What is transdermal medication?
Transdermal medication is medicine that is given through the skin. A drug is placed on top of the skin, where it is absorbed into the bloodstream. Transdermal medications have many advantages, and the main one is ease of application. It is often simpler to give medication through the skin than to give a pet pills or liquids.
In addition, drugs that are administered transdermally may be more effective or work faster than some oral medications because they are absorbed directly into the bloodstream and avoid initially passing through the intestinal tract and liver.
Can any medication be given transdermally?
No, relatively few drugs are currently available for transdermal application. The skin is a protective barrier, and it can be challenging to cross that barrier, especially in the consistent and controlled manner necessary for drug administration. It can be particularly complicated for dogs and cats, due to their fur and variations in their skin.
Most transdermal drugs must be dissolved in a gel or suspended in a patch. As techniques for transdermal administration improve, we expect to see more choices for veterinary medications.
What medications are available for transdermal administration?
Technology changes quickly, so it is best to ask your veterinarian. Your veterinarian may consult a compounding pharmacist to determine if your pet’s medication can be made into a transdermal gel or patch. Currently, several common medications are used successfully through transdermal application. They include methimazole (to treat hyperthyroidism), amitriptyline (to manage behavioral issues), mirtazapine (for appetite stimulation), fentanyl (for pain relief), and several heartworm, flea, and tick preventives.
The way each drug works and is absorbed transdermally varies considerably and may be influenced by the presence of hair, skin differences, skin infections, illness, and hydration status. If your pet is prescribed a transdermal medication and fails to improve, you may need to administer the drug orally.
Are there any risks with transdermal medications?
The biggest risk with a transdermal medication is that it could be insufficiently absorbed, resulting in inadequate drug levels and treatment. Other potential issues include:
- The pet inadvertently licking or ingesting the medication, causing gastrointestinal (GI) upset or more serious side effects
- Local irritation or hypersensitivity to the transdermal formulation
- Allergic reactions
- Accidental human exposure
- Changes in the original formulation, resulting in too much or too little of the active ingredient being delivered
Your veterinarian and pharmacist will work closely together to ensure your pet receives the proper amount of medication.
How do I give my pet transdermal medication?
Apply transdermal medications in a place with minimal hair, where the pet cannot easily lick or rub the medication. Some pets need to be shaved to allow for better administration. The inside of the outer ear flap (but not inside the ear canal) is an excellent area for many pets.
Most transdermal medications come in pre-dosed syringes or in gel form that can be drawn into a syringe to the prescribed dosage. Always wear protective gloves when handling transdermal medication. Remember that these drugs have been formulated to cross the skin barrier, so you can easily be exposed.
If your pet is prescribed a transdermal gel, you may need someone to assist you in applying it, especially at first. Here are some tips for administration:
- Have your helper gently hold your pet and distract it by petting or offering a toy or treat.
- Make sure the area on the ear where you are going to apply the medication is clean and dry.
- Slowly and deliberately apply the correct amount of medication onto your pet’s ear.
- If necessary, gently rub the gel into the skin using your gloved fingertip or the tip of the syringe. Do not to leave a clump, glob, or thick area of medication on the ear because it will come off if your pet shakes its head.
After you give your pet the medication, distract them from scratching or rubbing the ear for a few minutes by feeding them, taking them for a walk, or playing together. Giving your pet a reward like this immediately after applying medication also teaches them to not fear the medication process.
If your pet is prescribed a transdermal medication patch, your veterinarian may shave an area to affix the patch. Many patches last for several days, and the patch may have a protective wrap or bandage over it. Your veterinarian will explain the proper care, duration, and monitoring of transdermal patches.
It is important that your pet is not allowed to lick or swallow the patch. Serious side effects may result if a pet ingests a patch, especially if it contains fentanyl. Ask your veterinarian if you have any questions or concerns about your pet’s transdermal medication.
Transdermal medications are an excellent alternative for some veterinary drugs, and options increase each year. Talk to your veterinarian to determine if transdermal medication is appropriate for your pet.
