Can Pristiq (desvenlafaxine) be used to treat anxiety?

Pristiq (Desvenlafaxine) for Anxiety

Pristiq (desvenlafaxine) is not FDA-approved for anxiety disorders, though it may be considered as an alternative treatment option when first-line medications have failed. 1

Mechanism and Classification

Desvenlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI) that works by inhibiting the presynaptic reuptake of both serotonin and norepinephrine in the brain. It is the active metabolite of venlafaxine, another SNRI that is recognized in clinical guidelines for treating anxiety disorders. 2, 3

Evidence for Anxiety Treatment

While desvenlafaxine is only FDA-approved for major depressive disorder (MDD) in adults, there is some evidence supporting its use for anxiety:

• A pooled analysis of 9 randomized controlled trials showed that desvenlafaxine was associated with significantly greater improvement in anxiety symptoms compared to placebo in patients with MDD who had comorbid anxiety symptoms. 4

• Clinical guidelines for social anxiety disorder recognize venlafaxine (the parent compound of desvenlafaxine) as an effective treatment option. The Canadian Clinical Practice Guidelines list venlafaxine as a first-line treatment for social anxiety disorder. 2

• The AACAP guideline suggests SNRIs could be offered to patients with social anxiety, generalized anxiety, separation anxiety, or panic disorder, though this recommendation specifically mentions children and adolescents. 2

Treatment Algorithm for Anxiety

1. First-line options (based on strongest evidence):

   • SSRIs (escitalopram, sertraline, paroxetine, fluvoxamine)
   • SNRIs (venlafaxine)
   • CBT (cognitive behavioral therapy)

2. Second-line options (when first-line fails):

   • Other SNRIs including desvenlafaxine
   • Benzodiazepines (short-term use only)
   • Pregabalin

Dosing and Administration

If using desvenlafaxine for anxiety:

• Start with 50 mg once daily
• May increase to 100 mg if needed
• Take at approximately the same time each day
• Can be taken with or without food
• Tablets should be swallowed whole, not crushed or chewed

Potential Benefits of Desvenlafaxine

• Once-daily dosing
• Achieves steady-state plasma concentrations within 4-5 days
• Minimal impact on cytochrome P450 enzyme system, reducing risk for drug interactions
• May help with both anxiety and depression symptoms when they co-occur 3, 5

Important Precautions and Side Effects

• Suicidal thoughts: Increased risk of suicidal thinking and behavior, particularly in young adults
• Serotonin syndrome: Risk increases when combined with other serotonergic drugs
• Discontinuation syndrome: Abrupt discontinuation may cause withdrawal symptoms
• Common side effects: Nausea, dizziness, insomnia, hyperhidrosis, constipation
• Blood pressure: May increase blood pressure; monitoring recommended
• Pregnancy: Discuss risks/benefits; consider registry enrollment if used during pregnancy 1

Clinical Pitfalls to Avoid

1. Abrupt discontinuation: Always taper gradually to minimize discontinuation symptoms
2. Drug interactions: Avoid MAOIs within 14 days; use caution with other serotonergic medications
3. Monitoring gaps: Regular follow-up is essential, especially during initial treatment
4. Overlooking comorbidities: Anxiety often co-occurs with depression and other conditions
5. Dose adjustments: Required for patients with severe renal impairment or hepatic impairment

Conclusion

While Pristiq (desvenlafaxine) is not FDA-approved specifically for anxiety disorders, it may be considered as an alternative treatment option based on its pharmacological profile and limited evidence showing efficacy for anxiety symptoms, particularly in patients with comorbid depression. SSRIs and venlafaxine have stronger evidence and should generally be tried first for anxiety disorders.