Breed and placement affect skin drug delivery

Aug 2 2005

Skin creams and patches might be the easiest way to give your pets medicine but their success also depends on the breed and where it’s applied.

New research by University of Queensland Vet School senior lecturer Dr Paul Mills has shown that drug absorption through skin varies in different animals, such as dogs and cats, and also varies with where you apply it.

After testing greyhounds Dr Mills found that they absorbed fentanyl, a strong pain reliever, quicker and more effectively if the drug was applied to the groin instead of the throat or neck.

Many drugs have automatically been applied to the back of the neck in animals to prevent them scratching ointments off.

Dr Mills also revealed that Dencorub (methylsalicylate), a skincream used to relive sore animal joints in pets as well as humans, is absorbed deeper than just the skin.

In his test subjects, the cream penetrated directly into the joints as well as the animal’s blood, meaning that applying the creams over sore joints was effective.

“Yes, it’s a good thing because you’ve got to get the drug to the joint,” Dr Mills said.

“Until this study, the exact mechanism by which the creams acted was uncertain, but we’ve shown the mechanism in the dog because we’ve sampled joints afterwards.”

Dr Mills said skin creams and patches were becoming the preferred method of treating animals for heartworm, fleas and ticks, travel sickness and in surgery because they were easier to use administer than oral tablets or injections.

He said skin applications of drugs had a huge range of applications not only in the veterinary world but also for testosterone treatment and hormone replacement therapy in humans.

“The veterinary market for this is getting bigger and bigger, but more research needs to be done to ensure that new drugs are effective and safe.

“So we’re trying to look at some of these basic sciences.”

Dr Mills’ team is now testing horses since doping is a big issue for the horseracing industry.

In July, Dr Mills also won the Ian Clunies Ross Memorial Award, an award given to young vets who’ve made outstanding contributions to veterinary science in Australia or New Zealand.