Pre-emptive Analgesia.
Balanced Analgesia
Dose to Effect
Clinical Uses of Opioids
• Antitussive: cough suppressant action of opioids
•
Pre-anesthetic medication, analgesia and sedation
• Induction of anesthesia: sole drug for some species (humans), valuable adjuvant for veterinary patients
• Intraoperative analgesia: reduced anesthetic requirement, decrease complications and improve outcome
• Postoperative pain relief: improved outcome and quicker recovery, reasonable post-op comfort for all
• Critical care adjuvant: basic analgesia, facilitates mechanical ventilation, tolerance of tracheal tube, and other supportive
measures. Providing good analgesia improves clinical outcome for critically injured patients.
Opioid Analgesics and Recommended Doses
Morphine
• Dog: 0.25 - 0.5 mg/lb (0.5 - 1.0 mg/kg) IM, SC
• Cat: 0.025 - 0.05 mg/lb (0.05 - 0.1 mg/kg) IM, SC (Very useful at 1/10th the dog dose)
• Duration: 4-6 hours
•
Sedation accompanying analgesia
•
Vomiting, diarrhea, and bradycardia may occur
•
Hypotension and bronchoconstriction (histamine release, especially with IV use) may occur
Meperidine (Demerol)
• Dog: 1-5 mg/lb (2-10 mg/kg) IM, SC
• Cat: (usually effective, avoid high doses)
• Duration: 0.5-1 hour
•
Mild sedation
•
Rarely histamine release and hypotension
•
Cardiac and gastrointestinal effects are relatively minimal
Hydromorphone
• Dog: 0.025-0.05 mg/lb (0.05-0.1 mg/kg) IM, SC, IV
• Cat: 0.01-0.025 mg/lb (0.025-0.05 mg/kg) IM, SC, IV
• Duration: 4 hours
•
Panting, vomiting, diarrhea, bradycardia may occur
•
Dose-dependent sedation or excitement
Fentanyl
• Dog and Cats: 2-10 micrograms/kg/hr as a constant rate infusion after IV loading dose of 2-10 micrograms/kg
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Rapid onset and short duration
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Procedural uses and as a CRI for sustained and titratable analgesia in critical care
•
May be combined with lidocaine CRI
Mixed-Acting Agonist-Antagonist Opioid Analgesics:
Pentazocine (Talwin)
• Dog: 1-2 mg/lb (2-3 mg/kg) IM
• Cat: same as dog dose
•
Only mild analgesia
•
Minimal systemic effects
•
Narcotic reversal, ceiling effect
Butorphanol (Torbutrol, Torbugesic, Stadol)
• Dog: 0.1-0.2 mg/lb (0.2-0.5 mg/kg) IV, IM, SC
• Duration: 1-2 hours
•
Antitussive effect (often desirable)
•
Minimal systemic effects
•
Narcotic reversal (partial reversal)
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"Ceiling effect" – very limited analgesia, useful for mild sedation
•
Cat:(same as for dog, except for a longer duration of action 2-4 hours)
Nalbuphine (Nubain)
• Dog: 0.2-1.0 mg/lb (0.5-2.0 mg/kg) IM, IV
•
Limited effectiveness - "ceiling effect"
•
Minimal sedation
•
Minimal systemic effects
•
Narcotic reversal, ceiling effect
