What is the most appropriate treatment for onychomycosis caused by Trichophyton rubrum in a diabetic patient?

The most appropriate treatment for onychomycosis caused by Trichophyton rubrum in a diabetic patient is oral terbinafine. This antifungal medication is a first-line treatment for onychomycosis, particularly for infections caused by dermatophytes such as Trichophyton rubrum. Terbinafine works by inhibiting the fungal enzyme squalene epoxidase, leading to a reduction in ergosterol synthesis, an essential component of fungal cell membranes. This effective mechanism allows it to eliminate the fungal infection and promote nail regrowth.

In diabetic patients, achieving effective treatment for onychomycosis is crucial because they are at a higher risk for complications from infections, including potential progression to more severe infections. Oral terbinafine has been shown to have a higher cure rate and efficacy compared to other treatments available and is preferred due to its safe profile and favorable pharmacokinetics that ensure adequate drug levels in nail tissues.

While other antifungal medications exist, such as fluconazole and nystatin, they are not as specifically effective against dermatophyte infections like onychomycosis. Fluconazole is generally utilized for Candida infections, and nystatin is not effective for dermatophytes. Topical