Transdermal Patches That Must Be Removed Before MRI

August 26, 2016

Some transdermal patches containing aluminum or other metal in their nonadhesive backing shouldn't be worn during MRI.

This article was collaboratively written with Festus Durugo, a fourth-year PharmD candidate at Chicago State University College of Pharmacy.

Magnetic resonance imaging (MRI) is an important tool for diagnosing and evaluating diseases. The process can be summarized as induction of protons by a magnetic field, followed by excitation with radio frequency pulses and subsequent readout with receiver coils.1

Thorough screening of each patient for any implantable devices and foreign bodies, pregnancy, and other potential issues is mandatory prior to scanning. Although MRI’s capabilities are well-recognized, its inherent dangers can’t be overlooked.

One report from the Joint Commission showed burns are the most common injuries in the MRI suite.2 The most common objects to undergo significant heating are wires and leads, pulse oximeter sensors and cables, and safety pins and metal clamps. Others include drug-delivery patches (which may contain a metallic coil), cardiorespiratory cables, and tattoos (which may contain iron oxide pigment).

In another study, MRI-related incidence was significantly higher in inpatient settings compared with outpatient centers (74% vs 29%).3 Additionally, medication safety was reported as the third-most frequent safety incident.

Transdermal patches are self-contained discrete dosage forms that deliver drugs through the skin to the systemic circulation.4 Their structural elements include:

  • Backing layer,
  • Drug layer or reservoir,
  • Adhesive layer, and
  • Protective or release liner.

In some instances, the drug and penetration enhancers or solubilizers are included in the adhesive layer. In other cases, the drug in a reservoir with penetration enhancers/solvents is incorporated into a microporous or dense polymeric membrane, followed by an adhesive layer for skin contact.

Some transdermal patches containing aluminum or other metal in their nonadhesive backing shouldn’t be worn during MRI because of skin burn risk. Health care professionals should advise patients wearing medication patches about procedures for proper removal and disposal before MRI and replacement afterwards.1,5 The FDA is currently reviewing transdermal products containing metal (Table6) to ensure they carry a warning about burn risk during MRI.

Pharmacists can play an important role by being familiar with these patches and ensuring they’re dispensed with the right auxiliary labels, removed appropriately before MRI, and correctly replaced afterwards. As the FDA continues to work with manufacturers to ensure proper labelling of transdermal patches with metal backing, pharmacists should know the FDA’s list of transdermal patches needing to be removed before MRI was last updated in 2009. Therefore, pharmacists should refer to package inserts for proper guidance, as new prescription, generic, and even OTC products aren’t included in the FDA’s original list.

Table: Transdermal Patches That Must Be Removed Before MRI6

Generic Name

Brand Name

Delivery System

Comments

Clonidine

Catapres-TTS

Reservoir

• Remove before MRI

• Reapply same patch to another site afterwards

Diclofenac

Flector

Matrix

• Remove before MRI

• Reapply same patch afterward if <2 hours have elapsed since patch was removed

• Apply new patch if longer

Estradiol

Alora

Matrix

• Remove before MRI

• For reapplication after the procedure, follow same instructions as for patch falling off

Estradiol

Transdermal

System

Matrix

• Remove before MRI

Vivelle Dot

Matrix

• Removal before MRI is recommended because manufacturer can’t guarantee product doesn’t contain metal

Fentanyl

Duragesic

Matrix

• Remove before MRI

• After procedure, apply a new patch to an alternate site

Lidocaine and Tetracaine

Synera

Thin uniform drug layer with oxygen-activated

heating component

• Remove before MRI

Methyl Salicylate and Menthol

Salonpas

Matrix

• OTC product

• Remove before MRI

• Replace with fresh patch after procedure

Nicotine

Nicoderm CQ

Habitrol

Reservoir

• To avoid confusion, recommend removing patch, regardless clear or opaque, before MRI

• Reapply same patch after procedure

Oxybutynin

Oxytrol

Matrix

• Removal before MRI is recommended because manufacturer can’t guarantee product doesn’t contain metal

Rivastigmine

Exelon

Matrix

• Consider removal before MRI

• Patch hasn’t been studied in patients undergoing MRI

Rotigotine

Neupro

Matrix

• Remove before MRI or cardioversion

Selegiline

Emsam

Matrix

• Remove before MRI because manufacturer can’t guarantee patch doesn’t contain metal

Scopolamine

Transderm Scop

Reservoir

• Remove before MRI

• Place new patch on an alternate site following procedure

Testosterone

Androderm

Reservoir

• Remove before MRI

• For reapplication after the procedure, follow same instructions as for patch falling off

References

1. Chernoff D, et al. Principles of magnetic resonance imaging. UpToDate. Waltham, MA. 2016

2. The Joint Commission. Preventing accidents and Injuries in the MRI suite. jointcommission.org/assets/1/18/SEA_38.PDF. Updated February 18, 2008. Accessed August 25, 2016.

3. Mansouri M, et al. Rates of safety incidence reporting in MRI in a large academic medical center. J Magn Reson Imaging. 2016;43:998-1007.

4. Mitra AK, et al. Burns in MRI patients wearing transdermal drug delivery systems. accessdata.fda.gov/ScienceForums/forum06/K-26.htm. Updated August 28, 2008. Accessed August 25, 2016.

5. Kuehn B. FDA warning: remove drug patches before MRI to prevent burns to skin. JAMA. 2009;301(13):1328

6. PL Technician Tutorial. dispensing the right patch with the right instructions. Pharmacist/Pharmacy Technician’s Letter. August 2016.