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Pharmacokinetics of fluconazole in skin and nails.

Faergemann J.

Department of Dermatology, Sahlgrenska University Hospital, Gothenburg, Sweden.

Two studies on the pharmacokinetics of fluconazole in skin and nails are reported here. In 1 study, 12 healthy volunteers received fluconazole 50 mg once daily for 12 days and 11 healthy volunteers received fluconazole 150 mg once weekly for 2 weeks. Fluconazole assays were performed on samples of serum, stratum corneum, dermis-epidermis, and eccrine sweat. In a second study, 36 patients with toenail onychomycosis received either fluconazole 150 mg once weekly or griseofulvin 1000 mg once daily for 12 months. Fluconazole assays were performed on nail clippings and serum samples from the patients receiving fluconazole. Tissue concentrations of fluconazole regularly exceeded plasma concentrations in these studies. In the skin study, the highest concentrations were achieved in stratum corneum, with accumulation occurring up to the end of dosing. Subjects who received 50 mg once daily had higher levels of fluconazole in stratum corneum, sweat, and epidermis-dermis than those subjects who received 150 mg once weekly. In the toenail study, fluconazole concentrations increased for the first 6 months, reaching levels much higher than serum concentrations (P < .001), with no significant difference between healthy and diseased nails.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10367911&dopt=Abstract fluconazole Diflucan



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National surveillance of species distribution in blood isolates of Candida species in Japan and their susceptibility to six antifungal agents including voriconazole and micafungin.

Takakura S, Fujihara N, Saito T, Kudo T, Iinuma Y, Ichiyama S.

Department of Clinical Laboratory Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 6068507, Japan. stakakr kuhp.kyoto-u.ac.jp

OBJECTIVES: The aim of this study was to evaluate species distribution and antifungal susceptibility of Candida blood isolates in Japan. METHODS: In a 1 year surveillance programme, 535 Candida blood isolates were collected. Identification of species was followed by examination with the broth microdilution method, as described in NCCLS M27-A2, of antifungal susceptibility to six agents, including voriconazole and micafungin, with readings after 24 and 48 h of incubation. RESULTS: The overall species distribution was: 41% Candida albicans, 23% Candida parapsilosis, 18% Candida glabrata, 12% Candida tropicalis and 2% Candida krusei. The concentrations of fluconazole necessary to inhibit 90% of the isolates (MIC(90)) at 24/48 h were 0.25/1 mg/L for C. albicans, 0.5/2 mg/L for C. parapsilosis, 4/32 mg/L for C. glabrata and 4/>128 mg/L for C. tropicalis. Percentages of fluconazole resistance were 1.8% for C. albicans, 0.8% for C. parapsilosis, 5.2% for C. glabrata and 3.2% for C. tropicalis, taking the tendency of trailing growth of C. tropicalis into account. MIC(90) of voriconazole was 0.5 mg/L, although 35% of isolates less susceptible (>/=16 mg/L) to fluconazole showed resistance (>/=2 mg/L). Micafungin was very active against all species (MIC(90), 0.03 mg/L) except for C. parapsilosis (MIC(90), 2 mg/L). CONCLUSIONS: These data suggest that, in Japan, the species distribution of Candida bloodstream infections and the fluconazole resistance rate are similar to those reported previously in North America and Europe. Voriconazole and micafungin appear to have strong in vitro activity against Candida blood isolates, although continuing surveillance and further clinical research are needed.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14688039&dopt=Abstract fluconazole Diflucan



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[Genotype, serotype and sensitivity to fluconazole of Candida albicans strains isolated from HIV-positive patients]

[Article in French]

Bastide JM, Pujol C, Mallie M, Reynes J.

Laboratoire d'Immunologie et Parasitologie, Faculte de Pharmacie, Montpellier.

Genotype, serotype and susceptibility in vitro to fluconazole of 104 C. albicans strains isolated from HIV+ patients were studied. The possible correlations between genotype analysed by multilocus enzyme electrophoresis (MLEE) and phenotype of medical relevance (serotype and susceptibility to fluconazole) of Candida albicans isolated from these patients treated with fluconazole were evaluated by factorial correspondence analysis. No correlation was observed between genotype and in vitro or clinical response to fluconazole. In counterpart, serotype B C. albicans was associated with some multilocus genotypic patterns.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10371777&dopt=Abstract fluconazole Diflucan



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Specific chromosome alterations in fluconazole-resistant mutants of Candida albicans.

Perepnikhatka V, Fischer FJ, Niimi M, Baker RA, Cannon RD, Wang YK, Sherman F, Rustchenko E.

Department of Biochemistry and Biophysics, University of Rochester Medical School, Rochester, New York 14642, USA.

The exposure of Candida albicans to fluconazole resulted in the nondisjunction of two specific chromosomes in 17 drug-resistant mutants, each obtained by an independent mutational event. The chromosomal changes occurred at high frequencies and were related to the duration of the drug exposure. The loss of one homologue of chromosome 4 occurred after incubation on a fluconazole medium for 7 days. A second change, the gain of one copy of chromosome 3, was observed after exposure for 35 or 40 days. We found that the mRNA levels of ERG11, CDR1, CDR2, and MDR1, the candidate fluconazole resistance genes, remained either the same or were diminished. The lack of overexpression of putative drug pumps or the drug target indicated that some other mechanism(s) may be operating. The fluconazole resistance phenotype, electrophoretic karyotypes, and transcript levels of mutants were stable after growth for 112 generations in the absence of fluconazole. This is the first report to demonstrate that resistance to fluconazole can be dependent on chromosomal nondisjunction. Furthermore, we suggest that a low-level resistance to fluconazole arising during the early stages of clinical treatment may occur by this mechanism. These results support our earlier hypothesis that changes in C. albicans chromosome number is a common means to control a resource of potentially beneficial genes that are related to important cellular functions.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10383973&dopt=Abstract fluconazole Diflucan



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Multiple resistant phenotypes of Candida albicans coexist during episodes of oropharyngeal candidiasis in human immunodeficiency virus-infected patients.

Lopez-Ribot JL, McAtee RK, Perea S, Kirkpatrick WR, Rinaldi MG, Patterson TF.

Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284, USA. ribot uthscsa.edu

Mechanisms of resistance to azoles in Candida albicans, the main etiologic agent of oropharyngeal candidiasis (OPC), include alterations in the target enzyme (lanosterol demethylase) and increased efflux of drug. Previous studies on mechanisms of resistance have been limited by the fact that only a single isolate from each OPC episode was available for study. Multiple isolates from each OPC episode were evaluated with oral samples plated in CHROMagar Candida with and without fluconazole to maximize detection of resistant yeasts. A total of 101 isolates from each of three serial episodes of OPC from four different patients were evaluated. Decreasing geometric means of fluconazole MICs with serial episodes of infection were detected in the four patients. However, 8-fold or larger (up to 32-fold) differences in fluconazole MICs were detected within isolates recovered at the same time point in 7 of 12 episodes. Strain identity was analyzed by DNA typing techniques and indicated that isolates from each patient represented mainly isogenic strains, but differed among patients. A Northern blot technique was used to monitor expression of ERG11 (encoding lanosterol demethylase) and genes coding for efflux pumps. This analysis revealed that clinical isolates obtained from the same patient and episode were phenotypically heterogeneous in their patterns of expression of these genes involved in fluconazole resistance. These results demonstrate the complexity of the distribution of the molecular mechanisms of antifungal drug resistance and indicate that different subpopulations of yeasts may coexist at a given time in the same patient and may develop resistance through different mechanisms.

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Effect of fluconazole on human polymorphonuclear leucocyte functions ex vivo against Candida albicans.

Gurer US, Cevikbas A, Johansson C, Derici K, Yardimci T.

Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Marmara, Haydarpasa, Istanbul, Turkey.

Polymorphonuclear leucocytes (PMNs) are important components of host defence against fungi. We investigated the ex vivo effect of fluconazole on chemotaxis, adherence, superoxide anion (O-2) generation and intracellular killing of Candida albicans blastoconidia after the administration of fluconazole (300 mg per os) to healthy volunteers. With regard to chemotaxis in response to zymosan-activated serum (ZAS), as measured using an agarose gel technique, fluconazole neither increased, nor decreased the chemotaxis of PMNs. The adherence was significantly enhanced after exposure of PMNs to fluconazole under ex vivo conditions, whereas, O-2 production after stimulation of PMNs with ZAS was not affected by fluconazole. The effect of fluconazole on intracellular killing of C. albicans blastoconidia by PMNs was determined by viable colony count, after release of yeast cells from disturbed neutrophils. Fluconazole under in vitro conditions, at a therapeutic concentration, significantly increased the intracellular killing of C. albicans by PMNs at 30 min when compared with the results obtained in ex vivo experiments (p < 0.001). During 90 min of exposure, no significant difference was found between in vitro and ex vivo conditions (p > 0.05).

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In vitro activity of rilopirox against fluconazole-susceptible and fluconazole-resistant Candida isolates from patients with HIV infection.

Nenoff P, Taneva E, Pfeil B, Oswald U, Haustein UF.

Department of Dermatology, University of Leipzig, Germany.

The in vitro antifungal activity of the new hydroxypyridone antimycotic rilopirox has been evaluated against 38 fluconazole-susceptible and -resistant clinical isolates of Candida albicans together with other Candida species isolated from patients with human immunodeficiency virus (HIV) infection and oropharyngeal candidosis. Minimum inhibitory concentrations (MICs) of both rilopirox and fluconazole were measured by a microdilution method using high-resolution medium supplemented with asparagine and glucose at pH 7.0. In comparison, an agar dilution technique was carried out for susceptibility testing of the antifungal agents. Rilopirox was found to be able to inhibit growth of all clinical yeast isolates. The rilopirox MICs at which 50% and 90% of strains were inhibited (MIC50 and MIC90 respectively), as determined by the microdilution method, were 4 and 8 micrograms ml-1 respectively. The highest MIC values for rilopirox using microdilution and the agar dilution method were 32 or 25 micrograms ml-1 respectively. On the other hand, for fluconazole, the MIC50 and MIC90 achieved were 0.5 and 128 micrograms ml-1, respectively, which means that the MIC90 value of fluconazole was 16-fold higher than that of rilopirox. Using the agar dilution technique, the MIC values of rilopirox were in the range 0.006-25 micrograms ml-1 with a median of 3.12 micrograms ml-1. For fluconazole, the MIC90 value was four-fold higher than that for rilopirox, indicating a considerable proportion of yeast strains with high MICs of 100 micrograms ml-1, suggesting in vitro resistance to this azole antifungal. All strains with diminished fluconazole susceptibility were susceptible to rilopirox. Even Candida krusei and Candida glabrata exhibited good in vitro susceptibility to rilopirox. Therefore, this new antifungal agent may be used as an alternative not only in the treatment of vaginal candidosis, but also in oropharyngeal Candida infections, e.g. in AIDS patients.

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Fluconazole, with or without dexamethasone for experimental cryptococcosis: impact of treatment timing.

Lortholary O, Nicolas M, Soreda S, Improvisi L, Ronin O, Petitjean O, Dupont B, Tod M, Dromer F.

Unite de Mycologie, Institut Pasteur, Paris, France.

The time of initiation of fluconazole treatment with or without dexamethasone, and the impact on mycological outcome and drug pharmacokinetics were assessed in a murine model of disseminated cryptococcosis. Non-infected mice and mice with disseminated cryptococcosis were given saline, dexamethasone, or fluconazole +/- dexamethasone, 1 or 8 days after infection. Cfus were counted in tissues, and fluconazole concentrations were determined in plasma and tissues by HPLC and a bioassay. Despite fluconazole tissue and plasma concentrations which were above the minimal inhibitory concentration, the numbers of cfus in brain and lung tissues were reduced after early (P = 0.002 and 0.04, respectively), but not after late fluconazole treatment. The administration of dexamethasone did not have a deleterious effect on the number of cfus, fluconazole pharmacokinetics or antifungal activity. In conclusion, the size of the fungal burden influences the effective level of fluconazole activity in lung and brain. These results strongly suggest that potential antifungal agents should be studied following both early and late administration in experimental cryptococcosis.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10404321&dopt=Abstract fluconazole Diflucan