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

Metal-containing Patches

The nonadhesive backing of some patches has a metallic component.[53] The most commonly used metal in TDDS products is aluminum, but titanium dioxide is also used.[4] The metal layer serves as a protective barrier, separating the drug from other components of the patch formulation and holding the drug and inactive ingredients within the patch.[54]

The presence of aluminum in a patch poses a safety concern for patients undergoing magnetic resonance imaging (MRI) and patients who may need external defibrillation during cardiac resuscitation. Aluminum and other metals used in patches have the potential to conduct electric currents, which has led to serious thermal injuries.[4,50] After several cases of reported skin burns in patients wearing transdermal patches containing metal during an MRI scan, the Institute for Safe Medication Practices and FDA issued alerts to health care professionals recommending the removal of any patch known or suspected to contain aluminum or any other metal before MRI is performed.[4] (The labels of many TDDS products containing metal do not provide a warning on the risk of skin burns during an MRI.) Alternatively, if a patch cannot be safely removed, an ice pack may be applied directly over the patch;[53] however, this practice is not recommended, as it may substantially decrease the rates of drug delivery and absorption. While it may be difficult for practitioners to identify which patches contain metal, many aluminum-containing patches may be recognized by examining the surface of the patch, which is shiny and reflects light.[49] Information regarding the metal content of commonly used FDA-approved patches can be found in the appendix.


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