美沙酮

用途

• For perioperative pain control
• As a pre-anesthetic
• For moderate to severe pain
• For pain
• Analgesia
• Analgesia
• Analgesia
• As an analgesic
• As a pre-anesthetic
• For pain
• For perioperative pain control
• For analgesia
• Analgesia
• Analgesia
• Epidural analgesia

給藥方式

可能的副作用

• Panting
• Whining or vocalization
• Sedation
• Defecation
• Constipation
• Bradycardia
• Respiratory depression
• Pronounced CNS excitement (in horses at IV doses ≥ 0.1 mg/kg)
• Respiratory depression (primarily under general anaesthesia)
• Transient excitation (when given IV)
• Salivation (when given via oral transmucosal route in cats due to preservatives)
• Constriction of gastrointestinal sphincters (e.g., pyloric sphincter)
• Reduction in gastrointestinal motility (with prolonged use)
• Neonatal sedation (crosses the placenta)

注意事項與禁忌

• Late-term pregnancy (due to risks of respiratory depression and stillbirths)
• Known hypersensitivity to methadone
• No specific contraindications available in the monograph, but use with caution in patients with severe respiratory compromise or hepatic impairment.
• All opiates should be used with caution in patients with **heart failure**, **hypertension**, **head injuries**, **elevated CSF pressures**, and in **geriatric or severely debilitated patients**. > **Note:** Methadone can increase plasma amylase and lipase values up to 24 hours following administration due to increased biliary tract pressure.

藥物相互作用

• Class I & III Antiarrhythmics (e.g., lidocaine, procainamide, quinidine, amiodarone): May increase risks for arrhythmias
• Alpha2-Agonists (e.g., medetomidine, xylazine): Potentiates sedative and analgesic effects; combination with medetomidine may cause severe hypoxemia in dogs breathing room air
• Azole Antifungals (fluconazole, itraconazole, ketoconazole): May increase methadone levels in humans (does not appear to be true for dogs)
• Calcium Channel Blockers: May increase risks for arrhythmias
• CNS Depressants (anesthetics, antihistamines, phenothiazines, barbiturates, tranquilizers): May cause increased CNS or respiratory depression
• Corticosteroids (Mineralocorticoids): May increase potential for electrolyte abnormalities
• Diuretics: Opiates may decrease diuretic efficacy in CHF patients
• Macrolide Antibiotics (erythromycin, clarithromycin): May inhibit metabolism of methadone and increase levels in humans (does not appear to be true for dogs)
• Monoamine Oxidase Inhibitors (MAOIs) (e.g., amitraz, selegiline): Potential for severe CNS/behavioral reactions; concomitant use should be avoided
• Skeletal Muscle Relaxants: Methadone may enhance neuromuscular blockade
• Phenobarbital, Phenytoin: May decrease methadone levels in humans (probably does not affect dogs)
• Rifampin: May decrease methadone levels in humans (probably does not affect dogs)
• SSRI Antidepressants (fluoxetine, sertraline): May increase methadone levels
• St. John's Wort: May decrease methadone levels in humans (probably does not affect dogs)
• Tricyclic Antidepressants (clomipramine, amitriptyline): Methadone may exacerbate the effects of tricyclic antidepressants
• Warfarin: Opiates may potentiate anticoagulant activity
• Zidovudine: Methadone may increase zidovudine levels
• CNS depressants (anaesthetics, antihistamines, barbiturates, phenothiazines, tranquillizers): Increased CNS or respiratory depression

常見問題