A Novel Method Using Micropig Stratum Corneum In Vitro for the Evaluation of Anti- Trichophyton mentagrophytes Activity

Pharmaceutical R&D Laboratories, POLA Chemical Industries, Inc, Yokohama, Kanagawa, Japan.
Microbiology and Immunology (Impact Factor: 1.24). 08/2002; 46(8):521-5. DOI: 10.1111/j.1348-0421.2002.tb02729.x
Source: PubMed


Antifungal susceptibility testing under conditions close to clinical status is expected to provide more helpful information than that obtained by a conventional microdilution method. For this purpose, we developed a novel method to evaluate anti-Trichophyton mentagrophytes activity of antifungal agents in vitro by using disks of micropig stratum corneum epidermis (SCE). Basal agar medium containing K2HPO4, MgSO4, CaCl2 and three kinds of antibiotics. Bifonazole (BFZ), lanoconazole (LCZ) or terbinafine (TBF) was added to the basal agar medium to give serially doubling dilutions ranging from 0.0006 to 10 microg/ml. Five-hundred-microl portions of the agar media thus prepared were solidified in wells of flat-bottomed plates. SCE disks (6 mm in diameter) were placed on surfaces of the agar medium and 10(4) conidia of T. mentagrophytes were inoculated on each SCE disk. There was very good correlation between the initial concentration of the antifungal agents added to the basal agar medium (microg/ml) and the concentration of the agents impregnated into the SCE disks (microg/g) (r2>0.99). The minimum inhibitory concentration (MIC) values of BFZ, LCZ and TBF were respectively 26-, 10- and 78-times higher than those measured by the standard microdilution method. From the correlation between the concentration of the agents in the basal medium and that in the SCE disks, the above MIC values corresponded to the concentrations in SCE disks (microg/g), 832.95 for BFZ, 1.42 for LCZ and 8.87 for TBF. This novel method of antidermatophytic susceptibility testing using SCE would be useful as an in vitro screening of proper antimycotics for topical treatment of dermatophytosis.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Prodigiosins (PGs) are known to be a family of natural red pigments, characterized by a common pyrrolydipyrrolylmethane skeleton structure with a C-4 methoxy group, and some of these pigments have been isolated from some microorganisms. Members of the PG family have been reported to show several biological activities, such as immunosuppressive and cytotoxic activities. Recently, we discovered a bacterial strain (MS-02-063), from our microbial library, that produces large amounts of a PG analogue (PG-L-1). In this study, we examined the anti-Trichophyton activity of PG-L-1 (produced by strain MS-02-063) against clinically isolated Trichophyton spp., by a method using stratum corneum epidermis (SCE) of the Yucatan micropig, which is suitable for estimating the antifungal activity of drugs in vitro. In the National Committee for Clinical Laboratory Standards (NCCLS) method, PG-L-1 showed potent antifungal activity against nine clinically isolated strains of Trichophyton spp., although the minimum inhibitory concentration (MIC) values were slightly higher than those of bifonazole. In spite of the lower efficiency of PG-L-1 transfer into SCE from medium than that of bifonazole, PG-L-1 transferred into SCE showed more potent antifungal activity than bifonazole, at lower concentrations.
    No preview · Article · Jul 2005 · Journal of Infection and Chemotherapy
  • [Show abstract] [Hide abstract]
    ABSTRACT: The stratum corneum (SC) pharmacokinetics of terbinafine following single-dose administration of a novel cutaneous solution (film-forming solution, FFS) containing terbinafine hydrochloride and a film-forming agent, was investigated in three studies. Terbinafine 1% cream (Lamisil) was included as a benchmark in two of these studies. Drugs were applied to areas of the back, and skin strips were taken from defined areas at baseline and from 1 to 312 h after application. Samples were analysed using validated liquid chromatography/mass spectrometry. The residence time of the film on the skin was up to 72 h after application (up to 12 h for the 1% cream). After application of terbinafine FFS, 30% of the total amount of drug delivered into the SC occurred during the first 2 h, 31% from 2-12 h, and 39% thereafter. The C(max) was observed as early as 1.5 h (t(max)). SC levels were still detected after 13 days (24 ng/cm(2)) (t(1/2)) was 162 h). Terbinafine 1% cream showed a similar t(max) (2 h) with a lower C(max) than terbinafine 1% FFS, and mean SC levels after 7 days of treatment were 46 ng/cm(2) (day 13). The t(1/2) was 68 h. Washing at 30 min removed 86% of the film still present on the surface; the decrease of terbinafine concentration in the SC was 84%. A later washing at 12 h removed 73% of the film in comparison to non-washed skin and induced a decrease in the terbinafine content in the SC of 27%. The SC pharmacokinetic profile of terbinafine 1% FFS indicates that this novel formulation is efficient in delivering high amounts of terbinafine to the skin for a prolonged time and supports its use in the treatment of dermatophytoses with a single application.
    No preview · Article · Jul 2007 · Current Medical Research and Opinion
  • [Show abstract] [Hide abstract]
    ABSTRACT: What are efficient screening models for improved topical antifungals? The use of minimum inhibitory concentrations (MICs) as one such parameter is discussed; we focus on the use of animal membranes for in vitro testing while highlighting the pros and cons of each model, exploring alternatives and discussing the importance of data transferability to humans and the influence of penetration kinetics in topical antifungal efficacy. Ultimately, the gold standard of testing is in vivo in humans; however, initiating with human testing, especially for novel topical antifungal agents, may be impractical, which is why we seek the ideal experimental model that most closely mimics human skin. We conclude that the pig may be an appropriate model membrane for topical antifungal testing based on its similarities in anatomical structure, physiology and permeation to human skin. Most importantly, pig and human skins appear equally permeable to several antifungals in prior in vitro and in vivo work. We do not discuss all prior work but highlight important issues in designing the protocol and parameters of the ideal experimental model for topical antifungals.
    No preview · Article · Sep 2009 · Skin pharmacology and physiology