What is the use of venlafaxine (Effexor), a selective serotonin and norepinephrine reuptake inhibitor (SSNRI)?

From the Guidelines

Venlafaxine is an antidepressant medication that belongs to the serotonin-norepinephrine reuptake inhibitor (SNRI) class, and it is commonly prescribed to treat major depressive disorder, generalized anxiety disorder, social anxiety disorder, and panic disorder, as suggested by the Japanese Society of Anxiety and Related Disorders/Japanese Society of Neuropsychopharmacology clinical practice guideline for social anxiety disorder 1.

Key Points

• The typical starting dose of venlafaxine is 37.5 mg once or twice daily, which can be gradually increased to 75-225 mg daily based on response and tolerability.
• Venlafaxine is available in immediate-release tablets taken 2-3 times daily or extended-release capsules taken once daily.
• Common side effects include nausea, headache, dizziness, insomnia, increased sweating, and dry mouth.
• Blood pressure should be monitored regularly as venlafaxine can cause hypertension, particularly at higher doses.
• Importantly, venlafaxine should not be stopped abruptly as this can lead to discontinuation symptoms; dosage should be tapered gradually under medical supervision.

Mechanism of Action

The medication works by increasing the levels of serotonin and norepinephrine in the brain, which helps regulate mood, reduce anxiety, and improve energy levels.

Special Considerations

• Venlafaxine may be associated with greater suicide risk than other SNRIs, and both venlafaxine and desvenlafaxine have been associated with overdose fatalities, as noted in the clinical practice guideline for the assessment and treatment of children and adolescents with anxiety disorders 1.
• Duloxetine, another SNRI, has been associated with hepatic failure presenting as abdominal pain, hepatomegaly, and elevation of transaminase levels, and should be discontinued and not restarted in patients who develop jaundice or other evidence of clinically significant liver dysfunction 1.

From the FDA Drug Label

INDICATIONS AND USAGE Venlafaxine tablets, USP are indicated for the treatment of major depressive disorder The use of venlafaxine (Effexor), a selective serotonin and norepinephrine reuptake inhibitor (SSNRI), is for the treatment of major depressive disorder.

• Key points about the use of venlafaxine include:
  • The efficacy of venlafaxine was established in 6-week controlled trials of adult outpatients with major depression
  • Venlafaxine is also used to maintain an antidepressant response for up to 26 weeks following 8 weeks of acute treatment 2

From the Research

Use of Venlafaxine

• Venlafaxine is an antidepressive drug that inhibits both synaptic serotonin and norepinephrine reuptake, allowing for tailored treatment through differential dosing 3.
• It is used to treat major depression and major depression associated with anxiety, with a dose-related response observed in clinical improvements 4.
• Venlafaxine is also effective in the treatment of anxiety disorders, including generalized anxiety disorder, social anxiety disorder, panic disorder, post-traumatic stress disorder, and obsessive-compulsive disorder 5, 6.

Dosage and Efficacy

• The dosage of venlafaxine can range from 75 to 200 mg/day, with higher dosages associated with increased efficacy in severely ill patients 3, 4.
• A stepwise dosage regimen is suggested, with an increase of dosage to upper limits in cases of non-response before discontinuation of treatment with venlafaxine 3.
• Higher doses of venlafaxine may be cost-saving in relation to selected hospital resources, with patients spending fewer days in hospital and having fewer outpatient visits 7.

Safety and Tolerability

• Venlafaxine is generally well-tolerated, with common side effects including nausea, dizziness, somnolence, insomnia, dry mouth, and asthenia 4, 6.
• The overall tolerability profile of venlafaxine is generally comparable to that of selective serotonin reuptake inhibitors (SSRIs), although there is a greater incidence of noradrenergically mediated side effects 5.
• Concerns about safety in overdose have also recently emerged, highlighting the need for careful monitoring and dose adjustment 5.