Venlafaxine

Antidepressant Drug

Drug class: Serotonin-Norepinephrine Reuptake Inhibitor

Venlafaxine (EFFEXOR)（中文：文拉法辛）

Common Strengths of Venlafaxine

Venlafaxine are available in the following strengths:

• 25 mg, 37.5 mg, 50 mg, 75 mg, 100 mg, 150 mg, 225 mg

Drug Trade Names of Venlafaxine

• Effexor
• Effexor XR

Drug Usage

Venlafaxine is used to treat:

• Major depressive disorder (MDD)
• Generalized anxiety disorder (GAD)
• Social anxiety disorder (SAD)
• Panic disorder (PD)

Mechanism of Action

Venlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI). It works by inhibiting the reuptake of serotonin and norepinephrine, increasing their levels in the brain.

Route of Administration

Oral (immediate-release tablets and extended0release capsules)

Dosages

• Depression: 75 - 225 mg/day
• Anxiety: 75 - 225 mg/day
• Panic disorder: 37.5 - 225 mg/day

Renal dose based on eGFR:

• eGFR 30 - 89 mL/min: Reduce total daily dose by 25 - 50%
• eGFR <30 mL/min: Reduce total daily dose by 50% or more

Side Effects

Frequency	Adverse reactions
Common	Nausea: Stick to simple meals and avoid rich or spicy foods.
	Dry mouth: Chew sugar-free gum or sweets.
	Dizziness: Get up slowly from sitting or lying positions
	Constipation: Increase fiber intake and drink plenty of water
	Insomnia: Take venlafaxine in the morning
	Excessive Sweating: Wear loose clothing and use a fan if needed
	Decreased Appetite
	Fatigue or Sleepiness
	Sexual Dysfunction: includes decreased libido and difficulty achieving orgasm
Serious	Serious side effects are less common but require immediate medical attention, These include::
	Suicidal Thoughts or Actions: especially in the first few months of treatment or when the dose is changed. Symptoms include new or worsening depression, anxiety, or unusual changes in mood or behavior.
	Serotonin Syndrome: This potentially life-threatening condition can occur when there is too much serotonin in the body. Symptoms include agitation, hallucinations, rapid heart rate, fever, nausea, vomiting, diarrhea, and muscle twitching
	Severe Allergic Reactions: these include symptoms like diffculty breathing, swelling of the face, lips, tongue, or throat, and severe rash or hives.
	High blood pressure: Regular monitoring is necessary as venlafaxine can increase blood pressure
	Low sodium level: Symptoms include headache, confusion, weakness, an unsteadiness
	Bleeding problems: Increased risk when taken with NSAID, aspirin, or anticoagulant
	Seizures
	Eye problems: Blurred vision, changes in eyesight, or dilated pupils
	Heart issues: Fast or irregular heart beat, chest pain
	Liver problems: Yellowing of the skin or eyes, dark urine, light-colored stools
	Severe skin reactions: Stevens-Johonson syndrome, toxic epidermal necrolysis

Pharmacokinetics

• Extensively metabolized in the liver
• Elimination half-life: approximately 5 hours for venlafaxine, 11 hours for its active metabolite
• Onset: 1 - 4 weeks for full effect

Drug Precautions

Pregnancy

Use with caution; potential risks to the fetus, especially in the third trimester

Breastfeeding

Use with caution; venlafaxine is excreted in breast milk

Children and Elderly

• Not recommended for Children under 18 for depression
• Elderly may be more sensitive to side effects; lower doses may be needed

Monitoring Requirements

• Blood pressure
• Signs of serotonin syndrome
• Suicidal thoughts or behaviors
• Liver function

Drug Interactions

Interaction Type	Examples	Notes
Major	Other serotonergic drugs include other SNRIs, SSRIs, triptans, tricyclic antidepressants, opioids, lithium, buspirone, amphetamines, and St.John's Wort.	Risk of serotonin syndrome
Moderate	Antiplatelets Anticoagulants NSAID CYP2D6 substrates: dextromethorphan, metoprolol, nebivolol, tolterodine	Increased bleeding risks

FAQ

How Should I Take the Tablet?

Take the tablet with food, either as a single daily dose or divided into two doses. Extended-release capsules should be taken once daily with food.

What Should I Avoid While Taking?

Avoid alcohol and operating heavy machinery until you know how venlafaxine affects you. Avoid abrupt discontinuation of the medication.

What Happens if I Miss a Dose?

Take the missed doses as soon as you remember unless it is almost time for your next dose. Do not double doses,