Pharmacokinetics, serum inhibitory and bactericidal activity, and safety of telavancin in healthy subjects

Glycopeptides: Insights Towards Resistance, Clinical Pharmacokinetics and Pharmacodynamics

Glycopeptides have emerged as life-saving therapeutics in treating various gram-positive bacterial infections. Vancomycin being the first therapeutically approved glycopeptide has turned out as a blockbuster drug in the mitigation of gram-positive infections. However, long-term misuse of these glycopeptides led to the development of resistance which became a bottleneck in tackling various infections. Antimicrobial resistance has become a global threat exposing their impact on the public health domain. Concomitant to this the second-generation glycopeptides were developed through structural alterations and were approved by the USFDA which are serving as a last resort for an effective treatment. However, resistance against these also might develop shortly when misused. In this aspect, strategic approaches concerning structural activity for enhancing the antimicrobial activity and overcoming resistance were conferred. The clinical use of glycopeptides were also limited due to associated toxicity concerns and unusual pharmacokinetics. Understanding the pharmacokinetics of glycopeptides in different clinical conditions are necessary in tackling drug-induced resistance due to overdosing. Hence, dose optimization and therapeutic drug monitoring in different clinical conditions is necessary for better safety profiles and toxicity reduction. So, this review provides insights into glycopeptide-induced resistances, aspects of structural modifications to overcome resistance and their implications on pharmacokinetics and pharmacodynamics in different clinical conditions.

Rapid in vitro activity of telavancin against Bacillus anthracis and in vivo protection against inhalation anthrax infection in the rabbit model

Inhalation anthrax is the most severe form of Bacillus anthracis infection, often progressing to fatal conditions if left untreated. While recommended antibiotics can effectively treat anthrax when promptly administered, strains engineered for antibiotic resistance could render these drugs ineffective. Telavancin, a semisynthetic lipoglycopeptide antibiotic, was evaluated in this study as a novel therapeutic against anthrax disease. Specifically, the aims were to (i) assess in vitro potency of telavancin against 17 B. anthracis isolates by minimum inhibitory concentration (MIC) testing and (ii) evaluate protective efficacy in rabbits infected with a lethal dose of aerosolized anthrax spores and treated with human-equivalent intravenous telavancin doses (30 mg/kg every 12 hours) for 5 days post-antigen detection versus a humanized dose of levofloxacin and vehicle control. Blood samples were collected at various times post-infection to assess the level of bacteremia and antibody production, and tissues were collected to determine bacterial load. The animals' body temperatures were also recorded. Telavancin demonstrated potent bactericidal activity against all strains tested (MICs 0.06-0.125 μg/mL). Further, telavancin conveyed 100% survival in this model and cleared B. anthracis from the bloodstream and organ tissues more effectively than a humanized dose of levofloxacin. Collectively, the low MICs against all strains tested and rapid bactericidal in vivo activity demonstrate that telavancin has the potential to be an effective alternative for the treatment or prophylaxis of anthrax infection.

Physicochemical Characteristics of Antimicrobials and Practical Recommendations for Intravenous Administration: A Systematic Review

Most antimicrobial drugs need an intravenous (IV) administration to achieve maximum efficacy against target pathogens. IV administration is related to complications, such as tissue infiltration and thrombo-phlebitis. This systematic review aims to provide practical recommendations about diluent, pH, osmolarity, dosage, infusion rate, vesicant properties, and phlebitis rate of the most commonly used antimicrobial drugs evaluated in randomized controlled studies (RCT) till 31 March 2023. The authors searched for available IV antimicrobial drugs in RCT in PUBMED EMBASE®, EBSCO® CINAHL®, and the Cochrane Controlled Clinical trials. Drugs' chemical features were searched online, in drug data sheets, and in scientific papers, establishing that the drugs with a pH of <5 or >9, osmolarity >600 mOsm/L, high incidence of phlebitis reported in the literature, and vesicant drugs need the adoption of utmost caution during administration. We evaluated 931 papers; 232 studies were included. A total of 82 antimicrobials were identified. Regarding antibiotics, 37 reach the "caution" criterion, as well as seven antivirals, 10 antifungals, and three antiprotozoals. In this subgroup of antimicrobials, the correct vascular access device (VAD) selection is essential to avoid complications due to the administration through a peripheral vein. Knowing the physicochemical characteristics of antimicrobials is crucial to improve the patient's safety significantly, thus avoiding administration errors and local side effects.

Recent Advances in the Development of Semisynthetic Glycopeptide Antibiotics: 2014-2022

The accelerated appearance of drug-resistant bacteria poses an ever-growing threat to modern medicine's capacity to fight infectious diseases. Gram-positive species such as methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae continue to contribute significantly to the global burden of antimicrobial resistance. For decades, the treatment of serious Gram-positive infections relied upon the glycopeptide family of antibiotics, typified by vancomycin, as a last line of defense. With the emergence of vancomycin resistance, the semisynthetic glycopeptides telavancin, dalbavancin, and oritavancin were developed. The clinical use of these compounds is somewhat limited due to toxicity concerns and their unusual pharmacokinetics, highlighting the importance of developing next-generation semisynthetic glycopeptides with enhanced antibacterial activities and improved safety profiles. This Review provides an updated overview of recent advancements made in the development of novel semisynthetic glycopeptides, spanning the period from 2014 to today. A wide range of approaches are covered, encompassing innovative strategies that have delivered semisynthetic glycopeptides with potent activities against Gram-positive bacteria, including drug-resistant strains. We also address recent efforts aimed at developing targeted therapies and advances made in extending the activity of the glycopeptides toward Gram-negative organisms.

Pharmacokinetics and pharmacodynamics of peptide antibiotics

Antimicrobial resistance is a major global health challenge. As few new efficacious antibiotics will become available in the near future, peptide antibiotics continue to be major therapeutic options for treating infections caused by multidrug-resistant pathogens. Rational use of antibiotics requires optimisation of the pharmacokinetics and pharmacodynamics for the treatment of different types of infections. Toxicodynamics must also be considered to improve the safety of antibiotic use and, where appropriate, to guide therapeutic drug monitoring. This review focuses on the pharmacokinetics/pharmacodynamics/toxicodynamics of peptide antibiotics against multidrug-resistant Gram-negative and Gram-positive pathogens. Optimising antibiotic exposure at the infection site is essential for improving their efficacy and minimising emergence of resistance.

Efficacy of Telavancin in Comparison to Linezolid in a Porcine Model of Severe Methicillin-Resistant Staphylococcus aureus Pneumonia

Current guidelines recommend vancomycin and linezolid as first-line agents against methicillin-resistant Staphylococcus aureus (MRSA) nosocomial pneumonia. Telavancin is a potential new therapeutic alternative, specifically in monomicrobial MRSA pneumonia. This study compared the efficacies of telavancin versus linezolid in a porcine model of severe MRSA pneumonia. In 18 mechanically ventilated pigs (32.11 ± 1.18 kg), 75 ml of 10⁶ CFU/ml of MRSA was administered into each pulmonary lobe. After the onset of pneumonia, pigs were randomized into three groups: a control group, a group receiving 22.5 mg/kg of body weight every 24 h (q24h) of telavancin, and a group receiving 10 mg/kg q12h of linezolid intravenously. Tracheal aspirate and bronchoalveolar lavage (BAL) fluids were cultured every 24 h. After 48 h of treatment, tissue samples were collected from the ventral and dorsal sections of each lobe. Microbiological and histopathological analyses were performed. Lung tissue concentrations differed among the groups (P = 0.019), with the lowest MRSA lung burden in the telavancin group (P < 0.05 versus the control). MRSA was detected in 46.7%, 40.0%, and 21.7% of the lung tissue samples from the control, linezolid, and telavancin groups, respectively (P < 0.001). MRSA concentrations differed among the groups in tracheal aspirate fluid (P = 0.011) but not in BAL fluid. Furthermore, there was no increased risk of kidney injury during telavancin use. Thus, telavancin has higher bactericidal efficacy than linezolid during the first 48 h of treatment in a porcine model of severe MRSA pneumonia. However, studies are needed to confirm the benefits of telavancin in treating MRSA nosocomial pneumonia.

Adverse reactions to vancomycin and cross-reactivity with other antibiotics

PURPOSE OF REVIEW

Glycopeptide antibiotics such as vancomycin are frequently utilized to treat resistant Gram-positive infections such as methicillin-resistant Staphylococcus aureus. The current literature on glycopeptide and lipoglycopeptide structure, hypersensitivity and potential cross-reactivity was reviewed, highlighting implications for safe prescribing.

RECENT FINDINGS

Structurally similar, glycopeptides could theoretically cross-react. Immediate reactions to vancomycin include non-IgE-mediated reactions (e.g. red man syndrome) and IgE-mediated hypersensitivity (e.g. anaphylaxis), sharing clinical features. Vancomycin can activate mast cells via MAS-related G-protein-coupled receptor X2, an IgE-independent receptor implicated in non-IgE reactions. In-vivo and in-vitro testing for suspected IgE-mediated reactions to glycopeptides remain ill-defined. Vancomycin is increasingly recognized to cause severe cutaneous adverse reactions (SCAR), with drug reaction with eosinophilia and systemic symptoms (DRESS) predominantly reported. Vancomycin DRESS has been associated with HLA-A32:-01, with a number needed to prevent of 1 in 74. Data demonstrating cross-reactivity amongst glycopeptides and lipoglycopeptides is limited to case reports/series.

SUMMARY

Further studies and in-vivo/in-vitro diagnostics are required for better differentiation between IgE and non-IgE glycopeptide reactions. Despite its association with vanomycin DRESS, utility of pharmacogenomic screening for HLA-A32: 01 is ill-defined. Although HLA-A32:01 has been associated with vancomycin DRESS, its utility for pharmacogenomic screening is ill defined. Further clinical and immunological cross-reactivity data for glycopeptide/lipoglycopeptide antibiotics is required.

Pharmacokinetics of Telavancin in Adult Patients with Cystic Fibrosis during Acute Pulmonary Exacerbation

Adults with cystic fibrosis (CF) frequently harbor Staphylococcus aureus, which is increasingly antibiotic resistant. Telavancin is a once-daily rapidly bactericidal antibiotic active against methicillin-, linezolid-, and ceftaroline-resistant S. aureus Because CF patients experience alterations in pharmacokinetics, the optimal dose of telavancin in this population is unknown. Adult CF patients (n = 18) admitted for exacerbations received 3 doses of telavancin 7.5 mg/kg of body weight (first 6 patients) or 10 mg/kg (final 12 patients) every 24 h (q24h). Population pharmacokinetic models with and without covariates were fitted using the nonparametric adaptive grid algorithm in Pmetrics. The final model was used to perform 5,000-patient Monte Carlo simulations for multiple telavancin doses. The best fit was a 2-compartment model describing the volume of distribution of the central compartment (V_c ) as a multiple of total body weight (TBW) and the volume of distribution of the central compartment scaled to total body weight (V _θ) normalized by the median observed value (V_c  = V _θ × TBW/52.1) and total body clearance (CL) as a linear function of creatinine clearance (CRCL) (CL = CL_NR + CL_θ × CRCL), where CL_NR represents nonrenal clearance and CL_θ represents the slope term on CRCL to estimate renal clearance. The mean population parameters were as follows: V _θ, 4.92  ± 0.76 liters · kg^-1; CL_NR, 0.59  ± 0.30 liters · h^-1; CL_θ, 5.97 × 10^-3 ± 1.24 × 10^-3; V_p (volume of the peripheral compartment), 3.77  ± 1.41 liters; Q (intercompartmental clearance), 4.08  ± 2.17 liters · h^-1 The free area under the concentration-time curve (fAUC) values for 7.5 and 10 mg/kg were 30  ± 4.6 and 52  ± 12 mg · h/liter, respectively. Doses of 7.5 mg/kg and 10 mg/kg achieved 76.5% and 100% probability of target attainment (PTA) at a fAUC/MIC threshold of >215, respectively, for MIC of ≤0.12 mg/liter. The probabilities of reaching the acute kidney injury (AKI) threshold AUC (763 mg · h · liter^-1) for these doses were 0% and 0.96%, respectively. No serious adverse events occurred. Telavancin 10 mg/kg yielded optimal PTA and minimal risk of AKI, suggesting that this FDA-approved dose is appropriate to treat acute pulmonary exacerbations in CF adults. (The clinical trial discussed in this study has been registered at ClinicalTrials.gov under identifier NCT03172793.).

A population pharmacokinetic model of intravenous telavancin in healthy individuals to assess tissue exposure

Non-compartmental analysis of telavancin microdialysis data indicated a sustained exposure in soft tissues and that unbound plasma concentrations were underestimated in vitro. The objective of the present evaluation was to develop a population pharmacokinetic model of telavancin to describe its plasma protein binding, its distribution into muscle, and subcutaneous tissue and to predict pharmacokinetic/-dynamic target attainment (PTA). Total plasma concentrations and microdialysate concentrations (plasma, subcutaneous, and muscle tissue) were available up to 24 h (plasma microdialysate, up to 8 h) post-dose from eight healthy subjects after a single intravenous infusion of 10 mg/kg telavancin. Population pharmacokinetic modeling and simulations were performed using NONMEM. A two-compartment model with saturable protein binding best described plasma concentrations. Plasma unbound fractions at steady state were 23, 15, and 11% at 100, 50, and 10% of the maximum predicted concentrations respectively. Distribution into muscle and subcutaneous tissue was non-linear and described appropriately by one additional compartment each. Based on total plasma concentrations, predicted median (95% confidence interval) values of AUC/MIC (MIC 0.125 mg/L, clinical breakpoint for MRSA) at steady state were 4009 [3421-4619] with a PTA of 96 [78-100] %. The fAUC/MIC in muscle was 496 [227-1232] with a PTA of 100 [98-100] %. The %fT_>MIC was approximately 100% in plasma and interstitial space fluid of muscle and subcutaneous tissues up to an MIC of 0.25 mg/L. The model provided a new hypothesis on telavancin plasma protein binding in vivo. Proposed pharmacodynamic targets in plasma and muscle are achieved with currently approved doses of 10 mg/kg daily.

Effects of Microplate Type and Broth Additives on Microdilution MIC Susceptibility Assays

The determination of antibiotic potency against bacterial strains by assessment of their minimum inhibitory concentration normally uses a standardized broth microdilution assay procedure developed more than 50 years ago. However, certain antibiotics require modified assay conditions in order to observe optimal activity.

The determination of antibiotic potency against bacterial strains by assessment of their minimum inhibitory concentration normally uses a standardized broth microdilution assay procedure developed more than 50 years ago. However, certain antibiotics require modified assay conditions in order to observe optimal activity. For example, daptomycin requires medium supplemented with Ca²⁺, and the lipoglycopeptides dalbavancin and oritavancin require Tween 80 to be added to the growth medium to prevent the depletion of free drug via adsorption to the plastic microplate. In this report, we examine systematically the effects of several different plate types on microdilution broth MIC values for a set of antibiotics against Gram-positive and Gram-negative bacteria, both in medium alone and in medium supplemented with the commonly used additives Tween 80, lysed horse blood, and 50% human serum. We observed very significant differences in measured MICs (up to 100-fold) for some lipophilic antibiotics, such as the Gram-positive lipoglycopeptide dalbavancin and the Gram-negative lipopeptide polymyxins, and found that nonspecific binding plates can replace the need for surfactant additives. Microtiter plate types and any additives should be specified when reporting broth dilution MIC values, as results can vary dramatically for some classes of antibiotics.

Efficacy of Dalbavancin and Telavancin in the Treatment of Acute Bacterial Skin and Skin Structure Infections

Objectives

Two glycopeptide analogues, such as dalbavancin and telavancin, with improved pharmacokinetic/pharmacodynamic parameters have been developed. These two glycopeptide analogues are approved by Food and Drug Administration (FDA) for treatment of various Gram-positive bacterial skin infections.

Materials and methods

We have conducted an open labelled prospective randomized study to compare the efficacy of these two drugs. A total of 200 patients diagnosed with acute bacterial skin and skin structure infections (ABSSSI) were recruited for the study. They were randomized to receive either a single dose of dalbavancin 1500 mg i.v (Group I) or telavancin 10 mg/kg intravenously (i.v.) every 24 hours for six days (Group II). The skin infection rating score (SIRS) was calculated on Day 0 for all patients at the time of diagnosis. Signs and symptoms of the lesions were assessed based on the following factors: blistering, exudate/pus, erythema/inflammation and itching/pain. Each factor was classified as one of the following: absent - 0, minimal - 1, moderate - 2 and severe - 3.

Results

Clinically successful treatment was defined as complete resolution of clinically meaningful signs and symptoms of infection, including SIRS score of 0. The outcome measure was the percentage of patients with SIRS score of 0 on day 7 (clinical success). The third most common diagnosis at baseline was impetigo (13% in both groups). Patients who received dalbavancin had a higher clinical success rate than those receiving telavancin.

Conclusion

Findings of the present study show that single i.v dose of dalbavancin is better than telavancin repeated doses in treatment of ABSSSI.

Developments in Glycopeptide Antibiotics

Glycopeptide antibiotics (GPAs) are a key weapon in the fight against drug resistant bacteria, with vancomycin still a mainstream therapy against serious Gram-positive infections more than 50 years after it was first introduced. New, more potent semisynthetic derivatives that have entered the clinic, such as dalbavancin and oritavancin, have superior pharmacokinetic and target engagement profiles that enable successful treatment of vancomycin-resistant infections. In the face of resistance development, with multidrug resistant (MDR) S. pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA) together causing 20-fold more infections than all MDR Gram-negative infections combined, further improvements are desirable to ensure the Gram-positive armamentarium is adequately maintained for future generations. A range of modified glycopeptides has been generated in the past decade via total syntheses, semisynthetic modifications of natural products, or biological engineering. Several of these have undergone extensive characterization with demonstrated in vivo efficacy, good PK/PD profiles, and no reported preclinical toxicity; some may be suitable for formal preclinical development. The natural product monobactam, cephalosporin, and β-lactam antibiotics all spawned multiple generations of commercially and clinically successful semisynthetic derivatives. Similarly, next-generation glycopeptides are now technically well positioned to advance to the clinic, if sufficient funding and market support returns to antibiotic development.

Pharmacokinetics of Telavancin at Fixed Doses in Normal-Body-Weight and Obese (Classes I, II, and III) Adult Subjects

A recommended total-body-weight (TBW) dosing strategy for telavancin may not be optimal in obese patients. The primary objective of this study was to characterize and compare the pharmacokinetics (PK) of telavancin across four body size groups: normal to overweight and obese classes I, II, and III. Healthy adult subjects (n = 32) received a single, weight-stratified, fixed dose of 500 mg (n = 4), 750 mg (n = 8), or 1,000 mg (n = 20) of telavancin. Noncompartmental PK analyses revealed that subjects with a body mass index (BMI) of ≥40 kg/m² had a higher volume of distribution (16.24 ± 2.7 liters) than subjects with a BMI of <30 kg/m² (11.71 ± 2.6 liters). The observed area under the concentration-time curve from time zero to infinity (AUC_0-∞) ranged from 338.1 to 867.3 mg · h/liter, with the lowest exposures being in subjects who received 500 mg. AUC_0-∞ values were similar among obese subjects who received 1,000 mg. A two-compartment population PK model best described the plasma concentration-time profile of telavancin when adjusted body weight (ABW) was included as a predictive covariate. Fixed doses of 750 mg and 1,000 mg had similar target attainment probabilities for efficacy as doses of 10 mg/kg of body weight based on ABW and TBW, respectively. However, the probability of achieving a target area under the concentration-time curve from time zero to 24 h of ≥763 mg · h/liter in association with acute kidney injury was highest (19.7%) with TBW-simulated dosing and lowest (0.4%) at the 750-mg dose. These results suggest that a fixed dose of 750 mg is a safe and effective alternative to telavancin doses based on TBW or ABW for the treatment of obese patients with normal renal function and Staphylococcus aureus infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02753855.).

Telavancin and Hydroxy Propyl-β-Cyclodextrin Clearance during Continuous Renal Replacement Therapy: An in vitro Study

Background/Aims

Telavancin is a lipoglycopeptide antimicrobial agent which has been approved in Europe and has been recently FDA approved in the United States. Telavancin's parenteral solution contains hydroxy propyl-β-cyclodextrin (HP-β-CD) to enhance its solubility. The disposition of telavancin and HP-β-CD during continuous renal replacement therapies (CRRT) has not been previously reported.

Methods

The transmembrane clearances (CLtm) of telavancin and HP-β-CD during continuous hemofiltration and hemodialysis were assessed using an in vitro bovine blood model with AN69 and polysulfone hemodiafilters at varying ultrafiltrate and dialysate flow rates (1, 2, 3, & 6 l/hr).

Results

The mean telavancin sieving coefficient ranged from 0.25 to 0.31 during continuous hemofiltration. At all ultrafiltration rates, no differences were observed in telavancin CLtm between the two hemodiafilter types. For continuous hemodialysis, mean telavancin saturation coefficients ranged from 0.10 to 0.43 and CLtm tended to be higher for the polysulfone hemodiafilter than the AN69 hemodiafilter, especially at higher flow rates. Mean HP-β-CD sieving coefficients ranged from 0.63 to 1.03 and saturation coefficients from 0.63 to 1.38, resulting in a CLtm that was similar to ultrafiltrate and dialysate flow rates.

Conclusion

Telavancin CLtm is dependent on hemodiafilter type, dialysate and ultrafiltration rates. CRRT with high ultrafiltrate or dialysate rates may result in sufficient telavancin clearance to alter telavancin dosing. HP-β-CD clearance by continuous hemodialysis or continuous hemofiltration is substantial and may be sufficient to prevent HP-β-CD accumulation in subjects receiving CRRT. Pharmacokinetic studies conducted in patients receiving CRRT and telavancin are needed to confirm these in vitro findings.

Comparative Pharmacodynamics of Telavancin and Vancomycin in the Neutropenic Murine Thigh and Lung Infection Models against Staphylococcus aureus

The pharmacodynamics of telavancin and vancomycin were compared using neutropenic murine thigh and lung infection models. Four Staphylococcus aureus strains were included. The telavancin MIC ranged from 0.06 to 0.25 mg/liter, and the vancomycin MIC ranged from 1 to 4 mg/liter. The plasma pharmacokinetics of escalating doses (1.25, 5, 20, and 80 mg/kg of body weight) of telavancin and vancomycin were linear over the dose range. Epithelial lining fluid (ELF) pharmacokinetics for each drug revealed that penetration into the ELF mirrored the percentage of the free fraction (the fraction not protein bound) in plasma for each drug. Telavancin (0.3125 to 80 mg/kg/6 h) and vancomycin (0.3125 to 1,280 mg/kg/6 h) were administered by the subcutaneous route in treatment studies. Dose-dependent bactericidal activity against all four strains was observed in both models. A sigmoid maximum-effect model was used to determine the area under the concentration-time curve (AUC)/MIC exposure associated with net stasis and 1-log₁₀ kill relative to the burden at the start of therapy. The 24-h plasma free drug AUC (fAUC)/MIC values associated with stasis and 1-log kill were remarkably congruent. Net stasis for telavancin was noted at fAUC/MIC values of 83 and 40.4 in the thigh and lung, respectively, and 1-log kill was noted at fAUC/MIC values of 215 and 76.4, respectively. For vancomycin, the fAUC/MIC values for stasis were 77.9 and 45.3, respectively, and those for 1-log kill were 282 and 113, respectively. The 24-h ELF total drug AUC/MIC targets in the lung model were very similar to the 24-h plasma free drug AUC/MIC targets for each drug. Integration of human pharmacokinetic data for telavancin, the results of the MIC distribution studies, and the pharmacodynamic targets identified in this study suggests that the current dosing regimen of telavancin is optimized to obtain drug exposures sufficient to treat S. aureus infections.

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.

Telavancin: a novel semisynthetic lipoglycopeptide agent to counter the challenge of resistant Gram-positive pathogens

Telavancin (TD-6424), a semisynthetic lipoglycopeptide vancomycin-derivative, is a novel antimicrobial agent developed by Theravance for overcoming resistant Gram-positive bacterial infections, specifically methicillin-resistant Staphylococcus aureus (MRSA). The US Food and Drug Administration (USFDA) had approved telavancin in 2009 for the treatment of complicated skin and skin structure infections (cSSSIs) caused by Gram-positive bacteria, including MRSA (S. aureus, Streptococcus agalactiae, Streptococcus pyogenes, Streptococcus anginosus group, or Enterococcus faecalis). Telavancin has two proposed mechanisms of action. In vitro, telavancin has a rapid, concentration-dependent bactericidal effect, due to disruption of cell membrane integrity. Telavancin has demonstrable in vitro activity against aerobic and anaerobic Gram-positive bacteria. Telavancin and vancomycin have similar spectra of activity. Gram-negative bacteria are usually non-susceptible to telavancin. Telavancin has been successfully tested in various animal models of bacteremia, endocarditis, meningitis, and pneumonia. Phase II Telavancin versus Standard Therapy for Treatment of Complicated Skin and Soft-Tissue Infections due to Gram-Positive Bacteria (FAST 1 and FAST 2) and phase III [Assessment of Telavancin in Complicated Skin and Skin Structure Infections 1 (ATLAS 1 and ATLAS 2)] clinical trials have been conducted for evaluating telavancin's efficacy and safety in cSSSIs. Phase III clinical trials have been carried out for evaluating telavancin's safety and efficacy in nosocomial pneumonia [Assessment of Telavancin for Treatment of Hospital acquired Pneumonia 1 and 2 (ATTAIN 1 and ATTAIN 2)]. A phase II randomized, double-blind, clinical trial has been carried out for evaluating telavancin's safety and efficacy in uncomplicated S. aureus bacteremia [Telavancin for Treatment of Uncomplicated S. aureus Bacteremia (ASSURE)]. Pacemaker lead-related infective endocarditis due to a vancomycin intermediate S. aureus (VISA) strain (non-daptomycin susceptible) was successfully treated with parenteral telavancin for 8 weeks. Telavancin extensively binds to serum albumin (~93%) and has a relatively small volume of distribution. Telavancin is not biotransformed by any cytochrome P450 microsomal enzymes and excreted mainly in the urine. Though well-tolerated, worrisome adverse effects, including renal dysfunction and QTc prolongation are of potential concern. Given its extensive binding to plasma proteins, long half-life, and a long post-antibiotic effect, it represents a promising addition to the therapeutic armamentarium in combating infections caused by resistant Gram-positive pathogens, namely, MRSA.

Multidrug-Resistant Enterococcal Infections: New Compounds, Novel Antimicrobial Therapies?

Over the past two decades infections due to antibiotic-resistant bacteria have escalated world-wide, affecting patient morbidity, mortality, and health care costs. Among these bacteria, Enterococcus faecium and Enterococcus faecalis represent opportunistic nosocomial pathogens that cause difficult-to-treat infections because of intrinsic and acquired resistance to a plethora of antibiotics. In recent years, a number of novel antimicrobial compound classes have been discovered and developed that target Gram-positive bacteria, including E. faecium and E. faecalis. These new antibacterial agents include teixobactin (targeting lipid II and lipid III), lipopeptides derived from nisin (targeting lipid II), dimeric vancomycin analogues (targeting lipid II), sortase transpeptidase inhibitors (targeting the sortase enzyme), alanine racemase inhibitors, lipoteichoic acid synthesis inhibitors (targeting LtaS), various oxazolidinones (targeting the bacterial ribosome), and tarocins (interfering with teichoic acid biosynthesis). The targets of these novel compounds and mode of action make them very promising for further antimicrobial drug development and future treatment of Gram-positive bacterial infections. Here we review current knowledge of the most favorable anti-enterococcal compounds along with their implicated modes of action and efficacy in animal models to project their possible future use in the clinical setting.

Telavancin in the treatment of Staphylococcus aureus hospital-acquired and ventilator-associated pneumonia: clinical evidence and experience

Telavancin (TLV) is a lipoglycopeptide derivative of vancomycin (VAN), which has activity against Gram-positive aerobic bacteria, and is especially effective against methicillin-resistant Staphylococcus aureus (MRSA) and Gram-positive bacteria resistant to VAN. Comparative clinical studies of TLV have demonstrated noninferiority compared with VAN in the treatment of hospital-acquired Gram-positive pneumonia, with high cure rates for TLV-treated patients with monomicrobial S. aureus infection, including isolates with reduced VAN susceptibility. The results based on the patients' clinical response were supported by supplemental post-hoc analyses of 28-day mortality. In Europe and the USA, TLV is approved as a useful alternative for patients with difficult-to-treat, hospital-acquired MRSA pneumonia when there are very few alternatives. The present article reviews TLV's pharmacological characteristics and clinical efficacy resulting from clinical trials giving a detailed picture of its properties and position in the management of hospital-acquired pneumonia.

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.

Current and Future Considerations for the Treatment of Hospital-Acquired Pneumonia

Hospital-acquired pneumonia (HAP) and health-care-associated pneumonia (HCAP) are leading causes of death, morbidity, and resource utilization in hospitalized patients, and are associated with a broad range of Gram-positive and Gram-negative pathogens. Here, we discuss the different definitions of HAP and HCAP, review current guidelines regarding the treatment of these conditions, highlight the shortcomings of current therapeutic options, and discuss new antibiotic treatments. To optimize therapeutic outcomes in patients with HAP/HCAP, initial antimicrobial treatment must be appropriate and should be given as soon as possible; inappropriate or delayed therapy greatly increases morbidity and mortality. Selection of the most appropriate antimicrobial agent depends on the causative pathogen(s); initial broad-spectrum therapy is commonly recommended and should cover all pathogens that may be present. Treatment selection should also take into consideration the following factors: knowledge of underlying local risk factors for antimicrobial resistance, disease staging, and risk factors related to specific pathogens such as Pseudomonas aeruginosa, Acinetobacter spp., and methicillin-resistant Staphylococcus aureus (MRSA). Guidelines consistently emphasize the importance of treating HAP and HCAP with early and appropriate broad-spectrum antibiotics, and recent developments in this field have resulted in the availability of several additional treatment options. Telavancin shows potent activity against Gram-positive bacteria including MRSA and can be administered once daily; it was approved in the USA and European Union for the treatment of HAP after demonstrating non-inferiority to vancomycin. Ceftobiprole medocaril exhibits rapid antimicrobial activity against a broad range of both Gram-positive and Gram-negative pathogens, including MRSA. It was approved for the treatment of HAP (excluding ventilator-associated pneumonia) and community-acquired pneumonia in Europe in 2013. These new treatments may offer effective alternative therapeutic options for the management of HAP.

FUNDING

Basilea Pharmaceutica Ltd., Basel, Switzerland.

Case-Control Study of Telavancin as an Alternative Treatment for Gram-Positive Bloodstream Infections in Patients with Cancer

Gram-positive bacterial infections are an important cause of morbidity and death among cancer patients, despite current therapy. In this case-control study, we evaluated the clinical outcomes and safety of telavancin in cancer patients with uncomplicated Gram-positive bloodstream infections (BSIs). Between March 2011 and May 2013, we enrolled cancer patients with uncomplicated Gram-positive BSIs to receive intravenous telavancin therapy for at least 14 days for Staphylococcus aureus and 7 days for other Gram-positive cocci. Patients with baseline creatinine clearance (CLCR) values of >50 ml/min received 10 mg/kg/day of telavancin, and those with CLCR values between 30 and 49 ml/min received 7.5 mg/kg/day. Patients were compared with a retrospective cohort of 39 historical patients with Gram-positive BSIs, matched for underlying malignancy, infecting organism, and neutropenia status, who had been treated with vancomycin. A total of 78 patients were analyzed, with 39 in each group. The most common pathogen causing BSIs was S. aureus (51%), followed by alpha-hemolytic streptococci (23%), Enterococcus spp. (15%), coagulase-negative staphylococci (8%), and beta-hemolytic streptococci (3%). Sixty-two percent of patients had hematological malignancies, and 38% had solid tumors; 51% of the patients were neutropenic. The overall response rate determined by clinical outcome and microbiological eradication at 72 h following the initiation of therapy, in the absence of relapse, deep-seated infections, and/or infection-related death, was better with telavancin than with vancomycin (86% versus 61%; P = 0.013). Rates of drug-related adverse events were similar in the two groups (telavancin, 31%; vancomycin, 23%; P = 0.79), with similar rates of renal adverse events. Telavancin may provide a useful alternative to standard vancomycin therapy for Gram-positive BSIs in cancer patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01321879.).

A review of telavancin activity in in vitro biofilms and animal models of biofilm-associated infections

ABSTRACT 

Tissue- and device-associated biofilm infections are important medical problems. These infections are difficult to treat due to a high-level of tolerance to antibiotics. Telavancin has been studied in several in vitro biofilm models and has demonstrated efficacy against staphylococcal and enterococcal-associated biofilm infections, including those formed by methicillin-resistant Staphylococcus aureus. Telavancin was effective against the difficult-to-treat vancomycin- and glycopeptide-intermediate strains of S. aureus in these models. Furthermore, the efficacy of telavancin has been evaluated in several biofilm-related in vivo models, including osteomyelitis, endocarditis and device-associated infections in rabbits. Overall, telavancin exhibited similar or greater efficacy than vancomycin and other comparators in these animal models and maintained activity against vancomycin-intermediate and daptomycin nonsusceptible strains of S. aureus.

Telavancin demonstrates activity against methicillin-resistant Staphylococcus aureus isolates with reduced susceptibility to vancomycin, daptomycin, and linezolid in broth microdilution MIC and one-compartment pharmacokinetic/pharmacodynamic models

Methicillin-resistant Staphylococcus aureus (MRSA) isolates have arisen with reduced susceptibility to several anti-MRSA agents. Telavancin (TLV), a novel anti-MRSA agent, retains low MICs against these organisms. Our objective was to determine the MICs for TLV, daptomycin (DAP), vancomycin (VAN), and linezolid (LZD) against daptomycin-nonsusceptible (DNS) S. aureus, vancomycin-intermediate S. aureus (VISA), heteroresistant VISA (hVISA), and linezolid-resistant (LZD(r)) S. aureus. We also evaluated these agents against each phenotype in pharmacokinetic/pharmacodynamic (PK/PD) models. Seventy DNS, 100 VISA, 180 hVISA, and 25 LZD(r) MRSA isolates were randomly selected from our library and tested to determine their MICs against TLV, DAP, VAN, and LZD via broth microdilution and a Trek panel. Four isolates were randomly selected for 168-h in vitro models to evaluate treatment with TLV at 10 mg/kg of body weight/day, DAP at 10 mg/kg/day, VAN at 1 g every 12 h (q12h), and LZD at 600 mg q12h. The MIC50/90 for TLV, DAP, VAN, and LZD against 70 DNS S. aureus isolates were 0.06/0.125 μg/ml, 2/4 μg/ml, 1/2 μg/ml, and 2/2 μg/ml, respectively. Against 100 VISA isolates, the MIC50/90 were 0.06/0.125 μg/ml, 1/1 μg/ml, 4/8 μg/ml, and 1/2 μg/ml, respectively. Against 170 hVISA isolates, the MIC50/90 were 0.06/0.125 μg/ml, 0.5/1 μg/ml, 1/2 μg/ml, and 1/2 μg/ml, respectively. Against 25 LZD(r) isolates, the MIC50/90 were 0.03/0.06 μg/ml, 1/1 μg/ml, 2/2 μg/ml, and 8/8 μg/ml, respectively. The TLV MIC was >0.125 μg/ml for 10/365 (2.7%) isolates. In PK/PD models, TLV was universally bactericidal at 168 h and statistically superior to all antibiotics against DNS S. aureus strain R2334. These data further establish the potency of TLV against resistant MRSA. The model data demonstrate in vitro bactericidal activity of TLV against hVISA, VISA, DNS S. aureus, and LZD(r) S. aureus strains. Further clinical research is warranted.

Telavancin (VIBATIV) for the treatment of complicated skin and skin structure infections

Methicillin-resistant Staphylococcus aureus has emerged as a major causative pathogen in complicated skin and skin structure infections (cSSSIs). Unfortunately, treatment failure with vancomycin has been increasingly reported. Over the past decade, several alternative antimicrobial agents have been studied and approved for the treatment of cSSSIs. One such agent is the lipoglycopeptide telavancin, which was approved by the US FDA 2009. Given its dual mechanism of action, telavancin is characterized by a highly bactericidal activity and low potential for resistance selection. In addition, in clinical trials, it was efficacious and safe in the treatment of cSSSI. The purpose of this review is to give a background overview of telavancin, highlighting its microbiological, pharmacokinetic and pharmacodynamics characteristics, to summarize the available evidence for its use in the treatment of cSSSIs, and to provide an updated evaluation of its safety profile.

Pharmacokinetics of intravenous telavancin in healthy subjects with varying degrees of renal impairment

Purpose

We evaluated the effect of renal impairment (RI) on the pharmacokinetics of telavancin and hydroxypropylbetadex (excipient in the telavancin drug product).

Methods

Adults with normal, mild, moderate or severe RI or end-stage renal disease (ESRD) receiving haemodialysis were included in two open-label, phase I studies of single-dose telavancin at 7.5 mg/kg (study A, n = 29) or 10 mg/kg (study B, n = 43). Pharmacokinetic analysis of telavancin and hydroxypropylbetadex plasma concentration versus time was performed in these subjects.

Results

The results in studies A and B were similar: telavancin systemic exposure (area under the concentration–time curve from 0 to infinity [AUC_0–∞]) increased with RI. Telavancin half-life (h, mean ± SD) increased in subjects with severe RI compared with subjects with normal renal function from 6.9 ± 0.6 in study A and 6.5 ± 0.9 in study B to 14.5 ± 1.3 and 11.8 ± 6.7, respectively. Conversely, clearance (ml/h/kg, mean ± SD) decreased in subjects with severe RI compared with subjects with normal renal function from 13.7 ± 2.1 in study A and 17.0 ± 3.2 in study B to 6.18 ± 0.63 and 6.5 ± 1.5, respectively. Systemic exposures for hydroxypropylbetadex also increased with severity of RI.

Conclusions

Results from two independent phase 1 studies suggest that dose adjustment of telavancin is required in subjects with varying degrees of RI.

Update on the emerging role of telavancin in hospital-acquired infections

Telavancin is a lipoglycopeptide that has activity against Gram-positive aerobic and anaerobic bacteria. It has activity against methicillin-resistant Staphylococcus aureus, vancomycin-intermediate S. aureus and non-Van-A strains of vancomycin-resistant enterococci. It has been approved by the US Food and Drug Administration (FDA) for complicated skin and skin structure infections and hospital-acquired pneumonia. There is a need for more clinical studies to determine the role of telavancin in treating bacteremia and prosthetic device infections. In this review, we discuss the published data on the use of telavancin in treating hospital-acquired infections and provide an update on new research.

Development of novel antibacterial drugs to combat multiple resistant organisms

BACKGROUND

Infections due to multidrug-resistant (MDR) bacteria are increasing both in hospitals and in the community and are characterized by high mortality rates. New molecules are in development to face the need of active compounds toward resistant gram-positive and gram-negative pathogens. In particular, the Infectious Diseases Society of America (IDSA) has supported the initiative to develop ten new antibacterials within 2020. Principal targets are the so-called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacteriaceae).

PURPOSE

To review the characteristics and the status of development of new antimicrobials including new cephalosporins, carbapenems, beta-lactamase inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines.

CONCLUSIONS

While numerous new compounds target resistant gram-positive pathogens and have been approved for clinical use, very few new molecules are active against MDR gram-negative pathogens, especially carbapenemase producers. New glycopeptides and oxazolidinones are highly efficient against methicillin-resistant S. aureus (MRSA), and new cephalosporins and carbapenems also display activity toward MDR gram-positive bacteria. Although new cephalosporins and carbapenems have acquired activity against MRSA, they offer few advantages against difficult-to-treat gram-negatives. Among agents that are potentially active against MDR gram-negatives are ceftozolane/tazobactam, new carbapenems, the combination of avibactam with ceftazidime, and plazomicin. Since a relevant number of promising antibiotics is currently in development, regulatory approvals over the next 5 years are crucial to face the growing threat of multidrug resistance.

Antibiotics and bacterial resistance in the 21st century

Dangerous, antibiotic resistant bacteria have been observed with increasing frequency over the past several decades. In this review the factors that have been linked to this phenomenon are addressed. Profiles of bacterial species that are deemed to be particularly concerning at the present time are illustrated. Factors including economic impact, intrinsic and acquired drug resistance, morbidity and mortality rates, and means of infection are taken into account. Synchronously with the waxing of bacterial resistance there has been waning antibiotic development. The approaches that scientists are employing in the pursuit of new antibacterial agents are briefly described. The standings of established antibiotic classes as well as potentially emerging classes are assessed with an emphasis on molecules that have been clinically approved or are in advanced stages of development. Historical perspectives, mechanisms of action and resistance, spectrum of activity, and preeminent members of each class are discussed.

Pharmacokinetics and safety of recently approved drugs used to treat methicillin-resistant Staphylococcus aureus infections in infants, children and adults

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant cause of morbidity in hospitalized infants. Over the past 15 years, several drugs have been approved for the treatment of S. aureus infections in adults (linezolid, quinupristin/dalfopristin, daptomycin, telavancin, tigecycline and ceftaroline). The use of the majority of these drugs has extended into the treatment of MRSA infections in infants, frequently with minimal safety or dosing information. Only linezolid is approved for use in infants, and pharmacokinetic data in infants are limited to linezolid and daptomycin. Pediatric trials are underway for ceftaroline, telavancin, and daptomycin; however, none of these studies includes infants. Here, we review current pharmacokinetic, safety and efficacy data of these drugs with a specific focus in infants.

Treatment options for multidrug-resistant bacteria

As a consequence of antibiotic overuse and misuse, nosocomial infections caused by multidrug-resistant bacteria represent a physician's nightmare throughout the world. No newer antimicrobials active against Pseudomonas aeruginosa, the main multidrug-resistant nosocomial pathogen, are available or under investigation. The only exceptions are linezolid, some newer glycopeptides (dalbavancin, oritavancin and telavancin) and daptomycin (a lipopeptide), which are active against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) strains, as well as tigecycline, a potent in vitro glycylcycline against MRSA, VRE, Acinetobacter baumannii and entended-spectrum beta-lactamase (ESBL)+ Enterobacteriaceae. Colistin, an antibiotic of the 1950s has been rediscovered by intensive care unit physicians for use against ESBL+ Enterobacteriaceae, as well as against multidrug-resistant P. aeruginosa and A. baumannii isolates. Although success rates with colistin range between 50 and 73%, almost all studies are retrospective. Immunostimulation efforts against S. aureus are still under development. As antibiotic research and development stagnate, rational policies for prescribing existing antibiotics plus strict infection control are the current mainstay efforts for preventing and combating multidrug-resistant bacterial infections.

Telavancin: a review of its use in patients with nosocomial pneumonia

Telavancin (Vibativ(®)), a lipoglycopeptide antibacterial agent, exhibits potent in vitro activity against Gram-positive bacteria associated with nosocomial pneumonia infections, including meticillin/oxacillin-resistant Staphylococcus aureus (MRSA) isolates and S. aureus isolates with reduced susceptibility to vancomycin. In two multinational trials in adult patients with nosocomial pneumonia caused by Gram-positive bacteria, including infections caused by MRSA isolates, a 1-h intravenous infusion of telavancin 10 mg/kg once daily was noninferior to intravenous vancomycin 1 g every 12 h in terms of clinical cure rates in the all-treated (AT) and clinically evaluable (CE) populations at the follow-up/test-of-cure (FU/TOC) visit. At this visit, clinical cure rates in the AT populations of both groups were approximately 60 %, with rates increasing to ≥80 % in the CE population. Pooled analyses of these trials also generally showed no significant between-group differences in clinical cure rates at the FU/TOC visit in the AT, CE and microbiologically evaluable (ME) populations. In the ME population, clinical cure rates were generally similar in the telavancin and vancomycin groups, irrespective of whether infections were mono- or polymicrobial, or caused by MRSA or methicillin/oxacillin-susceptible S. aureus isolates. Telavancin was generally well tolerated in patients with nosocomial pneumonia participating in clinical trials, with a tolerability profile that was generally similar to that of vancomycin. Telavancin offers an alternative treatment option in patients with nosocomial pneumonia caused by Gram-positive S. aureus, including those caused by MRSA and S. aureus isolates with reduced susceptibility to vancomycin.

Importance of relating efficacy measures to unbound drug concentrations for anti-infective agents

For the optimization of dosing regimens of anti-infective agents, it is imperative to have a good understanding of pharmacokinetics (PK) and pharmacodynamics (PD). Whenever possible, drug efficacy needs to be related to unbound concentrations at the site of action. For anti-infective drugs, the infection site is typically located outside plasma, and a drug must diffuse through capillary membranes to reach its target. Disease- and drug-related factors can contribute to differential tissue distribution. As a result, the assumption that the plasma concentration of drugs represents a suitable surrogate of tissue concentrations may lead to erroneous conclusions. Quantifying drug exposure in tissues represents an opportunity to relate the pharmacologically active concentrations to an observed pharmacodynamic parameter, such as the MIC. Selection of an appropriate specimen to sample and the advantages and limitations of the available sampling techniques require careful consideration. Ultimately, the goal will be to assess the appropriateness of a drug and dosing regimen for a specific pathogen and infection.

Recent advances in antibacterial drugs

The incidence of antimicrobial resistance is on continued rise with a threat to return to the “pre-antibiotic” era. This has led to emergence of such bacterial infections which are essentially untreatable by the current armamentarium of available treatment options. Various efforts have been made to develop the newer antimicrobials with novel modes of action which can act against these multi-drug resistant strains. This review aims to focus on these newly available and investigational antibacterials approved after year 2000, their mechanism of actions/resistance, and spectrum of activity and their phases of clinical trials. Newer unexploited targets and strategies for the next generation of antimicrobial drugs for combating the drug resistance and emerging pathogens in the 21^st century have also been reviewed in the present article.

Case report: artificial elevation of prothrombin time by telavancin

BACKGROUND

Methicillin-resistant Staphylococcus aureus infections are a well-documented risk of surgery and are becoming increasingly difficult to treat owing to continued acquired resistance. A new antibiotic for treatment of Staphylococcus aureus is telavancin.

CASE DESCRIPTION

A patient at our institution was prescribed telavancin for multiple spinal abscesses before spinal surgery. Routine preoperative testing revealed an international normalized ratio (INR) of 2.05 with no clear cause. Careful review of the patient's medication history and prescriber information revealed that telavancin may interfere with prothrombin time (PT/INR) testing. In vitro testing by our laboratory confirmed an association between telavancin dose and an increase in PT/INR. An alternative reagent for PT/INR testing unaffected by telavancin dose revealed a PT/INR of 0.97.

LITERATURE REVIEW

Telavancin interacts with artificial phospholipid surfaces used to monitor coagulation while having no actual effect on coagulation.

PURPOSES AND CLINICAL RELEVANCE

All physicians, especially orthopaedic surgeons, should be aware of the effects of telavancin and ensure proper measures are taken to acquire the true INR by switching the reagent used to test PT/INR or ensuring the PT/INR is drawn before telavancin dosing.

Transplacental transfer of vancomycin and telavancin

OBJECTIVE

We sought to determine the bidirectional transfer and distribution of vancomycin and telavancin across the dually perfused term human placental lobule.

STUDY DESIGN

The technique of dually perfused placental lobule was used in its recirculating mode to determine the maternal to fetal (M→F) (n = 20) and fetal to maternal (n = 18) transfer of each antibiotic, which were coperfused with their radioactive isotopes. The concentrations of drugs were determined by liquid scintillation spectrometry.

RESULTS

In the M→F direction, the transfer of vancomycin (9.6 ± 4%) and telavancin (6.5 ± 2%) were low; however, telavancin retention by the perfused lobule was greater than that of vancomycin (P < .01). The normalized transplacental transfer of telavancin across the placental lobule in the fetal to maternal direction was higher than in the M→F direction (P < .01), suggesting the involvement of placental efflux transporters.

CONCLUSION

The ex vivo perfusion experiments revealed low transfer of vancomycin and telavancin to the fetal circuit.

Telavancin for the treatment of nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA)

Telavancin is a bactericidal lipoglycopeptide antibiotic that is structurally related to vancomycin. It demonstrates in vitro activity against a variety of Gram-positive pathogens including, but not limited to, methicillin-resistant Staphylococcus aureus (MRSA). Telavancin is currently FDA-approved for the treatment of complicated skin and skin-structure infections. Recently, two randomized clinical trials demonstrated the efficacy and safety of telavancin compared to vancomycin for the treatment of nosocomial pneumonia. Overall, telavancin has a favorable safety profile. However, mild gastrointestinal disturbances and reversible increases in serum creatinine were observed in clinical studies. Additional clinical studies are needed to evaluate telavancin's efficacy and safety in comparison to other antistaphylococcal agents for the treatment of infections such as bacteremia and endocarditis.

Population pharmacokinetics of telavancin in healthy subjects and patients with infections

A population pharmacokinetic model of telavancin, a lipoglycopeptide antibiotic, was developed and used to identify sources of interindividual variability. Data were obtained from healthy subjects (seven phase 1 studies), patients with complicated skin and skin structure infections (cSSSI; two phase 2 and two phase 3 studies), and patients with hospital-acquired pneumonia (HAP; two phase 3 studies). A two-compartment open model with zero-order input best fit the telavancin data from healthy individuals and patients with cSSSI or HAP. Telavancin clearance was highly correlated with renal function and, to a lesser extent, with body weight. Other covariates were related to at least one parameter in cSSSI (gender, bacterial eradication, and surgery) or HAP (age of ≥ 75 years) but did not markedly affect exposure. These analyses support current dosing recommendations for telavancin based on patient weight and renal function.