Daptomycin Study - Collection of Pharmacokinetic Samples in Patients With Renal Failure

This will be a prospective, multicenter, open-labeled, non-comparative pharmacokinetic study conducted in 10 critically ill, anuric patients receiving CVVHDF. Enrollment will take place at 3-5 clinical sites in the United States. A study coordinator at each site will be identified and institutional specific processes (e.g., pharmacy records, etc.) will be utilized to identify patients. Full evaluation of inclusion and exclusion criteria will be conducted by each site's coordinator within 48 hours of initiation of daptomycin therapy. Subjects receiving daptomycin 6mg/kg (total body weight) once daily for a suspected/documented infection, as deemed necessary by the treating clinician will be screened for inclusion in the current study. Dialysate, ultrafiltrate, and blood flow rate utilized during the CVVHDF procedure will be determined by clinicians at discretion to optimize stability of patients. Daptomycin samples will be obtained around the third dose in an attempt to achieve approximate steady-state concentrations. Pre- and post-filter blood samples will be collected simultaneously with dialysate and ultrafiltrate specimens at multiple time points. Protein binding will be assessed by filtration of the serum samples at the peak drug concentration time points.