Pristiq Tapering Guide
desvenlafaxine
Boxed Warning
Suicidality risk in children, adolescents, and young adults under 25 during initial treatment.
Overview
Desvenlafaxine is the active metabolite of venlafaxine, formulated as an extended-release SNRI for major depressive disorder. It was designed to provide more predictable pharmacokinetics by bypassing CYP2D6 metabolism.
25mg, 50mg, 100mg
Extended-release tablets: 25mg, 50mg, 100mg
Category C (risk cannot be ruled out)
Mechanism of Action
Serotonin-norepinephrine reuptake inhibitor (SNRI). Inhibits both the serotonin and norepinephrine transporters. Unlike its parent compound venlafaxine, it does not require CYP2D6 activation.
Taper Notes
Extended-release tablet matrix prohibits splitting or crushing. Available strengths (25, 50, 100 mg) limit step granularity; compounding pharmacy is essential for doses between commercial strengths. Discontinuation syndrome similar in severity to venlafaxine.
Maudsley Deprescribing Guidance
Compounded suspension is required for hyperbolic reductions below the 25 mg minimum strength. Do not crush or split ER tablets — matrix integrity is required for controlled release.
Common Withdrawal Symptoms
Interactions & Safety
Drug Interactions
- MAOIs — contraindicated (serotonin syndrome risk)
- Serotonergic drugs increase serotonin syndrome risk
- Weak inhibitor of CYP2D6; minor effect on CYP2D6 substrates
Food Interactions
- No significant food effect on pharmacokinetics
- Avoid alcohol during treatment
Contraindications
- MAOIs within 14 days
- Known hypersensitivity to desvenlafaxine or venlafaxine
Toxicity
Serotonin syndrome with serotonergic combinations. Sustained hypertension. Lipid elevations reported. Severe discontinuation syndrome similar to venlafaxine.
Pharmacokinetics
ADME Profile
Bioavailability ~80%. Tmax ~7.5 hours. Food does not significantly affect pharmacokinetics.
~3.4 L/kg
Hepatic conjugation (UGT) and to a minor extent CYP3A4-mediated oxidation. Does not rely on CYP2D6 for activation.
Renal (~45% unchanged, ~24% as glucuronide conjugate). Total urinary recovery ~~70%.
~30%
~215 mL/min (total body clearance)
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