Venlafaxine

1. Introduction

Venlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI) used to treat major depressive disorder (MDD), generalised anxiety disorder (GAD), panic disorder, and social anxiety disorder. It increases serotonin and norepinephrine levels, improving mood and reducing anxiety.

2. Indications

• Major Depressive Disorder (MDD)
• Generalised Anxiety Disorder (GAD)
• Panic Disorder (PD)
• Social Anxiety Disorder (SAD)
• Off-Label Uses:
  • Neuropathic pain
  • Migraine prevention
  • Menopausal hot flashes

3. Dosage

Adults:

• Major Depressive Disorder (MDD):
  • Immediate-Release (IR): 37.5 mg twice daily, increasing to 75–375 mg/day in divided doses.
  • Extended-Release (XR): Start with 75 mg once daily, increasing to 150–225 mg/day if needed.
• Generalised Anxiety Disorder (GAD) / Social Anxiety Disorder (SAD):
  • Extended-Release (XR) Only: Start with 75 mg once daily, up to 225 mg/day if necessary.
• Panic Disorder (PD):
  • Extended-Release (XR) Only: 37.5 mg daily for 7 days, then 75 mg daily, up to 225 mg/day.

Elderly:

• Start at lower doses (37.5 mg daily) and titrate slowly due to increased sensitivity.

Renal Impairment:

• Mild to moderate (CrCl 30–89 mL/min): Reduce dose by 25–50%.
• Severe (CrCl <30 mL/min): Reduce dose by 50%.

Hepatic Impairment:

• Mild impairment: Reduce dose by 25–50%.
• Severe impairment: Avoid use if possible due to increased drug accumulation.

4. Administration

• Take with food to reduce nausea.
• Swallow extended-release capsules whole—do not crush or chew.
• Take in the morning if insomnia occurs, or at night if causing drowsiness.

5. Forms Available

• Immediate-Release (IR) Tablets: 25 mg, 37.5 mg, 50 mg, 75 mg, 100 mg
• Extended-Release (XR) Capsules: 37.5 mg, 75 mg, 150 mg, 225 mg

6. Side Effects

6.1 Common Side Effects:

• Nausea
• Insomnia or drowsiness
• Dizziness
• Sweating
• Increased blood pressure

6.2 Less Common Side Effects:

• Sexual dysfunction
• Dry mouth
• Headache
• Weight loss or gain

6.3 Rare but Serious Side Effects:

• Hypertension (Dose-Dependent)
• Serotonin Syndrome (if combined with other serotonergic drugs)
• Discontinuation Syndrome (Severe withdrawal effects if stopped suddenly)
• QT Prolongation (Risk of arrhythmias in susceptible patients)
• Hyponatraemia (Low sodium levels, particularly in elderly patients)

7. Warnings

• Risk of Increased Blood Pressure: Monitor BP, especially at doses ≥150 mg/day.
• Suicidal Thoughts: Increased risk in young adults and adolescents—monitor closely.
• Discontinuation Syndrome: Avoid abrupt stopping—taper gradually over weeks to months.
• Risk of Serotonin Syndrome: Avoid combining with SSRIs, MAOIs, or serotonergic drugs.

8. Precautions

• Avoid alcohol due to increased CNS depression.
• Caution in patients with uncontrolled hypertension—may increase blood pressure.
• Monitor for worsening anxiety or agitation in the first few weeks.
• Caution in seizure disorders—may lower seizure threshold.

9. Interactions

• MAOIs (e.g., phenelzine, selegiline): Contraindicated—risk of serotonin syndrome.
• SSRIs/SNRIs (e.g., fluoxetine, duloxetine): Increased serotonin syndrome risk.
• NSAIDs, Aspirin, Warfarin: Increased bleeding risk.
• CYP3A4 and CYP2D6 Inhibitors (e.g., fluvoxamine, ritonavir): May increase venlafaxine levels.
• Antihypertensives: May reduce effectiveness due to BP elevation.

10. Monitoring Parameters

• Blood pressure (BP): Monitor every 2–4 weeks, especially at doses ≥150 mg.
• Mood and suicidal thoughts: Assess in young adults and high-risk patients.
• Sodium levels (hyponatraemia risk in elderly patients).
• Discontinuation symptoms—taper dose if stopping.

11. Use in Children

• Not approved for depression in children—increased suicidal risk.
• Occasionally used off-label for paediatric anxiety disorders under specialist guidance.

12. Use in Pregnancy

• Category C:
  • Not recommended unless benefits outweigh risks.
  • May cause withdrawal symptoms in newborns (neonatal adaptation syndrome).

13. Use in Elderly

• Start at lower doses (37.5 mg daily) due to increased sensitivity.
• Increased risk of hyponatraemia and falls.

14. Use in Kidney Disease

• CrCl 30–89 mL/min: Reduce dose by 25–50%.
• CrCl <30 mL/min: Reduce dose by 50% or avoid.

15. Use in Liver Disease

• Mild hepatic impairment: Reduce dose by 25–50%.
• Severe hepatic impairment: Avoid use if possible.

16. Patient Counselling Points

• Take with food to reduce nausea.
• Monitor blood pressure regularly, especially at higher doses.
• Avoid abrupt stopping—gradual tapering is required to prevent withdrawal symptoms.
• May take 2–4 weeks for full effect—continue taking even if no immediate benefit.
• Report any mood changes, suicidal thoughts, or agitation.

17. Table of Brand Names, Manufacturer, and Prices in USD

18. 15 FAQs (Frequently Asked Questions)

1. What is Venlafaxine used for?
It is used for depression, anxiety disorders, and panic disorder.

2. How does Venlafaxine work?
It increases serotonin and norepinephrine levels, improving mood and reducing anxiety.

3. How long does Venlafaxine take to work?
Effects start within 2 weeks, but full benefits may take 4–6 weeks.

4. Can I stop Venlafaxine suddenly?
No, withdrawal symptoms can be severe—taper gradually under medical supervision.

5. Does Venlafaxine cause weight gain?
It may cause weight changes (gain or loss), but weight gain is less common than with SSRIs.

6. Can I take Venlafaxine at night?
Yes, but it may cause insomnia—taking in the morning is preferred.

7. Does Venlafaxine cause high blood pressure?
Yes, especially at doses ≥150 mg/day—monitor BP regularly.

8. Can I take Venlafaxine with alcohol?
No, alcohol increases dizziness and sedation.

9. Can Venlafaxine cause sexual dysfunction?
Yes, it may reduce libido and cause erectile dysfunction.

10. How should Venlafaxine be stored?
Store at room temperature, away from moisture.