メデトミジン

動物種別の用量

投与経路

禁忌

• Cardiac disease
• Respiratory disorders
• Liver or kidney diseases
• Shock or severe debilitation
• Animals stressed due to heat, cold, or fatigue
• Pregnancy (insufficient safety data; use only if benefits clearly outweigh risks)
• Cardiovascular disease
• Systemic disease
• Geriatric patients
• Pregnant animals
• Conditions where vomiting is contraindicated (e.g., gastrointestinal foreign body, raised intraocular pressure)
• Diabetes mellitus

有害事象

• Bradycardia (often profound)
• Atrioventricular (AV) blocks
• Decreased respiratory rate and potential apnea
• Hypothermia
• Increased urination (diuresis)
• Vomiting (especially in cats)
• Hyperglycemia
• Pain on intramuscular injection
• Blanched or cyanotic mucous membranes (due to peripheral vasoconstriction)
• Rarely: prolonged sedation, paradoxical excitation, hypersensitivity, death from circulatory failure
• Bradycardia
• Decreased cardiac output
• Initial hypertension followed by normotension/hypotension
• Vomiting (especially common after IM administration)
• Diuresis (due to ADH suppression)

薬物相互作用

• Atropine / Glycopyrrolate · Controversial. Using anticholinergics to treat medetomidine-induced bradycardia can lead to severe hypertension, increased myocardial work, and arrhythmias. Concomitant use is generally discouraged, especially at higher medetomidine doses (>20 mcg/kg).
• Opiates (Fentanyl, Butorphanol, Meperidine) · Synergistic enhancement of sedation and analgesia. Adverse cardiovascular and respiratory effects may also be pronounced. Reduced dosages and careful monitoring are advised.
• Propofol · When used after medetomidine, severe hypoxemia may occur. Significant dosage reductions of propofol are required along with adequate respiratory monitoring.
• Yohimbine · May reverse the effects of medetomidine, but atipamezole is the preferred and more specific reversal agent.
• Other anesthetic agents (e.g., propofol, alfaxalone) · Significantly reduces the dose required for induction and maintenance of anesthesia. · major
• Volatile anesthetics (e.g., isoflurane, sevoflurane) · Reduces the dose required to maintain anesthesia by up to 70%. · major
• Sympathomimetic amines · Contraindicated; may cause severe cardiovascular complications. · major
• Opioids · Synergistic sedation and analgesia (beneficial interaction). · moderate

モニタリング

• Level of sedation and analgesia
• Heart rate and rhythm (ECG recommended in high-risk patients)
• Body temperature (monitor for hypothermia)
• Blood pressure
• Respiratory rate and depth
• Pulse oximetry (SpO2)
• Heart rate and rhythm (bradycardia is expected, but monitor for severe arrhythmias)
• Blood pressure (initial hypertension followed by normotension/hypotension)
• Oxygen saturation (SpO2)
• Body temperature (risk of hypothermia due to reduced metabolic rate and peripheral vasoconstriction)
• Depth of sedation

過量投与

Single doses of up to **5X (IV)** and **10X (IM)** have been tolerated in dogs, though severe adverse effects (profound bradycardia, AV blocks, respiratory depression) can occur. Death has occurred rarely in dogs (1 in 40,000) receiving 2X doses. > **Important**: Treatment of medetomidine-induced bradycardia with anticholinergic agents (atropine or glycopyrrolate) is **not recommended** due to the risk of severe hypertension, increased myocardial oxygen demand, and arrhythmias. **Atipamezole** (an alpha-2 antagonist) is the safest and most effective choice to reverse medetomidine-induced cardiovascular and sedative effects.