In this video, veterinary pharmacologist Dr. Dawn Boothe helps you decide whether you should administer drugs transdermally and when this route might work.
Dawn Merton Boothe, DVM, MS, PhD, Dip. ACVIM, Dip. ACVCP
Department of Anatomy, Physiology, and Pharmacology
College of Veterinary Medicine Auburn University, Alabama
Transdermal delivery is a process that involves administering medications through the skin. The drug, dissolved or suspended in some gel or patch, is absorbed through the skin and into the bloodstream. This system of drug delivery is often used in people but has only recently become popular in animals. The most significant advantage of transdermal medications is the ability to administer drugs to cats that cannot or will not take oral medications.
However, there are some disadvantages associated with transdermal drug delivery.
- Applying drugs transdermally on a cat's pinna (ear lobe) has obvious benefits, but absorption of most drugs through the skin is low.
- Although transdermal medications have been employed in human medicine for decades, not as much research has been done in animals (Dr. Boothe is one of the veterinarians who has done much in this regard). Therefore, we don't always know whether a specific drug will actually get absorbed through the skin to have any measurable effect.
- The amount of a drug absorbed through cats' relatively thick skin is unpredictable and absorption may be erratic.
- Some drugs cannot be made into transdermal formulations because the dose of the medication is too high. Others are too potent and carry a high risk of toxicity.
- Other potential complications associated with transdermal drug delivery include skin reactions and allergy to the medication.
- Finally, since cats constantly groom themselves, there is a risk of them ingesting the medication.