A thorough QT study with dalbavancin: A novel lipoglycopeptide antibiotic for the treatment of acute bacterial skin and skin-structure infections

Dalbavancin in the treatment of acute bacterial skin and skin structure and other infections: a safety evaluation

INTRODUCTION

Dalbavancin is a second-generation lipoglycopeptide that was approved since 2014 to treat acute bacterial skin and skin-structure infections (ABSSSI). Dalbavancin is characterized by Gram-positive activity and novel pharmacokinetic properties that result in a prolonged terminal half-life, allowing once weekly dosing in adults. A good safety profile was reported by randomized clinical trials and meta-analyses.

AREAS COVERED

Dalbavancin safety and tolerability data from trials and post-marketing studies were reviewed. While most trials included predominantly ABSSSI, 2 clinical trials and recent observational studies have explored the use of dalbavancin for off-label indications, mainly including bloodstream and osteoarticular infections.

EXPERT OPINION

The occurrence of drug-related adverse effects (AE) was similar between dalbavancin and comparators in clinical trials enrolling patients with ABSSSI. Most common AE included gastrointestinal symptoms, infusion reaction, and hypersensitivity. Low rates of drug discontinuation and serious AE were reported across studies. In the past 5 years, several observational studies have reported safety data on the use of dalbavancin, confirming its favorable safety profile. Nevertheless, data from dalbavancin off-label use often derived from prolonged (> 2 weeks) treatments with variable dosing regimens, were mainly retrospective, and lacked comparators. Further research is required to allow a reliable analysis of short- and long-term dalbavancin-related AE in non-ABSSSI.

Validation and Clinical Application of a New Liquid Chromatography Coupled to Mass Spectrometry (HPLC-MS) Method for Dalbavancin Quantification in Human Plasma

Dalbavancin (DBV) is an intravenous long-acting second-generation glycolipopeptide antibiotic with high efficacy and excellent tolerability, approved for use in the treatment of Gram-positive skin and skin structure infections (ABSSSI). Nevertheless, little is known about its pharmacokinetic/pharmacodynamic (PK/PD) properties in real life, which is also due to technical challenges in its quantification in human plasma, preventing an effective application of therapeutic drug monitoring (TDM). In fact, DBV has a high affinity to plasma proteins, possibly resulting in poor recovery after extraction procedure. The aim of this study was to validate a simple, cheap and reliable HPLC-MS method for use in TDM, in accordance with FDA and EMA guidelines. The optimized protein precipitation protocol required 50 μL of plasma, while chromatographic analysis could be performed in 12 min/sample. This method fulfilled the guidelines requirements and then, it was applied for routine DBV TDM in patients receiving off-label high doses (two 1500 + 1500 mg weekly infusions instead of 1000 + 500 mg), with normal renal function or undergoing hemodialysis: continuous hemodiafiltration caused a relevant reduction in DBV exposure, while intermittent dialysis showed comparable DBV concentrations with those of patients with normal renal function. This confirmed the eligibility of the presented method for use in TDM and its usefulness in clinical practice.

Development of Amphiphilic Coumarin Derivatives as Membrane-Active Antimicrobial Agents with Potent In Vivo Efficacy against Gram-Positive Pathogenic Bacteria

Increases in drug-resistant pathogens are becoming a serious detriment to human health. To combat pathogen infections, a new series of amphiphilic coumarin derivatives were designed and synthesized as antimicrobial agents with membrane-targeting action. We herein report a lead compound, 25, that displayed potent antibacterial activity against Gram-positive bacteria, including MRSA. Compound 25 exhibited weak hemolytic activity and low toxicity to mammalian cells and can kill Gram-positive bacteria quickly (within 0.5 h) by directly disrupting the bacterial cell membranes. Additionally, compound 25 demonstrated excellent efficacy in a murine corneal infection caused by Staphylococcus aureus. These results suggest that 25 has great potential to be a potent antimicrobial agent for treating drug-resistant Gram-positive bacterial infections.

Real-World Use of Dalbavancin in the Era of Empowerment of Outpatient Antimicrobial Treatment: A Careful Appraisal Beyond Approved Indications Focusing on Unmet Clinical Needs

Dalbavancin is a novel, long-acting lipoglycopeptide characterized by a long elimination half-life coupled with excellent in vitro activity against multidrug-resistant Gram-positives. Although it is currently approved only for the treatment of acute bacterial skin and skin structure infections, an ever-growing amount of evidence supports the efficacy of dalbavancin as a long-term therapy in osteomyelitis, prosthetic joint infections, endocarditis, and bloodstream infections. This article provides a critical reappraisal of real-world use of dalbavancin for off-label indications. A search strategy using specific keywords (dalbavancin, osteomyelitis, endocarditis, long-term suppressive therapy, bloodstream infection, pharmacokinetic/pharmacodynamic profile) until April 2021 was performed on the PubMed-MEDLINE database. As for other novel antibiotics, a conundrum between approved indications and potential innovative therapeutic uses has emerged for dalbavancin as well. The promising efficacy in challenging scenarios (i.e., osteomyelitis, endocarditis, prosthetic joint infections), coupled with the unique pharmacokinetic/pharmacodynamic properties, makes dalbavancin a valuable alternative to daily in-hospital intravenous or outpatient antimicrobial regimens in the treatment of long-term Gram-positive infections. This makes dalbavancin valuable in the current COVID-19 scenario, in which hospitalization and territorial medicine empowerment are unavoidable.

Population pharmacokinetics of dalbavancin and dosing consideration for optimal treatment of adult patients with staphylococcal osteoarticular infections

Background: Dalbavancin is gaining interest in the treatment of complex osteoarticular (OA) infections.Objective: To conduct a population pharmacokinetic analysis of dalbavancin in a prospective cohort of adult patients with Gram-positive OA infections and to identify optimal dosing regimens for long term-treatment.Methods: Non-linear mixed-effects modelling was performed with Monolix. Monte Carlo simulations were performed with six dalbavancin regimens (1500mg at day 1; 1000mg at day 1 plus 500mg at day 8; 1500mg at day1 and 8; 1500mg at day1 and 8 plus 500, 1000 or 1500mg at day 36) to assess the PTA of three pharmacodynamic target of fAUC_24h/MIC against S. aureus (>27.1, 53.3 and 111.1). Cumulative fraction of response (CFR) was calculated against MIC distribution of both MRSA and MSSA as well. Desirable PTAs and CFRs were ≥90%.Results: Fifteen patients provided 120 plasma concentrations. Most (73.3%) had prosthetic joint infections. Clinical cure rate was 87%. A two-compartment model with linear elimination well described the data. No covariate was retained in the final model. Pharmacokinetic dalbavancin estimates were 0.106L/h for CL and 36.4L for V_ss The tested dosing regimens granted desirable CFRs against S. aureus at the most effective PK/PD target for a period ranging 3-to-9 weeks. Conclusion: Giving a two 1500mg dosing regimen of dalbavancin one week apart may ensure efficacy against both MSSA and MRSA up to 5 weeks in patients with OA infections. Clinical assessment at that time may allow for considering whether or not an additional dose should be administered for prolonging effective treatment.

Review: A Safety Profile of Dalbavancin for On- and Off-Label Utilization

Introduction

Dalbavancin is a bactericidal lipoglycopeptide active against gram-positives. Its use has been approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI).

Methods

We conducted a narrative review of the literature on the safety profile of dalbavancin. The bibliographic research was carried out on the PubMed database on 6 November 2020 by seeking combinations of the following keywords: dalbavancin, adverse effects, safety, drug interactions, and skin infections.

Results

Five double-blind Phase 3 randomized clinical trials, 2 open-label randomized trials, and 4 retrospective studies were identified. No statistically significant differences were found between dalbavancin and comparators in the incidence of adverse events. Retrospective studies confirm the low incidence of adverse events.

Conclusion

Dalbavancin is a therapeutic option that has demonstrated an excellent safety profile, also in relation to the other MRSA therapies available. Its use represents a cost-effective solution for the treatment of those patients with ABSSSI who would need hospitalization. One limitation of this study is that most of the available data are from Phase III clinical trials. Further real-life studies with a larger sample size are therefore needed to better assess the safety profile of the dalbavancin, especially to investigate the true incidence of rare adverse events.

Epithelial Lining Fluid and Plasma Concentrations of Dalbavancin in Healthy Adults after a Single 1,500-Milligram Infusion

Dalbavancin is a lipoglycopeptide antibiotic with a prolonged half-life. A phase 1 study assessed dalbavancin levels in epithelial lining fluid (ELF) in 35 healthy adults using ELF bronchial microsampling up to 168 h after administration of 1,500 mg dalbavancin. The penetration of dalbavancin into ELF was 36%. ELF levels of dalbavancin exceeded the MIC₉₀s of Streptococcus pneumoniae and Staphylococcus aureus for ≥7 days.

Dalbavancin is a lipoglycopeptide antibiotic with a prolonged half-life. A phase 1 study assessed dalbavancin levels in epithelial lining fluid (ELF) in 35 healthy adults using ELF bronchial microsampling up to 168 h after administration of 1,500 mg dalbavancin. The penetration of dalbavancin into ELF was 36%. ELF levels of dalbavancin exceeded the MIC₉₀s of Streptococcus pneumoniae and Staphylococcus aureus for ≥7 days.

Single-Dose Dalbavancin: A Review in Acute Bacterial Skin and Skin Structure Infections

Intravenous dalbavancin (Dalvance^®, Xydalba^®), first approved as a two-dose regimen for the treatment of acute bacterial skin and skin structure infections (ABSSSI), has now been additionally approved as a single-dose regimen. This narrative review discusses the pharmacological properties of intravenous dalbavancin and its clinical efficacy and tolerability as a single-dose regimen in the treatment of adult patients with ABSSSI. Single-dose dalbavancin is an effective and generally well tolerated treatment option for adults with ABSSSI, with noninferior efficacy to the two-dose dalbavancin regimen with regard to early clinical response (at 48-72 h) and low rates of adverse events. Clinical success rates at days 14 and 28 also did not significantly differ between the single- and two-dose dalbavancin regimens; neither did clinical success rates at day 14 when analysed by baseline pathogen. It has a broad spectrum of activity against common ABSSSI-related pathogens, and a favourable pharmacokinetic profile allowing for the convenience of single-dose administration. Thus, dalbavancin presents a promising alternative to conventional antibacterials for the treatment of ABSSSI in adult patients.

Dosing strategies to optimize currently available anti-MRSA treatment options (Part 1: IV options)

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a predominant pathogen resulting in significant morbidity and mortality. Optimal dosing of anti-MRSA agents is needed to help prevent the development of antimicrobial resistance and to increase the likelihood of a favorable clinical outcome. Areas covered: This review summarizes the available data for antimicrobials routinely used for MRSA infections that are not administered orally or topically. We make recommendations and highlight the current gaps in the literature. A PubMed (1966 - Present) search was performed to identify relevant literature for this review. Expert commentary: Improvements in MIC determination and therapeutic drug monitoring are needed to fully implement individualized dosing that optimizes antimicrobial pharmacodynamics.Additional data will become available for these agents in regards to effectiveness for severe MRSA infections and pharmacokinetic data for special patient populations.

New agents approved for treatment of acute staphylococcal skin infections

Vancomycin has been a predominant treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections for decades. However, growing reservations about its efficacy led to an urgent need for new antibiotics effective against MRSA and other drug-resistant Staphylococcus aureus strains. This review covers three new anti-MRSA antibiotics that have been recently approved by the FDA: dalbavancin, oritavancin, and tedizolid. The mechanism of action, indications, antibacterial activity profile, microbial resistance, pharmacokinetics, clinical efficacy, adverse effects, interactions as well as available formulations and administration of each of these new antibiotics are described. Dalbavancin is a once-a-week, two-dose, long-acting intravenous bactericidal lipoglycopeptide antibiotic. Oritavancin, a lipoglycopeptide with bactericidal activity, was developed as a single-dose intravenous treatment for acute bacterial skin and skin-structure infections (ABSSSI), which offers simplifying treatment of infections. Tedizolid is an oxazolidinone-class bacteriostatic once-daily agent, available for intravenous as well as oral use. Increased ability to overcome bacterial resistance is the main therapeutic advantage of the novel agents over existing antibiotics.

New therapeutic options for skin and soft tissue infections

PURPOSE OF REVIEW

The occurrence of methicillin-resistance in Staphylococcus aureus, that represents the most frequent cause of complicated skin and soft tissue infections (cSSTIs) worldwide, is a major concern and has been associated with increased length of stay, health care costs, and overall mortality. Although vancomycin is still considered the standard therapy in this setting, limitations of its use in clinical practice are represented by a progressive increase in methicillin-resistant S. aureus (MRSA) minimum inhibitory concentrations, drug-related toxicity, and the lack of an oral formulation. New therapeutic options for MRSA cSSTIs have recently become available, with promising implications for the management of cSSTIs in clinical practice.

RECENT FINDINGS

A number of new antimicrobials with activity against MRSA have been recently approved for the treatment of cSSTIs, and other agents are under investigation. We have reviewed the recent developments, with a specific focus on the possible advantages of new drugs for the management of cSSTIs into the everyday clinical practice.

SUMMARY

The new approved drugs for the treatment of cSSTIs are expected to offer many advantages for the management of patients with suspected or confirmed MRSA cSSTIs. The most promising features of the new compounds include the availability of oral formulations, once-weekly intravenous regimens, and broad spectra of activity.

Safety of Dalbavancin in the Treatment of Skin and Skin Structure Infections: A Pooled Analysis of Randomized, Comparative Studies

Introduction

Dalbavancin is a new lipoglycopeptide that is active against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus. It has a half-life of 14.4 days, permitting intravenous treatment of acute bacterial skin and skin structure infections without the need for daily dosing.

Objective

The objective of these analyses was to compare the adverse event profile of dalbavancin with that of the comparator agents in the treatment of skin and skin structure infections.

Methods

Data on adverse events and laboratory assessments collected from 3002 patients enrolled in seven late-stage, randomized clinical trials were analyzed for patients receiving dalbavancin or a comparator antibiotic.

Results

Overall adverse event rates were similar or lower for patients receiving dalbavancin (799/1778; 44.9 %) compared with those receiving comparator agents (573/1224; 46.8 %, p = 0.012). The most common treatment-emergent adverse events were nausea, headache, diarrhea, constipation, vomiting, rash, urinary tract infection, pruritus, and insomnia. The duration and timing of the onset of adverse events were similar for patients receiving dalbavancin relative to the comparators.

Conclusion

Dalbavancin exhibits a favorable overall safety profile for treatment of acute bacterial skin and skin structure infections due to Gram-positive bacteria.

Dalbavancin for the treatment of paediatric infectious diseases

To review the topics of interest related to the use of dalbavancin in paediatric patients. PubMed was used to search for all of the studies published over the last 15 years using the key word "dalbavancin". A total of 36 manuscripts were selected, and due to the limited pediatric experience a further research was performed in order to identify clinical trials ongoing. Three studies that concerned children were found in clinicaltrials.gov. This review considers also the manuscripts published on the adult population in order to highlight the gaps requiring further research at pediatric age. Dalbavancin has emerged as a promising agent against resistant Gram-positive invasive infections. It is approved in the United States and Europe for the treatment of adult patients with acute bacterial skin and skin structure infections (SSTIs). Compared to other available antibiotics that are active against multi-resistant bacteria, the advantages of dalbavancin include a lower potential for drug interactions and the possibility of fewer required doses due to a longer half-life. Pharmacokinetic characteristics of dalbavacin are attractive for its clinical impact, especially for children who may avoid prolonged hospitalization and central venous access. However, further studies are needed to establish its appropriate paediatric dosage before it can be licensed for use in newborns and children. For younger patients, at a time when infections due to multidrug-resistant Gram-positive pathogens are increasing, dosage, efficacy and safety data for dalbavancin are needed to ensure the highest antimicrobial efficacy while also minimizing the risk of adverse events.

Pharmacokinetics, Safety, and Tolerability of a Single 500-mg or 1000-mg Intravenous Dose of Dalbavancin in Healthy Japanese Subjects

Background and Objectives

Dalbavancin is a novel, once-weekly glycopeptide antibiotic approved for treatment of acute bacterial skin infections. Given the importance of understanding any pharmacokinetic variability across different patient populations, a double-blind, placebo-controlled study was conducted to evaluate the pharmacokinetics, safety, and tolerability of a single 500-mg and a single 1000-mg intravenous dose of dalbavancin in healthy Japanese subjects.

Methods

Ten subjects received intravenous dalbavancin 1000 mg, five subjects received intravenous dalbavancin 500 mg, and three subjects received intravenous placebo.

Results

After a single infusion of dalbavancin, the maximal plasma concentration (C_max) and area under the plasma concentration–time curve (AUC) increased in a proportional manner from 500 mg to 1000 mg (C_max: 157 μg/ml and 299 μg/ml; AUC_last: 10,850 μg·h/ml and 22,679 μg·h/ml, on the 500-mg and 1000-mg regimens, respectively) with low inter-subject variability. The mean terminal phase half-life (t_1/2) was 204 and 193 h after the 500-mg and 1000-mg dose, respectively. Clearance and volume of distribution were similar for the two dose concentrations. Treatment-emergent adverse events reported were considered to be of mild intensity. There were no relevant changes in laboratory values or vital signs over time in subjects in either treatment group.

Conclusions

Overall, dalbavancin 500 mg and dalbavancin 1000 mg, administered as a single 30-min infusion, was well tolerated in this population and resulted in plasma exposures similar to those in non-Asians.

Safety profiles of old and new antimicrobials for the treatment of MRSA infections

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of severe nosocomial and community-acquired infections. Various adverse effects have been associated with compounds that are commonly used in the treatment of MRSA.

AREAS COVERED

Prolonged use of high-dose vancomycin has been linked with nephrotoxicity. Linezolid use has been associated with lactic acidosis in regimens longer than 14 days and occurrence of thrombocytopenia in patients with renal impairment. Daptomycin use correlates with reversible and often asymptomatic myopathy. Among new compounds, telavancin has shown increased toxicity compared to vancomycin, especially in patients with severe renal impairment, while a low rate of adverse effects was reported others glycolipopeptides such as dalbavancin and oritavancin and for new cephalosporins. Recently studied oxazolidinones (tedizolid and radezolid) also showed mild adverse effects in Phase 2 and 3 clinical trials.

EXPERT OPINION

Due to the constant increase in antimicrobial resistance, the use of higher doses and prolonged regimens of antibiotics employed in the treatment of Gram-positive infections has become more common and linked to increased toxicity. Furthermore, new compounds with MRSA activity have been recently approved and will be regularly employed in clinical practice. The knowledge of the adverse effects and risk factors for the development of toxicity associated with anti-MRSA antimicrobials is paramount for the correct use of old and new compounds, especially in the treatment of severe infections.

A Randomized Clinical Trial of Single-Dose Versus Weekly Dalbavancin for Treatment of Acute Bacterial Skin and Skin Structure Infection

BACKGROUND

Acute bacterial skin and skin structure infections (ABSSSIs) are a cause of significant morbidity and therapy can be a burden to the healthcare system. New antibiotics that simplify treatment and avoid hospitalization are needed. This study compared the safety and efficacy of a single intravenous infusion of 1500 mg of dalbavancin to the 2-dose regimen.

METHODS

This study was a randomized, double-blind trial in patients aged >18 years with ABSSSIs. Patients were randomized to dalbavancin 1500 mg either as a single intravenous (IV) infusion or 1000 mg IV on day 1 followed 1 week later by 500 mg IV. The primary endpoint was a ≥20% reduction in the area of erythema at 48-72 hours in the intent-to-treat population. Noninferiority was to be declared if the lower limit of the 95% confidence interval (CI) on the difference in the outcomes was greater than -10%. Clinical outcome was also assessed at days 14 and 28.

RESULTS

Six hundred ninety-eight patients were randomized. Demographic characteristics were similar on each regimen, although there were more patients with methicillin-resistant Staphylococcus aureus (MRSA) at baseline on the 2-dose regimen (36/210 [17.1%] vs 61/220 [27.7%]). Dalbavancin delivered as a single dose was noninferior to a 2-dose regimen (81.4% vs 84.2%; difference, -2.9% [95% CI, -8.5% to 2.8%]). Clinical outcomes were also similar at day 14 (84.0% vs 84.8%), day 28 (84.5% vs 85.1%), and day 14 in clinically evaluable patients with MRSA in a baseline culture (92.9% vs 95.3%) in the single- and 2-dose regimens, respectively. Treatment-emergent adverse events occurred in 20.1% of the single-dose patients and 19.9% on the 2-dose regimen.

CONCLUSIONS

A single 1500-mg infusion of dalbavancin is noninferior to a 2-dose regimen, has a similar safety profile, and removes logistical constraints related to delivery of the second dose.

CLINICAL TRIALS REGISTRATION

NCT02127970.

Dalbavancin: A Novel Lipoglycopeptide Antibiotic with Extended Activity Against Gram-Positive Infections

Dalbavancin is a lipoglycopeptide antibiotic recently approved by the United States Food and Drug Administration (FDA) for acute bacterial skin and skin structure infections (ABSSSIs). It is active against gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), and minimum inhibitory concentrations (MICs) are consistently <0.125 µg/ml, much lower than most other anti-MRSA agents. Dalbavancin possesses an extended half-life of over 1 week, allowing an initial dose of 1000 mg followed by 500 mg 1 week later to complete a course of therapy for ABSSSI. It is approximately 95% protein bound and is widely distributed throughout the body, achieving concentrations similar to plasma levels in numerous tissues. Against MRSA, dalbavancin is 4–8 times more potent than vancomycin in vitro, and limited data suggest it possesses activity against MRSA with reduced susceptibility to vancomycin such as hVISA and VISA. Dalbavancin also possesses in vitro activity against streptococci and enterococci, although activity against vancomycin-resistant enterococci is lacking. In phase 3 ABSSSI studies, dalbavancin demonstrated similar activity to vancomycin and provides a more convenient dosing regimen. Limited phase 2 data suggest dalbavancin also possesses activity in catheter-related bloodstream infections. Potential further therapeutic uses include conditions that require long-term treatment such as osteomyelitis and infective endocarditis, although data are currently lacking. The extended half-life of dalbavancin, along with its in vitro activity against gram-positive organisms with reduced susceptibility to other anti-MRSA antibiotics, suggest it could have an exciting clinical role going forward.

Dalbavancin for the treatment of acute bacterial skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSI) have increased in incidence and severity. The involvement of resistant organisms, particularly methicillin-resistant Staphylococcus aureus, presents additional challenges. The lipoglycopeptide dalbavancin has a prolonged half-life, high protein binding, and excellent tissue levels which led to its development as a once-weekly treatment for ABSSSI. In the pivotal DISCOVER 1 and DISCOVER 2 trials, dalbavancin proved non-inferior to vancomycin followed by linezolid when used sequentially for ABSSSI, forming the basis for its recent approval in the US and Europe for ABSSSI.

AREAS COVERED

A literature search of published pharmacologic and clinical data was conducted to review the chemistry, pharmacodynamics, and pharmacokinetics of dalbavancin. We also discuss its development process, highlighting efficacy and safety data from pertinent clinical trials and the role it could play in the current clinical landscape.

EXPERT OPINION

DISCOVER 1 and DISCOVER 2 demonstrated dalbavancin's non-inferiority to vancomycin followed by linezolid for ABSSSI and confirmed its safety and tolerability. They were among the first trials to use new, early primary efficacy endpoints, and dalbavancin was among the first agents designated a Qualified Infectious Disease Product for expedited review. Dalbavancin may prove to be a valuable option for ABSSSI patients in whom conventional therapy is limited.

Extended-duration dosing and distribution of dalbavancin into bone and articular tissue

Dalbavancin is an intravenous lipoglycopeptide with activity against Gram-positive pathogens and an MIC90 for Staphylococcus aureus of 0.06 μg/ml. With a terminal half-life of >14 days, dosing regimens with infrequent parenteral administration become available to treat infectious diseases such as osteomyelitis and endocarditis that otherwise require daily dosing for many weeks. In order to support a rationale for these novel regimens, the pharmacokinetics over an extended dosing interval and the distribution of dalbavancin into bone and articular tissue were studied in two phase I trials and pharmacokinetic modeling was performed. Intravenous administration of 1,000 mg of dalbavancin on day 1 followed by 500 mg weekly for seven additional weeks was well tolerated and did not demonstrate evidence of drug accumulation. In a separate study, dalbavancin concentrations in cortical bone 12 h after infusion of a single 1,000-mg intravenous infusion were 6.3 μg/g and 2 weeks later were 4.1 μg/g. A two-dose, once-weekly regimen that would provide tissue exposure over the dalbavancin MIC for Staphylococcus aureus for 8 weeks, maximizing the initial exposure to treatment while minimizing the frequency of intravenous therapy, is proposed.