venlafaxine hydrochloride

ven·la·fax·ine hydrochloride (vnl-fksn, -sn)

n.

An oral antidepressant that inhibits neuronal reuptake of serotonin, norepinephrine, and dopamine in the central nervous system.

---

venlafaxine hydrochloride

Efexor (UK), Effexor, Effexor XR

Pharmacologic class: Phenethylamine derivative

Therapeutic class: Antidepressant, anxiolytic

Pregnancy risk category C

FDA Boxed Warning

• Drug may increase risk of suicidal thinking and behavior in children and adolescents with major depressive disorder and other psychiatric disorders. Risk must be balanced with clinical need, as depression itself increases suicide risk. With patient of any age, observe closely for clinical worsening, suicidality, and unusual behavior changes when therapy begins. Advise family and caregivers to observe patient closely and communicate with prescriber as needed.
• Drug isn't approved for use in pediatric patients.

Action

Inhibits neuronal serotonin and norepinephrine reuptake and slightly inhibits dopamine reuptake

Availability

Capsules (extended-release): 37.5 mg, 75 mg, 150 mg

Tablets: 25 mg, 37.5 mg, 50 mg, 75 mg, 100 mg

⊘Indications and dosages

➣ Depression

Adults: In outpatients, 75 mg P.O. daily in two or three divided doses; may increase in increments of 75 mg/day q 4 or more days to a maximum of 225 mg/day; extended-release form can be given as a single daily dose. In hospitalized patients, 75 mg P.O. daily in two or three divided doses; may increase in increments of 75 mg/day q 4 days to a maximum of 375 mg/day given in three divided doses.

➣ Generalized anxiety disorder

Adults: Single dose of 37.5 to 75 mg (extended-release) P.O. daily; may increase in increments of 75 mg/day q 4 days to a maximum of 225 mg/day

➣ Panic disorder

Adults: 37.5 mg (extended-release) P.O. daily for 7 days; increase to 75 mg P.O. daily for 7 days; then increase by 75 mg daily at weekly intervals to a maximum of 225 mg P.O. daily

Dosage adjustment

• Hepatic or renal impairment

Off-label uses

• Premenstrual dysphoric disorder

Contraindications

• Hypersensitivity to drug
• MAO inhibitor use within past 14 days

Precautions

Use cautiously in:
• cardiovascular disease; hypertension; heart failure, recent myocardial infarction, and other conditions in which increased heart rate poses a danger; hepatic or renal impairment; glaucoma; hyperthyroidism; hyponatremia; syndrome of inappropriate antidiuretic hormone secretion (SIADH)
• history of seizures, neurologic impairment, or drug abuse
• pregnant or breastfeeding patients
• children younger than age 18.

Administration

☞ Don't give within 14 days of MAO inhibitors.

Route	Onset	Peak	Duration
P.O.	Within 2 wk	2-4 wk	Unknown

Adverse reactions

CNS: abnormal dreams, anxiety, dizziness, headache, insomnia, nervousness, abnormal thinking, agitation, confusion, depersonalization, drowsiness, emotional lability, worsening depression, twitching, tremor, asthenia, paresthesia, mania, hypomania, suicidal ideation or behavior (especially in child or adolescent)

CV: chest pain, hypertension, palpitations, tachycardia, vasodilation

EENT: visual disturbances, blurred vision, mydriasis, tinnitus, rhinitis

GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, flatulence, dry mouth, anorexia

GU: urinary frequency or retention, sexual dysfunction, abnormal ejaculation, anorgasmia, erectile dysfunction

Metabolic: hyponatremia, SIADH

Skin: bruising, pruritus, rash, diaphoresis, photosensitivity

Other: altered taste, weight loss, chills, yawning

Interactions

Drug-drug. Cimetidine: increased venlafaxine effects

MAO inhibitors: potentially fatal reactions

Sumatriptan, trazodone: serotonin syndrome (including altered level of consciousness)

Drug-diagnostic tests. Sodium: decreased level

Drug-herbs. Chamomile, hops, kava, skullcap, valerian: increased CNS depression

S-adenosylmethionine (SAM-e), St. John's wort: increased risk of sedative or hypnotic effects

Patient monitoring

☞ Monitor neurologic status, particularly for seizures, worsening depression, and suicidal ideation.
• Closely monitor vital signs and cardiovascular status. Stay alert for hypertension and tachycardia.
• Monitor nutritional status, hydration, and weight.

Patient teaching

• Tell patient taking extended-release capsules to swallow them whole without chewing, breaking, dividing, or dissolving.
☞ Caution patient not to stop therapy abruptly.
☞ Advise patient to promptly report seizures, worsening depression, or suicidal thoughts (especially in child or adolescent).
• Caution patient to avoid driving and other dangerous activities until drug effects are known.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs mentioned above.