Contact dermatitis from topical imidazole antifungals: 15 new cases

Recent drug development and treatments for fungal infections

Fungal infections are now becoming a hazard to individuals which has paved the way for research to expand the therapeutic options available. Recent advances in drug design and compound screening have also increased the pace of the development of antifungal drugs. Although several novel potential molecules are reported, those discoveries have yet to be translated from bench to bedside. Polyenes, azoles, echinocandins, and flucytosine are among the few antifungal agents that are available for the treatment of fungal infections, but such conventional therapies show certain limitations like toxicity, drug interactions, and the development of resistance which limits the utility of existing antifungals, contributing to significant mortality and morbidity. This review article focuses on the existing therapies, the challenges associated with them, and the development of new therapies, including the ongoing and recent clinical trials, for the treatment of fungal infections. Advancements in antifungal treatment: a graphical overview of drug development, adverse effects, and future prospects.

Contact dermatitis to a canine anti-dandruff shampoo

A 40-year-old teacher presented after her third episode of acute facial oedema within 4 months. Each episode occurred 1-2 days after visiting her mother's house. Patch testing showed positive reactions to miconazole and econazole nitrate. The patient denied use of any antifungal creams, but it transpired that her mother's dog was being shampooed weekly with an antifungal shampoo containing miconazole. No further episodes were recorded after discontinuing the antifungal shampoo.

A study of 72 patients with contact allergy to tioconazole

Over a 3 1/2 year period, from 1991 to 1994, we detected contact allergy to tioconazole in 72 patients by epicutaneous testing. During this period, tioconazole was included in the standard series of epicutaneous tests. Except for the first 6 months, the incidence of positive patch test reactions to tioconazole was over 1% of patients tested for contact allergy. As well as those tested with the standard series, 18 additional patients with tioconazole allergy were detected by direct testing with an imidazole patch test series. Of the various imidazole derivatives, tioconazole was the most important contact allergen. About half of patients with contact hypersensitivity to tioconazole, had additional contact allergies detected by the standard series. Men and women were equally affected. The present study suggests that tioconazole is an important contact allergen, which should be included into the patch test series in countries where it is used as a topical antifungal agent.

Evaluation of patch testing in patients with chronic vulvar symptoms

The Dermogynaecology Clinic was established at the Mercy Hospital for Women in 1989. Since its inception, 700 patients have been investigated and 15% were clinically diagnosed as having contact dermatitis. Primary irritant dermatitis was regarded as the common cause but to investigate the place of contact allergy 50 patients were patch tested to a standard battery, medicaments, preservatives, corticosteroids and miscellaneous allergens. Twenty-one patients (42%) had a total of 44 positive tests. The most common positive reactions were to nickel (22%), cobalt (6%), fragrances (12%), caine mix (6%) and ethylenediamine (8%). Medicaments and fragrances were regarded as important allergens. Corticosteroid and imidazole allergy was not a problem in this series of patients.

Contact allergy to imidazoles used as antimycotic agents

The present article reviews the literature (up to 1994) on contact sensitivity to imidazoles and presents the results obtained from 15 patients observed at the Contact Allergy Unit in Leuven. The frequency as well as the cross-reaction patterns described are analyzed. Although allergic contact reactions may have been missed in the past (mainly because of problems with the correct choice of vehicle for patch testing), they seem to be relatively infrequent in view of their widespread use. The imidazole derivatives most frequently reported to be allergens are miconazole, econazole, tioconazole, and isoconazole. As far as cross-reactivity is concerned, statistically significant associations were found in the patient data between miconazole, econazole, and isoconazole; between sulconazole, miconazole, and econazole; and also between isoconazole and tioconazole. Patients sensitive to phenylethyl imidazoles (except ketoconazole) needing antimycotic therapy should be advised to use ketoconazole, clotrimazole, bifonazole, or, perhaps, the new flutrimazole. Clearly, non-imidazole antifungals can also be used.

Contact allergy to tioconazole

In 15 months, we detected allergic patch test reactions to tioconazole in 14 patients. 9 of the 14 patients were allergic to additional imidazole derivatives used as antifungal agents. The positive patch test reactions to tioconazole may have been caused either by simultaneous sensitization or more probably by cross-reactivity between the various commercially used imidazole derivatives with a similar chemical structure. The abundant use of tioconazole in concentrated (up to 28%) topical formulations in Finland could be the major cause of the apparent increase in allergic reactions.

Experimental study of the potential for contact sensitization and cross-reaction of imidazole antifungals

We examined the potential for contact sensitization of miconazole nitrate and croconazole hydrochloride and the cross-reaction between them in guinea pigs by the maximization test of Magnusson and Kligman. Contact sensitivity was induced by croconazole hydrochloride in 5 out of 7 animals which, after being injected with 5% croconazole hydrochloride, underwent a closed patch with 25% croconazole hydrochloride. Contact sensitivity was not induced by miconazole nitrate. The 5 animals sensitized to croconazole hydrochloride were tested with 8 other imidazole antifungals and positive reactions were observed to oxiconazole nitrate in 2 of the 5 animals. This response may be a cross-reaction.

Contact sensitivity to miconazole with ortho-chloro cross-sensitivity to other imidazoles

A case of allergic contact dermatitis from miconazole is reported. Patch testing with a series of azole antimycotics was positive only to miconazole, isoconazole, tioconazole and oxiconazole. Those reacting are all beta-substituted 1-phenethyl imidazoles with an ortho-chlorine substitution on the aromatic ring. For this hitherto unreported pattern of cross-sensitivity, the designation of "ortho-chloro cross-sensitivity" is proposed.