サクシニルコリン / スキサメトニウム
塩化サクシニルコリンは、超短時間作用型の脱分極性骨格筋弛緩薬（麻痺薬）です。 **臨床上の重要なポイント：** * **鎮痛・鎮静作用なし：** サクシニルコリンには鎮痛作用や意識消失作用は全くありません。患者は完全に覚醒し痛みを感じますが、完全に麻痺状態となります。必ず適切な鎮静薬、麻酔薬、鎮痛薬と併用する必要があります。 * **人工呼吸管理が必須：** 横隔膜や肋間筋を麻痺させるため、薬効が切れるまで機械的換気が必須です。 * **臨床用途：** 主に気管挿管（迅速導入挿管）、外科的・診断的処置のための短時間の筋弛緩、または痙攣時の筋収縮の軽減に使用されます。 * **種差：** ヒトや多くの動物では作用時間が非常に短い（2〜3分）ですが、犬では特異的に作用時間が延長（約20分）します。 * **現代の使用状況：** 獣医療における使用は、副作用が少なく拮抗可能な非脱分極性筋弛緩薬（アトラクリウム、ロクロニウムなど）に大きく取って代わられています。
作用機序: Succinylcholine acts as a depolarizing neuromuscular blocker. * **Binding:** It acts as a structural analog of acetylcholine (ACh) and binds to **nicotinic acetylcholine receptors (nAChRs)** at the motor endplate of the neuromuscular junction. * **Depolarization:** Unlike ACh, which is instantly degraded by acetylcholinesterase, succinylcholine remains bound, causing prolonged depolarization of the muscle membrane. This initial depolarization manifests clinically as transient muscle twitches (**fasciculations**). * **Paralysis:** Because the membrane cannot repolarize, it becomes unresponsive to subsequent ACh release → **flaccid paralysis** (Phase I block). * **Metabolism:** The blockade persists until succinylcholine diffuses away from the receptor and is rapidly hydrolyzed by **plasma pseudocholinesterase** (butyrylcholinesterase) in the blood.
動物種別の用量
- Muscle relaxation · 0.06 mg/kg · IV · Single dose
- Muscle relaxation · 0.11 mg/kg · IV · Single dose
- Muscle relaxation · 0.088-0.11 mg/kg · IV, IM · Single dose · See Precautions. ARCI UCGFS Class 2 Drug. 0.088 mg/kg IV may paralyze skeletal muscles without causing respiratory depression, but higher doses cause apnea.
- Muscle relaxation · 0.07 mg/kg · IV · Single dose
- Muscle relaxation · 0.22 mg/kg · IV · Single dose
- To relax an animal to allow intubation · 0.5-1 mg/kg · IM · Single dose · Especially helpful with turtles and crocodilians.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Severe liver disease
- Chronic anemias
- Chronic malnourishment
- Glaucoma or penetrating eye injuries
- Predisposition to malignant hyperthermia
- Increased CPK values with resultant myopathies
- Recent use of organophosphate agents
有害事象
- Muscle soreness
- Histamine release
- Malignant hyperthermia
- Excessive salivation
- Hyperkalemia
- Rash
- Myoglobinemia
- Myoglobinuria
- Bradycardia
- Tachycardia
- Hypertension
- Hypotension
- Arrhythmias
薬物相互作用
- Amphotericin B · May increase succinylcholine's effects by causing electrolyte imbalances
- Digoxin · Succinylcholine may cause a sudden outflux of potassium from muscle cells, causing arrhythmias in digitalized patients
- Opiates · Potential for increased incidences of bradycardia and sinus arrest
- Thiazide Diuretics · May increase succinylcholine's effects by causing electrolyte imbalances
- Aminoglycosides · May increase or prolong neuromuscular blockade
- Inhalant Anesthetics (Isoflurane, Desflurane) · May increase or prolong neuromuscular blockade
- Antiarrhythmics (Quinidine, Lidocaine, Procainamide) · May increase or prolong neuromuscular blockade
- Beta-Adrenergic Blockers · May increase or prolong neuromuscular blockade
- Corticosteroids · May increase or prolong neuromuscular blockade
- Magnesium Salts · May increase or prolong neuromuscular blockade
- Organophosphates · May increase or prolong neuromuscular blockade (Contraindicated)
モニタリング
- Level of muscle relaxation
- Cardiac rate and rhythm (ECG)
- Respiratory depressant effect (Apnea)
- Oxygenation (Pulse oximetry) and Ventilation (Capnography)
- Body temperature (risk of malignant hyperthermia)
過量投与
Inadvertent overdoses, or standard doses in patients deficient in pseudocholinesterase, may result in **prolonged apnea**. * **Treatment:** Mechanical ventilation with 100% O2 must be maintained until full spontaneous recovery occurs. * **Phase II Block:** Repeated or prolonged high dosages may cause patients to convert from a depolarizing (Phase I) block to a non-depolarizing-like (Phase II) block.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。