Contact allergy to tioconazole

Antifungal hypersensitivity reactions and cross-reactivity patterns

PURPOSE OF REVIEW

The goal of this article is to provide an updated understanding and evidence-based approach where possible for antifungal hypersensitivity. This includes recognition of clinical phenotype, implications for cross-reactivity and diagnostic, and management strategy for immediate and delayed hypersensitivity reactions.

RECENT FINDINGS

Antifungal hypersensitivity reactions can be classified according to their latency (immediate or delayed) and clinical phenotype. The majority of the cases described in the literature are delayed T-cell mediated reactions of various severities but immediate reactions consistent with non-Immunoglobulin E (IgE)-mediated mast cell activation and IgE-mediated reactions have also been described. Ancillary information such as skin testing, drug challenge and ex vivo experimental approaches can aid causality assessments and inform antifungal class cross-reactivity, which help optimize antifungal prescribing and stewardship.

SUMMARY

This review will update the clinician on mechanisms of drug hypersensitivity as well as providing a structured approach to the recognition, diagnosis and management of antifungal hypersensitivity reaction.

An innovative polysaccharide nanobased nail formulation for improvement of onychomycosis treatment

Tioconazole-loaded nanocapsule suspensions and its coating with a cationic polymer were developed for nail drug delivery. The colloidal systems presented a nanometric size around 155nm for uncoated nanoparticles and 162nm for those with the cationic coating, with negative and positive zeta potential values, respectively. Both nanosuspensions showed drug content close to theoretical values (1mgmL^-1), association efficiency close to 100% (HPLC) and were able to control tioconazol release. The developed formulations showed in vitro antifungal activity (agar diffusion method) against C. albicans. The cationic nanocapsules were considered bioadhesive, showed higher viscosity and were chosen to be incorporated into an ungueal formulation. Pullulan nanobased nail formulation showed adequate viscosity for nail application and drug content close to the theoretical values. It was equivalent to the commercial formulation Trosid^® in preventing nail infection by T. rubrum in an in vitro onychomycosis model. The nanocapsule suspensions and Pullulan nanobased nail formulation showed lower irritant potential than the commercial formulation and than free drug in an in vitro evaluation. Pullulan nanobased nail formulation is promising for the treatment of onychomycosis.

Spray-dried powders improve the controlled release of antifungal tioconazole-loaded polymeric nanocapsules compared to with lyophilized products

This work aimed to obtain solid formulations from polymeric nanocapsules and nanoemulsions containing tioconazole, a broad spectrum antifungal drug. Two dehydration methods were used: spray-drying and freeze drying, using lactose as adjuvant (10%, w/v). The liquid formulations had a mean particle size around 206 nm and 182 nm for nanocapsules and nanoemulsions, respectively, and an adequate polydispersity index. Tioconazole content was close to the theoretical amount (1.0 mg/mL). After drying, the content ranged between 98 and 102%with a mean nanometric size of the dried products after redispersion. Scanning electron microscopy showed that the particles are rounded, sphere-shaped for the dried products obtained by spray-drying, and shapeless and irregular shapes for those obtained by freeze-drying. In the microbiological evaluation, all dried products remained active against the yeast Candida albicans when compared to the original systems. The dried products obtained by spray-drying from nanocapsules presented better control of the tioconazole release when compared to the freeze-drying products.

[Antifungal agents for onychomycoses]

Nail fungal infections are considered one of the major dermatological problems due to their high rate of therapeutic failure, management and treatment difficulties. Long-term treatments, inadequate therapies, mycological misdiagnosis and follow-up, secondary alterations of the nail, and resistant microorganisms, are some of the causes of these complications. Although the discovery of new antifungal agents has provided some effective molecules, none of the current available drugs are totally effective. It is important to continue researching in this field to provide new antifungal agents and combined therapies.

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.

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.