Itraconazole is sometimes used for inflammatory skin diseases such as atopic eczema, seborrhoeic dermatitis or psoriasis, if a fungus or yeast is thought to be contributing to the condition.
Itraconazole has recently been observed to slow the growth of basal cell carcinoma, and is occasionally used for this purpose off-label.[1,2]
How does itracoanzole work?
Itraconazole binds to the fungal p450 enzymes and stops the cells making ergosterol, the main component of the cell wall.
How is itraconazole taken?
In New Zealand, itraconazole is available as 100 mg capsules on prescription and a 10 mg/mL liquid preparation. A generic, Itrazole, is funded under some circumstances. Sporanox™, is the registered trademark for itraconazole preparations, copyright Janssen-Cilag. Sporanox oral liquid is subsidised on Special Authority application for children with immunodeficiency and relevant infections.
The medication is better absorbed orally when it is taken with a fatty meal or acidic drink (eg, orange juice). It is bound to proteins such as albumin in the circulating blood and becomes concentrated in fat cells and within skin and nails. It takes one to three days for half of the medication to be cleared from the blood stream. The rest is eliminated in faeces and urine after conversion by the liver into inactive compounds.
Skin concentrations may be 3–10-fold higher than those in the blood. It may persist in the skin for up to 4 weeks after the drug has been discontinued and in the nails for up to a year.
Dose regime for itraconazole
Various regimes for itraconazole have been found successful; typical doses are listed below. Courses can be repeated and the medication can be continued for months if necessary.
Tinea unguium: 200 mg/day for 6-8 weeks (fingernails) or 3-4 months (toenails), OR 200 mg twice daily for 7 days, repeated monthly for 2 months (fingernails) or 3–4 months (toenails)
Pityriasis versicolor: 200 mg/day for 10 days, with a preventative dose of 200mg once monthly for 6 months.
The dose of itraconazole in children is usually 5 mg per kg body weight per day to maximum 200 mg per day, but is reserved for exceptional circumstances.
Side effects of itraconazole
Itraconazole appears to be a relatively safe drug. Side effects, usually minor, are more likely during a prolonged course of treatment.
Nausea and vomiting (5%)
Constipation
Headache
Dizziness
Abnormal liver function tests (up to 5% for those on long term therapy, 2% for pulse therapy); significant liver disease is rare
Endocrine effects including enlarged breasts (in males) and adrenal suppression
Tingling in the fingers and toes (very rare)
Congestive heart failure: itraconazole should be used with caution in those with heart problems.
Itraconazole is best avoided in pregnancy. Although only excreted in tiny amounts from breast milk, it should only be taken by a breast-feeding mother if essential.
Drug interactions with itraconazole
Itraconazole has important interactions with other medications.
As itraconazole needs acid for its absorption, antacids, H2 antagonists (cimetidine, famotidine, ranitidine) and omeprazole should not be taken for 2 hours after itraconazole.
Itraconazole is a P-glycoproteininhibitor and increases the concentration of some drugs.
These drugs should not be taken by those on itraconazole:
HMG Co-A reductase inhibitors (atorvastatin, lovastatin, simvastatin); fluvastatin, rosuvastatin and pravastatin are acceptable alternatives. Toxicity due to the combination of drugs results in muscle pain and weakness, which may be serious.
Cisapride
Midazolam, triazolam
The antihistamines astemizole (Hismanal®) and terfenadine (Teldane®); these are no longer available in New Zealand.
Itraconazole may increase the risk of bleeding from anticoagulants such as warfarin or dabigatran.
In recent years, both topical and oral allylamine and triazole antifungal drug resistance has become a problem, particularly in the Indian subcontinent.
Extensive therapy-resistant dermatophyte infection should prompt this as a possible problem. Where available, fungal culture and estimation of drug minimum inhibitory concentration determined to guide appropriate medication.
Approved datasheets are the official source of information for medicines, including approved uses, doses, and safety information. Check the individual datasheet in your country for information about medicines.
Kim DJ, Kim J, Spaunhurst K, Montoya J, Khodosh R, Chandra K, Fu T, Gilliam A, Molgo M, Beachy PA, Tang JY. Open-label, exploratory phase II trial of oral itraconazole for the treatment of basal cell carcinoma. J Clin Oncol. 2014 Mar 10;32(8):745–51. doi: 10.1200/JCO.2013.49.9525. PubMed
Kim J, Tang JY, Gong R, Kim J, Lee JJ, Clemons KV, Chong CR, Chang KS, Fereshteh M, Gardner D, Reya T, Liu JO, Epstein EH, Stevens DA, Beachy PA. Itraconazole, a commonly used antifungal that inhibits Hedgehog pathway activity and cancer growth. Cancer Cell. 2010 Apr 13;17(4):388–99. doi: 10.1016/j.ccr.2010.02.027. PubMed