BSN Tracker

venlafaxine

Brand: Effexor, Effexor XR

⚠ BBW Prototype Drug
Drug Class: antidepressant
Drug Family: antidepressant
Subclass: serotonin-norepinephrine reuptake inhibitor (SNRI)
Organ Systems: cns

Mechanism of Action

Inhibits reuptake of serotonin (primary at low doses) and norepinephrine (significant at doses ≥150 mg/day); weak dopamine reuptake inhibition at high doses; no significant receptor antagonism.

SERTnorepinephrine reuptake transporter (NET)

Indications

  • major depressive disorder
  • generalized anxiety disorder
  • social anxiety disorder
  • panic disorder
  • off-label: fibromyalgia, neuropathic pain, hot flashes, migraine prevention

Contraindications

  • concurrent MAOIs
  • uncontrolled narrow-angle glaucoma

Adverse Effects

Common

  • nausea
  • dry mouth
  • constipation
  • insomnia
  • diaphoresis
  • sexual dysfunction
  • hypertension (dose-dependent)

Serious

  • sustained diastolic hypertension (especially >225 mg/day)
  • serotonin syndrome
  • suicidal ideation
  • discontinuation syndrome (severe)

Pharmacokinetics (ADME)

Absorption ~45% bioavailability (XR equivalent but slower absorption)
Distribution Protein binding ~27%; Vd ~7.5 L/kg
Metabolism CYP2D6 to active O-desmethylvenlafaxine (ODV, also sold as desvenlafaxine)
Excretion Renal (~87%); dose reduction needed for CrCl <30 mL/min and hepatic impairment
Half-life 5 hours (venlafaxine); 11 hours (ODV)
Onset 2–4 weeks
Peak 2 hours (IR); 5.5 hours (XR)
Duration 12–24 hours
Protein Binding 27%
Vd ~7.5 L/kg

Drug Interactions

Drug / Agent Mechanism Severity
MAOIs serotonin syndrome — 14-day washout required major
CYP2D6 inhibitors (fluoxetine, paroxetine) increase venlafaxine and reduce ODV levels moderate
triptans additive serotonergic effect moderate

Nursing Considerations

  1. Monitor blood pressure at every visit; dose-dependent diastolic hypertension can occur and may require dose reduction or antihypertensive therapy
  2. Discontinuation syndrome is among the most severe of any antidepressant — taper over weeks to months; never abruptly stop
  3. Monitor suicidal ideation especially in young adults during first 4 weeks
  4. Counsel patients about the 2–4 week delay before therapeutic effect; early side effects (especially nausea) typically resolve within the first 2 weeks

Clinical Pearls

  • Venlafaxine has dose-dependent pharmacology: serotonergic at low doses (37.5–75 mg), noradrenergic effects emerge above 150 mg/day — clinical implications include dose-dependent hypertension and enhanced analgesic efficacy at higher doses
  • Among the most severe discontinuation syndromes of any antidepressant — 'brain zaps,' dizziness, nausea, and flu-like symptoms; structured taper is mandatory

Safety Profile

Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Antidepressant Generalized Anxiety Disorder Major Depressive Disorder Off-label: Fibromyalgia, Neuropathic Pain, Hot Flashes, Migraine Prevention Panic Disorder Social Anxiety Disorder
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