Bupivacaine

Bupivacaine – Clinical Overview (for Clinical Pharmacists)

1. Drug Class

  • Amide local anesthetic
  • Long-acting

Common brand names: Marcaine®, Sensorcaine®

Formulations: Plain solution; with epinephrine; liposomal bupivacaine (Exparel®)

2. Mechanism of Action

  • Reversibly blocks voltage-gated sodium (Na⁺) channels in neuronal membranes
  • Inhibits depolarization → blocks nerve impulse conduction
  • Preferentially affects pain fibers before motor fibers (dose/concentration dependent)

3. Clinical Uses

  • Local infiltration anesthesia
  • Peripheral nerve blocks
  • Epidural anesthesia/analgesia (labor, postoperative pain)
  • Spinal anesthesia (lower doses)
  • Postoperative analgesia (liposomal formulation)

4. Pharmacokinetics (Clinically Relevant)

  • Onset: Moderate (slower than lidocaine)
  • Duration: Long (3–10+ hours depending on site/dose)
  • Protein binding: High (~95%)
  • Metabolism: Hepatic (CYP-mediated amidase pathways)
  • Elimination: Renal (metabolites)

⚠️ Reduced clearance in hepatic impairment, pregnancy, and elderly

5. Dosing (Adult – Typical Ranges)

Use Concentration Notes
Local infiltration 0.25–0.5% With or without epinephrine
Peripheral nerve block 0.25–0.5% Volume determines spread
Epidural 0.0625–0.25% Lower conc. for analgesia
Spinal 0.5% (hyperbaric) Small doses only

Maximum dose (important):

  • Without epinephrine: ~2.5 mg/kg (max ~175 mg)
  • With epinephrine: ~3 mg/kg (max ~225 mg)

🚫 Do NOT exceed recommended doses — narrow safety margin

6. Adverse Effects

A. Local Anesthetic Systemic Toxicity (LAST) – CRITICAL

Bupivacaine is the most cardiotoxic local anesthetic

Early (CNS):

  • Perioral numbness
  • Tinnitus
  • Metallic taste
  • Dizziness, seizures

Late (Cardiac):

  • Ventricular arrhythmias
  • Hypotension
  • Cardiac arrest (often refractory)

⚠️ Risk ↑ with:

  • Intravascular injection
  • High total dose
  • Pregnancy
  • Acidosis, hypoxia

7. Black Box / High-Risk Warning

  • Severe, potentially fatal ventricular arrhythmias
  • Cardiotoxicity may be resistant to resuscitation
  • Greater risk vs lidocaine or ropivacaine

8. Management of LAST (Pharmacist-Critical Knowledge)

Immediate actions:

  • Stop local anesthetic
  • Airway/oxygenation
  • Seizure control (benzodiazepines)

Specific antidote:

  • 20% IV lipid emulsion
    • Bolus: 1.5 mL/kg
    • Infusion: 0.25 mL/kg/min
    • Repeat bolus if needed

📌 Pharmacists should ensure lipid rescue availability wherever bupivacaine is used.

9. Special Populations

  • Pregnancy: Increased sensitivity; ↓ protein binding
  • Hepatic disease: ↓ clearance → dose reduction
  • Elderly: Start low, titrate carefully
  • Pediatrics: Weight-based dosing essential

10. Drug Interactions & Additives

  • Epinephrine: ↓ systemic absorption, ↑ duration, ↓ toxicity
  • Additive toxicity with other amide anesthetics
  • Caution with antiarrhythmics (e.g., class I agents)

11. Liposomal Bupivacaine (Exparel®) – Key Differences

  • Sustained release → up to 72 hours analgesia
  • NOT interchangeable with standard bupivacaine
  • Do NOT mix with lidocaine (unless specific timing rules followed)
  • Used for postoperative pain control, not neuraxial blocks

12. Comparison with Other Local Anesthetics (Clinical Pearl)

Feature Bupivacaine Ropivacaine Lidocaine
Duration Long Long Short–medium
Cardiotoxicity High Lower Low
Motor block Strong Less Moderate
Preferred for labor No (risk) Yes Sometimes

13. Monitoring Parameters

  • Vital signs (BP, HR)
  • Neurologic status
  • ECG during high-dose/regional use
  • Signs of LAST
  • Total cumulative dose
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