Biomedical subjects

George L Drusano

Publications and source records attributed to George L Drusano.

At least 19 recordsLinked to original sources

PubMed2007

Piperacillin-tazobactam for Pseudomonas aeruginosa infection: clinical implications of an extended-infusion dosing strategy.

BACKGROUND: Piperacillin-tazobactam is frequently used to treat Pseudomonas aeruginosa infections in critically ill patients. In an effort to improve clinical outcomes, an extended-infusion dosing scheme for piperacillin-tazobactam therapy was devised using a Monte Carlo simulation and was adopted into clinical practice at Albany Medical Center (Albany, New York). This study evaluates the clinical implications of extended infusion of piperacillin-tazobactam therapy for critically ill patients with P. aeruginosa infection. METHODS: We performed a cohort study of patients who received piperacillin-tazobactam therapy for a P. aeruginosa infection that was susceptible to piperacillin-tazobactam during the period January 2000-June 2004. Prior to February 2002, all patients received intermittent infusions of piperacillin-tazobactam (3.375 g intravenously for 30 min every 4 or 6 h); after this time, all patients received extended infusions of piperacillin-tazobactam (3.375 g intravenously for 4 h every 8 h). Data on demographic characteristics, disease severity, and microbiology were collected, and outcomes were compared between groups. RESULTS: A total of 194 patients comprised the 2 study groups: 102 patients received extended infusions of piperacillin-tazobactam, and 92 patients received intermittent infusions of piperacillin-tazobactam. No differences in baseline clinical characteristics were noted between the 2 groups. Among patients with Acute Physiological and Chronic Health Evaluation-II scores > or =17, 14-day mortality rate was significantly lower among patients who received extended-infusion therapy than among patients who received intermittent-infusion therapy (12.2% vs. 31.6%, respectively; P=.04), and median duration of hospital stay after collection of samples for culture was significantly shorter for patients who received extended-infusion therapy than for patients who received intermittent-infusion therapy (21 days vs. 38 days; P=.02).Conclusions. These results indicate that extended-infusion piperacillin-tazobactam therapy is a suitable alternative to intermittent-infusion piperacillin-tazobactam therapy, and they strongly suggest that improved outcomes may be realized by administering extended-infusion piperacillin-tazobactam therapy to critically ill patients with P. aeruginosa infection.

APACHE↗

PubMed2006

Once-weekly micafungin therapy is as effective as daily therapy for disseminated candidiasis in mice with persistent neutropenia.

The effect of micafungin dose scheduling on the treatment of candidemia is unknown. Neutropenic mice with disseminated Candida glabrata infection were treated with single intraperitoneal micafungin doses of 0 to 100 mg/kg of body weight and sacrificed 7 days later. The maximal decline in kidney fungal burden was 5.8 log(10) CFU/g. A 1-week pharmacokinetic-pharmacodynamic study revealed a micafungin serum half-life of 6.13 h. In mice treated with > or =50 mg/kg, there was maximal fungal decline without regrowth during the 1-week dosing interval. Next, doses associated with 34% (34% effective dose [ED(34)]) and 50% (ED(50)) of maximal kill were administered at one of three dose schedules: a single dose at t = 0, two equal doses at t = 0 and t = 3.5 days, and 7 equal doses daily. Some mice received a single dose of 100 mg/kg. Fungal burden was examined on days 1, 5, and 7. In mice treated with the ED(34), microbial kill with the daily therapy initially lagged behind the intermittent doses but exceeded it by day 7. In mice treated with the ED(50), daily and intermittent doses had equivalent day 7 effects. In mice treated with 100 mg/kg, there was no regrowth. The relative likelihoods that the area under the concentration-time curve/MIC ratio was linked to microbial kill versus peak concentration/MIC ratio or time above the MIC was 10.3 and 10,161.2, respectively. In all the experiments, no paradoxical increase in fungal burden was observed with high micafungin doses. However, only a single Candida isolate was tested. Regimens that simulated micafungin concentration-time profiles in patients treated with a single micafungin dose of 1,400 mg once a week demonstrated maximal fungal decline. Once-weekly micafungin therapy is as efficacious as daily therapy in a murine model of disseminated candidiasis.

Animals↗

PubMed2006

Pathogenesis of Aspergillus fumigatus and the kinetics of galactomannan in an in vitro model of early invasive pulmonary aspergillosis: implications for antifungal therapy.

BACKGROUND: Little is known about the pathogenesis of invasive pulmonary aspergillosis and the relationship between the kinetics of diagnostic markers and the outcome of antifungal therapy. METHODS: An in vitro model of the human alveolus, consisting of a bilayer of human alveolar epithelial and endothelial cells, was developed. An Aspergillus fumigatus strain expressing green fluorescent protein was used. Invasion of the cell bilayer was studied using confocal and electron microscopy. The kinetics of culture, polymerase chain reaction, and galactomannan were determined. Galactomannan was used to measure the antifungal effect of macrophages and amphotericin B. A mathematical model was developed, and results were bridged to humans. RESULTS: A. fumigatus penetrated the cellular bilayer 14-16 h after inoculation. Galactomannan levels were inextricably tied to fungal invasion and were a robust measure of the antifungal effect of macrophages and amphotericin B. Neither amphotericin nor macrophages alone was able to suppress the growth of A. fumigatus; rather, the combination was required. Monte Carlo simulations showed that human dosages of amphotericin B of at least 0.6 mg/kg were required to achieve adequate drug exposure. CONCLUSIONS: This model provides a strategy by which relationships among pathogenesis, immunological effectors, and antifungal drug therapy for invasive pulmonary aspergillosis may be further understood.

Amphotericin B↗

PubMed2006

Isoniazid's bactericidal activity ceases because of the emergence of resistance, not depletion of Mycobacterium tuberculosis in the log phase of growth.

BACKGROUND: It is believed that the cessation of isoniazid's early bactericidal activity during the initial phase of antituberculosis therapy is due to the depletion of Mycobacterium tuberculosis in the exponential phase of growth. We examined the veracity of this cornerstone belief. METHODS: We used an in vitro infection model in which M. tuberculosis was exposed to isoniazid concentration-time profiles encountered in human patients. Experiments were performed to examine the time-related changes in the total bacterial population, the isoniazid-susceptible subpopulation, and the isoniazid-resistant subpopulation. RESULTS: The cessation of microbial kill occurred between days 3 and 4 of isoniazid therapy, as occurs in patients. There were multiple logs of organisms in the exponential phase of growth remaining at the time when bactericidal activity ceased. The isoniazid-susceptible subpopulation was replaced by an isoniazid-resistant subpopulation after 80 h of therapy. The size of the isoniazid-susceptible subpopulation continued to decrease after the total population had ceased to decrease, whereas the resistant subpopulation remained in the exponential phase of growth. Resistance was due to single point mutations in the catalase-peroxidase gene and to reserpine-inhibitable efflux pumps. CONCLUSIONS: The age-old hypothesis that isoniazid's microbial killing of M. tuberculosis during log-phase growth ceases because of the depletion of this bacillary population needs to be modified.

Antitubercular Agents↗

PubMed2006

Pharmacokinetics-pharmacodynamics of antimicrobial therapy: it's not just for mice anymore.

Since the advent of the modern era of antimicrobial chemotherapy in the 1930s, animal infection models have allowed for the in vivo evaluation of antimicrobial agents for the treatment of experimentally induced infection. Today, animal pharmacokinetic-pharmacodynamic (PK-PD) infection models serve as a cornerstone of the preclinical assessment process for antibacterial agents and dose and dosing interval selection, as decision support for setting in vitro susceptibility breakpoints, and, finally, for the evaluation of the meaning of in vitro resistance. Over the past 15 years, considerable PK-PD data have been derived from infected patients for many classes of antimicrobial agents. These data provide the opportunity to confirm knowledge gained from animal PK-PD infection models.

Animals↗

PubMed2006

The relationship between quinolone exposures and resistance amplification is characterized by an inverted U: a new paradigm for optimizing pharmacodynamics to counterselect resistance.

We determined the relationship between garenoxacin exposure and quinolone-resistant subpopulations for three bacterial isolates in an in vitro hollow-fiber infection model. An "inverted-U" relationship was identified wherein resistant subpopulations rose initially and then declined with increasing exposure, until reaching a threshold that prevented resistance amplifications. Different targets for the area under the concentration-time curve over 24 h/MIC ratio were required for different bacteria.

Anti-Bacterial Agents↗

PubMed2006

Effect of neutropenia and treatment delay on the response to antifungal agents in experimental disseminated candidiasis.

Disseminated candidiasis is associated with a high rate of morbidity and mortality. The presence of neutrophils and the timely administration of antifungal agents are likely to be critical factors for a favorable therapeutic outcome of this syndrome. The effect of neutropenia on the temporal profile of the burden of Candida albicans in untreated mice and those treated with amphotericin B was determined using a pharmacodynamic model of disseminated candidiasis. A mathematical model was developed to describe the rate and extent of the C. albicans killing attributable to neutrophils and to amphotericin B. The consequences of a delay in the administration of amphotericin B, flucytosine, or micafungin were studied by defining dose-response relationships. Neutrophils caused a logarithmic decline in fungal burden in treated and untreated mice. The combination of amphotericin B and neutrophils resulted in a high rate of Candida killing and a sustained anti-C. albicans effect. In neutropenic mice, 5 mg/kg of body weight of amphotericin B was required to prevent progressive logarithmic growth. An increased delay in drug administration resulted in a reduction in the maximum effect to a point at which no drug effect could be observed. Neutrophils and the timely initiation of antifungal agents are critical determinants in the treatment of experimental disseminated candidiasis.

Amphotericin B↗

PubMed2006

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.

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.

Antifungal Agents↗

PubMed2006

Anidulafungin pharmacokinetics and microbial response in neutropenic mice with disseminated candidiasis.

Candidemia is often fatal, especially in patients with persistent neutropenia. New therapies are needed. We performed 24-h pharmacodynamic studies to compare the efficacies of anidulafungin, fluconazole, and amphotericin B in neutropenic mice with disseminated candidiasis caused by one of three strains of Candida glabrata. Anidulafungin produced a maximal fungal kill (E(max)) of 1.4 to 1.9 log(10) CFU/g in kidneys and was not influenced by resistance to either fluconazole or amphotericin B. Fluconazole produced an E(max) of 1.3 log(10) CFU/g in mice infected with fluconazole-susceptible C. glabrata, but the E(max) was 0 for mice infected with a C. glabrata strain that had a fluconazole MIC of >/=32 mg/liter. Amphotericin B achieved an E(max) of 4.2 log(10) CFU/g in mice infected with amphotericin B-susceptible C. glabrata, but the E(max) was 0 for mice infected with a C. glabrata strain with an amphotericin B MIC of 2 mg/liter. In all instances, anidulafungin's maximal microbial kill was superior to that of fluconazole. Next, we performed a 96-h anidulafungin pharmacokinetic-pharmacodynamic study. Anidulafungin exhibited delayed peak concentrations in kidneys compared to those in serum, after which the concentrations declined, with a serum terminal half-life of 21.6 (+/-4.6) h. This was accompanied by a persistent 96-h decrease in the kidney fungal burden after treatment with a single anidulafungin dose of >/=8 mg/kg of body weight. This pharmacokinetic-pharmacodynamic picture of anidulafungin persistence in tissues and the resultant persistent fungal decline should be exploited to improve the efficacy of anidulafungin therapy for candidemia.

Algorithms↗

PubMed2006

Pharmacodynamic profiling of cefepime in plasma and cerebrospinal fluid of hospitalized patients with external ventriculostomies.

Population pharmacokinetic (PK) modeling and Monte Carlo simulation (MCS) were used to describe the pharmacodynamic profile of cefepime in the both plasma and cerebrospinal fluid (CSF). Plasma and CSF cefepime data were obtained from a PK study of 7 hospitalized patients with external ventricular drains. Concentration-time profiles in plasma and CSF were modeled using a 3-compartment model with zero-order infusion and first-order elimination and transfer. Estimates of the PK parameters were identified in the Big Non Parametric Adaptive Grid with adaptive gamma (BigNPAG) program of Leary, Jelliffe, Schumitzky, and Van Guilder. MCS (10,000 subjects) was performed to estimate the probability of attaining the targets of free plasma concentration (20% protein binding) and total drug CSF concentration of 50-100% T>minimal inhibitory concentration (MIC) for MICs 0.06-8 mg/L for cefepime 2 g, iv, every 8 h (0.5-h infusion); cefepime 2 g, iv, every 12 h (0.5-h infusion); and cefepime 2 g (0.5-h infusion) once and 250 mg/h continuous infusion. After the Bayesian step, the observed-predicted regression and r(2) for plasma and CNS were as follows: plasma, observed=0.984 x predicted+2.570, r(2)=0.944; CSF, observed=0.785 x predicted+0.868, r(2)=0.821. The median penetration of cefepime as measured by AUC(CSF)/AUC(plasma) was 7.8%. In the MCS, the target attainment rates in plasma for 60-70% fT>MIC were high at each MIC value between 0.03 and 8 microg/mL for each regimen examined. In CSF, none of the regimens achieved 50-100% T>MIC for>80% of patients for MICs>0.5 mg/L.

Adult↗

PubMed2006

Sex differences in CYP3A activity using intravenous and oral midazolam.

BACKGROUND: Studies examining sex differences in CYP3A activity have produced conflicting results. Our objective is to investigate whether sex differences exist in CYP3A activity as assessed by intravenous (IV) or oral midazolam pharmacokinetic analysis in healthy volunteers. METHODS: Data from 13 previous studies were used. A single dose of IV midazolam (0.025 mg/kg) was administered to 66 white adults (37 women and 29 men; mean age, 36.3+/-7.7 years). A single dose of oral midazolam, 0.075 mg/kg (5 studies), 0.15 mg/kg (1 study), or 5 mg (1 study), was administered to 72 adults (71 white and 1 Asian; 37 women and 35 men; mean age, 38.3+/-8.9 years). Pharmacokinetic parameters were determined via population methods by use of a nonparametric adaptive grid program and a 2-compartment IV and 1-compartment oral absorption model. The maximum a posteriori probability Bayesian method was used to estimate each subject's pharmacokinetic parameters. Monte Carlo simulation was performed to determine the probability distribution of the area under the concentration-time curves (AUCs). RESULTS: Women exhibited 11% higher mean weight-corrected total body midazolam clearance and 28% higher oral clearance compared with men (P<or=.01). The median AUC of IV midazolam was 0.05 mg.h/L (range, 0.02-0.14 mg.h/L) in women and 0.06 mg.h/L (range, 0.02-0.14 mg.h/L) in men. The median AUC of oral midazolam was 0.11 mg.h/L (range, 0.02-0.60 mg.h/L) in women and 0.12 mg.h/L (range, 0.04-0.45 mg.h/L) in men. CONCLUSIONS: Although women showed significantly greater hepatic and intestinal CYP3A activity, only a minor sex difference in AUC was noted. Therefore the observed disparity may be of negligible clinical importance.

Administration, Oral↗

PubMed2006

Population pharmacokinetic modeling and Monte Carlo simulation of varying doses of intravenous metronidazole.

Population pharmacokinetic modeling and Monte Carlo simulation (MCS) are approaches used to determine probability of target attainment (PTA) of antimicrobial therapy. The objectives of this study were 1) to determine a population pharmacokinetic model (PPM) using metronidazole and hydroxy-metronidazole concentrations from healthy subjects and critically ill patients, and 2) to determine the probability of attaining the pharmacodynamic target area under the plasma concentration (AUC)/MIC ratio >or=70 against 218 clinical isolates of Bacteroides fragilis using MCS. Eighteen healthy subjects were randomized to 3 dosages of intravenous metronidazole (500 mg every 8 h, 1000 mg day(-1), 1500 mg day(-1)) in an open-label 3-way crossover fashion. Serial blood samples were collected over 25.5 h on the 3rd day of each study period. An additional of 8 critically ill patients received intravenous metronidazole 500 mg every 8 h. Serial blood samples were collected over 8 h after the 2nd day of dosing. Plasma metronidazole and hydroxy-metronidazole concentrations were analyzed using a high-performance liquid chromatographic assay. The 834 plasma concentrations from 62 data sets were simultaneously modeled with Non-Parametric Adaptive Grid population modeling program. A 4-compartment model with a metabolite and zero-order infusion into the central compartment was used. The mean parameter vector and covariance matrix from PPM were inserted into the simulation module of ADAPT II. A 10,000-subject MCS was performed to determine the probability of PTA for a total drug AUC to MIC ratio >or=70 against 218 isolates of B. fragilis (MIC range, 0.125-2.0 mg L(-1)). Mean parameter values were CL(non-OH), 3.08 L h(-1); Vc, 35.4 L; K(OH), 0.04 h(-1); CL(OH), 2.78 L h(-1); and V(OH), 9.66 L. The regression values of the observed versus predicted concentrations (r2) of metronidazole and hydroxy-metronidazole were 0.972 and 0.980, respectively. The PTA for metronidazole 1500 mg day(-1) or 500 mg every 8 h (taken together) and 1000 mg day(-1) were 99.9% and 99.8%, respectively, over the reported MIC distribution range. For an MIC of 4 mg L(-1), the predicted PTA decreased to 80.0% and 28.5%, respectively. A PPM was determined by comodeling metronidazole and hydroxy-metronidazole concentrations from healthy subjects and critically ill patients. Based on this model, attainment of the target pharmacodynamic parameter (AUC/MIC ratio >or=70) against B. fragilis isolates is >99% when MICs are <2 mg L(-1), irrespective of the dosing interval of 24 h.

Administration, Intravesical↗

PubMed2006

Pharmacokinetic considerations and efficacy of levofloxacin in an inhalational anthrax (postexposure) rhesus monkey model.

Because the treatment of inhalational anthrax cannot be studied in human clinical trials, it is necessary to conduct efficacy studies using a rhesus monkey model. However, the half-life of levofloxacin was approximately three times shorter in rhesus monkeys than in humans. Computer simulations to match plasma concentration profile, area under the concentration-time curve (AUC), and time above MIC for a human oral dose of 500 mg levofloxacin once a day identified a dosing regimen in rhesus monkeys that would most closely match human exposure: 15 mg/kg followed by 4 mg/kg administered 12 h later. Approximately 24 h following inhalational exposure to approximately 49 times the 50% lethal doses of Bacillus anthracis (Ames strain), monkeys were treated daily with vehicle, levofloxacin, or ciprofloxacin for 30 days. Ciprofloxacin was administered at 16 mg/kg twice a day. Following the 30-day treatment, monkeys were observed for 70 days. Nine of 10 control monkeys died within 9 days of exposure. No clinical signs were observed in fluoroquinolone-treated monkeys during the 30 treatment days. One monkey died 8 days after levofloxacin treatment, and two monkeys from the ciprofloxacin group died 27 and 36 days posttreatment, respectively. These deaths were probably related to the germination of residual spores. B. anthracis was positively cultured from several tissues from the three fluoroquinolone-treated monkeys that died. MICs of levofloxacin and ciprofloxacin from these cultures were comparable to those from the inoculating strain. These data demonstrate that a humanized dosing regimen of levofloxacin was effective in preventing morbidity and mortality from inhalational anthrax in rhesus monkeys and did not select for resistance.

Aerosols↗

PubMed2006

Quinolone efflux pumps play a central role in emergence of fluoroquinolone resistance in Streptococcus pneumoniae.

The preferential use of older antimicrobial agents is, in general, sound public health policy and is meant to maintain susceptibility to newer agents. In the case of fluoroquinolones, however, this strategy is flawed and may actually hasten the spread of Streptococcus pneumoniae strains resistant to newer members of the class. In a mouse thigh infection model, we were unable to isolate clones of pneumococci resistant to the newer fluoroquinolone levofloxacin at 2 x or 4 x the baseline MIC. An initial exposure in vivo to the older agent, ciprofloxacin, allowed straightforward selection of clones resistant to levofloxacin in a subsequent experiment. The original ciprofloxacin exposure generated clones without changes in the parC/E and gyrA/B quinolone target sites almost exclusively but did allow overexpression of a reserpine-responsive pump. While this caused only minimal change in the levofloxacin MIC (0.6 mg/liter to 0.8 mg/liter), it allowed a major change in the mutational frequency to resistance for levofloxacin (<1/10(8.5) to approximately 1/10(4.5)), which allowed levofloxacin-resistant clones to be isolated in a subsequent in vivo experiment. The reason underlying ciprofloxacin's propensity to select for pump-overexpressed clones is likely related to its hydrophilicity. To preserve the susceptibility of Streptococcus pneumoniae to newer members of the class of quinolones, use of ciprofloxacin for community-acquired respiratory infections should be minimized.

Animals↗

PubMed2006

Application of antimicrobial pharmacodynamic concepts into clinical practice: focus on beta-lactam antibiotics: insights from the Society of Infectious Diseases Pharmacists.

In recent years there have been tremendous strides in understanding the relationship between the pharmacodynamics of beta-lactams and microbiologic response. For beta-lactams, in vitro and animal studies suggest that the amount of time in which free or non-protein-bound antimicrobial concentration exceeds the minimum inhibitory concentration (MIC) of the organism (fT>MIC) is the best predictor of bacterial killing and microbiologic response. Using population pharmacokinetic modeling and Monte Carlo simulation, it is possible to integrate pharmacokinetics, a pharmacodynamic target, and microbiologic surveillance data to generate empiric beta-lactam dosing strategies that maximize the likelihood of achieving fT>MIC associated with near maximal bactericidal effect against the range of pathogens encountered in clinical practice. At Albany Medical Center Hospital, these mathematical modeling techniques were used to devise alternative dosing schemes for piperacillin-tazobactam, meropenem, and cefepime. These alternative schemes optimized fT>MIC at a lower total daily dose than would be employed with traditional dosing methods. Moreover, they achieved the targeted fT>MIC with less administration time/day than would be needed for continuous infusion.

Anti-Bacterial Agents↗

PubMed2005

Surface response modeling to examine the combination of amphotericin B deoxycholate and 5-fluorocytosine for treatment of invasive candidiasis.

The strategy of combining antifungal drugs in a treatment regimen may improve the outcome of invasive candidiasis. Using a well-validated pharmacodynamic murine model of invasive candidiasis, we defined the effect of the combination of amphotericin B deoxycholate (AmB) and 5-fluorocytosine (5FC) by use of the Greco model of drug interaction. The combination was additive, meaning that the experimental effect did not deviate in a statistically significant manner from the null reference model (or additive surface) of the combined effect. From a clinical perspective, the addition of 5FC to a regimen of AmB may enable the near-maximum effect to be reached in circumstances in which the administration of a given dose of AmB alone produces a submaximum effect but an increase in the dose is not possible, because of dose-related toxicity. Our methods provide a way in which some of the complex issues surrounding antifungal combination treatment can be addressed.

Amphotericin B↗

PubMed2005

Bacterial-population responses to drug-selective pressure: examination of garenoxacin's effect on Pseudomonas aeruginosa.

The emergence of resistance to antibiotics is a serious problem often related to suboptimal drug dosing; such suboptimal dosing results in the preferential killing of drug-susceptible microbial subpopulations, allowing amplification of drug-resistant microbial subpopulations. We determined the effect that fluctuating concentrations of quinolone drugs have on both the total population and the resistant subpopulation of Pseudomonas aeruginosa, by employing, over a 48-h period, human pharmacokinetics and multiple regimens in an in vitro-infection model. All data were simultaneously modeled by use of 3 parallel inhomogeneous differential equations. Model parameters were used to derive the minimal, or breakpoint, drug exposure necessary to suppress amplification of the resistant subpopulation. In a prospective-validation study, we found that a drug exposure near to but below the calculated breakpoint amplified the resistant subpopulation, whereas a drug exposure at the breakpoint suppressed it. This approach allows delineation of target drug exposures (area under the concentration/time curve for 24 h : minimal inhibitory concentration [AUC(24) : MIC] = 190) that will suppress amplification of the antibiotic-resistant subpopulation, thereby preserving the susceptibility of target pathogens.

Area Under Curve↗

PubMed2005

Standardization of pharmacokinetic/pharmacodynamic (PK/PD) terminology for anti-infective drugs: an update.

Interest in the relationships between the pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobial agents has increased over recent years. Since the appearance 2 years ago of our first article describing terminology in PK/PD, the field has continued to expand rapidly, urgently requiring an update. This paper describes in a uniform manner the use of PK/PD expressions for antimicrobial agents, and their units.

Anti-Infective Agents↗