High-dose daptomycin in documented Staphylococcus aureus infections

Daptomycin is approved at a dose of 4-6 mg/kg/day for the treatment of complicated skin and soft-tissue infection and Staphylococcus aureus bloodstream infection. Clinical experience with doses >6 mg/kg/day is limited, but data reported to date suggest that daptomycin can be safe and effective at higher doses. We describe our experience with daptomycin at doses >6 mg/kg/day and ≤6 mg/kg/day for S. aureus infections. A retrospective chart review of all patients treated with daptomycin from January 2008 to 28 February 2010 was performed. During the study period, 53 patients received daptomycin, including 22 patients receiving daptomycin at a standard dose (SD) (mean 5 mg/kg/day, range 4-6 mg/kg/day) and 31 patients receiving a higher dose (HD) (mean 8 mg/kg/day, range 7-9 mg/kg). The median treatment duration was 13.5 days and 19 days for the SD and HD groups, respectively. Clinical success was observed in 16/22 patients (73%) in the SD group and 29/31 patients (94%) in the HD group (P=0.05). Microbiological success was observed in 13/19 patients (68%) and 27/29 patients (93%) in the SD and HD groups, respectively (P<0.05). Of the 53 patients, 2/22 treated with SD daptomycin and 3/31 treated with HD daptomycin experienced a grade 1 adverse event while receiving therapy (i.e. anaemia, diarrhoea, nausea, hypokalaemia and arthralgia) but did not require discontinuation of daptomycin treatment. These results suggest that daptomycin may be used at doses higher than 6 mg/kg/day without toxicity and possibly with better outcome than conventional doses. We recommend further randomised controlled prospective studies with higher doses of daptomycin.