venlafaxine EFFEXOR XR
Class: SNRIFDA Indications: MDD, GAD, Panic Disorder, Social Anxiety
Off-Label Use: PMDD, PTSD, Neuropathic Pain, Fibromyalgia, Narcolepsy, Migraines
Prescribing
Forms: 37.5, 75, 150mg extended-release capsuleDose Range: 37.5-375 mg/day
Starting: Start at 37.5 mg qd for 1 week, then increase no faster than 75 mg q4 days until desired efficacy achieved
Stopping: 50% dose reduction x3 days then another 50% dose reduction x3 days, then discontinue entirely. Taper more slowly for patients sensitive to withdrawal effects
Precautions
Contraindications: Concomitant use of MAOIsSerious Side Effects: Serotonin syndrome; ↑ risk of SI in children and young adults; may impair platelet aggregation; SIADH; Dose dependent HTN (3%)
Side Effects: HTN, insomnia, anxiety, weight loss, anorexia, hyponatremia, mydriasis, seizures (0.3%), nausea, sedation/somnolence, dizziness, insomnia, xerostomia, abnormal dreams, hyperhidrosis, abnormal vision, anorgasmia
Pharmacokinetics
t½: 5 (3-7)° TMAX: 5.5°Substrate of: 2D6; 3A4, 2C9, 2C19
Inhibits: 2D6 & 3A4 (weak); Induces: ∅
Active Metabolites: O-desvenlafaxine (has 9-13° t½)
DDIs
- - DO NOT CO-PRESCRIBE WITH MAOIs (need a 14-day washout period)
- - 2D6 inhibitors can ↑ serum levels; 2D6 inducers can ↓ serum levels
Misc
- - essentially an SSRI < 225mg, NET inhibition emerges at doses ≥ 225mg
- - notorious for severe discontinuation syndrome
- - from most to least noradrenergic: levomilnacipran (1:2, 5HT:NE ratio) >> duloxetine (10:1) > desvenlafaxine (12:1) > venlafaxine (30:1)
Special Populations
Category C—May be associated with cardiac defects, anencephaly & cleft palate. Neonatal withdrawal may occur. 2nd trimester use associated with low birth weight.
RID 6-9%; ∅AE's have been reported
No overall differences in effectiveness or safety were observed between geriatric & younger patients
↓ dose by 25-50%
↓ dose by 50%
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