From the Guidelines
Terbinafine should be considered as the first choice for treating onychomycosis due to its higher efficacy and tolerability compared to itraconazole. When treating onychomycosis, the goal is to achieve complete cure, defined as negative mycological analysis and a normal nail. According to the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1, terbinafine has been shown to be more effective than itraconazole in achieving this goal.
The recommended dosage for terbinafine is 250 mg per day for 6 weeks in fingernail and 12–16 weeks in toenail infection 1. Patients should be re-evaluated 3–6 months after treatment initiation and further treatment should be given if the disease persists. Key benefits of terbinafine include:
- Higher efficacy rates compared to itraconazole
- Better tolerability
- Ability to persist in the nail for a considerable period after elimination from the plasma, allowing for intermittent or ‘pulse’ treatment regimens
In contrast, itraconazole is licensed at a dose of 200 mg per day for 12 weeks continuously, or alternatively as pulse therapy at a dose of 400 mg per day for 1 week per month 1. However, studies have consistently shown that terbinafine has higher efficacy rates and lower relapse rates compared to itraconazole 1. For example, a multicentre, randomized trial involving 508 subjects demonstrated complete cure in 55% of patients receiving 16 weeks of continuous terbinafine, compared to 26% of patients receiving pulsed itraconazole 1.
Overall, terbinafine is the preferred treatment option for onychomycosis due to its superior efficacy and tolerability, and should be considered as the first choice unless there are contraindications 1.
From the FDA Drug Label
1 INDICATIONS AND USAGE Terbinafine tablets, USP are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium).
The FDA drug label does not answer the question about Onyfix.
From the Research
Onyfix Treatment
- Onyfix, also known as amorolfine, is a topical antifungal medication used to treat fungal nail infections, such as onychomycosis 2, 3, 4.
- The treatment of onychomycosis with amorolfine nail lacquer in combination with oral terbinafine has been shown to be more effective than oral terbinafine alone 3, 4.
- A study published in the British Journal of Dermatology found that the combination of amorolfine nail lacquer and oral terbinafine resulted in a higher success rate (59.2% vs. 45.0%) and was more cost-effective than terbinafine alone 4.
- Another study found that combining terbinafine with amorolfine tended to be more effective than terbinafine in conjunction with ciclopirox, with additive effects observed in most combinations 2.
Mechanism of Action
- Amorolfine has been shown to have a sporicidal effect, killing dormant fungal cells, which can survive in the affected nail keratin and evade the effect of antifungal drugs 5.
- The effectiveness of amorolfine depends on the drug concentration and the incubation time, with a concentration of 10-1000 times the minimum inhibitory concentration against growing hyphae cells needed to exert a sporicidal action 5.
- Amorolfine and ciclopirox have been shown to have the same sporicidal efficacy and kinetics for all three varieties of spores tested, and were more effective than fluconazole and bifonazole against microconidia and chlamydospores 5.
Comparison with Other Treatments
- A Cochrane review found that efinaconazole 10% solution was more effective than vehicle in achieving complete cure, clinical cure, and mycological cure, and was probably more effective than other topical treatments 6.
- The review also found that tavaborole 5% solution was probably more effective than vehicle in achieving complete cure and mycological cure, but may have a higher risk of adverse events 6.
- P-3051 (ciclopirox 8% hydrolacquer) was found to be probably more effective than ciclopirox 8% lacquer or amorolfine 5% in achieving complete cure, but there was probably little or no difference between the treatments in achieving mycological cure 6.