1. Clinical Overview
Atracurium besylate is a non-depolarizing, intermediate-duration, benzylisoquinolinium neuromuscular blocking agent (NMBA). It is a bisquaternary ammonium compound used as an adjunct to general anesthesia to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation. Its unique metabolism via Hofmann elimination (a non-enzymatic, pH- and temperature-dependent process) and ester hydrolysis makes it independent of hepatic and renal function for termination of action, which is a significant advantage in patients with organ dysfunction.
| Onset | Duration | Bioavailability |
|---|---|---|
| 2-3 minutes (after an intubating dose of 0.5 mg/kg) | 20-35 minutes (after an intubating dose of 0.5 mg/kg) | 100% (Administered intravenously only) |
2. Mechanism of Action
Atracurium is a competitive antagonist at the nicotinic acetylcholine receptors (nAChRs) located on the postjunctional membrane of the neuromuscular junction. It binds reversibly to the alpha subunits of the receptor, preventing acetylcholine from binding and initiating depolarization of the muscle endplate. This results in flaccid paralysis of skeletal muscles.
3. Indications & Uses
- Adjunct to general anesthesia to facilitate endotracheal intubation.
- Provision of skeletal muscle relaxation during surgical procedures.
- Facilitation of mechanical ventilation in Intensive Care Units (ICU) where sedation alone is insufficient.
4. Dosage & Administration
Adult Dosage: Intubation: 0.4-0.5 mg/kg IV bolus. Maintenance: 0.08-0.1 mg/kg bolus as required, or continuous infusion at 0.3-0.6 mg/kg/hr (5-10 mcg/kg/min). Dose must be individualized based on clinical response monitored via peripheral nerve stimulator.
Administration: For IV use only. Must be administered by or under the direct supervision of an anesthesiologist/intensivist. For bolus, inject over 30-60 seconds to minimize histamine release. For infusion, dilute in a compatible IV solution (e.g., 0.9% NaCl, 5% Dextrose) to a concentration typically between 0.2-0.5 mg/mL. Use a controlled infusion device. Monitor neuromuscular function with a peripheral nerve stimulator (Train-of-Four monitoring).
5. Side Effects
Common side effects may include:
- Transient hypotension (due to histamine release)
- Flushing/erythema at injection site
- Transient tachycardia
- Bronchospasm/wheezing (rare at recommended doses)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Volatile Anesthetics (Isoflurane, Sevoflurane, Desflurane) | Potentiate neuromuscular blockade, reducing dose requirement by 15-50%. | Major |
| Aminoglycosides (Gentamicin, Amikacin), Polymyxins, Clindamycin | Potentiate blockade, leading to prolonged apnea. | Major |
| Magnesium Sulfate | Potentiates blockade. | Major |
| Succinylcholine | Prior use may potentiate the depth and duration of atracurium blockade. | Moderate |
| Calcium Channel Blockers (Diltiazem, Verapamil) | May enhance neuromuscular blockade. | Moderate |
| Lithium | May prolong duration of blockade. | Moderate |
| Anticholinesterases (Neostigmine, Pyridostigmine) | Antagonize neuromuscular blockade (used for reversal). | Major (Therapeutic) |
7. Patient Counselling
- Do inform your anesthesiologist about all allergies, especially to medications.
- Do inform about any muscle disorders (e.g., myasthenia gravis), burns, or major illnesses.
- Do not expect to have any memory of the drug's effects; it is given under deep sedation/anesthesia.
8. Toxicology & Storage
Overdose: Prolonged neuromuscular blockade resulting in apnea, respiratory insufficiency/arrest, cardiovascular collapse (hypotension, bradycardia) due to histamine release.
Storage: Store below 25°C. Protect from freezing. The solution should be clear, colorless to slightly yellow. Do not use if discolored or if particulate matter is present. Once drawn into a syringe or diluted for infusion, use within 24 hours when stored at room temperature. Keep out of reach of children.