モルヒネ

動物種別の用量

投与経路

禁忌

• Hypersensitivity to narcotic analgesics
• Patients receiving monoamine oxidase inhibitors (MAOIs)
• Diarrhea caused by a toxic ingestion (until toxin is eliminated)
• Scorpion envenomation (Centruroides spp. - potentiates venom)
• Conditions where vomiting is contraindicated (e.g., raised intraocular pressure)

有害事象

• Histamine release (hypotension, vasodilation)
• Respiratory depression
• Bronchoconstriction
• CNS depression (dogs, primates) or excitation (cats, horses, ruminants)
• Physical dependence (with chronic use)
• Hyperthermia (cattle, goats, horses, cats)
• Hypothermia (dogs, rabbits)
• Nausea and vomiting
• Decreased intestinal peristalsis and constipation
• Initial defecation (dogs)
• Panting (dogs)
• Bradycardia or tachycardia
• Histamine release (if given rapidly IV)
• Vomiting (common in non-painful pre-operative patients)
• Transient excitation (IV administration)

薬物相互作用

• CNS Depressants (anesthetics, antihistamines, phenothiazines, barbiturates) · May cause increased CNS or respiratory depression when used with morphine.
• Diuretics · Opiates may decrease diuretic efficacy in congestive heart failure patients.
• Monoamine Oxidase Inhibitors (MAOIs, e.g., amitraz, selegiline) · Use with extreme caution; contraindicated in humans due to risk of severe opiate overdose signs.
• Skeletal Muscle Relaxants · Morphine may enhance neuromuscular blockade.
• Tricyclic Antidepressants (clomipramine, amitriptyline) · Morphine may exacerbate the effects of tricyclic antidepressants.
• Warfarin · Opiates may potentiate anticoagulant activity.
• CNS depressants (anaesthetics, antihistamines, barbiturates, phenothiazines, tranquillizers) · Increased CNS or respiratory depression · major

モニタリング

• Respiratory rate and depth
• CNS level of depression or excitation
• Blood pressure (especially with IV use)
• Analgesic activity
• Respiratory rate and depth (especially under general anaesthesia)
• Pain scores (to assess individual efficacy)
• Signs of histamine release (hypotension, tachycardia) during IV administration
• Gastrointestinal motility

過量投与

**Signs of Toxicity:** Overdosage may produce profound respiratory and/or CNS depression in most species. Newborns are more susceptible. Parenteral doses >100 mg/kg are thought to be fatal in dogs. Other toxic effects include cardiovascular collapse, hypothermia, and skeletal muscle hypotonia. Horses, cats, swine, and cattle may demonstrate CNS excitability (hyperreflexia, tremors) and seizures at high doses or if given rapidly intravenously. **Treatment:** * **Naloxone** is the agent of choice for treating respiratory depression. Doses may need to be repeated as naloxone's effects might diminish before sub-toxic levels of morphine are attained. * Mechanical respiratory support should be considered in severe cases. * Pentobarbital has been suggested for CNS excitement and seizures in cats, but extreme caution is required as barbiturates and narcotics have additive respiratory depressant effects.