Atrium25 mg/2.5 ml

Atrium is a non-depolarizing (curariform) skeletal muscle relaxant. Its established, evidence-based uses include:

• Adjunct to general anesthesia (FDA-approved/established use) — to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgical procedures.
• Facilitation of mechanical ventilation (established use) — to induce and maintain skeletal muscle paralysis in intubated, mechanically ventilated patients in intensive care unit (ICU) settings.

Atrium has no analgesic, sedative, or amnesic properties and must always be used together with adequate anesthesia, sedation, and/or analgesia, as it does not alter consciousness or the perception of pain on its own.

Each mL of injectable solution contains Atracurium Besilate equivalent to 10 mg of atracurium base, as a sterile, clear, colorless to pale yellow aqueous solution for intravenous use. Available strengths and pack sizes may vary by manufacturer (commonly 25 mg/2.5 mL and 50 mg/5 mL ampoules).

Atrium is an intermediate-duration, non-depolarizing neuromuscular blocking agent belonging to the benzylisoquinolinium class of skeletal muscle relaxants. It is used exclusively in hospital and operating room/critical care settings, always administered by or under the direct supervision of anesthesiologists or clinicians trained in airway management and the use of neuromuscular blocking agents.

A distinctive feature of Atrium is that it undergoes organ-independent breakdown in plasma via Hofmann elimination (a temperature- and pH-dependent chemical degradation) and non-specific ester hydrolysis, rather than relying primarily on hepatic or renal clearance. This makes its pharmacokinetics relatively predictable even in patients with hepatic or renal impairment.

Atracurium Besilate acts by competitively binding to nicotinic acetylcholine receptors at the motor endplate of the neuromuscular junction, blocking the action of acetylcholine and preventing depolarization of the muscle membrane. This produces flaccid skeletal muscle paralysis without affecting consciousness.

Unlike many other neuromuscular blockers, Atracurium Besilate is broken down primarily by two organ-independent pathways: Hofmann elimination (spontaneous, non-enzymatic chemical degradation dependent on physiologic pH and temperature) and ester hydrolysis by non-specific plasma esterases. Only a small fraction is metabolized by the liver or excreted renally unchanged.

Onset of action after an intubating dose is typically within 2–3 minutes, with clinically effective neuromuscular block lasting approximately 20–35 minutes; the effect is dose-dependent and can be prolonged with repeated or infusion dosing.

Atrium has clinically important interactions with several drug classes:

• Volatile inhalational anesthetics (e.g., isoflurane, sevoflurane, desflurane) — potentiate and prolong the neuromuscular blocking effect of Atrium; dose reduction is usually required.
• Aminoglycoside and certain other antibiotics (e.g., aminoglycosides, clindamycin, tetracyclines) — may enhance neuromuscular blockade, increasing the risk of prolonged paralysis or respiratory depression.
• Other neuromuscular blocking agents — concurrent or sequential use with other non-depolarizing or depolarizing blockers can result in either additive or, less predictably, reduced neuromuscular blockade depending on the specific agents and sequence used.
• Magnesium salts and calcium channel blockers — magnesium sulfate (e.g., used in obstetric practice) and calcium channel blockers can potentiate neuromuscular blockade.
• Chronic anticonvulsant therapy (e.g., phenytoin, carbamazepine) — has been associated with relative resistance to (shortened duration of) neuromuscular blockade with Atrium.

Reversal agents such as neostigmine (with an antimuscarinic such as glycopyrrolate or atropine) are used to antagonize residual block from Atrium; sugammadex is not effective for reversing benzylisoquinolinium agents such as Atrium (it is selective for aminosteroid blockers).

The most common adverse effects associated with Atrium relate to dose-related histamine release and include:

• Transient flushing or skin rash
• Hypotension (usually mild and transient)
• Tachycardia or, less commonly, bradycardia
• Bronchospasm/wheezing, particularly in patients with reactive airway disease

Rare but serious effects include severe anaphylactic or anaphylactoid reactions (with hypotension, bronchospasm, and/or airway edema), and prolonged neuromuscular blockade with resulting prolonged apnea/respiratory insufficiency, especially if underlying risk factors (see Precautions and Warnings) are present.

Atrium should be used during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus; it crosses the placenta only to a limited extent, and it has been used as part of balanced anesthesia for cesarean section under specialist supervision. Use in labor and delivery should be individualized by the attending anesthesiologist.

It is not known whether Atrium is excreted in human milk; because it is used only as a single intraoperative/ICU agent under direct medical supervision rather than as an outpatient medication, breastfeeding decisions after its use should be made in consultation with the treating physician.

Atrium must be administered only by, or under the direct supervision of, personnel experienced in the use of neuromuscular blocking agents and airway management, with immediate access to equipment for endotracheal intubation, oxygenation, and mechanical/artificial ventilation. Atrium has no effect on consciousness, pain perception, or memory, and must always be given together with adequate general anesthesia or sedation and analgesia.

• Histamine release: Use with caution in patients with significant cardiovascular disease or a history of asthma/bronchospasm, since Atrium can cause dose-related histamine release leading to flushing, hypotension, tachycardia, or bronchospasm (see Side Effects).
• Electrolyte and neuromuscular disorders: Patients with electrolyte imbalances or neuromuscular disease (e.g., myasthenia gravis, myasthenic syndrome) may show markedly altered (usually increased) sensitivity to Atrium; careful dose titration and monitoring are essential.
• Hypothermia: Reduced body temperature can prolong the duration of neuromuscular blockade produced by Atrium.
• Recovery confirmation: Adequate spontaneous recovery of neuromuscular function (or pharmacologic reversal, per anesthesia protocol) must be confirmed, using clinical assessment and/or peripheral nerve stimulation, before extubation or discontinuation of ventilatory support.

Overdose or excessive dosing with Atrium can cause prolonged neuromuscular blockade, resulting in extended apnea, inadequate spontaneous respiration, and cardiovascular effects such as hypotension. This is a medical emergency requiring immediate attention.

Management requires continued mechanical ventilation and full cardiovascular support until adequate spontaneous neuromuscular function returns; anesthesia/critical care personnel should be alerted immediately, and pharmacologic reversal may be considered per institutional protocol once early signs of spontaneous recovery are present. No specific home treatment is appropriate — any suspected overdose of Atrium must be managed only within a monitored hospital/critical care setting.

Store Atrium injection in a refrigerator (2°C to 8°C), protected from light; do not freeze. If refrigeration is not available, follow the manufacturer's specific labeling for permissible room-temperature storage duration. Keep out of reach of children, and discard any unused portion from opened ampoules.

Renal/hepatic impairment: Because Atrium is eliminated largely by organ-independent Hofmann elimination and ester hydrolysis, dosage adjustment is generally not required in renal or hepatic impairment, though individualized monitoring is still recommended.

Elderly patients: Onset may be somewhat slower and duration of action may be modestly prolonged in elderly patients; doses should be titrated carefully with monitoring.

Cardiovascular disease/asthma: Use with caution due to the risk of histamine-related hypotension or bronchospasm (see Precautions and Warnings).

Obese patients: Dosing is generally based on actual or ideal body weight per institutional protocol, with careful individualized titration.

Atrium is administered only for the duration of the surgical procedure requiring muscle relaxation, or for as long as continued neuromuscular blockade is clinically indicated to facilitate mechanical ventilation in an ICU setting; it is not intended for outpatient or long-term home use. Duration of individual doses/infusions is determined by the treating anesthesiologist or intensivist based on continuous clinical and neuromuscular monitoring.

Neuromuscular blocking agents (non-depolarizing, benzylisoquinolinium type); Atracurium Besilate is classified as an intermediate-acting skeletal muscle relaxant used in anesthesia.

Atracurium Besilate competitively antagonizes acetylcholine at nicotinic receptors on the motor endplate of the neuromuscular junction, preventing depolarization and resulting muscle contraction, thereby producing flaccid skeletal muscle paralysis; it is inactivated in the body chiefly through pH/temperature-dependent Hofmann elimination and plasma ester hydrolysis rather than hepatic or renal metabolism.

Category C

Atrium has been used in pediatric patients from 1 month of age onward as an adjunct to general anesthesia, with dosing generally similar to adult mg/kg dosing but requiring careful individualization and monitoring. Safety and effectiveness of Atrium in neonates (younger than 1 month) have not been well established, and use in this age group requires extra caution, specialist supervision, and close neuromuscular and cardiorespiratory monitoring.