Abstract
Dear Editor:
Transdermal fentanyl is a commonly administered opioid analgesic for cancer pain. Currently, six standard formulations are available, delivering fentanyl at rates of 12.5, 25, 37.5, 50, 75, and 100 mcg/h, but effective methods of adjusting drug dosage in increments <12.5 mcg/h have not been well established. Potential consequences of this limitation include the following:
• Toxicity from excessive dosing • Delays in making dose adjustments as patients need to obtain and fill new prescriptions • Diversion of unused patches • Wasted cost of unused patches
With drug delivery proportional to surface area, patch cutting offers an intuitive solution. The original gel-reservoir patches could not be cut because of drug leakage from the disrupted reservoir, 1 but newer matrix patches confine fentanyl within the patch adhesive, preventing leakage when the patch is cut. 2 The previously appropriate prohibition against cutting is no longer necessary, but is well entrenched, and as a result there have been inconsistencies in recommendations surrounding this practice within guidelines and among health providers, leading to confusion for patients and caregivers. Advice from some providers to partially cover the adhesive surface of a patch with an impermeable dressing is difficult for many patients and has not been studied.
We undertook a single-center, qualitative study at BC Cancer Agency (BCCA) in Vancouver, British Columbia to explore patient experiences with cutting fentanyl patches. Semistructured interviews were conducted by telephone with nine cancer patients (Table 1). Responses were coded and analyzed for themes, and saturation was reached after five interviews. Fentanyl blood levels were unavailable.
Participants have all needed to cut their fentanyl patches to achieve dosages unavailable in full-patch strengths.
Two patients, one male and one female, were interviewed through their caregivers.
Results
All nine participants found patch cutting “convenient.” Additional advantages included avoiding wastage of previously bought patches when dose requirements changed (two participants) and not needing dressings that could irritate sensitive skin (two participants).
Reduced skin adherence of cut patches was frequently reported (five participants). Effective solutions included using adhesive film over the top (e.g., Tegaderm®), fully drying skin before application, and pressing firmly after application. Five participants described satisfaction with the analgesia from cut patches as “good,” and for three of them, equivalent to that achieved with the next higher full-patch strength. Suboptimal analgesia was attributed to inadequate drug dosage while titrating to effect. No incidences of harm from cutting patches were reported.
Discussion
Compared with blocking absorption with occlusive films, 3 patch cutting offers greater convenience, less potential for skin irritation, and reduced wastage, as both halves remain usable after cutting. Having less actual drug available for absorption, whether intended or unintended, is also inherently safer. For patients with dose requirements intermediate between two full-patch strengths, or less than the smallest available full strength, our results suggest that cutting matrix patches is safe and effective.
The problem of poor adherence of full patches has been previously recognized, 4 and just as with full patches, there is potential risk from dropped pieces containing residual fentanyl being diverted or inadvertently ingested by children, pets, or other people in the home. We advise that prescribers warn all patients prescribed fentanyl patches, whether cut or not, that an additional fixative dressing may be needed to ensure adhesion.