Terbinafine for Foot Fungal Infections and Candida Vaginosis
Terbinafine is highly effective for treating foot fungal infections (dermatophyte infections), but it is NOT recommended as first-line therapy for candida vaginosis due to its limited efficacy against Candida species. 1, 2
Efficacy for Foot Fungal Infections
Dermatophyte Infections (Tinea Pedis)
- Terbinafine is the first-line treatment for dermatophyte foot infections with superior efficacy compared to other antifungals 3
- For tinea pedis (athlete's foot), oral terbinafine 250mg daily for 1-2 weeks can effectively treat the infection with mycological cure rates of approximately 80-90% 4
- Topical terbinafine 1% formulations applied once or twice daily for up to 2 weeks achieve mycological cure in >80% of patients with tinea pedis 4
Onychomycosis (Nail Infections)
- For toenail onychomycosis, oral terbinafine 250mg daily for 12-16 weeks is recommended 1, 5
- Terbinafine is superior to itraconazole both in vitro and in vivo for dermatophyte onychomycosis and should be considered the first-line treatment 1
- Terbinafine has a fungicidal mechanism of action against dermatophytes with an MIC:MFC ratio of 1:1, making it more effective than fungistatic medications 6
- Long-term studies show significantly lower relapse rates with terbinafine (23%) compared to itraconazole (53%) during a 5-year follow-up period 1
Limited Efficacy for Candida Vaginosis
- Terbinafine has lower fungistatic activity against Candida species compared to azole antifungals 1
- In a comparative study of vulvovaginal candidiasis treatment, terbinafine showed only a 33.3% mycological cure rate compared to 66.6% with fluconazole 2
- Clinical cure rates were 33.3% for terbinafine, 60% for itraconazole, and 66.6% for fluconazole 2
- While terbinafine could be considered an alternative treatment option for vulvovaginal candidiasis, it cannot be recommended as a first-line treatment 2
Mechanism of Action
- Terbinafine is an allylamine antifungal that inhibits squalene epoxidase in the biosynthetic pathway of ergosterol, an essential component of the fungal cell wall 1
- This results in both ergosterol depletion (fungistatic effect) and squalene accumulation (fungicidal effect) 1
- Terbinafine has potent fungicidal effects against dermatophytes but weaker fungistatic activity against Candida species 1, 5
Dosing Recommendations
- For tinea pedis: Oral terbinafine 250mg daily for 1-2 weeks 4
- For toenail onychomycosis: Oral terbinafine 250mg daily for 12-16 weeks 5
- For fingernail onychomycosis: Oral terbinafine 250mg daily for 6 weeks 5
- Topical terbinafine 1% can be applied once or twice daily for up to 2 weeks for tinea pedis 4
Safety Considerations
- Oral terbinafine is generally well tolerated but requires monitoring for potential side effects 1
- Most common side effects include gastrointestinal disturbances (49% of reported side effects) and dermatological reactions (23%) 1, 3
- Rare but serious adverse events include hepatotoxicity, Stevens-Johnson syndrome, and taste disturbance 1
- Baseline liver function tests and complete blood count are recommended for patients with risk factors such as heavy alcohol consumption, pre-existing liver disease, or history of hepatitis 1, 5
- Terbinafine is not recommended in patients with active or chronic liver disease 1
Clinical Pearls and Pitfalls
- The optimal clinical effect is seen some months after mycological cure due to the time required for outgrowth of healthy nail 5
- Terbinafine persists in the nail for a considerable period after elimination from plasma, allowing for shorter treatment courses compared to other antifungals 1
- Patients should be warned about the possibility of taste disturbance, which can rarely be permanent 1
- Terbinafine has minimal drug-drug interactions compared to azole antifungals, making it safer for patients on multiple medications 1, 4
- For prevention of recurrence, patients should thoroughly dry between toes after bathing, change socks daily, and periodically clean footwear 3