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M E Klepser

Publications and source records attributed to M E Klepser.

44 records · Page 3Linked to original sources
PubMed1995

Clinical pharmacokinetics of newer cephalosporins.

Several new cephalosporins have been developed in recent years. These agents include several oral and parenteral agents with extended activity against Gram-negative pathogens. The pharmacokinetic literature for these agents is quite extensive; therefore, we have summarised this information and presented it in tabular form for critical comparison. With a few exceptions, the newer cephalosporins share similar pharmacokinetic properties. Cefixime, cefetamet pivoxil and ceftibuten differ from the others in that they exhibit nonlinear pharmacokinetic properties. The nonlinear nature of these agents is reflected by decreasing maximal concentrations with escalating doses of cefixime and cefetamet pivoxil, decreasing area under the serum concentration-time curve with increasing doses for cefixime, and a reduced bioavailability with large doses of ceftibuten. Attention to such characteristics aid the clinician in selecting appropriate dosage regimens that will optimise drug absorption. The majority of agents are primarily renally eliminated; however, renal elimination accounts for only 20% of cefixime elimination. The pharmacokinetic parameters noted for the newer cephalosporins are not influenced by multiple-dose administration, suggesting lack of drug accumulation over time. The pharmacodynamics of antimicrobials should be considered when extrapolating pharmacokinetic information into the clinical arena. In the case of the beta-lactams, the time which drug concentrations remain above some critical threshold, such as the minimal inhibitory concentration, appears to have the greatest influence on bactericidal activity. Therefore, it is important to select dosage regimens that will optimise the time serum concentrations remain above this threshold. We present an evaluation of these agents with respect to their activity against a variety of pathogens in an effort to demonstrate a pharmacokinetically-based process of antimicrobial selection.

Animals↗
PubMedDate not supplied

Antifungal dynamics of LY 303366, an investigational echinocandin B analog, against Candida ssp.

Two isolates each of Candida albicans, Candida tropicalis, and Candida glabrata were selected for time-kill curve testing against LY 303366 at concentrations ranging from 0.125 x MIC to 16 x MIC. RPMI 1640 buffered morpholinepropanesulfonic acid (MOPS) was utilized as growth medium. Samples were obtained at predetermined time points over 24 hours and streaked for colony count determination. Against C. albicans (one strain) and C. glabrata isolates, LY 303366 exhibited fungicidal (> or = three log10 reduction in CFU) activity. In contrast, fungistatic activity was observed with LY 303366 against C. albicans (one strain) and C. tropicalis isolates at all of the multiples of the MIC tested. With the exception of one C. glabrata strain, the rate and extent of activity against test isolates was not enhanced with concentrations exceeding the MIC. Our data indicate that maximal antifungal activity with LY 303366 may be achieved by optimizing the time of fungal exposure to the drug. Additionally, these data suggest that use of the current interpretive endpoint for MICs in RPMI may underestimate the antifungal activity of LY 303366. Thus, the MIC endpoint may need to be re-evaluated, or perhaps an alternative media, such as antibiotic medium #3, should be utilized for determination of LY 303366 MICs.

Anidulafungin↗
PubMedDate not supplied

Oral absorption of trimethoprim-sulfamethoxazole in patients with AIDS.

STUDY OBJECTIVE: To determine the bioavailability of trimethoprim-sulfamethoxazole (TMP-SMX) in patients infected with the human immunodeficiency virus (HIV). DESIGN: Open-label, randomized, two-way crossover trial. SETTING: Outpatient clinical research center affiliated with a community-based teaching hospital. PATIENTS: Ten individuals diagnosed with the acquired immunodeficiency syndrome (AIDS) with CD4+ counts less than 200 cells/mm3, receiving TMP-SMX one double-strength tablet 3 times/week as prophylaxis for Pneumocystis carinii pneumonia (PCP), and without documented gastroenteropathy or diarrhea agreed to participate in the trial. One patient withdrew from the study secondary to development of symptomatic PCP. Data were available for analysis from the remaining nine subjects. INTERVENTIONS: Participants received TMP 160 mg and SMX 800 mg orally or intravenously during two study periods. Following dose administration, blood samples were collected at predetermined time points over 36 hours. MEASUREMENTS AND MAIN RESULTS: Analysis of TMP-SMX pharmacokinetic parameters (half-life, total body clearance, area under the serum concentration versus time curve, and peak concentration) failed to reveal any significant differences between intravenous and oral preparations. The calculated bioavailabilities of oral TMP and SMX (mean +/- SD) were 102.7% +/- 19.8% and 109.4% +/- 19.4%, respectively. CONCLUSION: The absorption of TMP-SMX is not adversely affected by HIV infection in the absence of HIV-induced gastroenteropathy or diarrhea.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Pharmacoeconomic impact of once-daily aminoglycoside administration.

A retrospective cost analysis compared hospital costs of standard gentamicin dosing and once-daily regimens in 1127 patients. Hospital costs compared were drug/supply/preparation/administration (DSPA; $4.56/500 mg once-daily dose and $3.32/100 mg every 8 hrs standard dose); therapeutic drug monitoring (TDM) ($25/gentamicin level); and nephrotoxicity management. The mean length of therapy was 4.5 days with both regimens. The mean number of blood samples drawn to measure drug levels was 0.65 for once-daily dosing and 1.7 for standard dosing. Mean DSPA and TDM costs/patient for a 4.5-day course of once-daily therapy were $20.52 and $16.25, respectively ($36.77/course of therapy). In comparison, estimated mean DSPA and TDM costs for 4.5 days standard therapy were $44.82 and $42.50, respectively ($87.32/course of therapy). We observed an overall reduction in nephrotoxicity from approximately 4% to 1.2% with the once-daily program, resulting in a nephrotoxicity management cost reduction from $182 to $55/patient exposed to aminoglycosides. The once-daily program resulted in a 58% reduction in aminoglycoside-associated hospital cost and a nephrotoxicity management savings of 70%/patient.

Anti-Bacterial Agents↗
PubMedDate not supplied

Update on clinical antifungal susceptibility testing for Candida species.

With the emergence of fungi as important nosocomial pathogens, increasing reports of antifungal resistance, and expanding drug therapy options, the need for clinically relevant antifungal susceptibility testing is evident. Over the last decade, the National Committee for Clinical Laboratory Standards (NCCLS) worked to standardize procedures for in vitro susceptibility testing of Candida species against fluconazole, itraconazole, 5-fluorocytosine, and amphotericin B. With the establishment of a reproducible methodology, correlation of antifungal susceptibility in vitro with clinical outcome is a priority. The NCCLS proposed susceptibility breakpoints for the three agents against Candida species, with breakpoints for amphotericin B forthcoming. These breakpoints could provide useful guidance in some clinical situations involving azole or 5-fluorocytosine therapy; however, routine susceptibility testing of fungal isolates should be discouraged.

Antifungal Agents↗
PubMedDate not supplied

Comparison of bactericidal activities of intermittent and continuous infusion dosing of vancomycin against methicillin-resistant Staphylococcus aureus and Enterococcus faecalis.

STUDY OBJECTIVE: To describe the pharmacokinetic profiles of vancomycin administered by continuous infusion and intermittent dosing and compare the duration of activity of the regimens. DESIGN: Randomized, open-label, crossover study. SETTING: Clinical research center at an academic medical center. SUBJECTS: Twelve healthy, nonpregnant volunteers age 27.6 +/- 2.3 years. INTERVENTION: Subjects received the following intravenous vancomycin regimens: 1 g every 12 hours; 2 g continuous infusion over 24 hours; and 1 g continuous infusion over 24 hours. Dosages were administered with and without gentamicin 2 mg/kg. MEASUREMENTS AND MAIN RESULTS: Serum samples were collected, drug concentrations determined, and bactericidal activity measured against two isolates each of methicillin-resistant Staphylococcus aureus and Enterococcus faecalis. Subjects had poor tolerability for continuous infusions. Trough concentration for the intermittent regimen was 5.5 +/- 1.9 mg/ml, and steady-state concentrations were 8.8 +/- 1.6 and 16.9 +/- 1.9 mg/ml for 1 and 2 g continuous infusions, respectively. In general, all regimens provided bactericidal activity throughout the study interval. Against one isolate of E. faecalis, 2 g continuous infusion plus gentamicin provided cidal activity for a significantly greater percentage of the dosing interval (p<0.001). CONCLUSION: Continuous infusion does not greatly improve the activity of vancomycin and should not be routinely administered. However, it may prove useful against isolates with reduced susceptibility to the agent.

Adult↗