アトラクリウムベシル酸塩
アトラクリウムは、主に全身麻酔の補助として使用される、広く利用されている**非脱分極性神経筋遮断薬**です。外科手術、気管挿管、および人工呼吸を容易にするために、強力な骨格筋弛緩を提供します。 **臨床上の重要なポイント：** * **臓器非依存性の消失：** アトラクリウムはホフマン脱離およびエステル加水分解によって代謝されるため、重篤な腎疾患または肝疾患を有する患者にとって非常に有用です。 * **鎮痛・鎮静作用なし：** 患者を麻痺させますが、鎮痛作用や意識消失作用は全くありません。単独の薬剤として使用してはなりません。 * **心血管系の安定性：** 標準用量では、古い神経筋遮断薬と比較して心血管系への影響は最小限ですが、まれにヒスタミン遊離を引き起こすことがあります。 * **動物種による感受性：** 馬では他の動物種よりも効力が高いことが知られています。
作用機序: 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).
動物種別の用量
- 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.
投与経路
禁忌
- Hypersensitivity to atracurium
- Relative contraindication: Myasthenia gravis
- Lack of ventilatory support (must have mechanical ventilation available)
有害事象
- Allergic reactions
- Inadequate or prolonged neuromuscular block
- Hypotension
- Vasodilation
- Bradycardia
- Tachycardia
- Dyspnea
- Bronchospasm
- Laryngospasm
- Rash
- Urticaria
- Injection site reaction
薬物相互作用
- 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.
モニタリング
- 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)
過量投与
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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