Effects of prior effective therapy on the efficacy of daptomycin and ceftriaxone for the treatment of community-acquired pneumonia.

OBJECTIVE: We sought to compare daptomycin with ceftriaxone for the treatment of patients with community-acquired pneumonia (CAP). METHODS: Two phase-3 randomized, double-blind trials that enrolled adult patients hospitalized with CAP were conducted. Patients received intravenous daptomycin (4 mg/kg) or ceftriaxone (2 g) once daily for 5-14 days. Aztreonam could be added for patients with gram-negative infections. Clinical responses at the test-of-cure visit among patients in the intent-to-treat and clinically evaluable populations were the primary efficacy end points. RESULTS: After combining data from the trials, the intent-to-treat population included 413 daptomycin-treated patients and 421 ceftriaxone-treated patients, and the clinically evaluable population included 369 daptomycin-treated patients and 371 ceftriaxone-treated patients. In the intent-to-treat population, the clinical cure rate among daptomycin-treated patients with CAP was 70.9%, compared with 77.4% among ceftriaxone-treated patients (95% confidence interval for the difference between cure rates, -12.4% to -0.6%). In the clinically evaluable population, the clinical cure rate was lower among daptomycin-treated patients (79.4%) than among ceftriaxone-treated patients (87.9%; 95% confidence interval for the difference between cure rates, -13.8% to -3.2%). A posthoc analysis revealed that, among those who had received up to 24 h of prior effective therapy, cure rates were similar among daptomycin-treated (90.7%) and ceftriaxone-treated patients (88.0%; 95% confidence interval for the difference between cure rates, -6.1% to 11.5%). CONCLUSIONS: Daptomycin is not effective for the treatment of CAP, including infections caused by Streptococcus pneumoniae and Staphylococcus aureus. The observation that as little as 24 h of prior effective therapy may impact clinical outcome suggests that trials to evaluate CAP treatment may need to exclude patients who have received any potentially effective therapy before enrollment.

Pharmacokinetics and tolerability of daptomycin at doses up to 12 milligrams per kilogram of body weight once daily in healthy volunteers.

Daptomycin, a novel lipopeptide, is bactericidal against a broad range of gram-positive strains, including methicillin- (MRSA) and vancomycin-resistant Staphylococcus aureus. Daptomycin is approved at 4 mg/kg of body weight given intravenously once daily for the treatment of complicated skin and skin structure infections and at 6 mg/kg for the treatment of S. aureus bloodstream infections (bacteremia), including right-sided endocarditis caused by methicillin-susceptible S. aureus and MRSA. The present study was designed to evaluate the multiple-dose pharmacokinetics and safety of daptomycin at doses of 6 to 12 mg/kg in healthy volunteers. Three cohorts of 12 subjects each were given daptomycin (10 mg/kg) or placebo once daily for 14 days, daptomycin (12 mg/kg) or placebo once daily for 14 days, or daptomycin (6 or 8 mg/kg) once daily for 4 days. Daptomycin produced dose-proportional increases in the area under the plasma concentration-time curve and in trough daptomycin levels and nearly dose-proportional increases in peak daptomycin concentrations. Other pharmacokinetic parameters measured on day 1 and at steady state were independent of the dose, including the half-life (approximately 8 h), weight-normalized plasma clearance (9 to 10 ml/h/kg), and volume of distribution (approximately 100 ml/kg). Plasma protein binding was 90% to 93% and was independent of the daptomycin concentration. Daptomycin did not produce electrocardiographic abnormalities or electrophysiological evidence of muscle or nerve toxicity. Daptomycin was well tolerated in subjects dosed with up to 12 mg/kg intravenously for 14 days. Doses of daptomycin higher than 6 mg/kg once daily may be considered in further studies to evaluate the safety and efficacy of daptomycin in difficult-to-treat infections.