to stop the treatment.

  • Venlafaxine may be detected in a drug test 48 hours after taking it.
  • Venlafaxine stays in your blood for three days and can be detected in a blood test.
  • Antidepressants are detectable in hair follicles for at least 16 months. Venlafaxine can be discovered in your hair for roughly 1.5 years.

How Long Does Venlafaxine Take Show Its Effect?

The total effect of immediate-release Venlafaxine tablets is seen 2-3 hours after administration if taken at regular intervals. The impact of the extended-release formulation is observed 5-9 hours after administration with standard doses.

But how long does Venlafaxine take to work for depression? The first effects of depression are seen 2-4 weeks, when the patient should experience a slight decrease in depression symptoms. Venlafaxine reaches its maximum efficacy after 8 weeks. Some patients might experience higher Anxiety levels at the beginning of the treatment, which will gradually decrease in the following weeks. These tablets should be taken for several months to avoid a relapse of depression. Skipping doses is not recommended as it can provoke Venlafaxine withdrawal symptoms. The treatment for depression usually lasts for six months, and generalized Anxiety disorder for around 18 months.

Venlafaxine increases the level of norepinephrine, serotonin, and dopamine. This leads to the availability of more transmitters at the synapse and ultimately increases the stimulation of postsynaptic receptors.
The withdrawal symptoms of Venlafaxine in some patients can be disabling and may make its tapering and discontinuation extremely difficult.
Venlafaxine has one of the highest brain zap (electric shock sensation) frequency rates associated with its discontinuation.

Are There Any Factors Influencing Venlafaxine's Stay?

The length of time it takes for Venlafaxine to leave your body depends on several factors, including:

Age: The time it takes for Venlafaxine to be eliminated can be affected by age. The medicine takes longer to be eliminated in elderly patients with poor blood flow and kidney function. Venlafaxine's half-life is shortened by 24% in older adults compared to younger people.

Genetic: Venlafaxine's ability to persist in the body is also influenced by genetics. When a person's pharmaceutical metabolism is poor, it takes longer to eliminate the drug and vice versa.

How much do You take?: The duration of the medicine is also determined by the dosage. Patients on lower dosages metabolize and eliminate the medication more quickly.

Additional substances: Venlafaxine's duration of action can be affected by taking it with other medications. Depending on the substances consumed, it may lower or raise the drug content in your blood. Mixing medications, however, can result in significant adverse effects; therefore, it's not a good idea.

The state of the liver: Venlafaxine's elimination half-life is similarly influenced by liver function. Patients with hepatic fibrosis or cirrhosis are more likely to keep the medication in their bodies than those with normal hepatic functioning.

Contraindications: Venlafaxine is not recommended for patients hypersensitive to Venlafaxine. It should not be taken by anyone allergic to this drug's inactive ingredients. It should not be taken in combination with MAO Inhibitors due to the potential to develop serotonin syndrome. Caution should also be taken in those with a seizure disorder. Venlafaxine has not been approved for use in children or adolescents.

Kidney, Liver, and Thyroid Disorders: The prescribed dose of Venlafaxine shall be adjusted for those with kidney, liver, or thyroid problems. Before taking this drug, it is vital to inform the concerned doctor of such disorders.

Heart Disease and Hypertension: During clinical trials, Venlafaxine caused an increase in mean heart rate of 4 b.p.m, along with a sustained rise in blood pressure in some people.

Glaucoma: Venlafaxine can cause an increase in eye pressure. So, people suffering from glaucoma should inform pharmacists or concerned doctors before taking Venlafaxine. 

Pregnancy: There is not any adequate study on Venlafaxine in pregnant women. Thus, Venlafaxine should only be used during pregnancy if needed, after a recommendation from the doctor.

Serotonin Syndrome: Treatment with Effexor may lead to developing a potentially life-threatening condition, 'serotonin syndrome. This majorly occurs with serotonergic drugs (SSRIs, SNRIs, and triptans).

Venlafaxine Abuse & Dependence

Venlafaxine is not a controlled substance. It has no affinity for benzodiazepine, phencyclidine (PCP), N-methyl-D-aspartic acid (NMDA), or opiate receptors. While Venlafaxine has not been systematically studied for its potential for abuse, there was no indication of drug-seeking behavior in the clinical trials.

However, evidence shows that large doses of Venlafaxine might produce Amphetamine-like effects. Thus, while treating patients with a history of alcohol or substance abuse, physicians should consider the abuse potential of Venlafaxine.

Bottom Line From Practical Anxiety Solutions1

Venlafaxine is an SSRI antidepressant drug used to treat major depression, Anxiety, and panic disorders. Venlafaxine's half-life depends on its formulation.

Venlafaxine's half-life for immediate-release tablets is 5 hours, whereas, for extended-release tablets, it is around 11 hours. It takes around a day and a half for the drug to be eliminated from your body—factors such as age, mixing with other medications, genetics, etc.

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  • Roseboom, Patrick H., and Ned H. Kalin. "Neuropharmacology of venlafaxine." Depression and anxiety 12.S1 (2000): 20-29. https://doi.org/10.1002/1520-6394(2000)12:1+%3C20::AID-DA3%3E3.0.CO;2-M Obtain On 02/12/2022
  • Morais, Simone, Christine PMCA Ryckaert, and Cristina Delerue-Matos. "Adsorptive stripping voltammetric determination of venlafaxine in urine with a mercury film microelectrode." Analytical letters 36.11 (2003): 2515-2526. https://doi.org/10.1081/AL-120024339 Obtain On 02/12/2022
  • Thase, Michael E. "Effects of venlafaxine on blood pressure: a meta-analysis of original data from 3744 depressed patients." Journal of Clinical Psychiatry 59.10 (1998): 502-508. https://doi.org/10.4088/jcp.v59n1002 Obtain On 02/12/2022
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