Cisatracurium

BRAND NAMES

Common brand names of Cisatracurium include:

• Nimbex (most widely known brand)

MECHANISM OF ACTION

Cisatracurium is a non-depolarizing neuromuscular blocker that works by competitively inhibiting acetylcholine at nicotinic receptors in the neuromuscular junction, preventing muscle contraction and causing temporary paralysis. It is broken down mainly by Hofmann elimination, making its action independent of liver and kidney function.

PHARMACOKINETICS

Absorption 

Cisatracurium is administered intravenously, so it is rapidly and completely available in the bloodstream with no need for absorption through the gastrointestinal tract. Its onset of action typically occurs within a few minutes after injection.

Distribution

Cisatracurium has a volume of distribution of about 0.1–0.2 L/kg, indicating that it is mainly confined to the extracellular fluid with limited tissue penetration.

Metabolism

Cisatracurium is metabolized mainly by Hofmann elimination, a non-enzymatic process that depends on body temperature and pH, producing inactive metabolites. This metabolism occurs independently of liver enzymes, making the drug suitable for patients with hepatic impairment.

Elimination

Cisatracurium is eliminated mainly through Hofmann elimination, a spontaneous chemical breakdown process, and to a lesser extent via organ-independent metabolism.. Because its clearance does not rely on kidney or liver function, its duration of action is relatively predictable in critically ill patients.

PHARMACODYNAMICS

Cisatracurium causes dose-dependent skeletal muscle paralysis by blocking nicotinic acetylcholine receptors at the neuromuscular junction, preventing muscle contraction without affecting consciousness or pain sensation.

ADMINISTRATION

Cisatracurium is given by intravenous (IV) injection or infusion, usually in hospital settings such as the operating room or ICU. The dose is individualized based on body weight and clinical need, often as a bolus for intubation followed by continuous infusion for maintained muscle relaxation.

DOSAGE AND STRENGTH

Cisatracurium is supplied as an IV injectable solution, commonly in strengths such as 2mg/mL (e.g., 10 mg/5 mL or 20 mg/10 mL vials).

Typical dosing varies by use:

• Intubation (bolus): about 0.15–0.2 mg/kg IV

• Maintenance (infusion): roughly 1–3 mcg/kg/min, adjusted based on neuromuscular monitoring and clinical response.

DRUG INTERACTIONS

Cisatracurium may have increased or prolonged effects when used with aminoglycoside antibiotics, magnesium, volatile anesthetics, or other neuromuscular blockers. These interactions can enhance muscle paralysis, so neuromuscular function should be closely monitored during concurrent use.

FOOD INTERACTIONS

Cisatracurium has no known clinically significant food interactions because it is administered intravenously and not absorbed through the gastrointestinal tract. Food intake does not affect its onset, duration, or elimination.

CONTRAINDICATIONS

Cisatracurium is contraindicated in patients with a known hypersensitivity to cisatracurium, atracurium, or other benzylisoquinolinium neuromuscular blockers. It should be used with caution in patients with a history of neuromuscular disorders (e.g., myasthenia gravis) or conditions that increase sensitivity to muscle relaxants, as it may cause prolonged or exaggerated paralysis.

SIDE EFFECTS

• Hypotension

• Bradycardia

• Flushing

• Prolonged muscle paralysis

• Muscle weakness (especially with prolonged ICU use)

• Allergic reactions (rash, anaphylaxis – rare)

OVER DOSE

Cisatracurium causes prolonged muscle paralysis and respiratory failure, requiring ventilatory support until the drug is cleared by Hofmann elimination.

TOXICITY

Cisatracurium is mainly due to excessive neuromuscular blockade, leading to prolonged muscle paralysis and respiratory failure requiring mechanical ventilation. It may also cause hypotension and bradycardia in higher doses or sensitive patients, and treatment is supportive until the drug is cleared via Hofmann elimination.