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Venlafaxine
Aka: Venlafaxine, Effexor, Venlafaxine Withdrawal
- See Also
- Desvenlafaxine (Pristiq)
- Serotonin Norepinephrine Reuptake Inhibitor (SNRI)
- SNRI Overdose
- Indications
- Major Depression including refractory cases
- Considered to be second-line agent
- Generalized Anxiety Disorder
- Obsessive Compulsive Disorder
- Post-Traumatic Stress Disorder
- Mechanism
- Similar activity as Tricyclic Antidepressants
- Serotonin Norepinephrine Reuptake Inhibitor
- Selective Serotonin Reuptake Inhibitor (<150 mg/day)
- Both Serotonin and Norepinephrine Reuptake Inhibitor (>150 mg/day)
- Minimally inhibits Dopamine uptake
- Pharmacokinetics
- Half life: 5 to 11 hours
- Background
- Cost (2013)
- Venlafaxine ER (Effexor XR): $20 per month
- Desvenlafaxine (Pristiq or the ER base): $140-160 per month
- Preparations: Venlafaxine
- Venlafaxine regular release (Effexor)
- Available as 25, 37.5, 75, 100 mg tablets (scored)
- Start: 25 mg PO tid
- Effective dose: 150-225 mg per day divided bid to tid
- Maximum dose: 375 mg per day
- Disadvantages: More adverse effects than Effexor XR
- Advantages: May be dosed once daily since metabolites offer similar duration to Effexor XR
- Venlafaxine extended release (Effexor XR)
- Available as 37.5, 75, 150 mg (capsules)
- Start: 37.5 to 75 mg orally daily
- Maximum: 225 mg orally daily
- Preparations: Desvenlafaxine
- Pristiq (Desvenlafaxine Succinate)
- Active metabolite of Effexor XR
- No added benefit over Effexor XR and with possibly more adverse effects
- Reference
- (2008) Prescriber's Letter 15(5): 28
- Desvenlafaxine ER (extended-release base preparation)
- Equivalent to Pristiq (but requires specific instructions to pharmacist to allow substitution)
- As with Pristiq, no significant benefit when compared with Venlafaxine XR (which is generic and much less expensive)
- References
- (2013) Presc Lett 20(7):40
- Adverse Effects: Prominent Withdrawal symptoms
- See also Antidepressant Withdrawal
- Symptoms start 1-3 days after stopping medication (mild symptoms may have onset within hours of missed pill)
- Dizziness
- Irritability
- Insomnia
- Headache
- Gastrointestinal upset
- Ataxia or Vertigo
- Paresthesias (including shock-like Sensations)
- Tachycardia
- Fever
- Effexor taper schedule
- Reduce dose 25 mg/day every 5-7 days
- Taper to 25-50 mg/day before stopping
- Effexor XR taper schedule
- Reduce dose 37.5 to 75 mg per day every 7 days
- Taper to 37.5 mg/day before stopping
- Alternatives to tapering with Effexor
- Start Sertraline (Zoloft) 50 mg orally daily on stopping Effexor
- Adverse Effects (higher with regular release Effexor)
- Anticholinergic (less than Tricyclic Antidepressants)
- Dizziness
- Somnolence
- Dry Mouth
- Nausea or Vomiting
- May be severe and limit dosing
- Start therapy at 25 mg per day
- Increased Blood Pressure
- Only seen with total daily doses 300 mg or higher
- Less Sexual Dysfunction than Prozac, Zoloft, Paxil
- Sexual Dysfunction in 10-15% of cases
- Similar to Luvox and Celexa
- See Antidepressant Induced Sexual Dysfunction
- More stimulating (anxiogenic) than sedating
- Agitation or Insomnia may occur
- Decreased appetite and Weight loss may occur
-
Drug Interactions
- Minimal Cytochrome P450 interactions
- References
- Mishler and Lovecchio (2017) Crit Dec Emerg Med 31(11): 15-20
- (1997) Am J Psych 154:1760 [PubMed]
- Sundberg (1995) Depression Primary Care, PGM, p. 45-57