Azithromycin: the first azalide antibiotic

Development of a dry powder formulation for pulmonary delivery of azithromycin-loaded nanoparticles

The COVID-19 pandemic has raised concern regarding respiratory system diseases and oral inhalation stands out as an attractive non-invasive route of administration for pulmonary diseases such as chronic bronchitis, cystic fibrosis, COVID-19 and community-acquired pneumonia. In this context, we encapsulated azithromycin in polycaprolactone nanoparticles functionalized with phospholipids rich in dipalmitoylphosphatidylcholine and further produced a fine powder formulation by spray drying with monohydrated lactose. Nanoparticles obtained by the emulsion/solvent diffusion-evaporation technique exhibited a mean hydrodynamic diameter around 195-228 nm with a narrow monomodal size distribution (PdI < 0.2). Nanoparticle dispersions were spray-dried at different inlet temperatures, atomizing air-flow, aspirator air flow, and feed rate, using lactose as a drying aid, resulting in a maximal process yield of 63% and an encapsulation efficiency of 83%. Excipients and the dry powder formulations were characterized in terms of morphology, chemical structure, thermal analyses and particle size by SEM, FTIR, DSC/TGA and laser light diffraction. The results indicated spherical particles with 90% at 4.06 µm or below, an adequate size for pulmonary delivery. Aerosolization performance in a NGI confirmed good aerodynamic properties. Microbiological assays showed that the formulation preserves AZM antimicrobial effect against Staphylococcus aureus and Streptococcus pneumoniae strains, with halos above 18 mm. In addition, no formulation-related cytotoxicity was observed against the human cell lines BEAS-2B (lung epithelial), HUVEC (endothelial) and HFF1 (fibroblasts). Overall, the approach described here allows the production of AZM-PCL nanoparticles incorporated into inhalable microparticles, enabling more efficient pulmonary therapy of lung infections.

Mechanistic Insights into Clinically Relevant Ribosome-Targeting Antibiotics

Antibiotics targeting the bacterial ribosome are essential to combating bacterial infections. These antibiotics bind to various sites on the ribosome, inhibiting different stages of protein synthesis. This review provides a comprehensive overview of the mechanisms of action of clinically relevant antibiotics that target the bacterial ribosome, including macrolides, lincosamides, oxazolidinones, aminoglycosides, tetracyclines, and chloramphenicol. The structural and functional details of antibiotic interactions with ribosomal RNA, including specific binding sites, interactions with rRNA nucleotides, and their effects on translation processes, are discussed. Focus is placed on the diversity of these mechanisms and their clinical implications in treating bacterial infections, particularly in the context of emerging resistance. Understanding these mechanisms is crucial for developing novel therapeutic agents capable of overcoming bacterial resistance.

Pharmacokinetics and Bioequivalence of Two Formulations of Azithromycin Tablets: A Randomized, Single-Dose, Three-Period, Crossover Study in Healthy Chinese Volunteers Under Fasting and Fed Conditions

BACKGROUND AND OBJECTIVE

Azithromycin is the first azalide antibiotic that is related to the macrolide family of antibiotics. Bioequivalence studies in China are initiated by the National Medical Products Administration (NMPA), which supports a generic consistency evaluation program for ensuring that generic products manufactured in China meet the required standards and provide equivalent therapeutic effects to their reference products. This study aimed to assess the bioequivalence of two azithromycin tablets under both fasting and fed conditions in healthy Chinese volunteers.

METHODS

This was a single-center, open-label, single-dose, randomized, three-way crossover trial with two independent groups (fasting group and fed group). A total of 72 healthy Chinese subjects (36 subjects in the fasting state and 36 subjects in the fed state) were enrolled and randomized to treatment. Blood samples were collected from 0 to 120 h after a single oral dose of a 250-mg generic azithromycin tablet (test, T) or branded azithromycin tablet (reference, R). The plasma concentrations of azithromycin were determined by high-performance liquid chromatography-tandem mass spectrometry (HPLC‒MS/MS). A non-compartmental analysis method was used to estimate the pharmacokinetic parameters. Adverse events were documented.

RESULTS

In a fasting state, the bioequivalence of maximum plasma concentration (Cmax) was evaluated using the reference-scaled average bioequivalence (RSABE) approach (within-subject standard deviation, SWR > 0.294), and the bioequivalence of area under the concentration-time curve from time 0 to the time of the last measurable plasma concentration (AUC0-t) and area under the concentration-time curve from time 0 extrapolated to infinity (AUC0-∞) were evaluated by the average bioequivalence (ABE) method (SWR <  0.294). The geometric mean ratio (GMR) of T/R for Cmax was 106.49%, while the 95% upper confidence bound was <  0. The GMRs of AUC0-t and AUC0-∞ were 103.34% and 101.28%, and the 90% confidence intervals (CIs) of the test/reference were 95.90-111.35%/94.85-108.15%, respectively. In the fed state, the RSABE approach was applied to estimate the bioequivalence of Cmax (SWR >0.294), and the ABE approach was applied to estimate the bioequivalence of AUC0-t and AUC0-∞ (SWR <  0.294). The GMR for Cmax was 99.80%, while the 95% upper confidence bound value was <  0. The GMRs of AUC0-t and AUC0-∞ were 97.07% and 98.15%, and the 90% CIs of the T/R were 90.02-104.68% and 90.66-106.25%, respectively. All adverse events were mild and transient.

CONCLUSIONS

The trial indicated that the test and the reference azithromycin tablets were bioequivalent and well tolerated in healthy Chinese volunteers under both fasting and fed conditions.

TRIAL REGISTRATION

Clinicaltrials, ChiCTR2300071630 (retrospectively registered in 19/05/2023).

Preclinical and Clinical Investigations of Potential Drugs and Vaccines for COVID-19 Therapy: A Comprehensive Review With Recent Update

The COVID-19 pandemic-led worldwide healthcare crisis necessitates prompt societal, ecological, and medical efforts to stop or reduce the rising number of fatalities. Numerous mRNA based vaccines and vaccines for viral vectors have been licensed for use in emergencies which showed 90% to 95% efficacy in preventing SARS-CoV-2 infection. However, safety issues, vaccine reluctance, and skepticism remain major concerns for making mass vaccination a successful approach to treat COVID-19. Hence, alternative therapeutics is needed for eradicating the global burden of COVID-19 from developed and low-resource countries. Repurposing current medications and drug candidates could be a more viable option for treating SARS-CoV-2 as these therapies have previously passed a number of significant checkpoints for drug development and patient care. Besides vaccines, this review focused on the potential usage of alternative therapeutic agents including antiviral, antiparasitic, and antibacterial drugs, protease inhibitors, neuraminidase inhibitors, and monoclonal antibodies that are currently undergoing preclinical and clinical investigations to assess their effectiveness and safety in the treatment of COVID-19. Among the repurposed drugs, remdesivir is considered as the most promising agent, while favipiravir, molnupiravir, paxlovid, and lopinavir/ritonavir exhibited improved therapeutic effects in terms of elimination of viruses. However, the outcomes of treatment with oseltamivir, umifenovir, disulfiram, teicoplanin, and ivermectin were not significant. It is noteworthy that combining multiple drugs as therapy showcases impressive effectiveness in managing individuals with COVID-19. Tocilizumab is presently employed for the treatment of patients who exhibit COVID-19-related pneumonia. Numerous antiviral drugs such as galidesivir, griffithsin, and thapsigargin are under clinical trials which could be promising for treating COVID-19 individuals with severe symptoms. Supportive treatment for patients of COVID-19 may involve the use of corticosteroids, convalescent plasma, stem cells, pooled antibodies, vitamins, and natural substances. This study provides an updated progress in SARS-CoV-2 medications and a crucial guide for inventing novel interventions against COVID-19.

Alterations of Growth, Biofilm-Forming, and Gene Expression of Bordetella pertussis by Antibiotics at Sub-Minimal Inhibitory Concentrations

Bordetella pertussis is the primary agent of the acute respiratory disease pertussis. It has been reported that the disease has recently become more common, especially in adults and adolescents, and adaptation of the pathogen is thought to have an important influence on the recurrence of the disease. This study aims to determine the effect of erythromycin, azithromycin, and trimethoprim-sulfamethoxazole used in the treatment of pertussis on the virulence gene expressions (prn, ptxS1, fhaB), biofilm-forming and growth of B. pertussis. In this study, the minimal inhibitory concentration (MIC) values of azithromycin and erythromycin in B. pertussis local strain Saadet were determined to be 0.09 μg/mL and 0.3 μg/mL, respectively. However, the Tohama-I and Saadet strains were resistant to trimethoprim-sulfamethoxazole (MIC>32 μg/mL). The biofilm-forming of the Saadet strain decreased with the increase in antibiotic doses. It was observed that 1/32MIC erythromycin and 1/32MIC azithromycin upregulated the expression of fhaB in Tohama-I, whereas the expression of ptxS1 and prn significantly decreased in sub-MICs of erythromycin. In the Saadet strain, only ptxS1 was highly expressed at 1/16MIC azithromycin and erythromycin (p>0.05). This is the first study to investigate the effect of sub-MIC antibiotics on the expression of virulence genes and biofilm-forming of B. pertussis.

Immunomodulatory Effects of Macrolides Considering Evidence from Human and Veterinary Medicine

Macrolide antimicrobial agents have been in clinical use for more than 60 years in both human and veterinary medicine. The discovery of the non-antimicrobial properties of macrolides and the effect of immunomodulation of the inflammatory response has benefited patients with chronic airway diseases and impacted morbidity and mortality. This review examines the evidence of antimicrobial and non-antimicrobial properties of macrolides in human and veterinary medicine with a focus toward veterinary macrolides but including important and relevant evidence from the human literature. The complete story for these complex and important molecules is continuing to be written.

A Reference-Scaled Average Bioequivalence Study of Azithromycin Tablets Manufactured in China and the United States: An Open-Label, Randomized, Single-Dose, 3-Way Crossover Study in Healthy Chinese Subjects Under Fasted and Fed Conditions

Azithromycin (Zithromax) is an azalide antibiotic that binds to the 50S ribosomal subunit of the susceptible organism and thereby interferes with its protein synthesis. An open-label, randomized, single-dose, 3-way crossover bioequivalence study was conducted to compare the rate and extent of absorption of the azithromycin 250-mg tablet manufactured at Pfizer Dalian (China) and that at Pfizer Barceloneta (United States) under fasted and fed conditions in healthy Chinese subjects. This study aimed to support a generic consistency evaluation program, initiated by the National Medical Products Administration, for evaluating the quality and efficacy of the products manufactured in China. In the study, the within-subject standard deviation for area under the serum concentration-time profile from time 0 to 72 hours after dosing in the fasted condition was <0.294, and the 90%CI for the ratio was within 80% to 125%; the within-subject SDs for serum peak concentration in the fasted condition, area under the serum concentration-time profile from time 0 to 72 hours after dosing in the fed condition, and serum peak concentration in the fed condition, were all >0.294, with the upper confidence bounds being <0.00, and the point estimates of the ratios being within 80% to 125%. The results support the bioequivalence between azithromycin tablets manufactured in China and the United States in fasted and fed conditions, with both tablets showing an acceptable safety/tolerability profile in the studied population.

An Investigation of the Predominant Structure of Antibiotic Azithromycin in Chloroform Solution through NMR and Thermodynamic Analysis

Azithromycin (AZM) is a well-known macrolide-type antibiotic that has been used in the treatment of infections and inflammations. Knowledge of the predominant molecular structure in solution is a prerequisite for...

Rational prioritization strategy allows the design of macrolide derivatives that overcome antibiotic resistance

Due to the development of resistance against commonly used antibiotics, new derivatives that avoid resistance mechanisms need to be developed. To address this problem, a rational prioritization strategy is outlined for macrolide antibiotics. Candidates are screened based on their solubility, membrane permeability, and binding affinity using a tiered optimization approach of free energy simulations and quantum mechanics/molecular mechanics calculations. After prioritization by computational methods, the best candidates are evaluated experimentally. The strategy creates a targeted substance library that is highly enriched in compounds with antibacterial activity. This allows for faster iterations in the development of new antibiotic derivatives.

Antibiotic resistance is a major threat to global health; this problem can be addressed by the development of new antibacterial agents to keep pace with the evolutionary adaptation of pathogens. Computational approaches are essential tools to this end since their application enables fast and early strategical decisions in the drug development process. We present a rational design approach, in which acylide antibiotics were screened based on computational predictions of solubility, membrane permeability, and binding affinity toward the ribosome. To assess our design strategy, we tested all candidates for in vitro inhibitory activity and then evaluated them in vivo with several antibiotic-resistant strains to determine minimal inhibitory concentrations. The predicted best candidate is synthetically more accessible, exhibits higher solubility and binding affinity to the ribosome, and is up to 56 times more active against resistant pathogens than telithromycin. Notably, the best compounds designed by us show activity, especially when combined with the membrane-weakening drug colistin, against Acinetobacter baumanii, Pseudomonas aeruginosa, and Escherichia coli, which are the three most critical targets from the priority list of pathogens of the World Health Organization.

Population genomics reveals distinct temporal association with the emergence of ST1 serotype V Group B Streptococcus and macrolide resistance in North America

Identified in the 1970s as the leading cause of invasive bacterial disease in neonates and young infants, Group B Streptococcus (GBS) is now also recognized as a significant cause of morbidity and mortality among adults with underlying medical conditions and the elderly. Concomitant with the increasing incidence of GBS invasive disease in adults is the rise of resistance among GBS isolates to second line antibiotics. Previous research shows that among serotype V GBS - one of the most common capsular types causing adult invasive disease - sequence type 1 (ST1) - accounts for an overwhelming majority of adult invasive disease isolates and frequently harbors macrolide resistance. In this study, using whole genome sequencing data from strains isolated in the USA and Canada over a 45-year period, we examined the association of antimicrobial resistance with the emergence of invasive serotype V ST1 GBS. Our findings show a strong temporal association between increased macrolide resistance and the emergence of serotype V ST1 GBS subpopulations that currently co-circulate to cause adult as well as young infant invasive disease. ST1 GBS subpopulations are defined, in part, by the presence of macrolide resistance genes in mobile genetic elements. Increased frequency of macrolide resistance-encoding mobile genetic elements among invasive GBS ST1 strains suggests the presence of such elements contributes to GBS virulence. Our work provides a foundation for the investigation of genetic features contributing to the increasing prevalence and pathogenesis of serotype V GBS in adult invasive disease.

Therapeutic efficacy of macrolides in management of patients with mild COVID-19

Evidence on the efficacy of adding macrolides (azithromycin or clarithromycin) to the treatment regimen for COVID-19 is limited. We testify whether adding azithromycin or clarithromycin to a standard of care regimen was superior to standard of supportive care alone in patients with mild COVID-19.This randomized trial included three groups of patients with COVID-19. The azithromycin group included, 107 patients who received azithromycin 500 mg/24 h for 7 days, the clarithromycin group included 99 patients who received clarithromycin 500 /12 h for 7 days, and the control group included 99 patients who received standard care only. All three groups received only symptomatic treatment for control of fever and cough .Clinical and biochemical evaluations of the study participants including assessment of the symptoms duration, real-time reverse transcription-polymerase chain reaction (rRT-PCR), C-reactive protein (CRP), serum ferritin, D-dimer, complete blood count (CBC), in addition to non-contrast chest computed tomography (CT), were performed. The overall results revealed significant early improvement of symptoms (fever, dyspnea and cough) in patients treated with either azithromycin or clarithromycin compared to control group, also there was significant early conversion of SARS-CoV-2 PCR to negative in patients treated with either azithromycin or clarithromycin compared to control group (p < 0.05 for all).There was no significant difference in time to improvement of fever, cough, dyspnea, anosmia, gastrointestinal tract "GIT" symptoms and time to PCR negative conversion between patients treated with azithromycin compared to patients treated with clarithromycin (p > 0.05 for all). Follow up chest CT done after 2 weeks of start of treatment showed significant improvement in patients treated with either azithromycin or clarithromycin compared to control group (p < 0.05 for all).Adding Clarithromycin or azithromycin to the therapeutic protocols for COVID-19 could be beneficial for early control of fever and early PCR negative conversion in Mild COVID-19.Trial registration: (NCT04622891) www.ClinicalTrials.gov retrospectively registered (November 10, 2020).

Azithromycin "ghost peak": A solution degradation product of azithromycin via leaching from borosilicate glass volumetric flasks and vials

An interference peak was found while detecting related substances of azithromycin. It is impressive that the degradation peak occurred at about 70 min in the next injection of the test solution (4 mg/mL or higher). Once the degradation peak was observed, it would keep growing. By using a strategy that Q-TOF high resolution mass spectrometry with mechanism-based stress studies, followed by preparative subsequent structure characterization by 1D and 2D NMR, the unknown peak was identified as azithromycin hydrogen borate. It apparently results from azithromycin and residual boron leaching out of the inner surface of the glass volumetric flasks and vials used in the sample preparation. By simulating the above chemical process, boric acid and azithromycin were dissolved in the same extraction diluent and a big interference peak occurred. It was found that boron-free flasks and vials, such as PMP or PP flasks and PTFE or PP vials could be used for the detection of azithromycin related substances to avoid the production of azithromycin hydrogen borate.

Therapeutic Effectiveness and Safety of Repurposing Drugs for the Treatment of COVID-19: Position Standing in 2021

COVID-19, transmitted by SARS-CoV-2, is one of the most serious pandemic situations in the history of mankind, and has already infected a huge population across the globe. This horrendously contagious viral outbreak was first identified in China and within a very short time it affected the world's health, transport, economic, and academic sectors. Despite the recent approval of a few anti-COVID-19 vaccines, their unavailability and insufficiency along with the lack of other potential therapeutic options are continuing to worsen the situation, with valuable lives continuing to be lost. In this situation, researchers across the globe are focusing on repurposing prospective drugs and prophylaxis such as favipiravir, remdesivir, chloroquine, hydroxychloroquine, ivermectin, lopinavir-ritonavir, azithromycin, doxycycline, ACEIs/ARBs, rivaroxaban, and protease inhibitors, which were preliminarily based on in vitro and in vivo pharmacological and toxicological study reports followed by clinical applications. Based on available preliminary data derived from limited clinical trials, the US National Institute of Health (NIH) and USFDA also recommended a few drugs to be repurposed i.e., hydroxychloroquine, remdesivir, and favipiravir. However, World Health Organization later recommended against the use of chloroquine, hydroxychloroquine, remdesivir, and lopinavir/ritonavir in the treatment of COVID-19 infections. Combining basic knowledge of viral pathogenesis and pharmacodynamics of drug molecules as well as in silico approaches, many drug candidates have been investigated in clinical trials, some of which have been proven to be partially effective against COVID-19, and many of the other drugs are currently under extensive screening. The repurposing of prospective drug candidates from different stages of evaluation can be a handy wellspring in COVID-19 management and treatment along with approved anti-COVID-19 vaccines. This review article combined the information from completed clinical trials, case series, cohort studies, meta-analyses, and retrospective studies to focus on the current status of repurposing drugs in 2021.

Efficacy and safety of azithromycin in Covid-19 patients: A systematic review and meta-analysis of randomized clinical trials

Azithromycin (AZM) is commonly used in Covid‐19 patients based on low‐quality evidence, increasing the risk of developing adverse events and antimicrobial resistance. The current systematic review and meta‐analysis investigated the safety and efficacy of AZM in treating Covid‐19 patients using published randomized controlled trials. Google Scholar, PubMed, Scopus, Cochrane Library, Clinical Trials.gov, MEDLINE, bioRxiv and medRxiv were searched for relevant studies. The random‐effects model was used to pool estimates using the Paule–Mandel estimate for heterogeneity. The odds ratio and raw difference in medians were used for dichotomous and continuous outcomes, respectively. The analysis included seven studies with 8822 patients (median age, 55.8 years; 61% males). The risk of bias was assessed as ‘low’ for five of the seven mortality results and as ‘some concerns’ and ‘high’ in one trial each. There were 657/3100 (21.2%) and 1244/5654 (22%) deaths among patients randomized to AZM and standard of care, respectively. The use of AZM was not associated with mortality in Covid‐19 patients (OR = 0.96, 95% CI 0.88–1.05, p = 0.317 based on the random‐effect meta‐analysis). The use of AZM was not associated with need for invasive mechanical ventilation (OR = 0.96, 95% CI 0.49–1.87, p = 0.85) and length of stay (Δ = 1.11, 95% CI −2.08 to 4.31, p = 0.49). The results show that using AZM as routine therapy in Covid‐19 patients is not justified due to lack of efficacy and potential risk of bacterial resistance that is not met by an increased clinical benefit.

An Update on Antiviral Therapy Against SARS-CoV-2: How Far Have We Come?

COVID-19 pandemic has spread worldwide at an exponential rate affecting millions of people instantaneously. Currently, various drugs are under investigation to treat an enormously increasing number of COVID-19 patients. This dreadful situation clearly demands an efficient strategy to quickly identify drugs for the successful treatment of COVID-19. Hence, drug repurposing is an effective approach for the rapid discovery of frontline arsenals to fight against COVID-19. Successful application of this approach has resulted in the repurposing of some clinically approved drugs as potential anti-SARS-CoV-2 candidates. Several of these drugs are either antimalarials, antivirals, antibiotics or corticosteroids and they have been repurposed based on their potential to negate virus or reduce lung inflammation. Large numbers of clinical trials have been registered to evaluate the effectiveness and clinical safety of these drugs. Till date, a few clinical studies are complete and the results are primary. WHO also conducted an international, multi-country, open-label, randomized trials-a solidarity trial for four antiviral drugs. However, solidarity trials have few limitations like no placebos were used, additionally any drug may show effectiveness for a particular population in a region which may get neglected in solidarity trial analysis. The ongoing randomized clinical trials can provide reliable long-term follow-up results that will establish both clinical safety and clinical efficacy of these drugs with respect to different regions, populations and may aid up to worldwide COVID-19 treatment research. This review presents a comprehensive update on majorly repurposed drugs namely chloroquine, hydroxychloroquine, remdesivir, lopinavir-ritonavir, favipiravir, ribavirin, azithromycin, umifenovir, oseltamivir as well as convalescent plasma therapy used against SARS-CoV-2. The review also summarizes the data recorded on the mechanism of anti-SARS-CoV-2 activity of these repurposed drugs along with the preclinical and clinical findings, therapeutic regimens, pharmacokinetics, and drug-drug interactions.

Design, synthesis, antibacterial evaluation, and computational studies of hybrid oxothiazolidin-1,2,4-triazole scaffolds

Bacterial infections are a serious threat to human health due to the development of resistance against the presently used antibiotics. The problem of growing and widespread antibiotic resistance is only getting worse with the shortage of new classes of antibiotics, creating a substantial unmet medical need in the treatment of serious bacterial infections. Therefore, in the present work, we report 18 novel hybrid thiazolidine-1,2,4-triazole derivatives as DNA gyrase inhibitors. The derivatives were synthesized by multistep organic synthesis and characterized by spectroscopic methods (¹ H and ¹³ C nuclear magnetic resonance and mass spectroscopy). The derivatives were tested for DNA gyrase inhibition, and the result emphasized that the synthesized derivatives have a tendency to inhibit the function of DNA gyrase. Furthermore, the compounds were also tested for antibacterial activity against three Gram-positive (Bacillus subtilis [NCIM 2063], Bacillus cereus [NCIM 2156], Staphylococcus aureus [NCIM 2079]) and two Gram-negative (Escherichia coli [NCIM 2065], Proteus vulgaris [NCIM 2027]) bacteria. The derivatives showed a significant-to-moderate antibacterial activity with noticeable antibiofilm efficacy. Quantitative structure-activity relationship (QSAR), ADME (absorption, distribution, metabolism, elimination) calculation, molecular docking, radial distribution function, and 2D fingerprinting were also performed to elucidate fundamental structural fragments essential for their bioactivity. These studies suggest that the derivatives 10b and 10n have lead antibacterial properties with significant DNA gyrase inhibitory efficacy, and they can serve as a starting scaffold for the further development of new broad-spectrum antibacterial agents.

Efficacy of azithromycin 1% and 1.5% ophthalmic solutions compared to tobramycin 0.3% eye drops: A systematic review and meta-analysis

Background:

Azithromycin 1% and 1.5% ophthalmic preparations are used widely in clinical practice for the treatment of signs and symptoms of eye diseases. The aim of this study was to render conclusive evidence by comparing the efficacy of azithromycin 1% and 1.5% over tobramycin 0.3% ophthalmic solutions for the treatment of eye diseases in a short duration in terms of bacterial resolution, the cure rate, and resolving clinical sign and symptoms.

Methods:

Systematic searches were performed in the electronic database (MEDLINE, Embase, Emcare, CINAHL, Scopus, PubMed, ProQuest, and Web of Science) and other sources. Multicenter randomized controlled trial studies conducted in English were identified and screened. Analysis of individual studies was conducted using the OpenMeta-analyst and Review Manager Version 5.3 software.

Results:

Eleven studies were included in the systematic review and meta-analysis. In clinical cure rate, azithromycin 1% and 1.5% eye drops were more effective than tobramycin 0.3% eye drops in short duration dosing (⩽5 days) with a twice-a-day regimen (relative risk = 1.13; 95% confidence interval: 1.008, 1.28), whereas on increased duration (>5 days), azithromycin is almost similarly as effective as tobramycin (relative risk = 1.007; 95% confidence interval: 0.96, 1.05). There was no significant difference in efficacy of bacterial resolution of azithromycin (1%, 1.5%) eye drops compared to tobramycin (0.3%) eye drops (relative risk = 0.99; 95% confidence interval: 0.96, 1.018). Azithromycin eye drops are effective in improving the signs and symptoms of eye disease.

Conclusion:

Azithromycin 1% or 1.5% is more effective in the clinical cure rate of eye disease than tobramycin 0.3% eye drops in ⩽5 days of treatment. It is also the best choice of treatment for improving the signs and symptoms of eye disease. So that we recommend clinicians to use azithromycin 1% or 1.5% eye drops.

Systematic Review Registration:

PROSPERO 2019 CRD42019139911

Clinical evidences on the antiviral properties of macrolide antibiotics in the COVID-19 era and beyond

Macrolides are a large group of antibiotics characterised by the presence of a macro-lactone ring of variable size. The prototype of macrolide antibiotics, erythromycin was first produced by Streptomyces and associated species more than half a century ago; other related drugs were developed. These drugs have been shown to have several pharmacological properties: in addition to their antibiotic activity, they possess some anti-inflammatory properties and have been also considered against non-bacterial infections. In this review, we analysed the available clinical evidences regarding the potential anti-viral activity of macrolides, by focusing on erythromycin, clarithromycin and azithromycin. Overall, there is no significant evidences so far that macrolides might have a direct benefit on most of viral infections considered in this review (RSV, Influenza, coronaviruses, Ebola and Zika viruses). However, their clinical benefit cannot be ruled out without further and focused clinical studies. Macrolides may improve the clinical course of viral respiratory infections somehow, at least through indirect mechanisms relying on some and variable anti-inflammatory and/or immunomodulatory effects, in addition to their well-known antibacterial activity.

Study of the Interaction of Zinc Cation with Azithromycin and its Significance in the COVID-19 Treatment: A Molecular Approach

Introduction:

On account of the current COVID-19 pandemic, we have explored the importance of azithromycin and zinc in the treatment of the coronavirus disease by studying the interaction between the cation Zn++ and azithromycin with the tools of the semi-empirical quantum mechanics PM3 method.

Methods:

By this approach, the niche in which Zn++ is located was determined. Zn++ creates a strong clastic binding between an amine and a hydroxyl group located on the amino-hexose side-chain. Such an interaction serves as a shuttle and allows zinc cation to invade endocellular structures.

Results:

In this triple collaborative association, the role of hydroxychloroquine would be more that of a chaotropic agent at plasmic membranes, which facilitates access to the azithromycin-Zn++ equipage into key internal compartments.

Conclusion:

Finally, we show that both azithromycin and Zn++ are susceptible to play a direct role against the replication and the assembly of SARS-CoV-2 particles.

Azithromycin-loaded respirable microparticles for targeted pulmonary delivery for the treatment of pneumonia

Pneumonia is a major contributor to infection-based hospitalizations and deaths in the United States. Antibiotics such as azithromycin (AZM), although effective at managing pneumonia, often suffer from off-target diffusion and poor bioavailability when administered orally or via intravenous injection. The formation of biofilms at the disease sites makes the treatment more complicated by protecting bacteria from antimicrobial agents and thus necessitating a much higher dosage of antibiotics to eradicate the biofilms. As such, targeted pulmonary delivery of antibiotics has emerged as a promising alternative by providing direct access to the lung while also allowing higher local therapeutic concentrations but minimal systemic exposure. In this study, AZM was encapsulated in N-fumaroylated diketopiperazine (FDKP) microparticles for efficient pulmonary delivery. Both in vitro and in vivo results demonstrated that AZM@FDKP-MPs administered via intratracheal insufflation achieved at least a 3.4 times higher local concentration and prolonged retention times compared to intravenous injection and oral administration, suggesting their potential to better manage bacterial pneumonia.

Saliva Versus Plasma Bioequivalence of Azithromycin in Humans: Validation of Class I Drugs of the Salivary Excretion Classification System

Aim

The aim of this study was to compare human pharmacokinetics and bioequivalence metrics in saliva versus plasma for azithromycin as a model class I drug of the Salivary Excretion Classification System (SECS).

Methods

A pilot, open-label, two-way crossover bioequivalence study was done, and involved a single 500-mg oral dose of azithromycin given to eight healthy subjects under fasting conditions, followed by a 3-week washout period. Blood and unstimulated saliva samples were collected over 72 h and deep frozen until analysis by a validated liquid chromatography with mass spectroscopy method. The pharmacokinetic parameters and bioequivalence metrics of azithromycin were calculated by non-compartment analysis using WinNonlin V5.2. Descriptive statistics and dimensional analysis of the pharmacokinetic parameters of azithromycin were performed using Microsoft Excel. PK-Sim V5.6 was used to estimate the effective intestinal permeability of azithromycin.

Results and Discussion

No statistical differences were shown in area under the concentration curves to 72 h (AUC_0–72), maximum measured concentration (C_max) and time to maximum concentration (T_max) between test and reference azithromycin products (P > 0.05) in the saliva matrix and in the plasma matrix. Due to the high intra-subject variability and low sample size of this pilot study, the 90% confidence intervals of AUC_0–72 and C_max did not fall within the acceptance range (80–125%). However, saliva levels were higher than that of plasma, with a longer salivary T_max. The mean saliva/plasma concentration of test and reference were 2.29 and 2.33, respectively. The mean ± standard deviation ratios of saliva/plasma of AUC_0–72, C_max and T_max for test were 2.65 ± 1.59, 1.51 ± 0.49 and 1.85 ± 1.4, while for the reference product they were 3.37 ± 2.20, 1.57 ± 0.77 and 2.6 ± 1.27, respectively. A good correlation of R = 0.87 between plasma and saliva concentrations for both test and reference products was also observed. Azithromycin is considered a class I drug based on the SECS, since it has a high permeability and high fraction unbound, and saliva sampling could be used as an alternative to plasma sampling to characterize its pharmacokinetics and bioequivalence in humans when adequate sample size is used.

Macrolides and associated antibiotics based on similar mechanism of action like lincosamides in malaria

Malaria, a parasite vector-borne disease, is one of the biggest health threats in tropical regions, despite the availability of malaria chemoprophylaxis. The emergence and rapid extension of Plasmodium falciparum resistance to various anti-malarial drugs has gradually limited the potential malaria therapeutics available to clinicians. In this context, macrolides and associated antibiotics based on similar mechanism of action like lincosamides constitute an interesting alternative in the treatment of malaria. These molecules, whose action spectrum is similar to that of tetracyclines, are typically administered to children and pregnant women. Recent studies have examined the effects of azithromycin and the lincosamide clindamycin, on isolates from different continents. Azithromycin and clindamycin are effective and well tolerated in the treatment of uncomplicated malaria in combination with quinine. This literature review assesses the roles of macrolides and lincosamides in the prophylaxis and treatment of malaria.

Predicting the optimum compositions of a parenteral nanoemulsion system loaded with azithromycin antibiotic utilizing the artificial neural network model

For the purpose of brain delivery via intravenous administration, the formulation of an azithromycin-loaded nanoemulsion system was optimized utilizing the artificial neural network (ANN) as a multivariate statistical technique.

Macrolides and lincosamides in cattle and pigs: use and development of antimicrobial resistance

Macrolides and lincosamides are important antibacterials for the treatment of many common infections in cattle and pigs. Products for in-feed medication with these compounds in combination with other antimicrobials are commonly used in Europe. Most recently approved injectable macrolides have very long elimination half-lives in both pigs and cattle, which allows once-only dosing regimens. Both in-feed medication and use of long-acting injections result in low concentrations of the active substance for prolonged periods, which causes concerns related to development of antimicrobial resistance. Acquired resistance to macrolides and lincosamides among food animal pathogens, including some zoonotic bacteria, has now emerged. A comparison of studies on the prevalence of resistance is difficult, since for many micro-organisms no agreed standards for susceptibility testing are available. With animal pathogens, the most dramatic increase in resistance has been seen in the genus Brachyspira. Resistance towards macrolides and lincosamides has also been detected in staphylococci isolated from pigs and streptococci from cattle. This article reviews the use of macrolides and lincosamides in cattle and pigs, as well as the development of resistance in target and some zoonotic pathogens. The focus of the review is on European conditions.

Development of a population pharmacokinetic model to describe azithromycin whole-blood and plasma concentrations over time in healthy subjects

Azithromycin (AZI), a broad-spectrum antibiotic, accumulates in polymorphonuclear cells and peripheral blood mononuclear cells. The distribution of AZI in proinflammatory cells may be important to the anti-inflammatory properties. Previous studies have described plasma AZI pharmacokinetics. The objective of this study was to describe the pharmacokinetics of AZI in whole blood (concentration in whole blood [Cb]) and plasma (concentration in plasma [Cp]) of healthy subjects. In this study, 12 subjects received AZI (500 mg once a day for 3 days). AZI Cb and Cp were quantified in serial samples collected up to 3 weeks after the last dose and analyzed using noncompartmental and compartmental methods. After the last dose, Cb was greater than Cp. Importantly, Cb, but not Cp, was quantifiable in all but one subject at 3 weeks. The blood area under the curve during a 24-h dosing interval (AUC24) was ∼2-fold greater than the plasma AUC24, but simulations suggested that Cb was not at steady state by day 3. Upon exploration of numerous models, an empirical 3-compartment model adequately described Cp and Cb, but Cp was somewhat underestimated. Intercompartmental clearance (CL; likely representing cells) was lower than apparent oral CL (18 versus 118 liters/h). Plasma, peripheral, and cell compartmental volumes were 439 liters, 2,980 liters, and 3,084 liters, respectively. Interindividual variability in CL was low (26.2%), while the volume of distribution variability was high (107%). This is the first report to describe AZI Cb in healthy subjects, the distribution parameters between Cp and Cb, and AZI retention in blood for up to 3 weeks following 3 daily doses. The model can be used to predict Cb from Cp for AZI under various dosing regimens. (This study has been registered at ClinicalTrials.gov under registration no. NCT01026064.).

Encapsulation of azithromycin into polymeric microspheres by reduced pressure-solvent evaporation method

Azithromycin loaded microspheres with blends of poly-l-lactide and ploy-D,L-lactide-co-glycolide as matrices were prepared by the atmosphere-solvent evaporation (ASE) and reduced pressure-solvent evaporation (RSE) method. Both the X-ray diffraction spectra and DSC thermographs demonstrated that poly-L-lactide existed in a crystalline form in the ASE microspheres, while an amorphous form was present in the RSE formulations. Besides, solvent removal at atmosphere gave microspheres of porous and rough surfaces, but smooth surfaces appeared in the RSE microspheres. The incorporation efficiency as well as the burst release (cumulative release in the first 24h) in the ASE formulations was 39.94 ± 1.18% and 23.96 ± 2.01% respectively, yet the encapsulation efficiency of the microspheres fabricated under 385 mmHg was high up to 57.19 ± 3.81% and the burst release was 4.12 ± 0.15%. The in vitro drug release studies indicated that the ASE microspheres presented a zero-order profile; while the RSE formulations followed first-order kinetics. Other factors including solidification time, temperature, drug to polymer ratio and pH value of the continuous phase could also influence the physicochemical characteristics and release profiles of microspheres. In conclusion, the overall improvement of microspheres in appearance, encapsulation efficiency and controlled drug release through the RSE method could be easily fulfilled under optimal preparation conditions.

Azithromycin in acute bacterial upper respiratory tract infections: an Indian non-interventional study

To assess the effectiveness, safety and tolerability of azithromycin in acute bacterial upper respiratory tract infections (URTIs). In this open-label, prospective, multi-center, non-interventional study in bacterial URTI, the decision to prescribe azithromycin was independent of enrolment. Follow up was 1 week after treatment and if possible, at Week 2. Investigators' assessment of clinical outcome (Success/Failure) at the end of study was the primary endpoint for efficacy analysis. Clinical outcome of 'Success' was defined as the global response of Cure or Improvement. A pharmacoeconomic analysis of management of URTIs was also attempted. Of the 410 patients recruited, all were evaluated for safety and 278 for efficacy. The median treatment duration was 3 days. Following treatment with azithromycin, overall success rate was 98.92% (95% CI 96.88-99.78%; Clopper-Pearson method). The success rate was similar across the sub-groups of acute otitis media-100%, bacterial sinusitis-95.83%, and pharyngotonsillitis-99.38%. The success rate was 100% among children and adolescents (age ≤18 years) and 98.6% among adults (age >18 years). Most of the common signs and symptoms of URTI reported during baseline, significantly improved at the end of the study. Sixteen (3.90%) patients reported treatment emergent adverse events, the most common being diarrhea-5 (1.2%) and flatulence-2 (0.5%). The average cost of treating bacterial URTI was INR 716 per patient. Azithromycin is effective and well tolerated in Indian patients with bacterial URTIs.

Azithromycin plus chloroquine: combination therapy for protection against malaria and sexually transmitted infections in pregnancy

Introduction:

The first-line therapy for the intermittent preventive treatment of malaria in pregnancy (IPTp) is sulphadoxine-pyrimethamine (SP). There is an urgent need to identify safe, well-tolerated and efficacious alternatives to SP due to widespread Plasmodium falciparum resistance. Combination therapy using azithromycin and chloroquine is one possibility that has demonstrated adequate parasitological response > 95% in clinical trials of non-pregnant adults in sub-Saharan Africa and where IPTp is a government policy in 33 countries.

Areas covered:

Key safety, tolerability and efficacy data are presented for azithromycin and chloroquine, alone and/or in combination, when used to prevent and/or treat P. falciparum, P. vivax, and several curable sexually transmitted and reproductive tract infections (STI/RTI). Pharmacokinetic evidence from pregnant women is also summarized for both compounds.

Expert opinion:

The azithromycin-chloroquine regimen that has demonstrated consistent efficacy in non-pregnant adults has been a 3-day course containing daily doses of 1 g of azithromycin and 600 mg base of chloroquine. The pharmacokinetic evidence of these compounds individually suggests that dose adjustments may not be necessary when used in combination for treatment efficacy against P. falciparum, P. vivax, as well as several curable STI/ RTI among pregnant women, although clinical confirmation will be necessary. Mass trachoma-treatment campaigns have shown that azithromycin selects for macrolide resistance in the pneumococcus, which reverses following the completion of therapy. Most importantly, no evidence to date suggests that azithromycin induces pneumococcal resistance to penicillin.

Review of macrolides (azithromycin, clarithromycin), ketolids (telithromycin) and glycylcyclines (tigecycline)

The advanced macrolides, azithromycin and clarithromycin, and the ketolide, telithromycin, are structural analogs of erythromycin. They have several distinct advantages when compared with erythromycin, including enhanced spectrum of activity, more favorable pharmacokinetics and pharmacodynamics, once-daily administration, and improved tolerability. Clarithromycin and azithromycin are used extensively for the treatment of respiratory tract infections, sexually transmitted diseases, and Helicobacter pylori-associated peptic ulcer disease. Telithromycin is approved for the treatment of community-acquired pneumonia. Severe hepatotoxicity has been reported with the use of telithromycin.

Pharmacokinetics of azithromycin in lactating dairy cows with subclinical mastitis caused by Staphylococcus aureus

Azithromycin is a time-dependent antimicrobial with long persistence. The main characteristics of azithromycin suggest that it could be useful for treating bovine mastitis caused by Staphylococcus aureus. To investigate this possibility, its pharmacokinetic (PK) behavior was studied. Six Holstein lactating cows with subclinical mastitis were administered two 10 mg/kg intramuscular (i.m.) doses of azithromycin, with a 48-h interval. Milk and plasma concentrations were measured by microbiological assay. The MIC(90) was determined in 51 S. aureus isolations to calculate pharmacokinetic/pharmacodynamic (PK/PD) parameters. Milk maximal concentration (C(max)) was 7.76 +/- 1.76 microg/mL (16.67 h post-first administration) and 7.82 +/- 2.18 microg/mL (14 h post-2(nd) administration). In plasma C(max) was 0.18 +/- 0.03 microg/mL (2 h post-1(rst) administration) and 0.11 +/- 0.03 microg/mL (14 h post-2(nd) administration). Azithromycin was eliminated from the milk with a half-life (T(1/2)lambda) of 158.26 +/- 137.7 h after 2(nd) administration, meanwhile plasma T(1/2)lambda resulted shorter(13.97 +/- 11.1 h). The mean area under the concentration vs. time curve from 0 to 24 h (AUC(0-24h)) was 153.82 +/- 34.66 microg.h/mL in milk secretion and 2.61 +/- 0.59 microgxh/mL in plasma. Infection presence in the quarters had a significant effect (P < 0.05) on the area under the concentration vs. time curve from 0 to infinity (AUC(0-infinity)) and clearance from the mammary gland (Cl(mam)/F). Moreover, it had influence on milk bioavailability (F(milk)), T(1/2)lambda, AUC(0-infinity) and mean residence time (MRT) in milk, which values resulted increased in mastitic quarters. In this study, it was determined that the production level and the mammary health status have an influence on PK parameters of azithromycin treatments in bovine mastitis.

Macrolides, ketolides, and glycylcyclines: azithromycin, clarithromycin, telithromycin, tigecycline

The advanced macrolides, azithromycin and clarithromycin, and the ketolide, telithromycin, are structural analogs of erythromycin. They have several distinct advantages when compared with erythromycin, including enhanced spectrum of activity, more favorable pharmacokinetics and pharmacodynamics, once-daily administration, and improved tolerability. Clarithromycin and azithromycin are used extensively for the treatment of respiratory tract infections, sexually transmitted diseases, and Helicobacter pylori-associated peptic ulcer disease. Telithromycin is approved for the treatment of community-acquired pneumonia. Severe hepatotoxicity has been reported with the use of telithromycin.

Analysis of macrolide antibiotics, using liquid chromatography-mass spectrometry, in food, biological and environmental matrices

Macrolides are a group of antibiotics that have been widely used in human medical and veterinary practices. Analysis of macrolides and related compounds in food, biological, and environmental matrices continue to be the focus of scientists for the reasons of food safety, pharmacokinetic studies, and environmental concerns. This article presents an overview on the primary biological properties of macrolides and their associated analytical issues, including extraction, liquid chromatography-mass spectrometry (LC-MS), method validation, and measurement uncertainty. The main techniques that have been used to extract macrolides from various matrices are solid-phase extraction and liquid-liquid extraction. Conventional liquid chromatography (LC) with C18 columns plays a dominant role for the determination of macrolides, whereas ultra-performance liquid chromatography (UPLC) along with sub-2 microm particle C18 columns reduces run time and improves sensitivity. Mass spectrometry (MS), serving as a universal detection technique, has replaced ultraviolet (UV), fluorometric, and electrochemical detection for multi-macrolide analysis. The triple-quadrupole (QqQ), quadrupole ion trap (QIT), triple-quadrupole linear ion trap, time-of-flight (TOF), and quadrupole time-of-flight (QqTOF) mass spectrometers are current choices for the determination of macrolides, including quantification, confirmation, identification of their degradation products or metabolites, and structural elucidation. LC or UPLC coupled to a triple-quadrupole mass spectrometer operated in the multiple-reaction monitoring (MRM) mode (LC/MS/MS) is the first choice for quantification. UPLC-TOF or UPLC-QqTOF has been recognized as an emerging technique for accurate mass measurement and unequivocal identification of macrolides and their related compounds.

Azithromycin-chloroquine and the intermittent preventive treatment of malaria in pregnancy

In the high malaria-transmission settings of sub-Saharan Africa, malaria in pregnancy is an important cause of maternal, perinatal and neonatal morbidity. Intermittent preventive treatment of malaria in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) reduces the incidence of low birth-weight, pre-term delivery, intrauterine growth-retardation and maternal anaemia. However, the public health benefits of IPTp are declining due to SP resistance. The combination of azithromycin and chloroquine is a potential alternative to SP for IPTp. This review summarizes key in vitro and in vivo evidence of azithromycin and chloroquine activity against Plasmodium falciparum and Plasmodium vivax, as well as the anticipated secondary benefits that may result from their combined use in IPTp, including the cure and prevention of many sexually transmitted diseases. Drug costs and the necessity for external financing are discussed along with a range of issues related to drug resistance and surveillance. Several scientific and programmatic questions of interest to policymakers and programme managers are also presented that would need to be addressed before azithromycin-chloroquine could be adopted for use in IPTp.

Pharmacokinetic and Pharmacodynamic Aspects of Antibiotic Use in High-Risk Populations

The study of pharmacokinetics includes the absorption, distribution, metabolism, and elimination of drugs. The pharmacologic effect that a medication has on the body is known as pharmacodynamics. With antimicrobials, pharmacokinetic and pharmacodynamic parameters become especially important because of the association between host drug concentrations, microorganism eradication, and resistance. This article focuses on the pharmacokinetic changes that can occur with antimicrobials when they are used in patients at high risk of infections and how they influence pharmacodynamic effects. The populations described here include patients with obesity and diabetes mellitus, renal or hepatic failure, chronic lung disease, severe burns, and long-term prosthetic devices and the elderly.

Darunavir: a second-generation protease inhibitor

PURPOSE

The pharmacology, pharmacokinetics, drug interactions, clinical efficacy, adverse events, dosage and administration, and place in therapy of darunavir are reviewed.

SUMMARY

Darunavir is the most recent protease inhibitor (PI) to receive approved labeling from the Food and Drug Administration for the treatment of human immunodeficiency virus (HIV). Darunavir is unique among currently available PIs because it maintains antiretroviral activity against a variety of multidrug-resistant HIV strains. Darunavir is well absorbed, and the bioavailability of darunavir increases by 30% when given with food. Darunavir is approximately 95% bound to plasma proteins. Darunavir is metabolized by and inhibits cytochrome P-450 (CYP) isoenzyme 3A4; therefore, darunavir is prone to CYP3A4-mediated drug-drug interactions. Two trials have demonstrated the clinical efficacy of darunavir in HIV-positive patients previously treated with antiretrovirals. One trial demonstrated a 2 log(10) decrease in plasma HIV RNA levels, compared with a decrease of <1 log(10) in the control group. Average increases in CD4+ T-cell counts for darunavir and control groups were 124 and 20 cells/mm(3), respectively. Adverse events reported from preliminary safety data indicate that darunavir has a similar safety profile to other currently available PIs. The recommended adult dosage of darunavir is 600 mg (two tablets) combined with ritonavir 100 mg every 12 hours with food. Darunavir should be used with caution in patients with hepatic dysfunction. No dosage adjustment is necessary for patients with mild or moderate renal dysfunction.

CONCLUSION

Darunavir is a new HIV PI that retains virological activity in the presence of multiple protease mutations. As such, darunavir appears to be a useful component of optimized combination antiretroviral therapy for HIV-infected patients previously treated with antiretrovirals.

Azithromycin and lower respiratory tract infections

Azithromycin is a macrolide antibiotic that has been structurally modified from erythromycin with an expanded spectrum of activity and improved tissue pharmacokinetic characteristics relative to erythromycin. This allows once-daily administration for 3-5 days of treatment compared with traditional multi dosing 7-10-day treatment regimens. It has been successfully employed in lower respiratory tract infections. Recent data indicate that azithromycin may exert anti-inflammatory/immunomodulatory effects that may be of use in the treatment of both acute and chronic airway diseases. This review examines the role of azithromycin in lower respiratory tract infections analysing published data on exacerbations of chronic bronchitis, community-acquired pneumonia and cystic fibrosis both in adults and children. In addition, pharmacokinetic and pharmacodynamic properties of the drug are also considered.

Clinical and bacteriological outcomes in hospitalised patients with community-acquired pneumonia treated with azithromycin plus ceftriaxone, or ceftriaxone plus clarithromycin or erythromycin: a prospective, randomised, multicentre study

This study compared patients with moderate-to-severe community-acquired pneumonia (CAP) requiring hospitalisation, who received initial therapy with either intravenous ceftriaxone plus intravenous azithromycin, followed by step-down to oral azithromycin (n = 135), with patients who received intravenous ceftriaxone combined with either intravenous clarithromycin or erythromycin, followed by step-down to either oral clarithromycin or erythromycin (n = 143). Clinical and bacteriological outcomes were evaluated at the end of therapy (EOT; day 12-16) or at the end of study (EOS; day 28-35). At baseline, mean APACHE II scores were 13.3 and 12.6, respectively, with >50% of patients classified as Fine Pneumonia Severity Index (PSI) category IV or V. Clinical success rates (cure or improvement) in the modified intent-to-treat (MITT) population at EOT were 84.3% in the ceftriaxone/azithromycin group and 82.7% in the ceftriaxone/clarithromycin or erythromycin group. At EOS, MITT success rates (cure only) were 81.7% and 75.0%, respectively. Equivalent success rates in the clinically evaluable population were 83% and 87%, respectively, at EOT, and 79% and 78%, respectively, at EOS. MITT bacteriological eradication rates were 73.2% and 67.4%, respectively, at EOT, and 68.3% vs. 60.9%, respectively, at EOS. Mean length of hospital stay (LOS) was 10.7 and 12.6 days, and the mean duration of therapy was 9.5 and 10.5 days, respectively. The incidence of infusion-related adverse events was 16.3% and 25.2% (p 0.04), respectively. An intravenous-to-oral regimen of ceftriaxone/azithromycin was at least equivalent in efficacy and safety to the comparator regimen and appeared to be a suitable treatment option for hospitalised patients with CAP.

Quantitative determination of azithromycin in human plasma by liquid chromatography–mass spectrometry and its application in a bioequivalence study

A sensitive, rapid liquid chromatographic-electrospray ionization mass spectrometric method for determination of azithromycin in human plasma was developed and validated. Azithromycin in plasma (0.2mL) was extracted with methyl tert-butyl ether-hexane (50:50, v/v), organic phase was transferred to another clear 1.5mL Eppendorf tube and evaporated to dryness at 40 degrees C and dissolved in mobile phase, samples were separated using a Thermo Hypersil HyPURITY C18 reversed-phase column (150mmx2.1mm i.d., 5microm), together with a mobile phase containing of 20mM ammonium acetate (pH 5.2)-acetonitrile-methanol (50:40:10, v/v/v) and was isocratically eluted at a flow rate of 0.2mL/min. Azithromycin and its internal standard, clarithromycin, were measured by electrospray ion source in positive selective ion monitoring mode. The method demonstrated that good linearity ranged from 2 to 1000ng/mL with r=0.9977. The limit of quantification for azithromycin in plasma was 2ng/mL with good accuracy and precision. The higher mean extraction recovery, say 81.2% and 75.5% for azithromycin and internal standard (IS), respectively, was obtained in this work. The intra-day and inter-day precision ranged from 4.8% to 8.6% and 6.4% to 10.7% (R.S.D.), respectively. The established method has been successfully applied to bioequivalence study of 2 azithromycin formulations for 24 healthy volunteers.

Pharmacokinetics and tissue tolerance of azithromycin after intramuscular administration to rabbits

The pharmacokinetics of azithromycin after intravenous and intramuscular injection at a single dose rate of 10mg/kg bodyweight were investigated in rabbits by using a modified agar diffusion bioassay for determining plasma concentrations. The plasma creatine kinase activity was determined after i.m. administration for the evaluation of the tissue tolerance. The elimination half-lives of azithromycin after intravenous and intramuscular administration were 24.1 and 25.1h, respectively. After intramuscular administration mean peak plasma concentration was 0.26+/-0.01 mg/L and bioavailability was 97.7%. Plasma CK activity rose sharply within 8h after i.m. injection of azithromycin; activity returned to pre-treatment level by 48-72 h post-treatment. The transient rise in serum CK activity indicates some degree of muscle tissue damage at the injection site.

Pharmacokinetics of azithromycin after intravenous and intramuscular administration to goats

Azithromycin is the first of a class of antimicrobial agents designated azalides. The aim of the present study was to investigate the disposition pharmacokinetics of azithromycin in goats and determine its bioavailability. A cross-over study was carried out in two phases separated by 30 days. Azithromycin was administered at a single dose of 20 mg/kg body weight by i.v. and i.m. routes. Plasma concentrations of azithromycin were determined by a modified agar diffusion bioassay. After a single i.v. dose plasma concentrations were best fitted to a three-compartment open model. A two-compartment open model with first-order absorption fitted best after i.m. administration. The values of the pharmacokinetic parameters after i.v. administration were: half-life 32.5 h, apparent volume of distribution at the steady-state 34.5 L/kg, clearance 0.85 L/kg. and mean residence time (MRT) 40.1 h. After i.m. administration half-life of 45.2 h, a MRT of 60.3 h, maximum plasma concentration 0.64 mg/L and a bioavalability 92.2% were obtained. The pharmacokinetic parameters of azithromycin after i.m. administration, principally its long half-life and high bioavailability, could provide an alternative to the oral route of administration in goats, although more studies are needed to establish a suitable pharmaceutical formulation, propose optimun dosage regimens, investigate clinical efficacy and study the tolerability of repeated doses.

Clinical Response of Azithromycin as an Adjunct to Non-Surgical Periodontal Therapy in Smokers

BACKGROUND

Antibiotic therapy can be used in very specific periodontal treatment situations such as in refractory cases of periodontal disease found to be more prevalent in smokers. This study was designed to determine the efficacy of azithromycin (AZM) when combined with scaling and root planing (SRP) for the treatment of moderate to severe chronic periodontitis in smokers.

METHODS

Thirty-one subjects were enrolled into a 6-month randomized, single-masked trial to evaluate clinical, microbial (using benzoyl- DL-arginine naphthylamine [BANA] assay), and gingival crevicular fluid (GCF) pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) levels in response to SRP alone or SRP + AZM. At baseline, patients who smoked > or =1 pack per day of cigarettes who presented with at least five sites with probing depths (PD) of > or =5 mm with bleeding on probing (BOP) were randomized into the test or control groups. At baseline and 3 and 6 months, clinical measurements (probing depth [PD], clinical attachment loss [CAL], and bleeding on probing [BOP]) were performed. GCF bone marker assessment (Ctelopeptide [ICTP] as well as BANA test analyses) were performed at baseline, 14 days, and 3 and 6 months.

RESULTS

The results demonstrated that both groups displayed clinical improvements in PD and CAL that were sustained for 6 months. Using a subject-based analysis, patients treated with SRP + AZM showed enhanced reductions in PD and gains in CAL at moderate (4 to 6 mm) and deep sites (>6 mm) (P <0.05). Furthermore, SRP + AZM resulted in greater reductions in BANA levels compared to SRP alone (P <0.05) while rebounds in BANA levels were noted in control group at the 6-month evaluation. No statistically significant differences between groups on mean BOP and ICTP levels during the course of the study were noted.

CONCLUSIONS

The utilization of AZM in combination with SRP improves the efficacy of non-surgical periodontal therapy in reducing probing depth and improving attachment levels in smokers with moderate to advanced attachment loss.

The Disease-Modifying Effects of Twice-Weekly Oral Azithromycin in Patients with Bronchiectasis

INTRODUCTION

Bronchiectasis is a chronic pulmonary process characterized by recurrent respiratory infections leading to destruction of airways secondary to inflammation. We investigated whether the addition of 6-months' twice-weekly azithromycin to the existing treatment regimen in patients with pulmonary bronchiectasis decreased the number of exacerbations and improved pulmonary function compared with a similar period of time without concurrent azithromycin.

METHODS

Thirty patients with high-resolution computed tomography scan-confirmed bronchiectasis were to be recruited. In random order, patients received usual medications for 6 months, and usual medications plus oral azithromycin 500mg twice weekly for 6 months. Patients receiving azithromycin first had a 1-month washout period prior to entering the second phase. Patients recorded weekly peak flow (PF) measurements. Pulmonary function tests (PFTs), 24-hour sputum volume, and needs for intervention with medication or ancillary support were collected at baseline and every 3 months. Exacerbation incidence and sputum volume measurements were compared from baseline to the end of each study phase.

RESULTS

Twelve patients were enrolled; 11 were included in the analysis. Owing to randomization, most patients received the azithromycin first, which was fairly well tolerated. PFTs did not change significantly during either study phase and PFs appeared to remain stable during azithromycin therapy and throughout the subsequent control phase. Azithromycin significantly decreased the incidence of exacerbations compared with usual medications (5 vs 16; p = 0.019). Mean 24-hour sputum volume significantly decreased (15% [p = 0.005]) during the active treatment phase, and remained decreased during the control phase (p = 0.028). Subjectively, patients reported increased energy and quality of life while receiving treatment with azithromycin.

CONCLUSIONS

The addition of twice-weekly azithromycin significantly decreased the incidence of exacerbation and 24-hour sputum volume and may have stabilized the PFTs and PFs in this 11-patient pilot study. The results of this study justify further investigation of adding azithromycin to the treatment regimens of patients with bronchiectasis for its disease-modifying effects.

Macrolides and ketolides: azithromycin, clarithromycin, telithromycin

The advanced macrolides, azithromycin and clarithromycin, and the ketolide telithromycin are structural analogues of erythromycin. They have several distinct advantages when compared with erythromycin including enhanced spectrum of activity, more favorable pharmacokinetics and pharmacodynamics, once daily administration, and improved tolerability. This article reviews the pharmacokinetics, antimicrobial activity, clinical use, and adverse effects of these antimicrobial agents.

Azithromycin inhibits interleukin-6 but not fibrinogen production in hepatocytes infected with cytomegalovirus and chlamydia pneumoniae

Chlamydia pneumoniae and cytomegalovirus (CMV) have been associated with the development of atherosclerosis. Inflammatory stimuli initiate the biosynthesis of fibrinogen, interleukin (IL)-6 and plasminogen activator inhibitor (PAI)-1 in the liver. Chronic infection may perpetuate the inflammatory status. We hypothesized that infection of human hepatocytes with the intracellular pathogens C pneumoniae and CMV accelerates biosynthesis of fibrinogen, IL-6, and PAI-1 but that this biosynthesis can be reduced with the use of azithromycin. HepG2 human hepatocytes were infected with C pneumoniae and CMV in vitro in the presence of 0, 0.016, 0.125, or 1 microg/mL azithromycin. We measured IL-6, PAI-1, and fibrinogen after 24, 48, 72, and 96 hours. C pneumoniae-infected hepatocytes produce IL-6 (2667 +/- 309 pg/mL vs 137 +/- 120 pg/mL in uninfected cells after 96 hours. Incubation with 0.016 microg/mL azithromycin decreased IL-6 levels to a mean of 1516 +/- 402 pg/mL, and incubation with 0.125 and 1 microg/mL azithromycin decreased IL-6 to 871 +/- 364 and 752 +/- 403 pg/mL, respectively. C pneumoniae-induced IL-6 production was time- and dose-dependent. The interaction of C pneumoniae with azithromycin treatment was significant, indicating an inhibitory effect of azithromycin on C pneumoniae-induced IL-6 production. CMV infection did not lead to IL-6 production by hepatocytes. C pneumoniae and CMV infection did not induce any changes in PAI-1 production. Fibrinogen production was increased by CMV infection after 72 hours (838 +/- 88 ng/mL; P <.01) and after 96 hours by infection with both C pneumoniae and CMV (765 +/- 100 and 846 +/- 123 ng/mL, respectively; P <.05). Azithromycin did not suppress CMV- or C pneumoniae-induced fibrinogen production. Moreover, we could not confirm an antiinflammatory effect of azithromycin in experiments with cross-titrations of azithromycin against either IL-1 or IL-6 (P >.05). Azithromycin reduces C pneumoniae-induced IL-6 production, but not fibrinogen production, by human hepatocytes. This is a result of the antimicrobial properties of azithromycin and not a direct antiinflammatory effect.

Single-Dose Azithromycin for Respiratory Tract Infections

OBJECTIVE

To describe the pharmacology, efficacy, and safety data of the use of single-dose azithromycin for respiratory tract infections in children and adults.

DATA SOURCES

A MEDLINE search (1990–September 2003) was performed to identify all pertinent studies and review articles. When appropriate information was not available in the literature, data were obtained from the product manufacturers or abstracts from international conferences.

STUDY SELECTION AND DATA EXTRACTION

All available studies were reviewed to provide pharmacokinetic, pharmacodynamic, efficacy, and safety data on use of single-dose azithromycin for respiratory tract infections.

DATA SYNTHESIS

Several studies have demonstrated that shorter regimens of azithromycin (1500 mg over 3 day vs 5 day or single dose vs 3 day) provide higher serum exposures compared with the longer regimens. This makes it possible to give the same dose over a shorter period of time and achieve the same efficacy with the potential for enhanced adherence. Single-dose azithromycin 30 mg/kg was approved in 2003 for treatment of acute otitis media (AOM) in children. Studies have demonstrated that, when administering azithromycin as a single dose, its efficacy and safety are comparable to that of other standard regimens for AOM. Single-dose regimens for treatment of respiratory tract infections in adults have not been studied widely, with only 2 studies being conducted for treatment of community-acquired pneumonia and one study for treatment of tonsillitis; all demonstrated at least equal efficacy with the single-dose regimen compared with comparators given for longer periods of time.

CONCLUSION

Available data regarding single-dose azithromycin are promising. Although use of this regimen in children is warranted based on studies to date, additional large-scale trials are needed prior to mainstream use of the regimen in adults.