What is the most appropriate oral therapy for a 70-year-old man with thickened and painful toenails?

The most appropriate oral therapy for a 70-year-old man with thickened and painful toenails is terbinafine. Terbinafine is an allylamine antifungal medication that is primarily used to treat onychomycosis, which is a fungal infection of the nails. This medication works by inhibiting the synthesis of ergosterol, a key component of fungal cell membranes, leading to fungal cell death.

In older adults, onychomycosis is a common condition that can lead to painful and thickened nails, affecting mobility and quality of life. Terbinafine has proven efficacy against dermatophyte infections, which are the most common cause of nail fungal infections.

Other antifungal options like fluconazole are usually used for systemic fungal infections or specific types of superficial fungal conditions. However, it is less effective for dermatophyte nail infections compared to terbinafine. Griseofulvin is another antifungal that is mainly used for dermatophyte infections of the skin and hair rather than nails, making it less suitable in this case. Caspofungin is an echinocandin antifungal used primarily for invasive fungal infections, particularly those caused by Candida or Aspergillus species, but it is not indicated