ACE 20B Sample Question

A 67-year-old man is scheduled to receive monitored anesthesia care for cardiac magnetic resonance imaging. His current medications include carvedilol, lisinopril, and transdermal nicotine. Which of these should MOST likely be held prior to this procedure?

A. Carvedilol X

B. Lisinopril X

C. Transdermal nicotine ✔

Read the discussion below.

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Discussion

Transdermal drug delivery systems may contain nicotine, hormonal contraceptives, opioids, scopolamine, or other drugs. These systems offer the potential for convenient, around-the-clock administration of medications for systemic delivery. Alternatively, they can deliver medications to a specific body part, minimizing systemic effects (eg, lidocaine and diclofenac patches). In addition to understanding the pharmacodynamic effects of a drug, an understanding of transdermal delivery systems and their components is also important to ensure patient safety.

Transdermal drug delivery systems often contain 4 elements: a backing layer, a drug layer or reservoir, an adhesive layer, and a protective or release liner. Certain transdermal drug delivery systems (Table 1) contain a conductive (most often aluminized) backing that can result in burns to patients during a magnetic resonance imaging (MRI) scan. Such events have been reported to the US Food and Drug Administration. 

Table 1. List of select medications with transdermal delivery systems containing metal.

A study from the Joint Commission showed that burns are the most common injury associated with MRI. Objects other than transdermal drug delivery systems that have been implicated include wires, electrocardiographic leads, pulse oximetry devices, safety pins, clamps, and tattoos. The Anesthesia Patient Safety Foundation and others recommend the removal of transdermal drug delivery systems prior to MRI and reapplication after completion of the imaging study or MRI-guided procedure.

Other periprocedural factors should be considered for patients with an existing transdermal patch. Notably, vasodilation from several anesthetic agents combined with heating devices (ie, forced-air convective warming devices) can significantly alter the pharmacokinetic parameters of transdermal delivery systems, resulting in rapid absorption and distribution of medications, with resultant safety implications for patients. 

Neither monitored anesthesia care nor MRI necessitate discontinuation of carvedilol or lisinopril.

REFERENCES

1. Hao J, Ghosh P, Li SK, Newman B, Kasting GB, Raney SG. Heat effects on drug delivery across human skin. Expert Opin Drug Deliv. 2016;13(5):755-768. doi:10.1517/17425247.2016.1136286
2. Kuehn BM. FDA warning: remove drug patches before MRI to prevent burns to skin. JAMA. 2009;301(13):1328. doi:10.1001/jama.2009.406
3. Mansouri M, Aran S, Harvey HB, Shaqdan KW, Abujudeh HH. Rates of safety incident reporting in MRI in a large academic medical center. J Magn Reson Imaging. 2016;43(4):998-1007. doi:10.1002/jmri.25055
4. Flood P, Rathmell JP, Urman RD, eds. Stoelting’s Pharmacology & Physiology in Anesthetic Practice. 6th ed. Wolters Kluwer; 2021:25.

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