Ivermectin for Scabies

I applaud the efforts of Chouela et al¹ in confirming the efficacy and safety of ivermectin for treating human scabies. Scabies can be difficult to diagnose and the regulations of the Clinical Laboratory Improvement Amendments of 1998² have severely hampered the dermatologist from making bedside diagnoses in nursing home patients. The sequelae of missed diagnoses of scabies in nursing home patients in the memory loss unit, where I consult, recently resulted in costs of $15,000 for cleaning and medications. Easily administered and safe oral treatments are welcome for the persistent and potentially serious problem of scabies and the subsequent costs. I agree with Chouela et al¹ that further studies are necessary to confirm the long-term safety and efficacy of ivermectin for the treatment of scabies, especially among immunosuppressed and pediatric patients.

Topical preparations containing permethrin and lindane, while effective and safe, lack the ideal characteristics for treating scabies in an institutional setting, such as a nursing home, for several reasons. First, even the best nursing homes are frequently understaffed, and current therapies greatly strain the limited nursing time. Second, applying creams to the entire body of a patient is difficult in nursing home populations because patients are frequently confused, hostile, and combative. For example, the phenomenon of sundowning experienced by patients with dementia makes the usual overnight topical application of these products a hazardous experience. Third, nursing home patients frequently have conditions, such as contractures, spasticity, and rigidity, that make applying topical products to the entire body a taxing, if not impossible, task. Finally, as pointed out in the editorial by del Giudice,³ treatment-related dermatitis can be difficult to distinguish from persistent scabies.

Based on current data, ivermectin appears to be the best available, first-line treatment for cases of scabies in adult nursing homes and institutions. The manufacturer (Merck, West Point, Pa) should work toward the availability of the use of the drug as oral treatment for patients with scabies. In addition, the US Food and Drug Administration should work with pharmacological manufacturers to facilitate the approval of ivermectin and other potential antiparasitic oral medications to fill this definite need.