Is an oral antifungal agent appropriate in a man aged 76 years who has a two-year history of onychomycosis? Treatment with ciclopirox 8% nail lacquer and gel in combination with 40% urea [Carmol 40] gel has been unsuccessful.
The patient reports no pain and has had no cellulitis or other complications related to his onychomycosis. He takes warfarin [Coumadin, Jantoven] for a history of deep vein thrombosis but is otherwise healthy. — Ann Keuhl, PA-C, Mokena, Ill.
Because nonfungal nail changes in the elderly can mimic onychomycosis, it may be prudent to obtain fungal-culture confirmation of clinically suspicious tinea unguium prior to starting systemic antimycotic therapy. Such systemic antifungals as terbinafine (Lamisil) and itraconazole (Onmel, Sporanox) can be used in older individuals, provided baseline laboratory studies are normal and appropriate periodic follow-up studies are performed. However, caution is advised when using systemic antifungals in a patient who is concurrently receiving warfarin.
Itraconazole can increase the plasma concentration of warfarin, thereby enhancing its anticoagulant effect. There have been spontaneous reports of an increase or a decrease in the prothrombin time (PT) of patients taking oral terbinafine and warfarin concomitantly. However, a causal relationship between terbinafine tablets and these changes has not been established.
In patients receiving warfarin anticoagulation, initial and periodic evaluation of bleeding parameters (PT and international normalized ratio) should be considered while they are concurrently being treated with either itraconazole or terbinafine. — Philip R. Cohen, MD (177-3)
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