Antibiotic use in the emergency department. IV: Single-dose therapy and parenteral-loading dose therapy

Fever and the rational use of antimicrobials in the emergency department

Any patient presenting to the emergency department (ED) with fever triggers consideration of the administration of an antimicrobial. Empiric antimicrobial therapy has become a cornerstone of treatment. Frequently, the decision to initiate empiric treatment needs to be made before the definitive diagnosis is known. In such cases, an organized approach is helpful. This article aims to provide a systems-based approach to prescribing antimicrobials to patients presenting to the ED with fever, while understanding the risk associated with overutilization. An understanding of the key considerations is needed to ensure that decisions are made well and appropriate treatment begins promptly.

Dose findings of antofloxacin hydrochloride for treating bacterial infections in an early clinical trial using PK-PD parameters in healthy volunteers

AIM

To find an appropriate dose regimen of the novel antibacterial agent antofloxacin for a phase II clinical trial using a population pharmacokinetic (PPK) study in healthy volunteers and the minimum inhibitory concentration (MIC) as pharmacodynamic (PD) parameters.

METHODS

Twenty-four healthy volunteers were enrolled in a double-blind crossover study and received antofloxacin (200 or 400 mg/d, po) for consecutive 5 d with 10 d washout between two separate periods. Blood concentrations were analyzed using HPLC with a UV-Vis detector. The values of area under the curve (AUC) with covariates were obtained from a PPK model, and the MICs came from the previous in vitro studies. The dose regimen was determined for the phase II clinical trial according to the ratio (>20) of AUC/MIC, and the efficacy of the dose was evaluated by the trial.

RESULTS

A two-compartment model best described the time-concentration data with first-order absorption. The PPK parameter estimates for CL, V(c), Q, V(p) and K(A) are 8.34 L/h, 142 L, 15.9 L/h, 52.2 L and 4.64 1/h, respectively. The covariates sex for K(A), weight for CL, weight for V(c) and interoccasion variability were included in the final model. The AUC/MIC was calculated based on the PPK model and the MIC of antofloxacin for Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus and Staphylococcus epidermidis were determined in previous researches. The 400 mg loading dose with 200 mg/d maintenance dose was recommended and confirmed by the phase II trial.

CONCLUSION

The ratio of AUC from the PPK model vs MIC as the PD parameter can be applied in a dose-finding trial of antofloxacin in treatment of bacterial infections. The PPK model suggests that sex and body weight may be considerations in regards to individual therapy, which should be investigated in larger clinical trials and serve as a potential reference for clinical therapies.

Loading doses for costly cancer biologicals: sound pharmacology or unnecessary extravagance?

The rising cost of new molecularly-targeted anticancer drugs has become a major issue in oncology. One small but significant factor contributing to this problem is the routine co-administration of loading doses, which may inflate the cost of the first treatment by as much as US$1000. Here, we question the cost-effectiveness of this practice in cancer patients on several grounds, including non-urgent pace of disease, lack of evidence for survival benefit, weak dose-dependency of biopharmaceutical efficacy in cancer and the unproven validity of the 'volume of distribution' concept applied to target-specific drugs.

Outpatient parenteral antibiotic therapy in the management of community-acquired lower respiratory infections

Within the past several years, the decision to employ outpatient parenteral antibiotic therapy (OPAT) is driven by adequacy of insurance, availability of appropriate resources within the community, and the clinical stability of the patient. Current dogma is that virtually any diagnosed disease can be treated outside the hospital, provided the former criteria are met. The decision to utilize OPAT is complex and involves a number of decision points that relate to the patient, the disease and pathogen, the antibiotic, and the facilities available in the community. This article discusses the decision-making process to utilize OPAT or hospitalization for community-acquired lower respiratory infections.