デクスメデトミジン
デクスメデトミジンは、獣医療において主に鎮静薬、鎮痛薬、麻酔前投薬として使用される強力で特異性の高い**アルファ2アドレナリン受容体作動薬**です。メデトミジンの右旋性エナンチオマーであり、ラセミ混合物の約2倍の効力を持ちます。
作用機序: Dexmedetomidine acts as a highly selective agonist at **pre-synaptic alpha-2 adrenergic receptors** in the central and peripheral nervous systems. * **CNS Effects:** Activation of alpha-2 receptors in the locus coeruleus → decreased norepinephrine release → profound sedation, anxiolysis, and analgesia. * **Cardiovascular Effects:** Activation of peripheral post-synaptic alpha-2B receptors in vascular smooth muscle → intense vasoconstriction → increased systemic vascular resistance (SVR) → reflex bradycardia mediated by baroreceptors. Central alpha-2A activation subsequently decreases sympathetic outflow. * **Other Effects:** Decreases GI secretions, alters intestinal motility, induces diuresis (via inhibition of ADH), and causes mild muscle relaxation.
動物種別の用量
- Sedation and analgesia · 40 micrograms/kg IM · IM · Single dose · Fasted for 12 hours prior. Apply eye lubricant. Peak effects at 30 minutes.
- Sedation and analgesia · 375 micrograms/m2 body surface area (BSA) IV; 500 micrograms/m2 BSA IM · IV/IM · Single dose · Microgram/kg dosage decreases as body weight increases. Fast for 12 hours prior. Peak effects at 30 minutes.
- Preanesthetic · 125-375 micrograms/m2 IM · IM · Single dose · Accurate dosing not possible < 2 kg.
- Premed prior to propofol or face mask induction (geriatric/renal/liver dysfunction) · 62.5 micrograms/m2 · IM/IV · Single dose · Combine with equal volumes of opioid and ketamine.
- Slightly heavier sedation for radiographic procedures (ASA II or III) · 125 micrograms/m2 · IM/IV · Single dose · Combine with equal volumes of opioid and ketamine.
- Minor surgery, Penn hip or OFA-types of radiographic procedures · 250 micrograms/m2 · IM/IV · Single dose · Combine with equal volumes of opioid and ketamine.
- Surgical plane of anesthesia for OHE, castration, or abdominal surgery · 375 micrograms/m2 · IM/IV · Single dose · Combine with equal volumes of opioid and ketamine. Lateral recumbency in 5-8 minutes.
- Immobilizing extremely fractious dogs and wolf-hybrid dogs · 500 micrograms/m2 · IM · Single dose · Combine with equal volumes of opioid and ketamine. Rarely required.
- Post-operative pain management in critically ill dogs · Loading dose of 25 micrograms/m2 IV, followed by a constant rate infusion for 24 hours at 25 micrograms/m2/hr · IV · CRI · 24 hours · Morphine rescue analgesia may be required.
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
- Cardiovascular disease
- Respiratory disorders
- Liver or kidney diseases
- Shock or severe debilitation
- Stress due to extreme heat, cold, or fatigue
- Puppies < 16 weeks (US label) or < 6 months (UK label)
- Kittens < 12 weeks (US label) or < 5 months (UK label)
- Hypersensitivity to the active substance
有害事象
- Bradycardia (profound)
- Occasional AV blocks
- Decreased respiration / Apnea
- Hypothermia
- Urination
- Vomiting
- Hyperglycemia
- Pain on injection (IM)
- Prolonged sedation
- Paradoxical excitation
- Hypersensitivity
- Pulmonary edema
- Death from circulatory failure (rare)
- Muscle tremors
- Transient hypertension
- Reduced tear production
薬物相互作用
- Anesthetics, Opiates, Sedative/Hypnotics · Effects may be additive; dosage reduction of one or both agents may be required. General anesthetic requirements may be reduced between 30-60%.
- Atropine, Glycopyrrolate · Can significantly increase arterial blood pressure and heart rate; use together is not recommended in dogs due to increased cardiac workload.
- Epinephrine · Possesses alpha agonist effects; do not use to treat cardiac effects caused by dexmedetomidine.
- Yohimbine · May reverse the effects, but atipamezole is preferred for clinical use.
モニタリング
- Level of sedation and analgesia
- Heart rate and rhythm
- Blood pressure
- Respiration rate and pulse oximetry
- Body temperature (monitor for hypothermia)
過量投与
Single doses of up to 5X (IV) and 10X (IM) were tolerated in dogs, but adverse effects (heart block, PVCs, tachycardia, profound sedation) can occur. > **Important:** Treatment of dexmedetomidine-induced bradycardia with anticholinergic agents (atropine or glycopyrrolate) is usually **not recommended** due to the risk of severe hypertension and arrhythmias. **Atipamezole** is the safest and most effective choice to reverse any dexmedetomidine-induced effects or overdose.
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。