From Dog

Codeine is an opioid drug with analgesic, antidiarrheal and antitussive properties.

Codeine is metabolized to numerous metabolites including morphine and codeine-6-glucuronide, which in addition to codeine appear to contribute to analgesic effects after codeine administration[1].

Oral administration has poor analgesic properties as there is poor oral bioavailability and lack of active metabolite formation in dogs[2].

When given parenterally, codeine results in significant antinociceptive effects, but the duration of effect is short lived (<2 hrs)[3]. Increasing doses does not significantly lengthen duration of effect, compared with other drugs such as morphine[4].

Codeine is used primarily in canine medicine for chronic bronchitis and other self-limiting upper respiratory diseases.

It is sometimes given parenterally for peri-operative pain management, solely or in combination with other analgesics such as tramadol or ketoprofen[5].

Side-effects are rare, and include CNS depression, constipation and ileus.


  1. Lötsch J et al (2006) Evidence for morphine-independent central nervous opioid effects after administration of codeine: contribution of other codeine metabolites. Clinical Pharmacology and Therapeutics 79:35–48
  2. Weinstein SH & Gaylord JC (1979) Determination of oxycodone in plasma and identification of a major metabolite. J Pharm Sci 68:527–528
  3. Skingle M & Tyers MB (1980) Further studies on opiate receptors that mediate antinoception: tooth pulp stimulation in the dog. British Journal of Pharmacology 70:323–327
  4. KuKanich B (2010) Pharmacokinetics of acetaminophen, codeine, and the codeine metabolites morphine and codeine-6-glucuronide in healthy Greyhound dogs. J Vet Pharmacol Ther 33(1):15-21
  5. Martins TL et al (2010) Comparison of the effects of tramadol, codeine, and ketoprofen alone or in combination on postoperative pain and on concentrations of blood glucose, serum cortisol, and serum interleukin-6 in dogs undergoing maxillectomy or mandibulectomy. Am J Vet Res 71(9):1019-1026