The use of antifungals in birds is characterized by interspecies and interindividual variability in the pharmacokinetics, affecting drug safety and efficacy. Oral antifungal drug absorption is a complex process affected by drug formulation characteristics, gastrointestinal anatomy, and physiology. New antifungal drug delivery systems can enhance drug stability, reduce off-target side effects, prolong residence time in the blood, and improve efficacy. Topical administration of antifungals through nebulization shows promising results. However, therapeutic output is highly influenced by drug formulation and type of nebulizer, indicating these factors should be taken into account when selecting this medication route.

Introduction Antifungal agents can be co-administered alongside several other medications for a variety of reasons such as the presence of comorbidities. Pharmacodynamic interactions such as synergistic and antagonistic interactions could be the result of co-administered medications. Pharmacokinetic interactions could also transpire through the inhibition of metabolizing enzymes and drug transport systems, altering the absorption, metabolism and excretion of co-administered medications. Both pharmacodynamic and pharmacokinetic interactions can result in hospitalization due to serious adverse effects associated with antifungal agents, lower therapeutic doses required to achieve desired antifungal activity, and prevent antifungal resistance. Areas covered The objective of this review is to summarize pharmacodynamic and pharmacokinetic interactions associated with common antifungal agents used to treat superficial fungal infections. Pharmacodynamic and pharmacokinetic interactions that impact the therapeutic effects of antifungal agents and drugs that are influenced by the presence of antifungal agents was the context to which these antifungal agents were addressed. Expert Opinion The potential for drug-drug interactions is minimal for topical antifungals as opposed to oral antifungals as they have minimal exposure to other co-administered medications. Developing non-lipophilic antifungals that have unique metabolizing pathways and are topical applied are suggested properties that could help limit drug-drug interactions associated with future treatments.

A 70-year-old patient who underwent uneventful primary implantation of Auro K Pro (a Type I Boston Keratoprosthesis-based device), developed infiltrates in the deep stroma of the carrier corneal graft and exudates on the optic stem of the keratoprosthesis assembly, 6 weeks postoperatively, which subsequently progressed to endophthalmitis. Vitreous tap was positive for a panfungal polymerase chain reaction, although corneal scrapings for both Gram stain and KOH wet mount yielded negative results. Aggressive management with systemic, topical, intravitreal, and intrastromal antifungal agents resulted in an initial resolution, but residual inflammatory vitreous membranes persisted. The patient was then lost to follow-up and presented 3 months later with a total, inoperable retinal detachment. Fungal infections after keratoprosthesis implantation remain a significant concern and may be associated with poor outcomes in the developing countries due to interplay of environmental and socioeconomic factors. Management protocols may need to be modified in accordance with the prevailing conditions in these regions.

Dermatophytoma is a little-known, difficult to treat fungal infection that complicates onychomycosis. First described by Roberts and Evans in the late 1990's, dermatophytoma presents as a dense concentration of fungal hyphae within or under the nail plate and is generally white or yellow/brown in color, and linear (streaks) or round (patches) in shape; primary etiologic organisms are dermatophytes. Oral antifungals have limited success in treating dermatophytoma owing to difficulties accessing and penetrating what is hypothesized to be a fungal biofilm. In this respect, dermatophytoma is generally treated with a combination therapy approach, often including both surgical and pharmacologic intervention for improved outcomes. A post-hoc assessment of Phase II tavaborole onychomycosis studies was conducted in order to assess the prevalence of dermatophytoma and outcomes in patients treated with topical tavaborole. Of the 366 subjects enrolled in the Phase II onychomycosis studies, we identified 102 cases of dermatophytoma; 21 of 86 (24.4%) subjects treated with tavaborole were able to achieve complete resolution of dermatophytoma by day 180, while no subjects on vehicle obtained resolution. Similarly, 23 of 86 subjects (26.7%) treated with tavaborole solution had complete resolution of dermatophytoma by day 360, while only 1 of 16 subjects (6.3%) on vehicle obtained resolution. Moreover, 13 of 19 subjects (68.4%) treated with tavaborole solution were able to sustain resolution, while only 6 of 19 (31.6%) had reoccurrence, of dermatophytoma during the 180-day washout period (day 360). We present 5 cases of dermatophytoma identified in Phase II trials that responded in a positive manner following treatment with tavaborole solution for onychomycosis of the great toenail. Although not representative of all subject outcomes, these findings provide insight into the use of topical tavaborole for dermatophytoma, a condition previously thought to respond only to oral or combination therapy. <p><em>J Drugs Dermatol. 2018;17(3):347-354.</em></p>.

A collection of clinical (n=47) and environmental (n=79) Fusarium isolates were tested against 10 antifungal drugs, including two novel imidazoles. Luliconazole and lanoconazole demonstrated very low GM MIC values of 0.005 μg/ml and 0.013 μg/ml, respectively, in comparison with 0.51 μg/ml for micafungin, 0.85 μg/ml for efinaconazole, 1.12 μg/ml for natamycin, 1.18 μg/ml for anidulafungin, 1.31 μg/ml for voriconazole, 1.35 μg/ml for caspofungin, 1.9 μg/ml for amphotericin B and 4.08 μg/ml for itraconazole. Results show that these drugs are potential candidates for (topical) treatment of skin and nail infections due to Fusarium species.

An adult male Amazonian manatee Trichechus inunguis under human care presented with 3 circular cutaneous lesions on the dorsal aspect of the rostrum and between the nostrils (plenum). Initially these lesions were superficial, hypopigmented, without warmth and non-painful. Microbiological cultures of skin swabs isolated Candida sp. and Pseudomonas aeruginosa, and topical treatment with antiseptic, antifungal, anti-inflammatory and antibiotic medication was instituted. This treatment strategy did not lead to any clinical improvement, and after 6 mo, the lesions progressed to a confluent abscess (5.0 × 3.0 cm) with increased temperature and obvious discomfort on palpation. An impression smear of a cutaneous biopsy was submitted for Ziehl-Neelsen staining and after detection of acid-fast bacilli, the cutaneous biopsy and a swab from the lesion were sent for histopathology, culture and sensitivity testing. After 5 d of incubation and through PCR-restriction analysis of the isolates, Mycobacterium fortuitum and M. abscessus were identified. Sensitivity testing indicated that the isolates were susceptible to ciprofloxacin and clarithromycin, and after draining of the lesion and administration of systemic antibiotic treatment, there was rapid clinical improvement. This report describes non-healing lesions in an aquatic animal and illustrates the importance of evaluating the presence of non-tuberculous mycobacteria, opportunistic pathogens which are ubiquitous in the aquatic environment, in protracted, non-responsive cases. We also highlight the importance of a correct diagnosis and treatment approach, and we review concerns that these bacteria are zoonotic agents and are frequently resistant to conventional antibiotics.