Effexor, Effexor XR
Classifications: psychotherapeutic; antidepressant; serotonin norepinephrine reuptake inhibitor (snri); Therapeutic: antidepressant (snri)
Pregnancy Category: C
25 mg, 37.5 mg, 50 mg, 75 mg, 100 mg tablets; 37.5 mg, 75 mg, 150 mg sustained release capsules
Potent inhibitor of neuronal serotonin and norepinephrine reuptake and weak inhibitor of dopamine reuptake.
Antidepressant effect presumed to be due to potentiation of neurotransmitter activity in the CNS.
Depression, generalized anxiety disorder; social anxiety disorder.
Hypersensitivity to venlafaxine, or other SNRI drugs; concurrent administration with MAO inhibitors; abrupt discontinuation;
neonates; pregnancy (category C), lactation.
Renal and hepatic impairment, renal failure; anorexia nervosa, history of mania, suicidal ideations; elevated intraocular
pressure, acute closed-angle glaucoma; cardiac disorders, recent MI, heart failure; hypertension; hyperthyroidism; concomitant
administration with CNS drugs, CNS depression; history of seizures or seizure disorders; older adults. Safety in children
<18 y is not established.
Route & Dosage
Adult: PO 25125 mg t.i.d.
Geriatric: PO Start with lower doses in older adults
Adult: PO Start with 37.5 mg sustained release q.d. and increase to 75225 mg sustained release per day
Clcr 1070 mL/min: reduce total daily dose by 2550%; <10 mL/min: reduce total daily dose by 50%
- Give with food. Sustained release capsules must be swallowed whole, must not be opened or chewed.
- Dosage increments of up to 75 mg/d are usually made at 4 d or longer intervals.
- Allow 14 d interval after discontinuing an MAO inhibitor before starting venlafaxine.
- Do not abruptly withdraw drug after 1 wk or more of therapy.
- Store at room temperature, 15°30° C (59°86° F).
Adverse Effects (≥1%) CV: Increased blood pressure and heart rate,
palpitations. CNS: Dizziness, fatigue
, headache, anxiety, insomnia
, somnolence. Endocrine:
Small but statistically significant increase in serum cholesterol, weight loss (approximately 3 lb). GI: Nausea, vomiting, dry mouth, constipation
Sexual dysfunction, erectile failure, delayed orgasm, anorgasmia, impotence, abnormal ejaculation. Special Senses:
Blurred vision. Body as a Whole: Sweating,
InteractionsDrug: Cimetidine, mao inhibitors
, desipramine, haloperidol
may increase venlafaxine levels and toxicity. Should not use in combination with mao inhibitors
: do not start until >14 d after stopping mao inhibitor
; do not start mao inhibitor
until 7 d after stopping venlafaxine. Trazodone
may lead to serotonin
syndrome. Herbal: St. John's wort, sour date nut
may cause serotonin
Well absorbed from GI tract. Onset:
2 wk. Peak:
Venlafaxine 12 h; metabolite 34 h. Duration:
Approximately 30% protein bound, but extensively tissue bound. Metabolism:
Undergoes substantial first-pass metabolism to its major active metabolite, O
-desmethylvenlafaxine, with similar activity to venlafaxine. Elimination:
60% in urine as parent compound and metabolites. Half-Life:
Venlafaxine 34 h, O
-desmethylvenlafaxine 10 h.
Assessment & Drug Effects
- Monitor for worsening of depression or emergence of suicidal ideation.
- Monitor cardiovascular status periodically with measurements of HR and BP.
- Lab tests: Periodic lipid profile.
- Monitor neurologic status and report excessive anxiety, nervousness, and insomnia.
- Monitor weight periodically and report excess weight loss.
- Assess safety, as dizziness and sedation are common.
Patient & Family Education
- Be aware of potential adverse effects and notify physician of those that are bothersome.
- Do not drive or engage in potentially hazardous activities until response to drug is known.
- Avoid using alcohol while on venlafaxine.
- Do not use herbal medications without consulting physician.