Evaluation of Daptomycin Exposure and Efficacy and Safety Endpoints To Support Risk-versus-Benefit Considerations.

The choice of an antimicrobial agent must balance optimization of efficacy endpoints with the minimization of safety events. The risk versus benefit of daptomycin for patients with Staphylococcus aureus bacteremia with or without infective endocarditis receiving daptomycin at 6, 8, and 10 mg/kg of body weight/day was assessed. The relationships between the area under the concentration-time curve over 24 h (AUC)/MIC ratio and both clinical response and time to decreased susceptibility were evaluated using data from patients with such infections who received daptomycin at 6 mg/kg/day. Using these relationships, plus the previously identified relationship between the minimum concentration and an elevation in the creatine phosphokinase (CPK) concentration (CPK elevation) (S. M. Bhavnani, C. M. Rubino, P. G. Ambrose, and G. L. Drusano, Clin Infect Dis 50:1568-1574, 2010) and Monte Carlo simulation, the probability of each outcome by MIC for daptomycin at 6, 8, and 10 mg/kg/day was calculated. The function for exposure-response relationships for clinical response (P = 0.06) and time to decreased susceptibility (P = 0.01) resembled U and inverted U shapes, respectively. Multivariable analyses demonstrated AUC/MIC ratio, creatinine clearance, albumin concentration, and disease category to be predictors of clinical response. The results of simulations failed to demonstrate large improvements in the probabilities of clinical success among cohorts of simulated patients defined by the above-described predictive factors or the probability of decreased susceptibility at 30 days when the daptomycin dose was increased from 6 to 10 mg/kg/day. The probability of CPK elevation increased from 0.073 to 0.156 over this dose range. These data can be used to inform risk-versus-benefit decisions for daptomycin dose selection in patients with S. aureus bacteremia with or without infective endocarditis. The risk of CPK elevation, which is reversible, should be weighed in the context of the mortality and severe morbidity associated with these types of serious staphylococcal infections.

Statins and daptomycin: safety assessment of concurrent use and evaluation of drug interaction liability.

BACKGROUND: Acute muscle injury and potentially fatal rhabdomyolysis may occur with use of statins and certain interacting medications. This investigation assessed risk for myopathy in patients receiving treatment with a statin in combination with daptomycin, a medication also associated with muscle injury. METHODS: Patients hospitalized from July 1, 2005, through June 30, 2010, who received simvastatin or rosuvastatin concurrently with daptomycin were identified and their medical records were examined. Patients were judged to have treatment-related muscle injury if their records contained evidence of myalgia with or without weakness and secondarily impaired mobility together with elevated creatine kinase (CK) levels. These assessments were compared with similar data from hospitalized patients who received a statin alone. RESULTS: A total of 52 patients received 66 courses of concurrent treatment with simvastatin or rosuvastatin and daptomycin. Of these, no patient (0%) met evidentiary requirements for diagnosis of myopathy or related complications. No patient (0%) developed muscle pain or discomfort and none developed markedly elevated CK levels. The incidence of asymptomatic elevations of CK in these simvastatin or rosuvastatin plus daptomycin recipients (9%) was statistically indistinguishable from the incidence of CK elevations found in a cohort of 105 inpatients who received simvastatin or rosuvastatin alone (21%; p=0.135). CONCLUSIONS: In patients receiving treatment with simvastatin or rosuvastatin and daptomycin, no symptoms or objective evidence of muscle injury attributable to a drug interaction were identified. These findings are consistent with data indicating that the myopathic effects of statins and daptomycin are incited by disparate and perhaps unique pharmacological mechanisms. Risk of muscle injury therefore appears to be no greater when a statin is administered with daptomycin than when either medication is used alone.

[Pharmacoeconomic analysis of the treatment of methicillin-resistant Staphylococcus aureus with daptomycin or vancomycin]. / Análisis farmacoeconómico del tratamiento de la bacteriemia por Staphylococcus aureus resistente a meticilina con daptomicina y vancomicina.

INTRODUCTION: The increased morbidity, mortality and high costs associated with bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) is a major public health problem. Pharmacoeconomic analysis was performed to compare the efficiency of daptomycin (DAP) against vancomycin (VAN) in the treatment of this infection. METHODS: Retrospective, deterministic and probabilistic cost-effectiveness analysis. The effectiveness of the treatments was estimated from the results of a randomized clinical trial, which compared DAP (6 mg / kg IV daily) and VAN (1 g IV every 12 hours), both with or without gentamicin (1 mg / kg IV every 8 hours). Resource utilization was estimated from the clinical trial of the drug datasheets and Spanish sources, the unit costs were obtained also from Spanish sources. Monte Carlo probabilistic analysis and deterministic analysis were performed. RESULTS: The clinical trial cure rates were higher with DAP (44.4%, 95% CI 43.5 to 45.4%) than with VAN (31.8%, 95% CI 30.9 to 32.7%) not statistically significant (p = 0.2203) but with economic impact. With DAP would occur less costs due to treatment failure (rescue antibiotics, additional tests, prolonged hospital stay and adverse reactions) than with VAN. In the base case the average cost of disease per patient was € 12,329 to € 12,696 with DAP and VAN (difference of 367 €). DAP treatment was dominant (more effective, with lower costs than VAN) both in the deterministic and probabilistic analysis. In the Monte Carlo simulation, DAP was the most cost-effective treatment in 100% of the 10,000 simulations, for a willingness to pay € 12,000 per additional cure (approximate cost of MRSA bacteraemia episode). CONCLUSIONS: According to this model, daptomycin is more cost-effective than vancomycin in treating MRSA bacteremia. The higher cost of acquisition of daptomycin does not imply a higher cost of treating this infection.

[Daptomycin: revitalizing a former drug due to the need of new active agents against grampositive multiresistant bacterias]. / Daptomicina: revitalizando un antiguo fármaco ante la necesidad de nuevos agentes activos frente a bacterias grampositivas multirresistentes.

The development of mechanisms of resistance of many Gram-positive bacterial strains that cause complicated skin and soft tissue infections, as well as sepsis and bacteremia, has necessitated the search for new drugs that will improve treatment strategies. Daptomycin is a cyclic lipopeptide antibacterial that was launched for the treatment of complicated skin and soft tissue infections caused by Gram-positive organisms. The drug's mechanism of action is different from that of any other antibiotic. It binds to bacterial membranes and causes a rapid depolarization of membrane potential. This loss of membrane potential causes inhibition of protein, DNA and RNA synthesis, which results in bacterial cell death. The in vitro spectrum of activity of daptomycin encompasses most clinically relevant aerobic Gram-positive pathogenic bacteria. Compared to other antibiotics with a similar antibacterial spectrum, daptomycin does not cause nephrotoxicity. Taking these and other characteristics into consideration, daptomycin appears to be a good alternative to other drugs used in the treatment of complicated skin and soft tissue infections and in Gram-positive bacteremial infections.