阿曲庫銨
阿曲庫銨是一種廣泛使用的**非去極化神經肌肉阻斷劑**，主要作為全身麻醉的輔助藥物。它能提供深度的骨骼肌鬆弛，以利於外科手術、氣管插管和機械通氣。 **臨床關鍵要點：** * **非器官依賴性代謝：** 阿曲庫銨透過霍夫曼消除（Hofmann elimination）和酯水解進行代謝，這使其對於患有嚴重肝腎疾病的病患極具價值。 * **無鎮痛或鎮靜作用：** 它會使病患癱瘓，但絕對不提供任何止痛或失去意識的效果。絕不能作為單一藥物使用。 * **心血管穩定性：** 在標準劑量下，與較舊的神經肌肉阻斷劑相比，其心血管副作用極小，儘管偶爾可能引發組織胺釋放。 * **物種敏感性：** 該藥物在馬匹體內的效力明顯高於其他物種。
作用機制: Atracurium acts by competitively binding to **nicotinic cholinergic receptors** at the motor end-plate of the neuromuscular junction. By occupying these receptors, it prevents **acetylcholine (ACh)** from binding → inhibits depolarization of the muscle cell membrane → results in flaccid paralysis of skeletal muscles. Because it is a competitive antagonist, its effects can be reversed by increasing the concentration of ACh at the neuromuscular junction (e.g., by administering acetylcholinesterase inhibitors like neostigmine or edrophonium).
各物種劑量
- Induction dose · 0.22 mg/kg IV · IV · Single dose · Give 1/10th to 1/6th of this dose initially as a 'priming' dose, followed 4-6 minutes later with the remainder and a sedative/hypnotic agent.
- Intraoperative dose · 0.11 mg/kg IV · IV · As needed
- Induction of respiratory muscle paralysis during mechanical ventilation · Loading dose: 0.2-0.5 mg/kg IV, then a constant rate infusion 5 minutes later of 0.37 micrograms/kg/min · IV · CRI · Use D5W or 0.9% sodium chloride for diluent; do not mix with other drugs.
- Critically ill patients when low concentrations of, or no inhalant anesthesia can be used · 0.2 mg/kg IV initial dose; subsequent doses 0.1 mg/kg IV · IV · every 20-30 minutes · Do not dose more frequently than every 20-30 minutes unless a peripheral nerve stimulator is applied. Positive pressure ventilation required.
- Intraoperative dose · 0.055 mg/kg IV · IV · As needed · Note: ARCI UCGFS Class 2 Drug. Atracurium is more potent in horses than in other species.
- Paralysis for periophthalmic surgery (Rabbits) · 0.1 mg/kg · IV · Single dose
- Critically ill patients when low concentrations of, or no inhalant anesthesia can be used · 0.2 mg/kg IV initial dose; subsequent doses 0.1 mg/kg IV · IV · every 20-30 minutes · Do not dose more frequently than every 20-30 minutes unless a peripheral nerve stimulator is applied, or voluntary movement is observed. Positive pressure ventilation required.
給藥途徑
禁忌症
- Hypersensitivity to atracurium
- Relative contraindication: Myasthenia gravis
- Lack of ventilatory support (must have mechanical ventilation available)
不良反應
- Allergic reactions
- Inadequate or prolonged neuromuscular block
- Hypotension
- Vasodilation
- Bradycardia
- Tachycardia
- Dyspnea
- Bronchospasm
- Laryngospasm
- Rash
- Urticaria
- Injection site reaction
藥物相互作用
- Aminoglycoside antibiotics (e.g., gentamicin) · May enhance the neuromuscular blocking activity of atracurium
- General anesthetics (enflurane, isoflurane, halothane, sevoflurane) · May enhance and prolong the neuromuscular blocking activity
- Bacitracin, Polymyxin B (systemic) · May enhance neuromuscular blocking activity
- Procainamide · May enhance neuromuscular blocking activity
- Quinidine · May enhance neuromuscular blocking activity
- Lithium · May enhance neuromuscular blocking activity
- Magnesium salts · May enhance neuromuscular blocking activity
- Anticonvulsants (Phenytoin, Carbamazepine) · Reported to decrease both the effects and duration of neuromuscular blockade
- Other muscle relaxant drugs · May cause a synergistic or antagonistic effect
- Succinylcholine · May speed the onset of action and enhance the neuromuscular blocking actions of atracurium. Do not give atracurium until succinylcholine effects have diminished.
監測
- Level of neuromuscular blockade (recommend use of a peripheral nerve stimulator to evaluate 'train of 4' twitches)
- Spontaneous ventilation and voluntary muscle movement (if nerve stimulator is unavailable)
- Cardiac rate and blood pressure
- Core body temperature and acid-base status (can affect drug metabolism)
過量
Overdosage increases the risks of **hypotension**, **histamine release**, and **prolonged duration of muscle blockade**. Overdose possibilities can be minimized by monitoring muscle twitch responses to peripheral nerve stimulation. **Treatment:** * Treat conservatively with mechanical ventilation, oxygen, and IV fluids. * **Reversal of blockade:** May be accomplished by administering an anticholinesterase agent such as **edrophonium** (0.5 mg/kg IV) or **neostigmine** (0.02-0.04 mg/kg IV) combined with an anticholinergic (**atropine** or **glycopyrrolate**) to prevent severe bradycardia. * Reversal is usually complete within 8-10 minutes. Because the duration of action of atracurium may be longer than the reversal agent, careful observation is required, and readministration of the reversal agent may be necessary.
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