ATRACURIUM BESYLATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ATRACURIUM BESYLATE (ATRACURIUM BESYLATE).
Competitive antagonist at nicotinic acetylcholine receptors at the neuromuscular junction, preventing acetylcholine binding and causing skeletal muscle relaxation.
| Metabolism | Hofmann elimination (non-enzymatic degradation at physiological pH and temperature) and ester hydrolysis (non-specific esterases); metabolism does not rely on hepatic or renal function. |
| Excretion | Renal (50-60% unchanged), biliary/fecal (20-30% as metabolites, mainly laudanosine), and Hofmann elimination (non-enzymatic, pH- and temperature-dependent) accounts for approximately 40-50% of clearance. |
| Half-life | Terminal elimination half-life is approximately 20 minutes (range 15-25 min) in healthy adults. Clinical context: Recovery from neuromuscular blockade is faster than for nondepolarizing relaxants cleared renally. Half-life may be prolonged in hypothermia or acidosis but is minimally affected by renal or hepatic impairment. |
| Protein binding | Approximately 82% bound, primarily to albumin and to a lesser extent to alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd is 0.15-0.18 L/kg (approximately 10-15 L in 70 kg adult). This small Vd indicates limited distribution to peripheral tissues, consistent with a highly polar quaternary ammonium compound. |
| Bioavailability | Intravenous: 100%. Intramuscular: Approximately 100% (rapid and complete absorption, but not routinely used due to local irritation). Oral: Negligible (less than 5% due to poor absorption and first-pass metabolism). |
| Onset of Action | Intravenous: 2-3 minutes (time to maximal blockade). Intramuscular: 10-15 minutes (time to clinical effect). |
| Duration of Action | Intravenous: 20-35 minutes (clinical duration to 25% recovery of twitch height). Prolonged with higher doses or in elderly (25-40 min). Recovery is independent of renal or hepatic function due to Hofmann elimination. |
0.4–0.5 mg/kg IV bolus for intubation; maintenance: 0.08–0.1 mg/kg IV as needed or infusion 5–10 mcg/kg/min
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for GFR >30 mL/min; caution with GFR <30 mL/min due to potential accumulation of laudanosine (risk of seizures); no specific dose reduction defined |
| Liver impairment | No dose adjustment required for Child-Pugh A; for Child-Pugh B or C, reduce dose by 50% and monitor effect due to altered metabolism |
| Pediatric use | Neonates and infants: 0.3–0.5 mg/kg IV; children: 0.4–0.6 mg/kg IV; maintenance 0.08–0.1 mg/kg IV or infusion 5–10 mcg/kg/min |
| Geriatric use | No specific dose adjustment; use lower initial doses (e.g., 0.3–0.4 mg/kg IV) and titrate due to increased sensitivity and slower recovery |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ATRACURIUM BESYLATE (ATRACURIUM BESYLATE).
| Breastfeeding | It is not known whether atracurium besylate is excreted in human milk. Due to its low oral bioavailability and short half-life, any ingestion via breast milk is unlikely to cause adverse effects in the infant. M/P ratio is unknown. |
| Teratogenic Risk | Atracurium besylate is a neuromuscular blocking agent. There are no adequate and well-controlled studies in pregnant women. Animal studies have not revealed evidence of teratogenicity. The drug should be used during pregnancy only if clearly needed. |
■ FDA Black Box Warning
Risk of profound neuromuscular blockade leading to prolonged apnea and paralysis; must be administered by trained personnel with immediate access to appropriate resuscitation equipment and reversal agents.
| Serious Effects |
Hypersensitivity to atracurium or cisatracurium; known hypersensitivity to benzyl alcohol (in multidose vials); neonates (benzyl alcohol toxicity).
| Precautions | May cause histamine release leading to hypotension and bronchospasm; use caution in patients with cardiovascular disease, asthma, or history of anaphylaxis. Monitor neuromuscular function with a nerve stimulator. Extended use in ICU may result in prolonged weakness. |
| Food/Dietary | No specific food interactions are documented. However, electrolyte imbalances (e.g., hypokalemia, hypocalcemia) from dietary deficiencies may potentiate neuromuscular blockade. Maintain normal electrolyte levels per standard perioperative care. |
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| Fetal Monitoring |
| Maternal monitoring includes heart rate, blood pressure, oxygen saturation, and continuous assessment of neuromuscular function using a peripheral nerve stimulator. Fetal monitoring is recommended during cesarean section. |
| Fertility Effects | No studies have been conducted on the effect of atracurium on human fertility. Animal reproduction studies have not shown impaired fertility. |
| Clinical Pearls | Atracurium besylate undergoes Hofmann elimination and ester hydrolysis, making it reliable in patients with hepatic or renal impairment. It can cause histamine release with rapid bolus, leading to hypotension, flushing, and bronchospasm; administer slowly over 60 seconds. It is incompatible with alkaline solutions (e.g., thiopental) and should be given via a dedicated IV line. Reversal with neostigmine requires prior anticholinergic (e.g., glycopyrrolate) to prevent bradycardia. Monitor neuromuscular function with a train-of-four (TOF) monitor. Avoid in patients with known hypersensitivity to bisbenzylisoquinolinium compounds. |
| Patient Advice | This medication is used to relax muscles during surgery or mechanical ventilation. · You will be unable to move or breathe on your own while under the effects; a breathing machine will support you. · Inform your anesthesiologist if you have any allergies, especially to muscle relaxants. · Tell your doctor about all medications you take, especially antibiotics, as some can increase muscle relaxation. · You may experience skin flushing or a temporary drop in blood pressure when the drug is given. · After surgery, you may feel weak or drowsy; avoid driving or operating machinery until fully recovered. |