Penetration of moxifloxacin into sternal bone of patients undergoing routine cardiopulmonary bypass surgery

The mysteries of target site concentrations of antibiotics in bone and joint infections: what is known? A narrative review

INTRODUCTION

Currently, antibiotic treatment is often a standard dosing regimen in bone and joint infections (BJI). However, it remains unknown if exposure at the target-site is adequate. The aim of this review is to gain more insight in the relationship between the target site concentration of antibiotic and the minimal inhibitory concentration to target the bacteria in bone and joint infections (BJI).

AREAS COVERED

A literature search was performed by Erasmus MC Medical library. Bone, bone tissue and synovial concentration of antibiotics were covered in humans. In addition, we reported number of patients, dose, sampling method, analytical method and tissue and plasma concentrations. We used the epidemiological cut-off value (ECOFF) values of the targeted micro-organisms. If more than 3 publications were available on the antibiotic, we graphically presented ECOFFS values against reported antibiotic concentrations.

EXPERT OPINION

For most antibiotics the literature is sparse. In addition, a lot of variable and total antibiotic concentrations are published. Ciprofloxacin, cefazolin, cefuroxime, vancomycin and linezolid seem to have adequate average exposure if correlating total concentration to ECOFF, when standard dosing is used. With regards to other antibiotics, results are inconclusive. More extensive pharmacokinetic/pharmacodynamic modeling in BJI is needed.

Recent advances in the local antibiotics delivery systems for management of osteomyelitis

Chronic osteomyelitis is a challenging disease due to its serious rates of mortality and morbidity while the currently available treatment strategies are suboptimal. In contrast to the adopted systemic treatment approaches after surgical debridement in chronic osteomyelitis, local drug delivery systems are receiving great attention in the recent decades. Local drug delivery systems using special carriers have the pros of enhancing the feasibility of penetration of antimicrobial agents to bone tissues, providing sustained release and localized concentrations of the antimicrobial agents in the infected area while avoiding the systemic side effects and toxicity. Most important, the incorporation of osteoinductive and osteoconductive materials in these systems assists bones proliferation and differentiation, hence the generation of new bone materials is enhanced. Some of these systems can also provide mechanical support for the long bones during the healing process. Most important, if the local systems are designed to be injectable to the affected site and biodegradable, they will reduce the level of invasion required for implantation and can win the patients’ compliance and reduce the healing period. They will also allow multiple injections during the course of therapy to guard against the side effect of the long-term systemic therapy. The current review presents different available approaches for delivering antimicrobial agents for the treatment of osteomyelitis focusing on the recent advances in researches for local delivery of antibiotics.

HIGHLIGHTS

Chronic osteomyelitis is a challenging disease due to its serious mortality and morbidity rates and limited effective treatment options.

Local drug delivery systems are receiving great attention in the recent decades.

Osteoinductive and osteoconductive materials in the local systems assists bones proliferation and differentiation

Local systems can be designed to provide mechanical support for the long bones during the healing process.

Designing the local system to be injectable to the affected site and biodegradable will reduces the level of invasion and win the patients’ compliance.

Antibiotic penetration into bone and joints: An updated review

Treatment of bone and joint infections can be challenging as antibiotics should penetrate through the rigid bone structure and into the synovial space. Several pharmacokinetic studies measured the extent of penetration of different antibiotics into bone and joint tissues. This review discusses the results of these studies and compares them with minimum inhibitory concentrations (MIC) of common pathogens implicated in bone and joint infections in order to determine which antibiotics may have a greater potential in the treatment of such infections. Clinical outcomes were also evaluated as data were available. More than 30 antibiotics were evaluated. Overall, most antibiotics, including amoxicillin, piperacillin/tazobactam, cloxacillin, cephalosporins, carbapenems, aztreonam, aminoglycosides, fluoroquinolones, doxycycline, vancomycin, linezolid, daptomycin, clindamycin, trimethoprim/sulfamethoxazole, fosfomycin, rifampin, dalbavancin, and oritavancin, showed good penetration into bone and joint tissues reaching concentrations exceeding the MIC₉₀ and/or MIC breakpoints of common bone and joint infections pathogens. Few exceptions include penicillin and metronidazole which showed a lower than optimum penetration into bones, and the latter as well as flucloxacillin had poor profiles in terms of joint space penetration. Of note, studies on joint space penetration were fewer than studies on bone tissue penetration. Although clinical studies in osteomyelitis and septic arthritis are not available for all of the evaluated antibiotics, these pharmacokinetic results indicate that agents with good penetration profiles would have a potential utilization in such infections.

Gender analysis of moxifloxacin clinical trials

PURPOSE

To determine the inclusion of women and the sex-stratification of results in moxifloxacin Clinical Trials (CTs), and to establish whether these CTs considered issues that specifically affect women, such as pregnancy and use of hormonal therapies. Previous publications about women's inclusion in CTs have not specifically studied therapeutic drugs. Although this type of drug is taken by men and women at a similar rate, adverse effects occur more frequently in the latter.

METHODS

We reviewed 158 published moxifloxacin trials on humans, retrieved from MedLine and the Cochrane Library (1998-2010), to determine whether they complied with the gender recommendations published by U.S. Food and Drug Administration Guideline.

RESULTS

Of a total of 80,417 subjects included in the moxifloxacin CTs, only 33.7% were women in phase I, in contrast to phase II, where women accounted for 45%, phase III, where they represented 38.3% and phase IV, where 51.3% were women. About 40.9% (n=52) of trials were stratified by sex and 15.3% (n=13) and 9% (n=7) provided data by sex on efficacy and adverse effects, respectively. We found little information about the influence of issues that specifically affect women. Only 3 of the 59 journals that published the moxifloxacin CTs stated that authors should stratify their results by sex.

CONCLUSIONS

Women are under-represented in the published moxifloxacin trials, and this trend is more marked in phase I, as they comprise a higher proportion in the other phases. Data by sex on efficacy and adverse effects are scarce in moxifloxacin trials. These facts, together with the lack of data on women-specific issues, suggest that the therapeutic drug moxifloxacin is only a partially evidence-based medicine.

Penetration of moxifloxacin into rat mandibular bone and soft tissue

OBJECTIVE

Based on its in vitro activity and spectrum of activity, the new 8-methoxyquinolone antibiotic moxifloxacin (MXF) seems suited for the antibiotic therapy of odontogenic infections. Penetration into the relevant tissue is another prerequisite for clinical efficacy. For this reason, the levels of MXF in plasma, soft tissue, and mandibular bone were determined in an animal model with Wistar rats.

MATERIAL AND METHODS

Samples of 49 rats were analyzed. Tissue samples were homogenized and proteins were precipitated. The pharmacokinetic evaluation was conducted based on non-compartmental analysis.

RESULTS

The concentration-time courses of tissues show a more plateau-shaped curve compared to plasma. Calculated AUC (area under the curve) ratios tissue:plasma were M. masseter:plasma = 2.64 and mandibles:plasma = 1.13.

CONCLUSIONS

Administration of antibiotics is considered an important part of therapy during and/or after surgical procedures in the maxillofacial area. Because of the good penetration into bone and muscle tissues demonstrated in Wistar rats, MXF might be an option for clinical application in this indication.

Penetration of moxifloxacin into bone evaluated by Monte Carlo simulation

Moxifloxacin is a fluoroquinolone with a broad spectrum of activity and good penetration into many tissues, including bone. Penetration of moxifloxacin into bone has not yet been studied using compartmental modeling techniques. Therefore, we determined the rate and extent of bone penetration by moxifloxacin and evaluated its pharmacodynamic profile in bone via Monte Carlo simulation. Twenty-four patients (10 males, 14 females) undergoing total hip replacement received 400 mg moxifloxacin orally 2 to 7 h prior to surgery. Blood and bone specimens were collected. Bone samples were pulverized under liquid nitrogen by a cryogenic mill, including an internal standard. Drug concentrations were analyzed by high-performance liquid chromatography. We used ADAPT II (results reported), NONMEM, and WinBUGS for pharmacokinetic analysis. Monte Carlo simulation was performed to reverse engineer the necessary area under the free concentration-time curve fAUC(SERUM)/MIC in serum and total AUC(BONE)/MIC in bone for a successful clinical or microbiological outcome. The median (10% to 90% percentile for between-subject variability) of the AUC in bone divided by the AUC in serum (AUC(BONE)/AUC(SERUM)) was 80% (51 to 126%) for cortical bone and 78% (42 to 144%) for cancellous bone. Equilibration between serum and bone was rapid. Moxifloxacin achieved robust (> or = 90%) probabilities of target attainment (PTAs) in serum, cortical bone, and cancellous bone up to MICs of < or = 0.375 mg/liter based on the targets fAUC(SERUM)/MIC > or = 40 and AUC(BONE)/MIC > or = 33. Moxifloxacin showed high bone concentrations and a rapid equilibrium between bone and serum. The favorable PTAs compared to the 90%-inhibitory MIC of Staphylococcus aureus warrant future clinical trials on the effectiveness of moxifloxacin in the treatment of bone infections.

Multidrug-resistant viridans streptococcus (MDRVS) osteomyelitis of the mandible successfully treated with moxifloxacin

Multidrug-resistant viridans group streptococcus (MDRVS) strains have emerged as important pathogens. Treatment of MDRVS infections is problematic. The use of fluoroquinolones for treatment of MDRVS osteomyelitis has not been established. We present the first case of MDRVS osteomyelitis of the mandible successfully treated with sequential intravenous then oral moxifloxacin, and review the literature on the subject.