Systemic uptake of buprenorphine by cats after oral mucosal administration

Buprenorphine can be effective when given to cats by mouth

source: S.A. Robertson el al
Veterinary Record vol 152 no 22, May 31 2003
starts p675, 4 pages long

A number of studies have noted that cats sometimes are not given adequate pain relief. This may be due to a number of reasons, such as fear of possible side effects, and lack of products licensed to be used with cats. Buprenorphine is commonly used to give pain relief to cats in the UK, while butorphanol tends to be used more in the US. Cats tend to be given just one injection of a painkiller, when they do receive any, but they need pain relief for over 24 hours after they have undergone major surgery. Injections can cause problems, for example, some cats do not have the sort of temperament that makes for easy injections, and it is not pleasant for a cat to have repeated injections. Owners are also unable to inject their own cats. This study assesses pain relief using buprenorphine given by mouth to six female shorthair cats, between two and 11-years-old.

The cats did not show any serious adverse effects. They had normal food intakes, and did not vomit. They did not salivate, or resist being given the drug. They were all easy to handle after being given the drug, and most were mildly euphoric, kneading using their forepaws, and purring.

Buprenorphine has a number of advantages, such as providing pain relief for a long period, and the rarity of vomiting as a side effect, compared with morphine. Buprenorphine has been shown to offer the highest bioavailability of a range of opiates when given to humans under the tongue. Even so, the bioavailability for buprenorphine administered this way in humans is only 51.4%, and is lower when administered between the lip and gum. Cats, however, have more alkaline mouths, and this helps to increase the bioavailability of buprenorphine administered in the mouth, whether under or on the tongue, or in the cat's cheek pouch. Compared with intramuscular injections, peak plasma concentrations were similar, though the oral route involved a median delay of 12 minutes later than when the drug was administered by injection. The pain relieving qualities of the drug are not correlated with its concentration in plasma, and the drug is slow to take effect as a painkiller, but its effects last for a long time. Owners tend to prefer mouth drops compared to other methods of giving drugs to cats. Further research is needed to assess whether oral administration of buprenorphine should be recommended.