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

Enrollment will take place at 3-5 clinical sites in the United States. 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.

Inclusion criteria

• This study will be conducted in adult critically ill patients receiving CVVHDF who are prescribed daptomycin 6mg/kg once daily as part of required medical care for suspected/documented infection, as deemed necessary by his or her treating clinician.

Exclusion criteria

• Daptomycin therapy will be chosen by the treating physician based on clinical indication and it is expected that risks of therapy will have already been considered; therefore, subjects are only to be excluded based on covariates that are expected to affect pharmacokinetics. Subjects will be excluded if they are:

• less than 18 years of age
• producing urine greater than 50 ml per 24 hours
• have a life expectancy less than 96 hours
• receiving CVVHDF utilizing rates or filters that are NOT otherwise considered "standard" by the enrolling site
• receive less than 3 doses of daptomycin
• participating in any other study