1. Clinical Overview
Cisatracurium besylate is a non-depolarizing neuromuscular blocking agent (NMBA) of the benzylisoquinolinium class. It is an intermediate-duration muscle relaxant used as an adjunct to general anesthesia to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation. It is a stereoisomer of atracurium (the 1R-cis 1'R-cis isomer), accounting for approximately 15% of the atracurium mixture. It is known for its cardiovascular stability and unique, organ-independent Hofmann elimination pathway.
| Onset | Duration | Bioavailability |
|---|---|---|
| 2-3 minutes (after an intubating dose of 0.15-0.2 mg/kg) | 40-55 minutes (after an intubating dose) | 100% (Administered intravenously) |
2. Mechanism of Action
Cisatracurium is a competitive antagonist at the nicotinic acetylcholine receptors (nAChRs) on the post-junctional 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 the ICU.
4. Dosage & Administration
Adult Dosage: Intubation: 0.15 to 0.2 mg/kg IV bolus. Maintenance: 0.03 mg/kg bolus or continuous infusion at 1-3 mcg/kg/min (0.06-0.18 mg/kg/hr). Dosage MUST be individualized based on response monitored with a peripheral nerve stimulator.
Administration: For IV use only. Must be administered as a bolus injection or continuous infusion. Bolus dose should be given over 5-10 seconds. For infusion, dilute in a compatible IV solution (e.g., 0.9% NaCl, 5% Dextrose) to a concentration commonly between 0.1 mg/mL to 0.4 mg/mL. Use a controlled infusion device. DO NOT mix with alkaline solutions (e.g., sodium bicarbonate, thiopental) in the same syringe or infusion line. Always ensure patient is adequately sedated and ventilated.
5. Side Effects
Common side effects may include:
- Prolonged neuromuscular block (beyond clinical need).
- Inadequate or insufficient block.
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Inhalational Anesthetics (Isoflurane, Sevoflurane, Desflurane) | Potentiate neuromuscular block, reducing cisatracurium requirement by 15-40%. | Major |
| Aminoglycosides, Polymyxins, Clindamycin, Vancomycin | Enhance neuromuscular blockade, potentially causing prolonged apnea. | Major |
| Magnesium Sulfate | Potentiates neuromuscular blockade. | Major |
| Lithium, Procainamide, Quinidine | May enhance neuromuscular blockade. | Moderate |
| Carbamazepine, Phenytoin | May induce resistance, requiring higher doses. | Moderate |
| Succinylcholine (Suxamethonium) | Prior use may potentiate the depth and duration of cisatracurium block. | Moderate |
| Opioids (Fentanyl, Morphine) | No direct interaction on NMJ, but synergistic for analgesia/sedation. | Minor |
7. Patient Counselling
- Do inform your anesthesiologist about all allergies, especially to medications.
- Do disclose all current medications, including over-the-counter drugs and supplements.
- Do inform about any history of neurological or muscular disorders (e.g., myasthenia gravis, stroke).
- Do not eat or drink as per pre-anesthesia fasting instructions.
8. Toxicology & Storage
Overdose: Symptoms are an extension of its pharmacological effect: prolonged and profound neuromuscular blockade resulting in apnea, respiratory insufficiency, or arrest. Cardiovascular effects are minimal even at high doses (up to 32 x ED95).
Storage: Store at 2°C to 8°C (refrigerate). Do not freeze. Protect from light. The product may be stored at temperatures not exceeding 30°C for up to 21 days. Once diluted for infusion, use within 24 hours. Discard any unused portion. Keep out of reach of children.