A 28-year-old male presents with a 3-month history of painful, inflammatory tinea pedis with maceration and secondary bacterial infection. Topical antifungals have failed. Which is the preferred systemic antifungal for severe, inflammatory tinea pedis?

Explanation

## Systemic Treatment of Severe Inflammatory Tinea Pedis **Key Point:** Terbinafine is the drug of choice for severe, inflammatory tinea pedis because of its potent fungicidal activity, rapid anti-inflammatory effect, and superior tissue penetration in the foot. ### Pathophysiology of Severe Tinea Pedis Severe inflammatory tinea pedis (especially interdigital and plantar forms) is often caused by *Trichophyton mentagrophytes* or *Trichophyton rubrum* and may be complicated by secondary bacterial infection and dermatophytid reactions. Systemic antifungal therapy is required to achieve adequate drug levels in the stratum corneum and nail apparatus. ### Drug Comparison for Severe Tinea Pedis | Drug | Fungicidal/Static | Onset | Duration | Tissue Penetration | Inflammatory Control | | --- | --- | --- | --- | --- | --- | | **Terbinafine** | Fungicidal | Rapid (1–2 weeks) | 2–6 weeks | Excellent (skin, nail) | Excellent (rapid resolution) | | Itraconazole | Fungistatic | Slower (2–3 weeks) | 4–8 weeks | Good | Moderate | | Griseofulvin | Fungistatic | Slow (3–4 weeks) | 6–8 weeks | Fair | Moderate | | Tolnaftate | Fungistatic | Slow | Not systemic | Poor | Poor | **High-Yield:** Terbinafine achieves the **highest concentration in skin and nails** among all systemic antifungals, making it ideal for foot infections where drug penetration is critical. ### Dosing for Tinea Pedis - **Terbinafine:** 250 mg once daily for 2–6 weeks (depending on severity and nail involvement) - Itraconazole: 200 mg once or twice daily for 4–8 weeks - Griseofulvin: 500 mg–1 g daily for 6–8 weeks **Clinical Pearl:** In severe inflammatory tinea pedis with secondary bacterial infection, consider: 1. Systemic terbinafine (antifungal) 2. Short course of oral antibiotics (e.g., cephalexin) for bacterial superinfection 3. Topical corticosteroid + antifungal combination (e.g., clotrimazole + betamethasone) for initial anti-inflammatory effect **Mnemonic:** **TERBINAFINE = Tinea's Best Friend** — Fastest fungicidal action, Excellent tissue penetration, Rapid resolution of inflammation, Best cure rates, In all dermatophytosis, Nail-penetrating, Antifungal efficacy, Fungicidal mechanism, In severe cases, Nail involvement, Essential first-line. ### Why Terbinafine Excels in Severe Tinea Pedis 1. **Fungicidal** — kills fungi rapidly, preventing recurrence 2. **Rapid anti-inflammatory effect** — reduces erythema and pruritus within 1–2 weeks 3. **Superior foot penetration** — achieves high concentrations in plantar skin and between toes 4. **Shorter treatment course** — 2–6 weeks vs. 6–8 weeks for alternatives 5. **Prevents nail involvement** — if toenails are at risk, terbinafine is most effective