VENLAFAXINE (Effexor): What is used for?

What is Venlafaxine?

Venlafaxine is an active ingredient used for the treatment of depression, anxiety and panic disorders. The product ingredient of Venlafaxine is Venlafaxine hydrochloride (hcl).

The trade names of Venlafaxine in the United States are: Effexor, Effexor XR.

Venlafaxine Mechanism of Action (MOA)

It is related to the potentiation of monoaminergic activity in the CNS.
Preclinical studies have shown that venlafaxine and its main metabolite, O-desmethylvenlafaxine, are potent inhibitors of the reuptake of serotonin and noradrenaline. Weakly inhibits dopamine reuptake.

Therapeutic indications, uses and benefits of Venlafaxine

  • Major depression.
  • Prevention of recurrences of major depressive episodes.
  • Also forms of prolonged release in generalized anxiety disorder, social anxiety disorder and panic disorder with or without agoraphobia.

Venlafaxine Dosage

Oral. Venlafaxine (25 mg, 37.5 mg, 50 mg, 75 mg, 100 mg, 150 mg, 225 mg)

– Immediate release: 75 mg/day in 2 or 3 doses. If they do not respond, increase to maximum dose: 375 mg/day. Increases will be made at intervals of 2 weeks or more, but not < 4 days.

– Prolonged release: 75 mg 1 time/day. In panic disorder 37.5 mg/day for 7 days, then increase to 75 mg/day. If they do not respond, increase to a maximum of 225 mg/day or 375 mg/day (major depression). Increases will be made at intervals of 2 weeks or more, but not < 4 days (major depression).

In severe renal failure and hemodialysis reduce the dose by 50%.
In hepatic insufficiency reduce the dose. Mild to moderate liver failure reduce by 50%; in severe liver failure, reductions greater than 50% may be necessary.
Periodically re-evaluate the usefulness of long-term treatment.

Mode of administration of Venlafaxine

Oral use.

Tablets: take with food at approximately the same time each day.

Prolonged-release tablets: give 1 time/day at the same time (morning or evening), swallow whole with a little water after meals.
Do not crush or chew.

Prolonged-release capsule: take with food at approximately the same time each day.
Swallow whole with some liquid, without breaking, crushing, chewing or dissolving.

Contraindications of Venlafaxine

  • Hypersensitivity;
  • Concomitant with MAOI.
  • Do not start until 14 days after the MAOI has been interrupted and interrupt at least 7 days before the MAOI is started.

Warnings and precautions with Venlafaxine

Recent history of heart attack or unstable heart disease, history of convulsions, patients whose conditions may be compromised by increases in heart rate, elevated IOP, or at risk for acute angle-closure glaucoma. Family history of bipolar disorder, history of aggression.
Bleeding disorders or predisposition to them, concomitant with anticoagulants, drugs that affect platelet function or increase the risk of bleeding.
Kidney failure, liver failure, elderly, under 18 years, diabetes.
Periodic control of blood pressure.

Hyponatremia and/or syndrome of inappropriate secretion of ADH may appear, usually in patients with depletion of volume or dehydrated.
Rigorous control in patients with a history of suicidal behavior and those who present a significant degree of suicidal ideation prior to the start of treatment since the risk of suicidal thoughts or attempted suicide during treatment is greater.
Gradually reduce the dose over a period of weeks or months to avoid withdrawal reactions.
Assess usefulness if akathisia/psychomotor agitation appears. It is recommended to monitor cholesterol levels.
Risk of serotonergic syndrome, particularly with concomitant use of other serotonergic agents, or affecting serotonin metabolism.
If concomitant treatment is clinically warranted, strict follow-up of the patient, especially at baseline and when increasing the dose.

Concomitant use with serotonergic precursors (tryptophan supplements) with antipsychotics or other dopamine antagonists is not recommended.
Consider risk/benefit in patients with elevated risk of severe cardiac arrhythmia or prolonged QTc.
Avoid concomitant administration with medications that prolong the QTc interval.

Liver failure

Reduce dose. Mild to moderate liver failure to reduce by 50%; in severe liver failure, reductions greater than 50% may be necessary.

Kidney failure

In severe renal failure and hemodialysis reduce by 50%.

Interactions with Venlafaxine

  • Potentiation of toxicity with risk of serotonergic syndrome with: triptanes, ISRS, ISRN, lithium, sibutramine, fentanyl and its analogues, dextromethorphan, tapentadol, pethidine, methadone, pentazocine, St. John’s wort, drugs affecting metabolism or precursors of serotonin.
  • Power effect of: warfarin.
  • Increased action by: cimetidine.
  • Power action and toxicity of: haloperidol.
  • Caution in co-administration with: imipramine, metoprolol.
  • Increased risk of QTc prolongation and/or ventricular arrhythmias with: drugs that prolong QTc interval (antiarrhythmics class Ia and III: quinidine, amiodarone, sotalol, dofetilide; antipsychotics such as thioridazine; some antihistamines; quinolonic antibiotics such as moxifloxacin; some macrolide antibiotics).
  • Avoid consumption of: alcohol
  • Lab: false + in urine immunoassays for phencyclidine (PCP) and amphetamines.

Pregnancy and Venlafaxine

Effectiveness and safety have not been established. Manage only if the potential benefit outweighs the risk.


Venlafaxine and its active metabolite, O-desmethylvenlafaxine, are excreted in breast milk.
A risk to the infant cannot be excluded, therefore a decision must be made on whether to continue/interrupt lactation or to continue/interrupt venlafaxine treatment taking into account the benefit of lactation for the child and the benefit of venlafaxine treatment for the woman.
There have been post-marketing notifications of infants who experienced crying, irritability and abnormal sleep patterns.
Symptoms consistent with withdrawal of venlafaxine following discontinuation of lactation have been reported.

Effects on driving ability

Venlafaxine can cause sedation, dizziness. Therefore, patients should be advised that if they experience sedation or dizziness, they should avoid performing potentially dangerous tasks, such as driving or using machines.

Adverse reactions and side effects of Venlafaxine

Asthenia, chills, fatigue.
Hypertension, vasodilatation, palpitations.
Decreased appetite, constipation, nausea, vomiting, xerostomia, dyspepsia. Hypercholesterolemia, weight loss.
Abnormal dreams, decreased libido, dizziness, dry mouth, headache, hypertension, insomnia, nervousness, paresthesia, sedation, drowsiness, tremor, confusion, depersonalization.
Yawning; sweating; anomalies in accommodation, mydriasis. Visual disorders; tinnitus.
Abnormal ejaculation/orgasms (males), anorgasmia, erectile dysfunction, impaired urination, menstrual disorders, dysuria, urinary frequency.
Persistence of sexual dysfunction.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 5656
NCI Thesaurus: C1278

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