PHARM | SNRIs Venlafaxine

💊 PHARM STUDY GUIDE: VENLAFAXINE Class: SNRI – Serotonin Norepinephrine Reuptake Inhibitor

🧠 Mechanism of Action (MOA): Blocks reuptake of serotonin (5-HT) and norepinephrine (NE) → ↑ levels in synaptic cleft → improved mood & anxiety control. Weak dopamine effect.

📋 Indications:

• Major Depressive Disorder (MDD) 🧩
• Generalized Anxiety Disorder (GAD) 😰
• Panic & Social Anxiety Disorders 😳
• Off-label: Menopausal hot flashes 🌡

⚠️ Red-Flag Side Effects (Prioritize 🚨): 1️⃣ Serotonin Syndrome (LIFE-THREATENING) – fever, shivering, agitation, hyperreflexia, rigidity, tachycardia, diarrhea, seizures. 👉 Action: STOP drug, supportive care, cyproheptadine if severe. 2️⃣ Suicidal Ideation – especially in <25 yrs or early therapy. 👉 Action: Monitor mood, report new/worsening depression. 3️⃣ Cardiac Events – ↑ BP, HR, QT prolongation, rare TdP. 👉 Action: Monitor VS, ECG, electrolytes; report chest pain or syncope. 4️⃣ Bleeding Risk – ↓ platelet serotonin → ↑ risk w/ NSAIDs, ASA, anticoagulants. 👉 Action: Monitor for GI bleed, bruising, petechiae. 5️⃣ Hyponatremia/SIADH – elderly or diuretic use. 👉 Action: Monitor Na⁺; report confusion, headache, weakness.

💉 Common Side Effects (Manage): Nausea 🤢, headache, insomnia, constipation, dry mouth, dizziness, sexual dysfunction. Tip: Take w/ food to ↓ GI upset.

🩺 Nursing Interventions:

• Assess suicidal risk, anxiety, BP, HR regularly.
• Watch for serotonin syndrome (esp. if on SSRIs, MAOIs, or triptans).
• Educate: may take 2–4 weeks for full effect.
• Taper gradually → abrupt stop = withdrawal (dizziness, “brain zaps”).
• Teach to take same time daily; XR form must be swallowed whole.
• Avoid alcohol 🍷 → risk of rapid drug release & toxicity.
• For hepatic/renal impairment → reduce dose 25–50%.

💣 Contraindications & Dangerous Combos: ❌ MAOIs, linezolid, methylene blue → fatal serotonin syndrome. ❌ Other serotonergic drugs (SSRIs, SNRIs, TCAs, tramadol). ❌ QT-prolonging agents (amiodarone, ziprasidone, macrolides).

📊 Pharmacokinetics Highlights:

• Metabolism: CYP2D6 (major), CYP3A4 (minor). Inhibitors ↑ toxicity risk.
• Half-life: Venlafaxine 5 h, metabolite (ODV) 11 h.
• Excretion: Mostly renal → dose adjust if impaired.

🎯 Top 5 High-Yield Takeaways: 1️⃣ Monitor suicidality early & during dose changes. 2️⃣ Never mix with MAOIs or other serotonergic meds. 3️⃣ Swallow XR whole & take with food. 4️⃣ Track BP/ECG & bleeding (esp. if on anticoagulants). 5️⃣ Taper off slowly to avoid severe withdrawal.

🧩 80/20 Rule Summary: 👉 SNRIs like venlafaxine boost serotonin + norepinephrine. Know serotonin syndrome, suicidality, BP/QT risk, bleeding, and withdrawal — that’s 20% of content, 80% of what you’ll be tested on.

⚡️“Start low, go slow, and watch the glow — serotonin can burn hot.”🔥

#PharmNerd 🧠 #EffexorXR #SNRI #NursingSchool #NCLEXPrep #MentalHealth