Cisatracurium (Nimbex)

ED / ICU / Transport

• Adjunct to general anesthesia for tracheal intubation: adults and children 1 month to 12 years. Not recommended for rapid sequence intubation. Onset is too slow for that job (see Rapid Sequence Intubation).
• Skeletal muscle relaxation during surgery: adults. Children 2–12 years get it as a bolus or as infusion maintenance. The infusion is for patients 2 years and older.
• Mechanical ventilation in the ICU: adults with a continuous infusion once spontaneous neuromuscular recovery has occurred. Protocol governs how it is used.

Other Uses

• Early severe ARDS (PaO₂/FiO₂ below 150): SCCM 2026 suggests continuous neuromuscular blockade (conditional). ATS 2024 does too (conditional, low certainty). This use is off-label. See ARDS.

Doses vary by protocol; follow local protocols and medical direction.

Available Forms

• 2 mg/mL (10 mg/5 mL): 10 mg per 5 mL single-dose vial. Benzyl alcohol-free.
• 2 mg/mL (20 mg/10 mL): 20 mg per 10 mL multiple-dose vial containing 9 mg/mL benzyl alcohol. Infants under 1 month and low birth-weight infants must not get this vial.
• 10 mg/mL (200 mg/20 mL): single-dose vial for ICU use only. Dilute it before infusion. Discard any unused portion.
• Transport: the 2 mg/mL vials are what usually travels. The 10 mg/mL ICU vial needs a pharmacy-prepared infusion.

Adult Dosing

Dosing weight: the label doses by weight and gives no obesity-specific instruction. Check Special Populations for the dosing-weight approach.

Pediatric Dosing

Continuous Infusion

Preparation & Administration

• Dilution: dilute to 0.1 mg/mL in 5% dextrose, 0.9% sodium chloride or 5% dextrose with 0.9% sodium chloride. Stable 24 h refrigerated or at room temperature. Lactated Ringer's alone is the wrong diluent (chemical instability).
• Rate examples: at 0.1 mg/mL, a 70 kg adult needs 42 mL/h for 1 mcg/kg/min, 84 mL/h for 2 mcg/kg/min and 126 mL/h for 3 mcg/kg/min.
• Push rate: over 5–10 seconds for pediatric bolus doses. Adult bolus is given as a single IV injection.
• Line: peripheral IV is acceptable. Y-site compatible with 5% dextrose, 0.9% sodium chloride, sufentanil, alfentanil, fentanyl, midazolam and droperidol (diluted as directed). Not compatible with propofol, ketorolac or alkaline solutions above pH 8.5 (for example barbiturate solutions).
• Light and temperature: refrigerate 2–8 °C in the carton; protect from light; do not freeze. After removal to room temperature, use within 21 days even if re-refrigerated.
• Pump: run it on an infusion pump with the dose-rate table. You need a peripheral nerve stimulator to titrate.

Contraindications

• Known hypersensitivity to cisatracurium. Severe anaphylactic reactions have been reported.
• 10 mL multiple-dose vial (20 mg/10 mL) in infants under 1 month or low birth-weight infants (benzyl alcohol).

Precautions

• Neuromuscular disease or carcinomatosis: higher risk of residual paralysis; maximum initial bolus 0.02 mg/kg.
• Renal or hepatic impairment with long infusions: laudanosine builds up. Watch the block and limit exposure.
• Cross-reactivity: be careful after anaphylaxis to any other neuromuscular blocker, depolarizing or nondepolarizing.
• Inadequate anesthesia: the patient can be paralyzed and aware. Sedation or analgesia comes first, and it keeps running.
• Burns: resistance. The label advises considering higher doses.
• Malignant hyperthermia: not studied in MH-susceptible patients. Know how to recognize and treat MH in any patient under general anesthesia.
• Hypothermia, acid-base and electrolyte disturbance: in CABG with induced hypothermia, consider half the normothermic infusion rate. Acid-base and serum electrolyte abnormalities, and magnesium salts, can potentiate block. Reassess with train-of-four.

Hold / Reassess If

• Train-of-four ratio below 0.9 at planned extubation (protocol threshold): do not extubate. Reverse and reassess. The label wants recovery to be sufficient before extubation.
• Signs of awareness under paralysis (heart rate or blood pressure rising, tearing, ventilator fighting): deepen sedation and analgesia before any further dose.
• No response (count 0) to nerve stimulation during infusion: hold the infusion until a response returns.
• Sustained return of 3–4 twitches, patient movement or ventilator dyssynchrony: deepen sedation and analgesia first, then re-bolus and increase the rate per protocol. Titrate to the protocol train-of-four target. The label's ICU study dosed to the presence of a single twitch.
• Seizure-like activity during a prolonged infusion with renal or hepatic failure: stop, support ventilation and assess.

Common

• Bradycardia (0.4%), hypotension (0.2%), flushing (0.2%), bronchospasm (0.2%) and rash (0.1%) in surgical trials.
• Prolonged recovery in some ICU patients. In one ICU study, 2 of 28 cisatracurium patients had prolonged recovery, versus 13 of 30 with vecuronium.
• Residual paralysis after the block ends. It shows up most often when extubation comes early.

Serious / Life-Threatening

Overdose & Toxicity Management

• Prolonged paralysis: maintain the airway and ventilate until recovery is assured.
• Reversal: give a cholinesterase inhibitor once recovery begins, not when the block is complete. Neostigmine is the usual agent (neostigmine). Dose per protocol and local reversal guidance. The label studied neostigmine 0.04–0.07 mg/kg at about 10% recovery.
• Sugammadex does not reverse cisatracurium (sugammadex).
• Neonatal benzyl alcohol toxicity: gasping syndrome (CNS depression, metabolic acidosis, gasping) with the 10 mL multiple-dose vial.

SCCM 2016 suggests against relying on a train-of-four count by itself during a continuous infusion. Read the count alongside the patient and the ventilator (see Figure 1).

Clinically Significant Interactions

IV Compatibility

• Y-site compatible: 5% dextrose, 0.9% sodium chloride, sufentanil, alfentanil, fentanyl, midazolam and droperidol (diluted as directed).
• Incompatible: propofol (Y-site), ketorolac, and alkaline solutions above pH 8.5 such as barbiturates.
• Do not dilute in Lactated Ringer's alone; dedicated line preferred for infusions.
• Verify with an institutional compatibility resource.

• Pediatrics: labeled from 1 month for intubation and from 2 years for infusion. Not established under 1 month. The doses sit in the Pediatric Dosing table. See weight-based dosing.
• Neonates: the 10 mL multiple-dose vial is contraindicated in infants under 1 month and low birth-weight infants. Editorial guidance: if a neonate needs the drug, specialist direction should choose a benzyl alcohol-free single-dose vial.
• Pregnancy: clinical trials give no data on pregnancy risk. Rat studies found no fetal harm at 0.8 times the human exposure from a 0.2 mg/kg bolus. If it is needed, use it. Prefer benzyl alcohol-free vials.
• Lactation: there are no data on cisatracurium in human milk. If the drug is needed, benzyl alcohol-free presentations are preferred.
• Older Adults: the maximum block comes about 1 minute slower. Allow at least 1 more minute before laryngoscopy. Greater sensitivity in some older patients cannot be ruled out. AGS Beers Criteria: not applicable (hospital-administered IV drug).
• Renal Impairment: recovery does not change after 0.1 mg/kg in end-stage renal disease, but the maximum block is about 1 minute slower. Laudanosine builds up with long infusions. Watch the block.
• Hepatic Impairment: in liver transplant patients, volume of distribution is slightly larger and clearance is higher. Laudanosine concentrations may run higher.
• Obesity / Dosing Weight: the label doses by weight and gives no obesity-specific instruction. SCCM 2016 suggests a consistent ideal or adjusted body weight for obese adults (protocol-dependent).
• Neuromuscular Disease: maximum initial bolus 0.02 mg/kg.
• Burns: resistance. Consider higher doses and a shorter duration.

• Scope: ICU and critical-care transport (CCT) use. EMS use is uncommon. Varies by state and agency protocol.
• Storage & Stability: refrigerate at 2–8 °C in the carton. Protect from light and do not freeze. After room-temperature storage, use within 21 days.
• Carried Concentration: 2 mg/mL vials are typical in transport. The 10 mg/mL ICU vial is a different strength and has to be diluted. Never draw it up without a label check.
• Infusions in Transport: use a pump, a dedicated line or verified compatibility. Carry the bag volume for the trip. A peripheral nerve stimulator has to be available for dose titration.
• Handoff Essentials: time and total dose of last bolus, current rate in mcg/kg/min and mL/h, last train-of-four, sedation status and reversal plan.

Mechanism of Action

• Target: it acts as a competitive antagonist (nondepolarizing) at nicotinic acetylcholine receptors on the motor endplate.
• Effect: it blocks depolarization of skeletal muscle, and the result is flaccid paralysis. Doubling the dose adds about 25 minutes of effective block.
• Elimination: Hofmann elimination at physiologic pH and temperature. It does not depend on organ function. Metabolites are cleared by liver and kidney.
• Consequence: recovery stays predictable in organ failure. Laudanosine (seizures in animals) can still accumulate with long infusions.

Pharmacokinetics

• Half-life: elimination half-life (t½β) about 22 minutes, in a two-compartment model. Clearance 4.57 mL/min/kg. Volume of distribution at steady state 145 mL/kg.
• Metabolism: Hofmann elimination. Laudanosine is a metabolite.
• Active metabolites: laudanosine (seizure risk in animals). Its half-life runs longer in renal or hepatic impairment.
• Protein binding: not reliably studied. The drug degrades at physiologic pH.

Generic name

Cisatracurium besylate

Brand names

Nimbex (original US brand); generic cisatracurium is marketed by several manufacturers.

Pharmacologic class

Nondepolarizing neuromuscular blocker (benzylisoquinolinium)

Therapeutic class

Skeletal muscle relaxant (adjunct to anesthesia; ICU ventilation)

Controlled substance

Not controlled

ISMP High-Alert

Yes: ISMP high-alert medication (neuromuscular blocking agents class, acute care list)

Look-Alike / Sound-Alike

None commonly reported