Small Animal Clinical Pharmacology - CYF MEDICAL DISTRIBUTION

CLINICAL PHARMACOLOGY OF INDIVIDUAL OPIOID AGONISTS
Table 14.3 Opioid dosages and duration of action (continued)
Drug Route of administration Dose rate (mg/kg) † Duration of analgesic
action (h)
Dog Cat ‡
Pethidine
(meperidine)
Methadone
Intravenous
Contraindicated in small
animals
Intramuscular or subcutaneous 2–10 2–10 1–2
Intravenous
0.05–0.1
0.05–0.1
4–6 §
Intramuscular or subcutaneous 0.1–1.0
0.1–1.0
4–6
Oxymorphone Intravenous 0.02–0.2 0.02–0.1 2–4 §
Intraoperative bolus 0.1 0.05
Intramuscular or subcutaneous 0.02–0.2 0.02–0.1 4–6
Epidural 0.02–0.1 0.02–0.1 8–12
Fentanyl Intraoperative IV bolus 0.002–0.005 0.001–0.005 0.3–0.5
Constant rate IV infusion:
Loading dose
0.01
0.005
Infusion rate
Anesthetic induction IV
+ diazepam (0.5 mg/kg) or
midazolam (0.2 mg/kg)
0.0025–0.010 mg/kg/h 0.0025–0.005 mg/kg/h
0.01 N/A
Transdermal:
2–4 µg/kg/h 2–4 µg/kg/h ≥72
Patch sizes: 25, 50, 75 and 100 mg/h
Intravenous induction
Intramuscular or subcutaneous
0.04 mL/kg
0.02–0.04 mL/kg
Contraindicated
0.5–1.0
Alfentanil Intravenous 0.01–0.025
Remifentanil* Intravenous 0.1–0.6 µg/kg/min 0.05–0.3 µg/kg/min Half-life approximately
4 min irrespective of
infusion duration
Codeine Oral 0.5–2.0 0.5–2.0 4–6
With paracetamol (acetaminophen) 0.5–2.0 Contraindicated 6–8
Subcutaneous 0.5–2.0 0.5–2.0
Buprenorphine Intravenous 0.005–0.02 0.005–0.01 3–4
Intramuscular or subcutaneous 0.005–0.04 0.005–0.04 4–12
Epidural 0.005–0.02 0.005–0.01 12–18
Butorphanol Intravenous 0.2–0.4 0.2–0.4 1–3 (dog)
4 (cat)
Intramuscular or subcutaneous 0.2–0.4 0.2–0.4 2–6
Antitussive dose 0.05–0.1 6–12
Oral 0.2–1.0 0.2–1.0 6–8
Pentazocine Intravenous 1–3 0.75–1.5 1–3
Intramuscular or subcutaneous 1–3 0.75–1.5 2–3
Oral 2–10 4–6
Antagonists
Naloxone Intravenous 0.01–0.04 20 min (0.3)
Intramuscular or subcutaneous
Nalorphine Intravenous 10–20 2–3
Intramuscular or subcutaneous 10–20 2–3
Nalbuphine Intravenous 0.5–1.5 1–6
Intramuscular or subcutaneous 0.5–2.0 4–8
Nalmefene Intravenous 0.03 ≥4
†
Dose selected will depend on desired effect, whether for sedation and/or analgesia, and other drugs concurrently administered.
‡
Where no dose rate is given for cats there are generally no recommendations available in the literature, rather than that drug being
contraindicated for use in cats. A similar or lower dose may be used with caution.
Duration of action will be affected by concurrent drug administration, desired effect and type of procedure performed and therefore act as a
guide only. These variables will influence the repeat dosing schedule and hence each animal should be assessed for evidence of pain and
response to therapy.
§
Intravenous boluses can be ‘titrated’ to effect by administering a bolus from the lower end of the dose range and repeating every 5–10 min
until the desired effect is achieved. At the same time, it is important not to overdose the patient.
* IPPV or support ventilation is mandatory at all but lower doses.
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