151
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Pascual A, Nieth V, Calandra T, Bille J, Bolay S, Decosterd LA, Buclin T, Majcherczyk PA, Sanglard D, Marchetti O. Variability of voriconazole plasma levels measured by new high-performance liquid chromatography and bioassay methods. Antimicrob Agents Chemother 2006; 51:137-43. [PMID: 17088483 PMCID: PMC1797701 DOI: 10.1128/aac.00957-06] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Voriconazole (VRC) is a broad-spectrum antifungal triazole with nonlinear pharmacokinetics. The utility of measurement of voriconazole blood levels for optimizing therapy is a matter of debate. Available high-performance liquid chromatography (HPLC) and bioassay methods are technically complex, time-consuming, or have a narrow analytical range. Objectives of the present study were to develop new, simple analytical methods and to assess variability of voriconazole blood levels in patients with invasive mycoses. Acetonitrile precipitation, reverse-phase separation, and UV detection were used for HPLC. A voriconazole-hypersusceptible Candida albicans mutant lacking multidrug efflux transporters (cdr1Delta/cdr1Delta, cdr2Delta/cdr2Delta, flu1Delta/flu1Delta, and mdr1Delta/mdr1Delta) and calcineurin subunit A (cnaDelta/cnaDelta) was used for bioassay. Mean intra-/interrun accuracies over the VRC concentration range from 0.25 to 16 mg/liter were 93.7% +/- 5.0%/96.5% +/- 2.4% (HPLC) and 94.9% +/- 6.1%/94.7% +/- 3.3% (bioassay). Mean intra-/interrun coefficients of variation were 5.2% +/- 1.5%/5.4% +/- 0.9% and 6.5% +/- 2.5%/4.0% +/- 1.6% for HPLC and bioassay, respectively. The coefficient of concordance between HPLC and bioassay was 0.96. Sequential measurements in 10 patients with invasive mycoses showed important inter- and intraindividual variations of estimated voriconazole area under the concentration-time curve (AUC): median, 43.9 mg x h/liter (range, 12.9 to 71.1) on the first and 27.4 mg x h/liter (range, 2.9 to 93.1) on the last day of therapy. During therapy, AUC decreased in five patients, increased in three, and remained unchanged in two. A toxic encephalopathy probably related to the increase of the VRC AUC (from 71.1 to 93.1 mg x h/liter) was observed. The VRC AUC decreased (from 12.9 to 2.9 mg x h/liter) in a patient with persistent signs of invasive aspergillosis. These preliminary observations suggest that voriconazole over- or underexposure resulting from variability of blood levels might have clinical implications. Simple HPLC and bioassay methods offer new tools for monitoring voriconazole therapy.
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Affiliation(s)
- Andres Pascual
- Infectious Diseases Service, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, CH-1011 Lausanne, Switzerland
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152
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Hope WW, Warn PA, Sharp A, Howard S, Kasai M, Louie A, Walsh TJ, Drusano GL, Denning DW. Derivation of an in vivo drug exposure breakpoint for flucytosine against Candida albicans and Impact of the MIC, growth rate, and resistance genotype on the antifungal effect. Antimicrob Agents Chemother 2006; 50:3680-8. [PMID: 16954320 PMCID: PMC1635226 DOI: 10.1128/aac.00369-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Drug exposure or pharmacodynamic breakpoints refer to a magnitude of drug exposure which separates a population into groups with high and low probabilities of attaining a desired outcome. We used a pharmacodynamic model of disseminated candidiasis to define an in vivo drug exposure breakpoint for flucytosine (5FC) against Candida albicans. The results were bridged to humans by using population pharmacokinetics and Monte Carlo simulation. An in vivo drug exposure breakpoint for 5FC was apparent when serum levels were above the MIC for 45% of the dosing interval. The Monte Carlo simulations suggested that using a human dose of 100 mg/kg of body weight/day in four divided doses, 5FC resistance was defined at an MIC of 32 mg/liter. Target attainment rates following administration of 25, 50, and 100 mg/kg/day were similar, suggesting that the use of a lower dose of 5FC is possible. Using six isolates of C. albicans with MICs ranging from 0.06 to >64 mg/liter, we also explored the influence that the MIC, the fraction of the dosing interval that the serum levels of 5FC remained above the MIC (T>MIC), the 5FC resistance genotype, and the in vivo growth rate had on the response to 5FC. The MIC and T>MIC were both critical measures affecting the generation of a drug effect but had no bearing on the magnitude of the maximal kill induced by 5FC. The in vivo growth rate was a critical additional determinant of the exposure-response relationship. There was a relationship between the 5FC resistance genotype and the exposure-response relationship.
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Affiliation(s)
- William W Hope
- Pediatric Oncology Branch, NCI/NIH, CRC Rm. 1-5750, 10 Center Dr., MSC 1100, Bethesda MD 20892-1100, USA.
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153
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Viscoli C, Bassetti M. Dose finding in aspergillosis. Med Mycol 2006; 44:S299-S303. [PMID: 30408920 DOI: 10.1080/13693780600838264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Invasive aspergillosis (IA) continues to represent a significant challenge for physicians in charge of immunocompromised patients. Voriconazole, caspofungin, itraconazole, and the different formulations of amphotericin B (AmB) are all approved for therapy of IA. To collect information on the effect of high dose of antifungals in the treatment of IA, data from the available medical literature were reviewed. For AmB there are no data demonstrating any better clinical activity of doses higher than standard. For liposomal-AmB preliminary data seem to show that high doses are not more efficacious than the standard dose, and it is probably more toxic. Anecdotal data of itraconazole suggest that high dosages might be feasible and it has been associated with good clinical results. Unpublished data about voriconazole suggest the absence of any better activity of high plasma concentrations. For caspofungin the efficacy of higher dosage did not seem to be better than that obtained with the traditional dosage. Prospective studies are required, because many confounding factors may obscure the effects of the higher dosages when data are retrieved retrospectively.
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Affiliation(s)
- Claudio Viscoli
- Division of Infectious Diseases, University of Genoa and San Martino Hospital, Genova, Italy
| | - Matteo Bassetti
- Division of Infectious Diseases, University of Genoa and San Martino Hospital, Genova, Italy
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154
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Serena C, Gilgado F, Mariné M, Pastor FJ, Guarro J. Efficacy of voriconazole in a guinea pig model of invasive trichosporonosis. Antimicrob Agents Chemother 2006; 50:2240-3. [PMID: 16723595 PMCID: PMC1479129 DOI: 10.1128/aac.00045-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have evaluated the efficacy of voriconazole (VRC) in a systemic infection by Trichosporon asahii in immunosuppressed guinea pigs. VRC was more effective than amphotericin B in prolonging survival and reducing tissue burden. The best results were obtained with VRC at 10 mg/kg of body weight/day.
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Affiliation(s)
- Carolina Serena
- Unitat de Microbiologia, Facultat de Medicina, Universitat Rovira i Virgili, Carrer Sant Llorenç, Reus, Spain
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155
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Pfaller MA, Diekema DJ, Rex JH, Espinel-Ingroff A, Johnson EM, Andes D, Chaturvedi V, Ghannoum MA, Odds FC, Rinaldi MG, Sheehan DJ, Troke P, Walsh TJ, Warnock DW. Correlation of MIC with outcome for Candida species tested against voriconazole: analysis and proposal for interpretive breakpoints. J Clin Microbiol 2006; 44:819-26. [PMID: 16517860 PMCID: PMC1393146 DOI: 10.1128/jcm.44.3.819-826.2006] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Developing interpretive breakpoints for any given organism-drug combination requires integration of the MIC distribution, pharmacokinetic and pharmacodynamic parameters, and the relationship between the in vitro activity and outcome from both in vivo and clinical studies. Using data generated by standardized broth microdilution and disk diffusion test methods, the Antifungal Susceptibility Subcommittee of the Clinical and Laboratory Standards Institute has now proposed interpretive breakpoints for voriconazole and Candida species. The MIC distribution for voriconazole was determined using a collection of 8,702 clinical isolates. The overall MIC90 was 0.25 microg/ml and 99% of the isolates were inhibited at < or = 1 microg/ml of voriconazole. Similar results were obtained for 1,681 Candida isolates (16 species) from the phase III clinical trials. Analysis of the available data for 249 patients from six phase III voriconazole clinical trials demonstrated a statistically significant correlation (P = 0.021) between MIC and investigator end-of-treatment assessment of outcome. Consistent with parallel pharmacodynamic analyses, these data support the following MIC breakpoints for voriconazole and Candida species: susceptible (S), < or = 1 microg/ml; susceptible dose dependent (SDD), 2 microg/ml; and resistant (R), > or = 4 microg/ml. The corresponding disk test breakpoints are as follows: S, > or = 17 mm; SDD, 14 to 16 mm; and R, < or = 13 mm.
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Affiliation(s)
- M A Pfaller
- Medical Microbiology Division, C606 GH, Department of Pathology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
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156
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Davis JL, Salmon JH, Papich MG. Pharmacokinetics of voriconazole after oral and intravenous administration to horses. Am J Vet Res 2006; 67:1070-5. [PMID: 16740104 DOI: 10.2460/ajvr.67.6.1070] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To characterize pharmacokinetics of voriconazole in horses after oral and IV administration and determine the in vitro physicochemical characteristics of the drug that may affect oral absorption and tissue distribution. ANIMALS 6 adult horses. PROCEDURES Horses were administered voriconazole (1 mg/kg, IV, or 4 mg/kg, PO), and plasma concentrations were measured by use of high-performance liquid chromatography. In vitro plasma protein binding and the octanol:water partition coefficient were also assessed. RESULTS Voriconazole was adequately absorbed after oral administration in horses, with a systemic bioavailability of 135.75 +/- 18.41%. The elimination half-life after a single orally administered dose was 13.11 +/- 2.85 hours, and the maximum plasma concentration was 2.43 +/- 0.4 microg/mL. Plasma protein binding was 31.68%, and the octanol:water partition coefficient was 64.69. No adverse reactions were detected during the study. CONCLUSIONS AND CLINICAL RELEVANCE Voriconazole has excellent absorption after oral administration and a long half-life in horses. On the basis of the results of this study, it was concluded that administration of voriconazole at a dosage of 4 mg/kg, PO, every 24 hours will attain plasma concentrations adequate for treatment of horses with fungal infections for which the fungi have a minimum inhibitory concentration <or= 1 microg/mL. Because of the possible nonlinearity of this drug as well as the potential for accumulation, chronic dosing studies and clinical trials are needed to determine the appropriate dosing regimen for voriconazole in horses.
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Affiliation(s)
- Jennifer L Davis
- Clinical Pharmacology, Research Laboratories, Department of Molecular and Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
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157
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Jullien V, Lortholary O. Les relations pharmacocinétique-pharmacodynamique des antifongiques. Conséquences pour le suivi thérapeutique. Therapie 2006; 61:209-17. [PMID: 16989121 DOI: 10.2515/therapie:2006044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Despite pharmacokinetic-pharmacodynamic relationships were clearly evidenced for antifungal drugs by the use of experimental models, few target plasma concentrations could be determined from studies performed in patients. The main causes explaining this lack of data are reviewed and the possible use in humans of the parameters obtained from animal models is discussed.
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Affiliation(s)
- Vincent Jullien
- Université Paris-Descartes, Faculté de Médecine, Paris, France.
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158
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te Dorsthorst DTA, Verweij PE, Meis JFGM, Mouton JW. Efficacy and pharmacodynamics of flucytosine monotherapy in a nonneutropenic murine model of invasive aspergillosis. Antimicrob Agents Chemother 2006; 49:4220-6. [PMID: 16189101 PMCID: PMC1251525 DOI: 10.1128/aac.49.10.4220-4226.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The therapeutic efficacy of flucytosine (5FC) monotherapy and the pharmacodynamic index predictive of efficacy were evaluated in a nonneutropenic mouse model of acute invasive aspergillosis. Mice were infected intravenously with an Aspergillus fumigatus isolate (the median MICs of 5FC were 128 mug/ml under the standard condition, 0.5 microg/ml at pH 6.0, and 0.031 microg/ml at pH 5.0) 2 h prior to the start of therapy and were treated for 7 days with different 5FC dosing regimens. The total doses ranged from 50 to 800 mg/kg of body weight/day and were administered at 6-, 12-, and 24-h intervals. The efficacy was assessed by means of survival. The survival rates of the treatment groups ranged from 40 to 90%, while the survival rate of the control group was 20%. The efficacy found depended primarily on the total daily dose. However, the power of our sample size may have been too low to exclude an effect of dose fractionation. The pharmacodynamic index that most strongly correlated with the efficacy was the area under the serum concentration-time curve and MIC ratio (R(2) = 0.86). We conclude that 5FC monotherapy is efficacious in a murine Aspergillus fumigatus infection model.
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Affiliation(s)
- D T A te Dorsthorst
- Department of Medical Microbiology and Infectious Diseases, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands
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159
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Hector RF. An Overview of Antifungal Drugs and Their Use for Treatment of Deep and Superficial Mycoses in Animals. ACTA ACUST UNITED AC 2005; 20:240-9. [PMID: 16317914 DOI: 10.1053/j.ctsap.2005.07.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fungal infections are often challenging to manage, given the limited numbers of therapeutics and a general lack of applicable clinical literature for their use in a given animal species. This article reviews some of the underlying principles that can affect the therapeutic outcome for a given antifungal, and provides specific information from the literature that is intended to highlight the distinctive properties of the most commonly used antifungals in veterinary medicine to better facilitate their successful application in clinical practice.
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Affiliation(s)
- Richard F Hector
- Institute for Global Health, University of California San Francisco, San Francisco, CA 94105, USA.
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160
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Clancy CJ, Yu VL, Morris AJ, Snydman DR, Nguyen MH. Fluconazole MIC and the fluconazole dose/MIC ratio correlate with therapeutic response among patients with candidemia. Antimicrob Agents Chemother 2005; 49:3171-7. [PMID: 16048920 PMCID: PMC1196236 DOI: 10.1128/aac.49.8.3171-3177.2005] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 03/24/2005] [Accepted: 04/30/2005] [Indexed: 11/20/2022] Open
Abstract
We tested 32 Candida isolates recovered in the early 1990s from the bloodstreams of patients with candidemia for in vitro susceptibility to fluconazole and determined if MIC and/or the daily dose of fluconazole/MIC ratio correlated with the response to therapy. This is a unique data set since 87.5% (28/32) of patients were treated with fluconazole doses now considered to be inadequate (=200 mg), which contributed to high therapeutic failure rates (53% [17/32]). The geometric mean MIC and dose/MIC ratio for isolates associated with therapeutic failure (11.55 mug/ml and 14.3, respectively) differed significantly from values associated with therapeutic success (0.95 mug/ml and 219.36 [P = 0.0009 and 0.0004, respectively]). The therapeutic success rates among patients infected with susceptible (MIC = 8 mug/ml), susceptible-dose dependent (S-DD) (MIC = 16 or 32 mug/ml), and resistant (MIC >/= 64 mug/ml) isolates were 67% (14/21), 20% (1/5), and 0% (0/6), respectively. A dose/MIC ratio >50 was associated with a success rate of 74% (14/19), compared to 8% (1/13) for a dose/MIC ratio =50 (P = 0.0003). Our data suggest that both fluconazole MIC and dose/MIC ratio correlate with the therapeutic response to fluconazole among patients with candidemia. In clinical practice, dose/MIC ratio might prove easier to interpret than breakpoint MICs, since it quantitates the effects of increasing fluconazole doses that are alluded to in the S-DD designation.
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Affiliation(s)
- Cornelius J Clancy
- University of Florida College of Medicine, P.O. Box 100277, JHMHC, Gainesville, FL 32610, USA.
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161
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Pfaller MA, Messer SA, Boyken L, Rice C, Tendolkar S, Hollis RJ, Doern GV, Diekema DJ. Global trends in the antifungal susceptibility of Cryptococcus neoformans (1990 to 2004). J Clin Microbiol 2005; 43:2163-7. [PMID: 15872236 PMCID: PMC1153799 DOI: 10.1128/jcm.43.5.2163-2167.2005] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antifungal susceptibilities of 1,811 clinical isolates of Cryptococcus neoformans obtained from 100 laboratories in 5 geographic regions worldwide between 1990 and 2004 were determined. The MICs of amphotericin B, flucytosine, fluconazole, voriconazole, posaconazole, and ravuconazole were determined by the National Committee for Clinical Laboratory Standards broth microdilution method. Isolates were submitted to a central reference laboratory (University of Iowa) from study centers in Africa (5 centers, 395 isolates), Europe (14 centers, 102 isolates), Latin America (14 centers, 82 isolates), the Pacific region (7 centers, 50 isolates), and North America (60 centers, 1,182 isolates). Resistance to amphotericin B, flucytosine, and fluconazole was < or = 1% overall. Susceptibility to flucytosine (MIC, < or = 4 microg/ml) ranged from 35% in North America to 68% in Latin America. Similarly, only 75% of isolates from North America were susceptible to fluconazole (MIC, < or = 8 microg/ml) compared to 94 to 100% in the other regions. Isolates remained highly susceptible to amphotericin B (99% susceptibility at a MIC of < or = 1 microg/ml) over the entire 15-year period. Susceptibility to flucytosine (MIC, < or = 4 microg/ml) increased from 34% in 1990 to 1994 to 66% in 2000 to 2004. Susceptibility to fluconazole (MIC, < or = 8 microg/ml) increased from 72% in 1990 to 1994 to 96% in 2000 to 2004. Voriconazole, posaconazole, and ravuconazole all were very active (99% of isolates susceptible at MIC of < or = 1 microg/ml) against this geographically diverse collection of isolates. We conclude that in vitro resistance to antifungal agents used in the treatment of cryptococcosis remains uncommon among isolates of C. neoformans from five broad geographic regions and has not increased over a 15-year period.
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Affiliation(s)
- M A Pfaller
- Medical Microbiology Division, C606 GH, Department of Pathology, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
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162
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Abstract
PURPOSE OF REVIEW Historically the anti-infective dose and dosing interval chosen in clinical trials have been based on an arbitrary goal of maintaining drug levels in serum above the minimum inhibitory concentration of infecting pathogens for most if not all of the dosing interval. Subsequent United States Food and Drug Administration approval of a dosing regimen is then based on clinical success in treatment trials. Over the past decade, the emergence of drug resistance has limited the clinical utility of an increasing number of antimicrobial agents. However, early in drug development clinical trials do not often define the impact of infection with these less susceptible pathogens. The field of pharmacodynamics provides analysis tools that can help predict the likelihood of treatment success with various antimicrobial treatment regimens against susceptible and resistant pathogens. RECENT FINDINGS In-vitro and animal model studies have begun to define the pharmacodynamic characteristics of a variety of antifungal compounds. In-vivo studies have demonstrated that the pharmacodynamic target associated with efficacy is similar among antifungal drugs within the same class and have shown the importance of considering protein. Analysis of clinical trial data suggests that the pharmacodynamic target identified in animal model studies is predictive of outcomes in humans. SUMMARY Antifungal pharmacodynamics can be used to understand the relationship between drug dosing, in-vitro susceptibility and treatment efficacy. Consideration of these relationships can be used to optimize dosing regimens with current antifungal agents, to develop susceptibility breakpoint guidelines, and in the design of dosing regimens for drugs in early development.
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Affiliation(s)
- David Andes
- Department of Medicine, Section of Infectious Diseases, University of Wisconsin, Madison, Wisconsin 53792, USA.
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163
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Cuenca-Estrella M, Gomez-Lopez A, Mellado E, Rodriguez-Tudela JL. Correlation between the procedure for antifungal susceptibility testing for Candida spp. of the European Committee on Antibiotic Susceptibility Testing (EUCAST) and four commercial techniques. Clin Microbiol Infect 2005; 11:486-92. [PMID: 15882199 DOI: 10.1111/j.1469-0691.2005.01166.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The correlation between results obtained with the European Committee on Antibiotic Susceptibility Testing (EUCAST) antifungal susceptibility testing procedure (document 7.1) and four commercial systems was evaluated for a collection of 93 clinical isolates of Candida spp. Overall, agreement between the EUCAST procedure and the Sensititre YeastOne and Etest methods was 75% and 90.4%, respectively. The correlation indices (p < 0.01) between the EUCAST and commercial methods were 0.92 for Sensititre YeastOne, 0.89 for Etest, - 0.90 for Neo-Sensitabs, and 0.95 for Fungitest. Amphotericin B MICs obtained by Sensititre YeastOne were consistently higher than with the EUCAST method and, although very major errors were not observed, 91% of MICs were misclassified. Amphotericin B- and fluconazole-resistant isolates were identified correctly with Sensititre YeastOne, Etest and Fungitest. Neo-Sensitabs identified amphotericin B-resistant isolates, but misclassified > 5% of fluconazole-resistant isolates as susceptible. The commercial methods, particularly Etest and Fungitest, appeared to be suitable alternatives to the EUCAST procedure for antifungal susceptibility testing of clinical isolates of Candida.
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Affiliation(s)
- M Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
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164
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Brown J, Freeman BB. Rethinking the use of voriconazole therapeutic drug monitoring in allogeneic hematopoietic stem cell transplant recipients. Bone Marrow Transplant 2005; 36:177. [PMID: 15908975 DOI: 10.1038/sj.bmt.1705012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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165
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Cantón E, Pemán J, Gobernado M, Viudes A, Espinel-Ingroff A. Synergistic activities of fluconazole and voriconazole with terbinafine against four Candida species determined by checkerboard, time-kill, and Etest methods. Antimicrob Agents Chemother 2005; 49:1593-6. [PMID: 15793148 PMCID: PMC1068629 DOI: 10.1128/aac.49.4.1593-1596.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The in vitro activities of fluconazole or voriconazole plus terbinafine were evaluated against 20 Candida isolates by the checkerboard, time-kill, and Etest methods. Synergism (C. albicans, C. glabrata, and C. tropicalis) and indifference (C. krusei) were observed. Correlation among methods was good. The Etest is a suitable method to determine drug interactions.
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Affiliation(s)
- Emilia Cantón
- Unidad de Microbiología Experimental, Centro de Investigación, Hospital Universitario La Fe, Avenida Campanar 21, 46009 Valencia, Spain.
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166
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Xiong Q, Hassan SA, Wilson WK, Han XY, May GS, Tarrand JJ, Matsuda SPT. Cholesterol import by Aspergillus fumigatus and its influence on antifungal potency of sterol biosynthesis inhibitors. Antimicrob Agents Chemother 2005; 49:518-24. [PMID: 15673727 PMCID: PMC547240 DOI: 10.1128/aac.49.2.518-524.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
High mortality rates from invasive aspergillosis in immunocompromised patients are prompting research toward improved antifungal therapy and better understanding of fungal physiology. Herein we show that Aspergillus fumigatus, the major pathogen in aspergillosis, imports exogenous cholesterol under aerobic conditions and thus compromises the antifungal potency of sterol biosynthesis inhibitors. Adding serum to RPMI medium led to enhanced growth of A. fumigatus and extensive import of cholesterol, most of which was stored as ester. Growth enhancement and sterol import also occurred when the medium was supplemented with purified cholesterol instead of serum. Cells cultured in RPMI medium with the sterol biosynthesis inhibitors itraconazole or voriconazole showed retarded growth, a dose-dependent decrease in ergosterol levels, and accumulation of aberrant sterol intermediates. Adding serum or cholesterol to the medium partially rescued the cells from the drug-induced growth inhibition. We conclude that cholesterol import attenuates the potency of sterol biosynthesis inhibitors, perhaps in part by providing a substitute for membrane ergosterol. Our findings establish significant differences in sterol homeostasis between filamentous fungi and yeast. These differences indicate the potential value of screening aspergillosis antifungal agents in serum or other cholesterol-containing medium. Our results also suggest an explanation for the antagonism between itraconazole and amphotericin B, the potential use of Aspergillus as a model for sterol trafficking, and new insights for antifungal drug development.
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Affiliation(s)
- Quanbo Xiong
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main St., Houston, TX 77005, USA
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167
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Trifilio S, Ortiz R, Pennick G, Verma A, Pi J, Stosor V, Zembower T, Mehta J. Voriconazole therapeutic drug monitoring in allogeneic hematopoietic stem cell transplant recipients. Bone Marrow Transplant 2005; 35:509-13. [PMID: 15654347 DOI: 10.1038/sj.bmt.1704828] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Voriconazole, a new antifungal agent, is increasingly being used after HSCT. The hepatic cytochrome P450 isoenzyme 2C19 plays a significant role in voriconazole metabolism. As CYP2C19 exhibits significant genetic polymorphism, some patients metabolize voriconazole poorly resulting in increased plasma drug levels. The clinical significance of this is unknown, and the utility of monitoring voriconazole levels is unclear. Steady-state trough plasma voriconazole levels were obtained in 25 allogeneic HSCT recipients using an HPLC assay. Patients had drug levels checked once (n=13), twice (n=10), or > or =3 times (n=2) 5-18 days (median 10) after starting voriconazole or dose modification. The 41 voriconazole levels were 0.2-6.8 microg/ml (median 1.6); 6 (15%) were <0.5 (possibly below the in vitro MIC90 for Aspergillus spp.). Voriconazole concentrations correlated with aspartate aminotranferase (AST) (r=0.5; P=0.0009) and alkaline phosphatase (r=0.34; P=0.03), but not with creatinine, bilirubin and alanine aminotransferase (ALT). Since liver dysfunction is common after HSCT, it was not possible to determine if elevated AST and alkaline phosphatase levels were the cause or the consequence of higher voriconazole levels. We conclude that trough voriconazole levels vary considerably between patients, and suggest monitoring levels in patients receiving voriconazole for confirmed fungal infections, and in those with elevated AST or alkaline phosphatase levels.
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Affiliation(s)
- S Trifilio
- Pharmacy Department, Northwestern Memorial Hospital, Chicago, IL, USA
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168
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Andes D. Antifungal pharmacokinetics and pharmacodynamics: understanding the implications for antifungal drug resistance. Drug Resist Updat 2004; 7:185-94. [PMID: 15296860 DOI: 10.1016/j.drup.2004.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 06/04/2004] [Accepted: 06/07/2004] [Indexed: 10/26/2022]
Abstract
Pharmacodynamics (PDs) describe the relationship between drug exposure and outcome. The drug exposures in these analyses are most commonly expressed in a variety of pharmacokinetic terms. The outcome of interest with anti-infective therapy is either microbiologic resolution or a clinical surrogate of treatment efficacy. An in vitro measure of drug potency, such as the minimum inhibitory concentration (MIC) is also frequently considered in this relationship. Examination of the relationships among drug pharmacokinetics, MIC, and efficacy has provided a framework for choice of antifungal drug and dose. These analyses provide a PD target for drug class/organism combinations. The PD target can be useful for defining the upper MIC limit for a drug-dosing regimen that would be expected to result in treatment efficacy. The PD target can be used to optimize dosing regimens and to aid in defining susceptibility breakpoints.
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Affiliation(s)
- David Andes
- Department of Medicine, Section of Infectious Diseases, University of Wisconsin, 600 Highland Ave, Room H4/572, Madison, WI 53792, USA.
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169
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Conte JE, Golden JA, Kipps J, McIver M, Zurlinden E. Intrapulmonary pharmacokinetics and pharmacodynamics of itraconazole and 14-hydroxyitraconazole at steady state. Antimicrob Agents Chemother 2004; 48:3823-7. [PMID: 15388441 PMCID: PMC521869 DOI: 10.1128/aac.48.10.3823-3827.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We determined the steady-state intrapulmonary pharmacokinetic and pharmacodynamic parameters of orally administered itraconazole (ITRA), 200 mg every 12 h (twice a day [b.i.d.]), on an empty stomach, for a total of 10 doses, in 26 healthy volunteers. Five subgroups each underwent standardized bronchoscopy and bronchoalveolar lavage (BAL) at 4, 8, 12, 16, and 24 h after administration of the last dose. ITRA and its main metabolite, 14-hydroxyitraconazole (OH-IT), were measured in plasma, BAL fluid, and alveolar cells (AC) using high-pressure liquid chromatography. Half-life and area under the concentration-time curves (AUC) in plasma, epithelial lining fluid (ELF), and AC were derived using noncompartmental analysis. ITRA and OH-IT maximum concentrations of drug (C(max)) (mean +/- standard deviation) in plasma, ELF, and AC were 2.1 +/- 0.8 and 3.3 +/- 1.0, 0.5 +/- 0.7 and 1.0 +/- 0.9, and 5.5 +/- 2.9 and 6.6 +/- 3.1 microg/ml, respectively. The ITRA and OH-IT AUC for plasma, ELF, and AC were 34.4 and 60.2, 7.4 and 18.9, and 101 and 134 microg. hr/ml. The ratio of the C(max) and the MIC at which 90% of the isolates were inhibited (MIC(90)), the AUC/MIC(90) ratio, and the percent dosing interval above MIC(90) for ITRA and OH-IT concentrations in AC were 1.1 and 3.2, 51 and 67, and 100 and 100%, respectively. Plasma, ELF, and AC concentrations of ITRA and OH-IT declined monoexponentially with half-lives of 23.1 and 37.2, 33.2 and 48.3, and 15.7 and 45.6 h, respectively. An oral dosing regimen of ITRA at 200 mg b.i.d. results in concentrations of ITRA and OH-ITRA in AC that are significantly greater than those in plasma or ELF and intrapulmonary pharmacodynamics that are favorable for the treatment of fungal respiratory infection.
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Affiliation(s)
- John E Conte
- University of California, San Francisco, 350 Parnassus Ave., Suite 507, San Francisco, CA 94117, USA.
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170
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Drusano GL. How does a patient maximally benefit from anti-infective chemotherapy? Clin Infect Dis 2004; 39:1245-6. [PMID: 15486851 DOI: 10.1086/424673] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 07/02/2004] [Indexed: 11/04/2022] Open
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171
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Walsh TJ, Karlsson MO, Driscoll T, Arguedas AG, Adamson P, Saez-Llorens X, Vora AJ, Arrieta AC, Blumer J, Lutsar I, Milligan P, Wood N. Pharmacokinetics and safety of intravenous voriconazole in children after single- or multiple-dose administration. Antimicrob Agents Chemother 2004; 48:2166-72. [PMID: 15155217 PMCID: PMC415618 DOI: 10.1128/aac.48.6.2166-2172.2004] [Citation(s) in RCA: 232] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
We conducted a multicenter study of the safety, tolerability, and plasma pharmacokinetics of the parenteral formulation of voriconazole in immunocompromised pediatric patients (2 to 11 years old). Single doses of 3 or 4 mg/kg of body weight were administered to six and five children, respectively. In the multiple-dose study, 28 patients received loading doses of 6 mg/kg every 12 h on day 1, followed by 3 mg/kg every 12 h on day 2 to day 4 and 4 mg/kg every 12 h on day 4 to day 8. Standard population pharmacokinetic approaches and generalized additive modeling were used to construct the structural pharmacokinetic and covariate models used in this analysis. In contrast to that in adult healthy volunteers, elimination of voriconazole was linear in children following doses of 3 and 4 mg/kg every 12 h. Body weight was more influential than age in accounting for the observed variability in voriconazole pharmacokinetics. Elimination capacity correlated with the CYP2C19 genotype. Exposures were similar at 4 mg/kg every 12 h in children (median area under the concentration-time curve (AUC), 14,227 ng. h/ml) and 3 mg/kg in adults (median AUC, 13,855 ng. h/ml). Visual disturbances occurred in 5 (12.8%) of the 39 patients and were the only drug-related adverse events that occurred more than once. No withdrawals from the study were related to voriconazole. We conclude that pediatric patients have a higher capacity for elimination of voriconazole per kilogram of body weight than do adult healthy volunteers and that dosages of 4 mg/kg may be required in children to achieve exposures consistent with those in adults following dosages of 3 mg/kg.
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Affiliation(s)
- Thomas J Walsh
- Pediatric Oncology Branch, National Cancer Institute, Bldg. 10, Rm. 13N240, Bethesda, MD 20892, USA.
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172
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Pfaller MA, Messer SA, Boyken L, Tendolkar S, Hollis RJ, Diekema DJ. Geographic variation in the susceptibilities of invasive isolates of Candida glabrata to seven systemically active antifungal agents: a global assessment from the ARTEMIS Antifungal Surveillance Program conducted in 2001 and 2002. J Clin Microbiol 2004; 42:3142-6. [PMID: 15243073 PMCID: PMC446248 DOI: 10.1128/jcm.42.7.3142-3146.2004] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Revised: 03/14/2004] [Accepted: 03/28/2004] [Indexed: 11/20/2022] Open
Abstract
We examined the susceptibilities to amphotericin B, flucytosine, fluconazole, posaconazole, ravuconazole, voriconazole, and caspofungin of 601 invasive isolates of Candida glabrata and grouped the isolates by geographic location: North America (331 isolates), Latin America (58 isolates), Europe (135 isolates), and Asia-Pacific (77 isolates). Caspofungin (MIC at which 90% of isolates tested are susceptible [MIC(90)], 0.12 microg/ml; 100% of strains are susceptible [S] at a MIC of =1 microg/ml) and flucytosine (MIC(90), 0.12 microg/ml; 99.2% S) were the most active agents in all geographic regions. Fluconazole susceptibility was highest in the Asia-Pacific region (80.5% S, 3.9% resistant [R]) and lowest in North America (64% S, 10.3% R) and Latin America (62.1% S, 3.4% R). The extended-spectrum triazoles were most active in the Asia-Pacific region (90 to 96.1% S) and least active in North America (82.5 to 90.3% S). All 46 isolates that were resistant to fluconazole were susceptible to caspofungin (MIC(90), 0.06 microg/ml) and flucytosine (MIC(90), 0.12 microg/ml) and exhibited variable cross-resistance to posaconazole, ravuconazole, and voriconazole.
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Affiliation(s)
- M A Pfaller
- Department of Pathology, Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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