What are the dosing and therapy guidelines for itraconazole (antifungal medication) in the treatment of onychomycosis (fungal infection of the nails)?

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 two pulses for fingernails and three pulses for toenails, as recommended by the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1. The treatment regimen for itraconazole can vary depending on the type of onychomycosis and the patient's overall health.

• Key considerations for itraconazole therapy include:
  • Taking the medication with food to enhance absorption, and considering acidic beverages like cola or orange juice to further improve bioavailability.
  • Monitoring liver function tests, especially in patients with pre-existing liver conditions or those receiving continuous therapy for more than a month.
  • Being aware of potential drug interactions, as itraconazole is metabolized through the CYP3A4 pathway. The British Association of Dermatologists' guidelines 1 provide a comprehensive overview of the treatment options for onychomycosis, including itraconazole, and emphasize the importance of careful patient selection and monitoring to minimize adverse effects.
• Common adverse reactions to itraconazole include headache and gastrointestinal upset, and patients should be informed of these potential side effects before starting treatment. Overall, itraconazole remains a viable treatment option for onychomycosis, particularly for patients who are unable to tolerate other medications or have specific contraindications.

From the Research

Itraconazole Dosing and Therapy Guidelines for Onychomycosis

• The preferred regimen for itraconazole in the treatment of dermatophyte onychomycosis is pulse therapy, with the drug being administered for 1 week with 3 weeks off treatment between successive pulses 2.
• The specific dosing regimen for itraconazole in the treatment of dermatophyte onychomycosis is 200mg twice daily for 1 week per month for 3 pulses 2.
• Itraconazole is effective against Candida onychomycosis, and the pulse therapy regimen is also effective for this type of infection 2, 3.
• The pharmacokinetics of itraconazole in the nail results in drug remaining at therapeutic levels for 6-9 months after completion of therapy 3.
• Both continuous and pulse therapy regimens of itraconazole are safe and effective, with few adverse effects, and the pulse regimen has an improved adverse-effects profile and is more cost-effective 3.

Efficacy of Itraconazole in Onychomycosis Treatment

• Clinical cure rates for itraconazole in the treatment of toenail onychomycosis have been reported to be around 52-58% at follow-up 12 months after the start of therapy 2, 3.
• Mycologic cure rates for itraconazole in the treatment of toenail onychomycosis have been reported to be around 74-77% at follow-up 12 months after the start of therapy 2, 3.
• Itraconazole has been shown to be effective in the treatment of fingernail onychomycosis, with clinical cure rates of around 82% at follow-up 9 months after the start of therapy 3.

Comparison with Other Antifungal Agents

• Itraconazole has been compared to other antifungal agents, such as terbinafine and fluconazole, in the treatment of onychomycosis, and has been shown to be effective and safe 2, 4.
• Terbinafine has been reported to be more effective than itraconazole in some studies, with clinical cure rates of around 81% at follow-up 6 months after the start of therapy 4.
• Fluconazole has been reported to be less effective than itraconazole and terbinafine in the treatment of onychomycosis, with clinical cure rates of around 37% at follow-up 6 months after the start of therapy 4.