Terbinafine, an allylamine derivative, represents the most effective of this new chemical class of antimycotic compounds. Under in vitro conditions, terbinafine proved to be highly active against dermatophytes (MIC range, 0.001 to 0.01 ,ug/ml), aspergilli (MIC range, 0.05 to 1.56 tig/ml), and Sporothrix schenckii (MIC range, 0.1 to 0.4 ,ug/ml) and also exerted good activity against yeasts (MIC range, 0.1 to >100 ,ig/ml). The growth of Malasseziafurfur was inhibited also (MIC range, 0.2 to 0.8 ,ig/ml). Terbinafine displays a primary fungicidal action against dermatophytes, other filamentous fungi, and S. schenckii. The type of action against yeasts is species dependent and can be primarily fungicidal (Candida parapsilosis) or fungistatic (Candida albicans). The in vitro activity of terbinafine is pH dependent and rises with increasing pH value.The discovery of the antifungal activity of naftifine (Exoderil), which has been shown in vitro and in vivo against a variety of medically important species of fungi (3, 6), led to intensive chemical and biological investigations of the structure-activity relationships of allylamine derivatives at the Sandoz Forschungsinstitut, Vienna, Austria (12,13). The antifungal activities of these compounds are based on the inhibition of fungal ergosterol biosynthesis at the point of squalene epoxidation (5,(8)(9)(10).The most active derivative of this new chemical class of antimycotics found so far is terbinafine (7, 14; G. Petranyi, J. G. Meingassner, and H. Mieth, 9th Int. Congr. Int. Soc. Hum. Anim. Mycol. (ISHAM), abstr. no. P1-27, 1985). In this report we describe the antifungal activity of this compound in vitro.(These data were presented in part at the 13th Interna- 5%, which were then stored as 1.5-ml portions in liquid nitrogen (2). The CFU of the stock cultures were determined after freezing. Appropriate dilutions were made with saline or broth before use.Malassezia strains were cultivated at 37°C in broth media by the method of Weary and Graham (15) by serial transfers.Assessment of antifungal activity. Serial dilution tests were used to determine the MICs of the test compounds for dermatophytes, molds, biphasic fungi, and yeasts. The MIC for Malassezia strains was evaluated by an agar dilution test. Activity against dermatophytes was assessed by an agar diffusion test also. Since it was found in radiolabeling studies that terbinafine tends to stick to plasticware, the assays were performed in glass.Serial dilution test. The MIC for filamentous fungi was determined in Sabouraud dextrose 2% broth (initial pH, 6.5). Malt extract broth (initial pH, 6.5; E. Merck) was used for yeasts.Glass tubes (16 by 160 mm) were filled with 0
The allylamine derivative terbinafine is the first antifungal agent with primary fungicidal properties against dermatophytes which acts systemically after oral application as well as locally after topical application. Comparative oral studies carried out with griseofulvin and ketoconazole in model infections such as guinea pig trichophytosis and microsporosis revealed terbinafine to be superior to the reference compounds both clinically and mycologically. An excellent antimycotic activity of terbinafine was also demonstrable after topical treatment of guinea pig dermatophytoses caused by Trichophyton mentagrophytes or Microsporum canis. Results of comparative chemotherapeutic studies carried out with econazole and tolnaftate demonstrated superior efficacy of terbinafine in the treatment of both trichophytosis and microsporosis. Skin infections of guinea pigs caused by Candida albicans and vaginal candidiasis in rats proved to be responsive to a topical application of terbinafine also. However, the reference compounds, clotrimazole and miconazole, exhibited activity superior to that of terbinafine in both models.
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Tritrichomonas foetus KV 1 , a nitroimidazole-susceptible strain, and KV 1 /M100, its nitroimidazole-resistant daughter strain, differed markedly in their in vivo susceptibility to metronidazole. In vitro susceptibility testing in multiwell plates and tubes with different trichomonad media containing no, or low concentrations of, ascorbate demonstrated that the resistant strain behaves like the susceptible one, if tested under anaerobic conditions (deep cultures in tubes or multiwell plates in anaerobic jars), but shows resistance if tested in the presence of air (multiwell plates exposed to air). In media containing high concentrations of ascorbate, no resistance was observed even in air. The results suggest that the two strains differ in the regulation of internal redox systems and underscore the role testing methods may play in the in vitro detection of nitroimidazole-resistant protozoan parasites.
Naftifine exhibits an interesting in vitro spectrum of activity against dermatophytes (38 strains; minimal inhibitory concentration [MIC] range, 0.1 to 0.2 ,ug/ ml), aspergilli (6 strains; MIC range, 0.8 to 12.5 jig/ml), Sporothrix schenckii (2 strains; MICs, 0.8 and 1.5 ,ug/ml), and yeasts of the genus Candida (77 strains; MIC range, 1.5 to >100 ,ug/ml). Its degree of efficacy is unaffected by the organism density in the test medium, and it is primarily fungicidal against dermatophytes as well as yeasts. Its in vitro efficacy is pH dependent and rises with increasing pH values.
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