Topical vs. Transdermal Drug Delivery: A Function of Formulation
- Peripheral tissue activity
- Systemic side effects less likely
- If analgesic, applied directly over painful site
- Insignificant serum levels
- Systemic activity
- Potential for adverse effects
- If analgesic, may be applied away from painful site
- Serum levels necessary for effect
Medications that relieve pain, reduce inflammation, and relax muscles can have side effects that are detrimental to athletic performance, such as drowsiness. However, when these medications are administered topically, the therapeutic benefit can be enhanced while significantly reducing the risk of adverse effects.
For example, research has shown that topically-applied ketoprofen provides a high local concentration of drug below the site of application but decreases systemic exposure and significantly reduces the risk of gastrointestinal upset or bleeding. When properly compounded into an appropriate base, tissue concentrations of ketoprofen were found to be 100-fold greater below the application site (knee) compared to systemic concentrations. Muscle relaxants can be similarly prepared to minimize the risk of drowsiness.