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.Daptomycin is the first member of the novel cyclicallipopeptide class, which provides rapid, concentration-dependent bactericidal activity against a broad range of gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) (2, 6, 9, 10). Daptomycin causes bacterial cell death by a mechanism unique among available antimicrobial agents (8,11). It binds to the cell membranes of gram-positive bacteria, thereby disrupting their membrane potential, initiating potassium efflux with rapid cell death.The safety and efficacy of daptomycin in treating complicated skin and skin structure infections were demonstrated in two randomized, controlled clinical trials (1). When administered at a dose of 4 mg/kg of body weight intravenously once daily for 7 to 14 days, daptomycin provided clinical success rates comparable to those of vancomycin and penicillinaseresistant penicillins and showed safety and tolerability similar to those of the comparators. On the basis of these studies, daptomycin was approved by the FDA and the European Medicines Agency for the treatment of complicated skin and skin structure infections caused by susceptible gram-positive strains, including MRSA (3). Because of its antibacterial profile, daptomycin may also b...

The pharmacokinetics and safety of ceftolozane, a novel cephalosporin, and tazobactam, a ␤-lactamase inhibitor, alone and in combination as a 2:1 ratio in single doses of up to 2,000 and 1,000 mg of ceftolozane and tazobactam, respectively, and multiple doses of up to 3,000 and 1,500 mg of ceftolozane and tazobactam, respectively, per day were evaluated in healthy adult subjects. In part 1, groups of six subjects each received single ascending doses of ceftolozane, tazobactam, and ceftolozane-tazobactam in a within-cohort crossover design. In part 2, groups of 5 or 10 subjects each received multiple doses of ceftolozane, tazobactam, or ceftolozane-tazobactam for 10 days. After a single dose of ceftolozane alone, the ranges of mean values for half-life (2.48 to 2.64 h), the total clearance (4.35 to 6.01 liters/h), and the volume of distribution at steady state (11.0 to 14.1 liters) were consistent across dose levels and similar to those observed when ceftolozane was coadministered with tazobactam. Mean values after multiple doses for ceftolozane alone and ceftolozane-tazobactam were similar to those seen following a single dose. The pharmacokinetics of the dosing regimens evaluated were dose proportional and linear. Ceftolozane-tazobactam was well tolerated and systemic adverse events were uncommon. Mild infusion-related adverse events were the most commonly observed following multiple-dose administration. Adverse events were not dose related, and no dose-limiting toxicity was identified.T he emergence of drug resistance in common pathogens has become a major medical issue; increased resistance in Gram-negative pathogens, such as Pseudomonas aeruginosa and extended-spectrum ␤-lactamase (ESBL)-producing Enterobacteriaceae, is especially concerning due to the increased morbidity and mortality associated with such infections (5). However, the number of antimicrobial products currently being developed to address these unmet medical needs appears to be limited (1).Ceftolozane-tazobactam, formerly referred to as CXA-201, is a novel oxyimino-aminothiazolyl cephalosporin (ceftolozane) and ␤-lactamase inhibitor (tazobactam) combination being developed for the treatment of serious Gram-negative infections (6,7,8). The addition of tazobactam extends its spectrum of activity to cover ESBL-producing organisms. The pharmacokinetics (PK) and safety of multiple doses of ceftolozane alone has already been established (3) but needs to be investigated for the coadministration of ceftolozane and tazobactam. In the present study, the PK and safety of single and multiple doses of ceftolozane and tazobactam alone and in combination at a 2:1 ratio were investigated in healthy adult subjects. MATERIALS AND METHODSStudy population and study design. Healthy male and female subjects, 18 to 65 years of age, were enrolled in a single-center, prospective, randomized, double blind study of single ascending doses (part 1) and multiple ascending doses (part 2) of intravenous (i.v.) ceftolozane, tazobactam, and ceftolozane-tazobactam. In part 1, t...

We found that the HDSD regimen had a safety profile similar to that seen in previous studies. Although the differences were not statistically significant, clinical success rates for comparator were higher than for daptomycin. In post hoc analyses HDSD daptomycin performed better in some subgroups (e.g. outpatients) than in others (e.g. certain MRSA infections). These observations require confirmation in larger trials.

Plasma concentrations of oxycodone, oxymorphone, and noroxycodone were determined after administration of 20 mg oral controlled-release oxycodone tablets to four subject groups: young (aged 21 to 45 years) men, elderly (aged 65 to 79 years) men, young women, and elderly women. Area under the oxycodone and noroxycodone concentration-time curve (AUC) values were comparable among the four groups. Compared with oxycodone, the oxymorphone AUC values were small, with significant differences between subject groups. AUC values were also calculated for the pharmacodynamic variable "drug effect," scored on a 100 mm visual analog scale. The two groups with the highest oxycodone AUC values (young and elderly women) had the lowest oxymorphone AUC values and the greatest drug effect AUC values. The two groups with the lowest oxycodone AUC values (young and elderly men) had the highest oxymorphone AUC values and the lowest drug effect AUC values. These results support oxycodone, and not oxymorphone, as being primarily responsible for pharmacodynamic and analgesic effects.

A single administration of bupivacaine-dexamethasone microspheres produces an effective chest wall analgesia of several days' duration. This may prove useful clinically for thoracic surgery or trauma.