FAQ

Comparative Evaluation of Amorolfine and Terbinafine:

1. Mechanism of Action:

• Amorolfine: Inhibits two key enzymes (Δ14-reductase and Δ8→Δ7-isomerase) in the ergosterol biosynthesis pathway of fungi, disrupting membrane integrity.
• Terbinafine: Non-competitively inhibits squalene epoxidase, causing accumulation of toxic squalene and depletion of ergosterol, essential for fungal cell membrane stability.

2. Efficacy:

• Amorolfine: Demonstrates broad-spectrum activity against dermatophytes, yeasts, and molds, with potent fungicidal effects at low concentrations (e.g., 1 μg/mL against Candida albicans).
• Terbinafine: Exhibits superior fungicidal activity against dermatophytes (e.g., Trichophyton rubrum) and some yeasts, with lower MIC values (e.g., 0.001–0.01 μg/mL against dermatophytes).

3. Nail Penetration:

• Ex Vivo Studies: Both drugs penetrate nail plates effectively. However, amorolfine achieves higher concentrations relative to its MIC₉₀ (191-fold vs. 48-fold for terbinafine), suggesting potential clinical advantages in onychomycosis treatment.

4. Clinical Use:

• Amorolfine: Topical formulations (5% lacquer) are FDA-approved for onychomycosis, with efficacy comparable to oral antifungals but lower relapse rates.
• Terbinafine: Available in oral (250 mg/day) and topical (1% cream/gel) forms, with oral therapy showing 60–80% cure rates for onychomycosis but associated with hepatotoxicity risks.

5. Safety and Tolerability:

• Amorolfine: Minimal systemic absorption; local side effects (e.g., burning, itching) are rare and transient.
• Terbinafine: Oral use may cause hepatotoxicity, gastrointestinal disturbances, and taste disturbances; topical formulations are better tolerated but less effective for nail infections.