Fosfomycin as a potential therapy for the treatment of systemic infections: a population pharmacokinetic model to simulate multiple dosing regimens.

Fosfomycin has emerged as a potential therapy for multidrug-resistant bacterial infections. In most European countries, the oral formulation is only approved as a 3 g single dose for treatment of uncomplicated cystitis. However, for the treatment of complicated systemic infections, this dose regimen is unlikely to reach efficacious serum and tissue concentrations. This study aims to investigate different fosfomycin-dosing regimens to evaluate its rationale for treatment of systemic infections. Serum concentration-time profiles of fosfomycin were simulated using a population pharmacokinetic model based on published pharmacokinetic parameter values, their uncertainty, inter-individual variability and covariates. The model was validated on published data and used to simulate a wide range of dosing regimens for oral and intravenous administration of fosfomycin. Finally, based on the minimum inhibitory concentration for E. coli, surrogate pharmacodynamic indices were calculated for each dosing regimen. This is the first population pharmacokinetic model to describe the oral pharmacokinetics of fosfomycin using data from different literature sources. The model and surrogate pharmacodynamic indices provide quantitative evidence that a dosing regimen of 6-12 g per day divided in 3 doses is required to obtain efficacious exposure and may serve as a first step in the treatment of systemic multi-drug-resistant bacterial infections.

Intrapleural extravasation of epirubicin, 5-fluouracil, and cyclophosphamide, treated with dexrazoxane.

The extravasation of DNA-binding vesicant drugs, such as epirubicin, is a feared complication of chemotherapy and can lead to extensive damage at injury sites. We describe a 56-year-old woman with breast cancer who received adjuvant chemotherapy after a breast-preserving surgical procedure. Due to catheter tip misplacement, epirubicin, 5-fluouracil, and cyclophosphamide were administered intrapleurally. To minimize long-term sequelae, flushing of the cavities and systemic administration of steroids were performed. Besides this treatment, empirically, 3-day therapy with dexrazoxane was added to prevent tissue damage and the risk of cardiac damage. Because of the potential benefits of dexrazoxane and its relatively mild side effects, its use should be considered in cases of the intrapleural extravasation of anthracyclines. We do emphasis the need for stringent surgical and oncological nursing procedures when using central venous access catheters in oncology.