Background　There is a move toward greater use of generic medicine in recent years, and loxoprofen sodium hydrate patches are often used in the field of orthopedic surgery. However, patients’ complaints of usage sensations and side effects differ between original medicine and generic medicine, and few reported basic investigations have yielded evidence for the causes of dermopathy with these medicines.
Methods　Loxoprofen sodium hydrate tapes and cataplasms, and ketoprofen tapes, were applied to 8-week-old female hairless mice. The patches were removed after 24 hours, and the skin was observed after 1 and 24 hours. Specifically, the number of abrasions triggered by skin irritation from the patches, horny layer water retention, exfoliation, epidermal thickness, and substance P expression were investigated.
Results　With loxoprofen sodium hydrate, greater skin damage was seen with tapes than with cataplasms. No differences were found between loxoprofen sodium hydrate preparations in any of the experiments. With Mohrus^® tape the number of abrasions increased, horny layer moisture decreased, and the epidermis thickened compared with loxoprofen sodium hydrate.
Conclusion　Dermopathy with Mohrus^® tape is thought to be affected by some substance derived from the tape. Even with loxoprofen sodium hydrate, patches have a stronger effect on the skin than non-patch applications. This suggests that close attention to itching and inflammation is needed in patients with the dry skin characteristic of elderly people. Further study, for example on the pre-application of moisturizing agents, is needed to identify appropriate patch sites for transdermal delivery systems.