1. Clinical Overview
Atracurium besylate is a non-depolarizing, intermediate-duration neuromuscular blocking agent (NMBA) of the benzylisoquinolinium class. It is a skeletal muscle relaxant used as an adjunct to general anesthesia to facilitate endotracheal intubation and provide skeletal muscle relaxation during surgery or mechanical ventilation. Its unique metabolism via Hofmann elimination and ester hydrolysis makes it independent of hepatic and renal function, which is a significant advantage in patients with organ impairment.
| Onset | Duration | Bioavailability |
|---|---|---|
| 2-3 minutes | 20-35 minutes | 100% (Intravenous administration) |
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 to the alpha subunits of the receptor, preventing acetylcholine (ACh) from binding and depolarizing the motor endplate. This inhibition prevents the generation of an action potential, leading to flaccid paralysis of skeletal muscles.
3. Indications & Uses
- Adjunct to general anesthesia to facilitate endotracheal intubation
- Provision of skeletal muscle relaxation during surgical procedures
- Provision of skeletal muscle relaxation during mechanical ventilation in ICU settings
4. Dosage & Administration
Adult Dosage: Intubation: 0.4-0.5 mg/kg IV bolus. Maintenance: 0.08-0.10 mg/kg IV bolus as required, or continuous infusion at 0.3-0.6 mg/kg/hr (5-10 mcg/kg/min). Dose must be individualized. Use peripheral nerve stimulator for monitoring.
Administration: For IV use only. Must be administered by or under the supervision of an experienced anesthesiologist/intensivist. Bolus dose should be given 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 commonly between 0.2-0.5 mg/mL. Incompatible with alkaline solutions (e.g., thiopentone). Always use a peripheral nerve stimulator to assess degree of blockade and guide dosing.
5. Side Effects
Common side effects may include:
- Transient hypotension
- Flushing (erythema)
- Skin reactions (wheals, urticaria) at injection site
- Bradycardia
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Inhalational Anesthetics (Isoflurane, Sevoflurane, Desflurane) | Potentiate neuromuscular blockade, reducing atracurium requirement by 30-50%. | Major |
| Aminoglycosides (Gentamicin, Amikacin) | Potentiate neuromuscular blockade, may cause prolonged apnea. | Major |
| Magnesium Sulfate | Potentiates neuromuscular blockade. | Major |
| Calcium Channel Blockers (Verapamil, Diltiazem) | May enhance neuromuscular blocking effect. | Moderate |
| Lithium | May prolong duration of neuromuscular blockade. | Moderate |
| Procainamide, Quinidine | May enhance neuromuscular blockade. | Moderate |
| Corticosteroids (chronic use) | May induce resistance to non-depolarizing NMBAs. | Moderate |
| Carbamazepine, Phenytoin | May induce resistance, requiring higher doses of atracurium. | Moderate |
| Succinylcholine | Prior use may potentiate the depth and duration of atracurium blockade. | Moderate |
7. Patient Counselling
- Do inform your anesthesiologist about all allergies, especially to medications.
- Do inform about any muscle diseases (e.g., myasthenia gravis), burns, or major illnesses.
- Do not drive or operate machinery for at least 24 hours after surgery involving muscle relaxants.
8. Toxicology & Storage
Overdose: Prolonged and profound neuromuscular blockade leading to apnea, respiratory insufficiency or arrest, cardiovascular collapse (from histamine release).
Storage: Store at 2°C to 8°C (refrigerate). Do not freeze. Protect from light. The product may be stored at room temperature (not exceeding 30°C) for up to 14 days. Once diluted for infusion, use within 24 hours. Discard any unused portion. Keep out of reach of children.