While the molecular properties of doxycycline do allow it to be absorbed transdermally, other factors should be considered when deciding whether or not to prescribe it for your patients. The side effects of doxycycline, the risks of anti-biotic resistance, and the high risk infections that doxycycline is meant to treat all make transdermal application of the drug a sub-par choice at best.
1. The Side Effects of Transdermal Doxycycline
The biggest risk of using doxycycline transdermally is that it is photosensitizing. This means that your feline patients may experience severe sunburns when exposed to sunlight after doxycycline is applied.
Oral doxycycline has been known to ulcerate when lodged in a cat’s esophagus, therefore, there is a significant risk that rubbing a concentrated doxycycline gel on a cats ear will have the same ulceration effect on the pinnae of the ear, which is painful and could put your patient at risk of a secondary infection.
2. Transdermal Doxycycline can Cause Antibiotic Resistance
Transdermal medications take longer to reach effective concentrations versus oral or injectable routes. As the doxycycline is building to optimal strength, your patient’s body is already building a resistance to it. The initial suboptimal concentrations of antibacterial transdermal medications can lead to bacterial resistance that makes treatment of a recurring infection more difficult and dangerous for your patient.
Resistance to doxycycline, for instance, would leave few alternatives for treating and tick-borne diseases that your feline patient may pick up in the future. This leaves your patient exposed and vulnerable and limits your ability to treat him or her in the future.
3. Infections Can Be Serious Health Emergencies
Infections should be treated quickly to prevent spreading the infection to other animals and to limit any long-term health consequences. Transdermal delivery should not be used in acute situations where the effect of the drug needs to be seen right away. Because transdermal delivery takes time to reach optimal levels, your patient could become severely ill, crippled, or even die while waiting for the transdermal treatment to take effect.
Oral or injectable administration provides therapeutic doxycycline levels much more quickly than transdermal can. If transdermal doxycycline has been administered in the past, it could make your patient more resistant to the emergency treatment they currently need.
The risk of bacterial resistance along with the physical side effects of doxycycline make it a bad idea to use transdermally. Other routes of administration for doxycycline should be used to treat infections – especially in an emergency situation. Be aware of the risks associated with transdermal doxycycline and educate your fellow clinicians and staff members to protect the health of your patients.
For more information on the risks and benefits of other transdermal medications contact EPC. We can help you determine if transdermal application is necessary and beneficial for your patient and their current health situation.
– Bryce Walker, Veterinary Compounding Pharmacy Student under the direction of Drew Olson, DVM, Veterinary Division – National Director