Safety Page Transdermal patches: High risk for error?

Although transdermal patches that the patches are not being derm, there is potential for confusion, provide a useful alternative to oral applied appropriately. which may result in the patches being medications, patch administration can •Why can’t you tape it on? The technol- applied to the wrong area. be complicated. Transdermal patches ogy of most patches is designed to use Errors have been reported wherein are a common route of administration the occlusive dressing to facilitate the patients receive or apply multiple for hormonal therapy, narcotic analge- absorption of the drug through the patches at once. One man did not sia, and nicotine. There are patches skin. Some patients do not realize that survive after his wife applied six fen- available for over-the-counter and pre- the patch must be applied directly to tanyl patches to his skin at one time. scription-only use. the skin. There was a report of a Another common problem is that the Medication errors with patches patient who applied his new patch old patch is not removed when the occur in every healthcare practice set- directly on top of the old one. This new patch is applied. ting—patients’ homes, physician continued until he had four patches Clear patches have become popular offices, intensive care units, cardiac stuck to one another instead of to his because you cannot see them on the step-down units, day care facilities, skin. In one case, a practitioner skin; however, this feature has also inpatient institutional settings, emer- applied the overlay to the patient’s made them error-prone. Nitroglycerin gency departments, etc. Outcomes skin and taped the medicated patch and nicotine patches are available as have been associated with patient on top of the overlay patch. clear patch formulations. These patch- harm, including death. The highest Additionally, some patients do not es become problematic for practition- risk is with the narcotic analgesic realize they must remove the protec- ers and patients because they are diffi- patches because of the potential for tive liner (usually a plastic/paper lin- cult to find on the patient’s skin when respiratory depression associated ing such as you see on an adhesive it is time to remove or replace them. with this class of medications. bandage) in order to expose the adhe- The risk for errors is increased sive and medication to the skin for when there are multiple caregivers, for Not all patches are equal absorption. One report describes only example, when nurses change shifts Like all medication errors, mistakes partial removal of the backing, where- or if multiple family members take associated with transdermal patches by a patient does not receive the prop- turns helping patients with their med- are multifactorial. One common cause er amount of drug because the protec- ications. This arrangement can result of error seems to be related to the tive lining blocks the absorption. in miscommunication, or lack of com- patch designs, which have confused Many patches have different munication, about where and when patients, caregivers, and practitioners. instructions for where the patch is to the last patch was placed and the next The transdermal patch products be placed. Most patch directions sug- one is due. It is also possible for a available in this country vary in units gest rotating the area of application to patient’s transdermal patch therapy to of dosage-strength expression, fre- avoid skin irritation. For example, go unnoticed by the staff as they tran- quency of administration, shape, size, there are patches that are applied to sition between different levels of care color, and site of administration. the torso or trunk of the body in the healthcare environment. Given all these factors and the com- between the neck and waistline; to plex healthcare environment, oppor- the scrotal tissue; on the skin behind Nomenclature issues tunities for errors abound. the ear or upper arm. Various units of measure are used to In the case of Testoderm patches, express the dosage strength of trans- Application, removal of patches one type is to be applied to the scrotal dermal patches. Some are expressed •What is an overlay? The overlay is tissue, while the other is not. Since as mg/hour, mg/day, mcg/hr, or sim- the portion of the two-piece patch both patches have the name Testo- ply as milligrams. For patches that are that secures the medicated patch to changed weekly, you may see the the skin of the patient. In the institu- By dosage strength expressed as mg/ tional setting, the overlay is some- Marci Lee, Pharm.D., and Jerry day/week. times returned to the pharmacy in Phillips, R.Ph. Another source of confusion is the the patient drawers when the med- use of obscure abbreviations as modi- ication cassettes are exchanged. This fiers. What does TTS mean? TTS can be a clue to the pharmacy staff stands for Transdermal Therapeutic To report a problem with an FDA-regulated product, please call 1-800-FDA-1088.

54 DRUG TOPICS APRIL 1 2002 www.drugtopics.com Safety Page

System, and some patches include this dispense all patches to nurses intact, were its own order), as well as the in the name of the product (for exam- with instructions as appropriate. application of each new patch. Docu- ple, Catapres-TTS and Testoderm mentation of patch administration TTS). TTS has been read as an abbrevi- Safe patch storage and disposal should include site of application— ation for Tuesday, Thursday, Saturday, Accidental and intentional ingestion critical if there are multiple caregivers resulting in patch application on three of transdermal patches has been involved in the patient care. days instead of once weekly. reported. Safe storage and disposal of In the inpatient setting, monitor transdermal patches are critical to pre- medication cassettes for return of Dosing intervals for patches venting accidental poisoning of chil- overlay patches to pharmacy, and fol- •When do I change my patch? Patches dren and pets. Some patches come low up on this issue with the practi- are changed daily, every three days, with a container for safe disposal. It tioners caring for that patient to rule twice weekly, weekly, every three may be safer to cut a used patch into out improper patch application. weeks, and so on. Confusion sur- pieces before disposing of it. Monitor patients with two-piece rounding the frequency of patch patches to ensure they are receiving administration presents another Strategies for error prevention active drug. If the therapy seems to be opportunity for error. And it seems When possible, avoid prescribing, ineffective, rule out improper patch that the longer the time between patch purchasing, or adding to the formula- application. changes, the greater the risk for forget- ry any CLEAR patches. Patient education can help prevent ting where the patch was placed or To prevent duplication of therapy in patch-related medication errors. forgetting to remove the old patch. the institutional setting, document the Marci Lee, Pharm.D., is a safety evaluator, and Jerry Phillips, R.Ph., associate director, Division of Medica- patch removal on the patient medica- tion Errors and Technical Support, Office of Drug Appropriate prescribing of patches tion administration record (as if it Safety, Food & Drug Administration. It is possible for prescribers to confuse the dosing interval, dosage strengths, and instructions for use among vari- ous patch formulations. An order for Catapres TTS was written in error as once daily instead of once weekly. Ironically, even after clarification of the dosing interval took place, an error still occurred because the practitioner applied only the overlay patch and not the medicated patch portion. Many products are available in multiple dosage formulations, includ- ing a transdermal patch and oral or injectable forms. There is a potential for error when a patient is being switched from one form to another. Additionally, there is potential for patients to receive duplicate therapy with the same or similar medications. For example, it is possible for a patient to receive a nitroglycerin transdermal patch and oral isosorbide mononi- trate, in error. Pediatric patch issues For the pediatric patient population, only small portions of transdermal patches may be needed. Although some patches can be cut for partial patch administration, cutting others destroys the release of the medication. It is recommended that pharmacists

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