Regulatory utility of pharmacometrics in the development and evaluation of antimicrobial agents and its recent progress in China

Pharmacometrics is an emerging science that interprets drug, disease, and trial information in a mathematical fashion to inform and facilitate efficient drug development and/or regulatory decisions. Pharmacometrics study is increasingly adopted in the regulatory review of new antimicrobial agents. We summarized the 31 antimicrobial agents approved by the US Food and Drug Administration (FDA) and the 26 antimicrobial agents approved by European Medicines Agency (EMA) from January 2001 to May 2019. We also reviewed recent examples of utilizing pharmacometrics to support antimicrobial agent's registration in China, including modeling and simulation methods, effects of internal/external factors on pharmacokinetic (PK) parameters, safety and efficacy evaluation in terms of exposure-response analysis, refinement of the wording of product labeling and package leaflet, and possible postmarketing clinical trial. Ongoing communication among regulator, academia, and industry regarding pharmacometrics is encouraged to streamline and facilitate the development of new antimicrobial agents. The industry can maximize its benefit in drug development through continued pharmacometrics education/training.

In vitro antifungal susceptibility patterns of Trichophyton benhamiae complex isolates from diverse origin

BACKGROUND

Species from the Trichophyton benhamiae complex are mostly zoophilic dermatophytes which cause inflammatory dermatophytosis in animals and humans worldwide.

OBJECTIVES

This study was purposed to (a) to identify 169 reference and clinical dermatophyte strains from the T benhamiae complex species by molecular method and adhering to the newest taxonomy in the complex (b) to evaluate the in vitro antifungal susceptibility profile of these strains against eight common and new antifungal agents that may be used for the treatment of dermatophytosis.

METHODS

All isolates, mainly originated from Europe but also from Iran, Japan and USA, were subjected to ITS-rDNA sequencing. The in vitro antifungal susceptibility profiles of eight common and new antifungal drugs against the isolates were determined by CLSI M38-A2 protocol and according to microdilution method.

RESULTS

Based on the ITS-rDNA sequencing, T benhamiae was the dominant species (n = 102), followed by T europaeum (n = 29), T erinacei (n = 23), T japonicum (n = 10), Trichophyton sp (n = 4) and T eriotrephon (n = 1). MIC ranges across all isolates were as follows: luliconazole: 0.0002-0.002 µg/ml, terbinafine: 0.008-0.125 µg/ml, efinaconazole: 0.008-0.125 µg/ml, ciclopirox olamine: 0.03-0.5 µg/ml, itraconazole: 0.06-2 µg/ml, griseofulvin: 0.25-4 µg/ml, amorolfine hydrochloride: 0.125-4 µg/ml and tavaborole: 1-16 µg/ml.

CONCLUSION

Luliconazole, efinaconazole and terbinafine were the most potent antifungals against T benhamiae complex isolates, regardless of the geographic locations where strains were isolated. These data might help dermatologists to develop effective therapies for successful treatment of infections due to T benhamiae complex species.

Design and evaluation of microemulsion-based efinaconazole formulations for targeted treatment of onychomycosis through transungual route: Ex vivo and nail clipping studies

The onychomycosis treatment remains a big challenge for onychologist due to the shorter nail residence time of topical formulations and the lack of availability of novel formulations in markets for new generation antifungal drugs. The objective of this work was to design, develop, optimize, and evaluate microemulsion formulations for effective delivery of efinaconazole through transungual route in onychomycosis treatment. Capmul® MCM (Glyceryl Caprylate/Caprate) as oil, Labrasol® (caprylocaproyl polyoxyl-8 glycerides) as a surfactant, and Transcutol® P (diethylene glycol monoethyl ether) as co-surfactant exhibited higher solubility of efinaconazole and surfactant-cosurfactant mixture (Smix) in a ratio of 1:1 rendered higher microemulsion region in the pseudo-ternary phase diagram. The optimized microemulsion formulation containing 6%w/w oil phase, 22.5%w/w surfactant, 22.5%w/w co-surfactant, and 49%w/w demineralized water was converted into gel formulation using 1.0%w/w Carbopol® 934 P gelling agent and evaluated for stability of 6 months. The optimized microemulsion formulation globule size was less than 100 nm. The ex vivo permeation confirmed improved permeation of efinaconazole from microemulsion formulations (346.36±12.90μgcm^-2) in comparison to reference formulation without observing any lag in drug permeation through the nail plate. The in vitro antifungal study data indicated increased antifungal efficacy relative to efinaconazole topical solution against Trichophyton rubrum, Trichophyton mentagrophytes, and Candida albicans species. Further, an in vitro cell cytotoxicity study exhibited no toxic effect for any excipients used in the formulation while applied on nail cells. Hence, the efinaconazole loaded microemulsion formulations could be considered as an effective therapy in the treatment of onychomycosis.

Onychomycosis in children - review on treatment and management strategies

BACKGROUND

Onychomycosis is an uncommon condition in children with increasing global prevalence. Health practitioners should confirm the diagnosis through mycology examination and examine family members of affected individuals for onychomycosis and tinea pedis.

OBJECTIVE

To comprehensively summarize the treatment and management strategies for pediatric onychomycosis.

METHODS

We performed a comprehensive literature search in the PubMed database to identify clinical studies on treatment for mycologically-confirmed dermatophyte onychomycosis in children <18 years. The exclusion criteria were combination therapy, case reports, reviews, systematic reviews and duplicate studies.

RESULTS

Per-weight dosing regimens of systemic antifungal agents such as terbinafine, itraconazole, and fluconazole are found to be safe in children and are used off-label for the treatment of pediatric onychomycosis with high efficacy. Topical antifungal agents such as ciclopirox, efinaconazole, and tavaborole have established safety and efficacy in children. Children respond better than adults to topical therapy due to their thinner, faster growing nails. There is no data on the efficacy of medical devices for onychomycosis in children.

CONCLUSION

Efinaconazole topical solution 10% and tavaborole topical solution 5% are FDA approved for the treatment of onychomycosis in children ≥6 years; ciclopirox topical solution 8% nail lacquer is approved in children ≥12 years.

In Vitro Activities of Luliconazole, Lanoconazole, and Efinaconazole Compared with Those of Five Antifungal Drugs against Melanized Fungi and Relatives

The in vitro activities of novel azoles compared to those of five antifungal drugs against clinical (n = 28) and environmental (n = 102) isolates of black mold and melanized yeast were determined. Luliconazole and lanoconazole had the lowest geometric mean MICs, followed by efinaconazole, against tested isolates compared to the other drugs. Therefore, it appears that these new imidazole and triazole drugs are promising candidates for the treatment of infections due to melanized fungi and their relatives.

An Assessment of In Vitro Antifungal Activities of Efinaconazole and Itraconazole against Common Non-Dermatophyte Fungi Causing Onychomycosis

Onychomycosis is a fungal nail infection which is relatively common and difficult to treat. Treatment modalities include nail avulsion, surgical debridement and combination therapy with oral and topical antifungal drugs. In spite of a host of available drugs, clinical cure rates remain discouraging. Drug toxicities, prolonged regimens, lack of patient compliance, and high keratin affinity of drugs are all contributive factors. Efinaconazole is a novel topical triazole antifungal agent that has shown excellent in vitro activity against both dermatophyte and non-dermatophyte fungi causing onychomycosis. This study presents the in vitro susceptibility profiles of 44 common non-dermatophyte fungi against efinaconazole and itraconazole, another azole drug used in the treatment of onychomycosis.

Tavaborole, Efinaconazole, and Luliconazole: Three New Antimycotic Agents for the Treatment of Dermatophytic Fungi

Fungal diseases of the nail bed (onychomycosis) and epidermis are recurrent illnesses in the elderly and immunocompromised patients, which have few efficacious treatment options. Current treatment options for onychomycosis are limited to topical agents, laser treatment, and oral antifungals. Previous generations of topical agents were not efficacious, owing to poor penetration of the nail bed. Oral antifungal drugs, such as itraconazole, terbinafine, and fluconazole, not only give better response rates but also inhibit a host of CYP450 enzymes. Oral antifungals can exacerbate drug–drug interactions for patients taking other medications concurrently. Newer topical agents might recognize improved efficacy and provide therapeutic alternatives when the use of oral antifungal agents is contraindicated. Recently, the Food and Drug Administration (FDA) approved efinaconazole and tavaborole for the treatment of onychomycosis. Additionally, the FDA approved luliconazole for the treatment of tinea pedis, tinea cruris, and tinea corporis. This review examines the mechanism of action, spectrum of activity, pharmacokinetics, and clinical trials data and considers the place in therapy for these 3 new antimycotic agents.