Practical Considerations for Optimal Transdermal Drug Delivery

Cheryl Durand; Abdullah Alhammad; Kristine C. Willett


Am J Health Syst Pharm. 2012;69(2):116-124. 

In This Article

Advantages and Drawbacks

Medication delivery to the systemic circulation through the skin is an alternative to oral and parenteral routes of administration. The first TDDS entered the U.S. market in 1979 with the approval of the scopolamine patch by the Food and Drug Administration (FDA) for treatment of motion sickness.[1,2] Today there are more than 20 different types of medication patches available, and researchers are constantly striving to develop additional and improved methods for transdermal delivery of medications.[3,4]

TDDS products can offer advantages over oral or parenteral medication delivery that may enhance the clinical benefits of drug therapy and improve patient compliance.[2,5] With medication patches it is possible to (1) circumvent "first-pass" inactivation by the liver, (2) reduce the likelihood of gastrointestinal irritation, (3) provide for the steady absorption of medication over long periods of time, (4) reduce the frequency of dosing, which may improve adherence, and (5) lower the frequency of adverse effects through the avoidance of high serum drug peaks.[2]

The clonidine patch is one example of a TDDS offering several of those benefits. Clonidine patches are applied once every seven days, allowing a reduced dosing frequency relative to oral administration of the drug and potentially improving compliance. Furthermore, transdermal clonidine provides steady serum drug concentrations, resulting in lower peak levels of the drug, which may reduce the frequency of adverse effects. When clonidine use is discontinued, a patient receiving transdermal rather than oral therapy is less likely to experience rebound hypertension, since serum levels of clonidine gradually decline over several days once the patch is removed.

For many patients, TDDS products expand the options for medication administration, offer a noninvasive alternative to parenteral therapy, and typically permit less frequent dosing relative to oral therapy, all of which may be advantageous for patients and caregivers.[2,6,7] However, the administration of medications using a TDDS also has disadvantages, including the potential for skin reactions ranging from allergic contact dermatitis to irritant contact dermatitis. One review of published data on skin reactions in patients using TDDS products showed the rate of skin reactions to be 20–50%, although most reactions tended to be mild and the discontinuation rate was low (1.7–6.8%).[3]

Another drawback of the use of medication patches is a delayed onset of action in comparison with oral and parenteral administration; for example, therapeutic concentrations are not attained for two to three days after the application of transdermal clonidine. Moreover, drug absorption rates may differ by the site of TDDS application, as some areas are more easily permeated (e.g., palms, face, genitalia) and patch manufacturers generally make recommendations on the placement of patches for optimal absorption. Another drawback of using medication patches is the potential for the loss of adhesive properties, which may lead to decreased drug delivery. TDDS adhesion failures may result from everyday activities such as showering, swimming, and sweating.[2,3,8]


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