From the Guidelines
Itraconazole should be prescribed 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, with 2 pulses recommended for fingernail onychomycosis and 3 pulses for toenail onychomycosis, as stated in the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1.
Treatment Regimens
The treatment of onychomycosis with itraconazole can be administered in two regimens: continuous or pulse therapy.
- Continuous regimen: 200 mg of itraconazole once daily for 12 weeks for toenail infections or 6 weeks for fingernail infections.
- Pulse therapy: 400 mg per day for 1 week per month, with the number of pulses depending on the type of nail infection.
Mechanism of Action and Administration
Itraconazole works by inhibiting fungal cell membrane synthesis through disruption of ergosterol production. The drug concentrates in the nail plate and remains active even after stopping treatment. It is essential to take itraconazole with food to enhance absorption and be aware of potential drug interactions, particularly with medications metabolized by CYP3A4, as noted in the guidelines 1.
Monitoring and Precautions
Liver function monitoring is recommended before starting therapy, and the medication should be avoided in patients with heart failure or liver disease, as highlighted in the guidelines 1. Complete nail clearance may take 6-12 months as the nail needs to grow out fully, even after the medication course is completed.
Comparison with Other Treatments
While itraconazole is an effective treatment for onychomycosis, other options like terbinafine may have higher efficacy rates, as demonstrated in a multicentre, randomized trial involving 508 subjects 1. However, itraconazole remains a viable alternative, especially in patients who cannot tolerate other treatments, as discussed in the context of fluconazole 1.
From the Research
Itraconazole Dosing for Onychomycosis
- The dosing regimen for itraconazole in the treatment of onychomycosis can vary depending on the type of onychomycosis and the patient population 2, 3.
- For toenail onychomycosis, a continuous therapy of 200 mg/day for 3 months has been shown to result in clinical cure, clinical response, and mycologic cure rates of 52%, 86%, and 74%, respectively, at follow-up 12 months after the start of therapy 2.
- Pulse therapy with itraconazole has also been effective in treating toenail onychomycosis, with three pulses of therapy resulting in clinical cure, clinical response, and mycologic cure rates of 58%, 82%, and 77%, respectively, at follow-up 12 months after the start of therapy 2, 3.
- For fingernail onychomycosis, a continuous therapy of 200 mg/day for 6 weeks has been shown to result in clinical cure, clinical response, and mycologic cure rates of 82%, 90%, and 86%, respectively, at follow-up 9 months after the start of therapy 2.
- Pulse therapy with itraconazole has also been effective in treating fingernail onychomycosis, with two pulses of therapy resulting in clinical cure, clinical response, and mycologic cure rates of 78%, 89%, and 87%, respectively, at follow-up 9 months after the start of therapy 2, 3.
- Itraconazole pulse therapy has been shown to be effective and safe in the treatment of onychomycosis in children, with a clinical cure rate of 94% and no reported adverse reactions 4.
Comparison with Other Antifungal Agents
- Itraconazole is a broad-spectrum antifungal agent that is effective against dermatophytes, Candida, and some non-dermatophyte molds 2, 5.
- Terbinafine is another antifungal agent that is commonly used to treat onychomycosis, and has been shown to have high cure rates and a well-established safety record 5.
- Fluconazole is also an antifungal agent that can be used to treat onychomycosis, but its optimal dosing regimen is not well established 6.