The pharmacokinetics (PK) of daptomycin has not been previously characterized in Japanese pediatric patients with complicated skin and soft tissue infections (cSSTI) or bacteremia. An aim of the study including evaluation of PK of daptomycin in Japanese pediatric patients and an appropriateness of the age-specific, weight-based dosing regimens in Japanese pediatric patients based on PK comparison with Japanese adult patients.

The phase 2 trial enrolled Japanese pediatric patients (age 1–17 years) with cSSTI (n = 14) or bacteremia (n = 4) caused by gram-positive cocci in order to evaluate safety, efficacy and PK. The Phase 3 trial in Japanese adult patients (SSTI n = 65, septicemia/right-sided infective endocarditis (RIE) n = 7) was referred to for PK comparison between adult and pediatric. Daptomycin concentrations in plasma were analyzed by reverse-phase high-performance liquid chromatography (HPLC). PK parameters were determined using non-compartmental analysis in Japanese pediatric and Japanese adult patients. The exposures in Japanese pediatric patients were graphically compared with those in Japanese adult patients. The relationship between daptomycin exposures and creatine phosphokinase (CPK) elevation was explored visually.

Following administration of the age-specific, weight-based dosing regimens, daptomycin exposures were overlapping across age groups in pediatric patients with cSSTI with similar observations based on clearance. The distribution of individual exposure in Japanese pediatric patients was overlapping with that in Japanese adult patients. No apparent relationship between daptomycin exposures and CPK elevation in Japanese pediatric patients was observed.

The results suggested that the age-specific, weight-based dosing regimens are considered to be appropriate in Japanese pediatric patients.