Alveolar Macrophage Concentrations Research Articles

Pharmacokinetics of SPR206 in Plasma, Pulmonary Epithelial Lining Fluid, and Alveolar Macrophages following Intravenous Administration to Healthy Adult Subjects.

SPR206 is a next-generation polymyxin being developed for the treatment of multidrug-resistant (MDR) Gram-negative infections. This Phase 1 bronchoalveolar lavage (BAL) study was conducted to evaluate SPR206's safety and pharmacokinetics in plasma, pulmonary epithelial lining fluid (ELF), and alveolar macrophages (AM) in healthy volunteers. Subjects received a 100 mg intravenous (IV) dose of SPR206 infused over 1 h every 8 h for 3 consecutive doses. Each subject underwent 1 bronchoscopy with BAL at 2, 3, 4, 6, or 8 h after the start of the third IV infusion. SPR206 concentrations in plasma, BAL, and cell pellet were measured with a validated LC-MS/MS assay. Thirty-four subjects completed the study and 30 completed bronchoscopies. Mean SPR206 peak concentrations (Cmax) in plasma, ELF, and AM were 4395.0, 735.5, and 860.6 ng/mL, respectively. Mean area under the concentration-time curve (AUC0-8) for SPR206 in plasma, ELF, and AM was 20120.7, 4859.8, and 6026.4 ng*h/mL, respectively. The mean ELF to unbound plasma concentration ratio was 0.264, and mean AM to unbound plasma concentration ratio was 0.328. Mean SPR206 concentrations in ELF achieved lung exposures above the MIC for target Gram-negative pathogens for the entire 8-h dosing interval. Overall, SPR206 was well tolerated; 22 subjects (64.7%) reported at least 1 treatment-emergent adverse event (TEAE). Of the 40 reported TEAEs, 34 (85.0%) were reported as mild in severity. The most frequent TEAEs were oral paresthesia (10 subjects [29.4%]) and nausea (2 subjects [5.9%]). This study demonstrates pulmonary penetration of SPR206 and supports further development of SPR206 for the treatment of patients with serious infections caused by MDR Gram-negative pathogens.

625. SPR206 Pharmacokinetics (PK) in Plasma, Epithelial Lining Fluid (ELF), and Alveolar Macrophages (AM) in Healthy Adult Subjects

Abstract Background SPR206 is a novel intravenously (IV)-administered next-generation polymyxin being developed for the treatment of multi-drug resistant (MDR) Gram-negative (GN) infections. A Phase 1 bronchoalveolar lavage (BAL) study was conducted to evaluate SPR206 safety and PK in plasma and pulmonary matrices (ELF and AM) in healthy volunteers. Methods Subjects received 100 mg SPR206 administered intravenously over 1 h q8h for 3 consecutive doses. Blood samples were collected pre-dose (second and third dose) and at 2, 3, 4, 6, and 8 h after the start of the last dose. Each subject underwent one standardized bronchoscopy with BAL at 2, 3, 4, 6 or 8 hours after the start of the third IV infusion. Concentrations of SPR206 in plasma, BAL, and cell pellet were measured with a validated LC-MS/MS assay. Plasma, ELF, and AM PK parameters were determined by noncompartmental analysis. SPR206 AUC0–8 in ELF and AM were calculated using the mean concentration values at the BAL sampling times. SPR206 AUC0–8 ratios of ELF and AM to unbound plasma were determined using plasma protein binding value of 8.6%. Results Thirty-four subjects were enrolled and completed the study and 30 of 34 completed bronchoscopy. The mean SPR206 Cmax concentrations in plasma, ELF, and AM were 4395.0, 735.5, and 860.6 ng/mL, respectively. Mean AUC0-8 h values in plasma, ELF, and AM concentrations were 20120.7, 4859.8, and 6026.4 ng*h/mL, respectively--leading to a free ELF to plasma concentration ratio of 0.264 and free AM to plasma ratio of 0.328. Importantly, mean concentrations of SPR206 in the ELF achieved lung exposures above its minimum inhibitory concentration for the targeted gram-negative pathogens for the entire 8-hour dosing interval. Figure 1 displays the mean (±SD) SPR206 total and unbound plasma, ELF, and AM concentrations at the BAL sampling times. Overall, SPR206 was well tolerated; 22 subjects (64.7%) experienced at least 1 TEAE, mostly mild with a few moderate. The most frequently reported TEAEs were oral paresthesia [10 subjects (29.4%)] and nausea [2 subjects (5.9%)], which were reversible. Conclusion This study demonstrates pulmonary penetration of SPR206 and supports further development of SPR206 for the treatment of patients with pneumonia caused by MDR GN infections. Figure 1.Mean (±SD) plasma (total and unbound), epithelial lining fluid (ELF), and alveolar macrophage (AM) concentrations of SPR206 in healthy adult subjects. This study was conducted in collaboration with, and with financial support from, the United States Department of Defense (Award No. W81XWH1910295). Disclosures Keith A. Rodvold, PharmD, Spero Therapeutics: Advisor/Consultant|Spero Therapeutics: Honoraria Justin Bader, n/a, Spero Therapeutics: Employee Vipul K. Gupta, Ph.D., Spero Therapeutics: Employee Troy Lister, Ph.D., Spero Therapeutics: Employee Praveen Srivastava, Ph.D., Spero Therapeutics: Employee Jon Bruss, M.D., Spero Therapeutics: Employee.

Predictions of Systemic, Intracellular, and Lung Concentrations of Azithromycin With Different Dosing Regimens Used in COVID-19 Clinical Trials.

Azithromycin (AZ), a broad‐spectrum macrolide antibiotic, is being investigated in patients with coronavirus disease 2019 (COVID‐19). A population pharmacokinetic model was implemented to predict lung, intracellular poly/mononuclear cell (peripheral blood monocyte (PBM)/polymorphonuclear leukocyte (PML)), and alveolar macrophage (AM) concentrations using published data and compared against preclinical effective concentration 90% (EC90) for severe acute respiratory syndrome‐coronavirus 2 (SARS‐CoV‐2). The final model described the data reported in eight publications adequately. Consistent with its known properties, concentrations were higher in AM and PBM/PML, followed by lung tissue, and lowest systemically. Simulated PBM/PML concentrations exceeded EC90 following the first dose and for ~ 14 days following 500 mg q.d. for 3 days or 500 mg q.d. for 1 day/250 mg q.d. on days 2–5, 10 days following a single 1,000 mg dose, and for > 20 days with 500 mg q.d. for 10 days. AM concentrations exceeded the 90% inhibitory concentration for > 20 days for all regimens. These data will better inform optimization of dosing regimens for AZ clinical trials.

Effect of Iron Deficiency on a Murine Model of Smoke-induced Emphysema.

Smoking is a major risk factor for chronic obstructive pulmonary disease (COPD). Smoking susceptibility is important for the onset and development of COPD. We previously reported an association between serum iron concentrations and pulmonary function in male smokers. However, the mechanism governing smoking susceptibility in relation to iron deficiency is unclear; this study aimed to elucidate this mechanism. C57BL/6 male mice were fed an iron-deficient or normal diet and then exposed to cigarette smoke. BAL, histological analysis, and pulmonary function tests were performed after cigarette smoke exposure. Human alveolar type II epithelial A549 cells were treated with an iron chelator. Subsequently, A549 cells were exposed to cigarette smoke extract. In mice exposed to cigarette smoke for 2 weeks, the concentration of alveolar macrophages in the BAL fluid recovered from iron-deficient mice was significantly higher than that in normal diet mice. IL-6 and MCP-1 (monocyte chemotactic protein 1) concentrations in the BAL fluid increased significantly from baseline in iron-deficient mice, but not in normal diet mice. In mice exposed to cigarette smoke for 8 weeks, the pathological mean linear intercepts, physiological total lung capacity, and functional residual capacity in the lungs of iron-deficient mice were significantly greater than in normal diet mice. Phosphorylation of NF-κB was enhanced in the lungs of iron-deficient mice exposed to cigarette smoke and in the iron-chelating A549 cells exposed to cigarette smoke extract. Iron deficiency exaggerated cigarette smoke-induced pulmonary inflammation, suggesting that it may accelerate COPD development.

Plasma and Intrapulmonary Concentrations of Cefepime and Zidebactam following Intravenous Administration of WCK 5222 to Healthy Adult Subjects.

WCK 5222 is a combination of cefepime and the novel β-lactam enhancer zidebactam being developed for the treatment of serious Gram-negative bacterial infections. The objective of this study was to compare plasma (total), epithelial lining fluid (ELF), and alveolar macrophage (AM) concentrations of cefepime and zidebactam in healthy adult subjects. The WCK 5222 dosing regimen was 2 g cefepime/1 g zidebactam administered as a 1-h intravenous infusion every 8 h for a total of 7 doses. Subjects were assigned to one bronchoalveolar lavage (BAL) sampling time at 0.5, 1.25, 3, 6, 8, or 10 h after the seventh dose. Noncompartmental pharmacokinetic parameters were determined from serial plasma concentrations collected over 8-hour and 10-hour intervals following the first and seventh doses, respectively. Penetration ratios were calculated from the area under the plasma concentration-time curve from 0 to 8 h (AUC0-8) for plasma, ELF, and AM using mean and median concentrations at each BAL sampling time. The plasma maximum concentration of drug (Cmax) and AUC values of cefepime and zidebactam increased by 8% to 9% after the seventh versus the first dose of WCK 5222. The respective AUC0-8 values based on mean concentrations of cefepime and zidebactam in ELF were 127.9 and 52.0 mg · h/liter, and 87.9 and 13.2 mg · h/liter in AM. The ELF to total plasma penetration ratios of cefepime and zidebactam based on mean AUC0-8 values were 0.39 and 0.38, respectively. The AM to total plasma ratios were 0.27 and 0.10, respectively. The observed plasma, ELF, and AM concentrations of cefepime and zidebactam support studies of WCK 5222 for treatment of pneumonia caused by susceptible pathogens.

Comparison of Plasma, Epithelial Lining Fluid, and Alveolar Macrophage Concentrations of Solithromycin (CEM-101) in Healthy Adult Subjects

The steady-state concentrations of solithromycin in plasma were compared with concomitant concentrations in epithelial lining fluid (ELF) and alveolar macrophages (AM) obtained from intrapulmonary samples during bronchoscopy and bronchoalveolar lavage (BAL) in 30 healthy adult subjects. Subjects received oral solithromycin at 400 mg once daily for five consecutive days. Bronchoscopy and BAL were carried out once in each subject at either 3, 6, 9, 12, or 24 h after the last administered dose of solithromycin. Drug concentrations in plasma, ELF, and AM were assayed by a high-performance liquid chromatography-tandem mass spectrometry method. Solithromycin was concentrated extensively in ELF (range of mean [± standard deviation] concentrations, 1.02 ± 0.83 to 7.58 ± 6.69 mg/liter) and AM (25.9 ± 20.3 to 101.7 ± 52.6 mg/liter) in comparison with simultaneous plasma concentrations (0.086 ± 0.070 to 0.730 ± 0.692 mg/liter). The values for the area under the concentration-time curve from 0 to 24 h (AUC(0-24) values) based on mean and median ELF concentrations were 80.3 and 63.2 mg · h/liter, respectively. The ratio of ELF to plasma concentrations based on the mean and median AUC(0-24) values were 10.3 and 10.0, respectively. The AUC(0-24) values based on mean and median concentrations in AM were 1,498 and 1,282 mg · h/L, respectively. The ratio of AM to plasma concentrations based on the mean and median AUC(0-24) values were 193 and 202, respectively. Once-daily oral dosing of solithromycin at 400 mg produced steady-state concentrations that were significantly (P < 0.05) higher in ELF (2.4 to 28.6 times) and AM (44 to 515 times) than simultaneous plasma concentrations throughout the 24-h period after 5 days of solithromycin administration.

Intrapulmonary Distribution and Pharmacokinetics of Laninamivir, a Neuraminidase Inhibitor, after a Single Inhaled Administration of Its Prodrug, Laninamivir Octanoate, in Healthy Volunteers

A single inhaled dose of laninamivir octanoate (LO), a long-acting neuraminidase inhibitor, exhibits efficacy in treating both adult and pediatric patients with influenza virus infection. The intrapulmonary pharmacokinetics (PK) of LO and laninamivir, a pharmacologically active metabolite, were investigated by a single-center, open-label study of healthy adult volunteers. Subgroups of five subjects each underwent bronchoalveolar lavage (BAL) 4, 8, 24, 48, 72, 168, and 240 h following a single inhaled administration of LO (40 mg). Plasma, BAL fluid, and alveolar macrophages (AM) were analyzed to determine LO and laninamivir concentrations, using validated liquid chromatography-tandem mass spectrometry methods. The concentrations in epithelial lining fluid (ELF) and AM from the first and subsequent BAL fluid samples were determined separately to explore the drug distribution in airways. Mean laninamivir concentrations in ELF, calculated using the first BAL fluids and BAL fluids collected 4 h after inhaled administration, were 8.57 and 2.40 μg/ml, respectively. The laninamivir concentration in ELF decreased with a longer half-life than that in plasma, and it exceeded the 50% inhibitory concentrations for viral neuraminidases at all time points examined for 240 h after the inhalation. Laninamivir exposure in ELF from the first BAL samples was 3.2 times higher than that in ELF from the subsequent BAL fluid samples. ELF concentration profiles of laninamivir support its long-lasting effect for treatment of patients with influenza virus infection by a single inhaled administration.

Pharmacokinetics of clarithromycin in bronchial epithelial lining fluid

BAL is an established technique for measuring antibiotic concentrations in the epithelial lining fluid (ELF) of the bronchiolar-alveolar regions. However, the results may not reflect concentrations in bronchial regions. Bronchoscopic microsampling (BMS) is a technique for repeated sampling of bronchial ELF. The objective of the present study was to determine the time versus concentration profile of clarithromycin and its active metabolite, 14-hydroxy-clarithromycin, in bronchial ELF, as determined by BMS. BMS was performed at 1, 2, 3, 5 and 10 h after a single oral administration of 200 mg clarithromycin in five healthy volunteers. BAL was performed 3 h after administration to determine clarithromycin concentrations in alveolar ELF and alveolar macrophages (AM). The maximum concentration (C(max)) of clarithromycin was 0.36 +/- 0.07 mg/L in serum and 1.44 +/- 0.49 mg/L in bronchial ELF (P < 0.01). C(max) for 14-hydroxy-clarithromycin was 0.34 +/- 0.13 mg/L in serum and 0.68 +/- 0.34 mg/L in bronchial ELF. The area under the concentration-time curve from 0 to 10 h (AUC(0-10)) for clarithromycin was 2.10 +/- 0.49 mg.h/L for serum and 7.37 +/- 2.07 mg.h/L for bronchial ELF (P < 0.01). The concentrations of clarithromycin in alveolar ELF and AM, 3 h after oral administration, were 4.84 +/- 3.39 mg/L and 10.7 +/- 8.7 mg/L, respectively. A single oral dose of clarithromycin produces a significantly higher C(max) and AUC(0-10) for clarithromycin in bronchial ELF than in serum, and higher concentrations in alveolar ELF and AM than in serum. BMS might be useful for measuring the pharmacokinetic profile of clarithromycin in bronchial ELF.

Intrapulmonary Distribution of Intravenous Telavancin in Healthy Subjects and Effect of Pulmonary Surfactant on In Vitro Activities of Telavancin and Other Antibiotics

Steady-state concentrations of telavancin, a novel, bactericidal lipoglycopeptide, were determined in the plasma, pulmonary epithelial lining fluid (ELF), and alveolar macrophages (AMs) of 20 healthy subjects. Telavancin at 10 mg of drug/kg of body weight/day was administered as a 1-h intravenous infusion on three successive days, with bronchoalveolar lavage performed on five subjects, each at 4, 8, 12, and 24 h after the last dose. Plasma samples were collected before the first and third infusions and at 1, 2, 3, 4, 8, 12, and 24 h after the third infusion. The plasma telavancin concentration-time profile was as reported previously. Telavancin (mean +/- standard deviation) penetrated well into ELF (3.73 +/- 1.28 microg/ml at 8 h and 0.89 +/- 1.03 microg/ml at 24 h) and extensively into AMs (19.0 +/- 16.8 microg/ml at 8 h, 45.0 +/- 22.4 microg/ml at 12 h, and 42.0 +/- 31.4 microg/ml at 24 h). Mean concentrations in AMs and plasma at 12 h were 45.0 microg/ml and 22.9 microg/ml (mean AM/plasma ratio, 1.93), respectively, and at 24 h were 42.0 microg/ml and 7.28 microg/ml (mean AM/plasma ratio, 6.67), respectively. Over the entire dosing interval, telavancin was present in ELF and AMs at concentrations up to 8-fold and 85-fold, respectively, above its MIC 90 for methicillin-resistant Staphylococcus aureus (0.5 microg/ml). Pulmonary surfactant did not affect telavancin's in vitro antibacterial activity. Telavancin was well tolerated. These results support the proposal for further clinical evaluation of telavancin for treating gram-positive respiratory infections.

Concentrations in plasma, epithelial lining fluid, alveolar macrophages and bronchial mucosa after a single intravenous dose of 1.6 mg/kg of iclaprim (AR-100) in healthy men

A validated microbiological assay was used to measure concentrations of iclaprim (AR-100) in plasma, bronchial mucosa (BM), alveolar macrophages (AM) and epithelial lining fluid (ELF) after a single 1.6 mg/kg intravenous 60 min iv infusion of iclaprim. Male volunteers were randomly allocated to three nominal sampling time intervals 1-2 h (Group A), 3-4 h (Group B) and 5.5-7.0 h (Group C) after the start of the drug infusion. Mean iclaprim concentrations in plasma, BM, AM and ELF, respectively, were for Group A 0.59 mg/L (SD 0.18), 0.51 mg/kg (SD 0.17), 24.51 mg/L (SD 21.22) and 12.61 mg/L (SD 7.33); Group B 0.24 mg/L (SD 0.05), 0.35 mg/kg (SD 0.17), 7.16 mg/L (SD 1.91) and 6.38 mg/L (SD 5.17); and Group C 0.14 mg/L (SD 0.05), no detectable level in BM, 5.28 mg/L (SD 2.30) and 2.66 mg/L (SD 2.08). Iclaprim concentrations in ELF and AM exceeded the MIC(90) for penicillin-susceptible Streptococcus pneumoniae (MIC90 0.06 mg/L), penicillin-intermediate S. pneumoniae (MIC90 2 mg/L), penicillin-resistant S. pneumoniae (MIC90 4 mg/L) for 7, 7 and 4 h, respectively, and Chlamydia pneumoniae (MIC90 0.5 mg/L) for 7 h. Mean iclaprim concentrations in ELF exceeded the MIC90 for Haemophilus influenzae (MIC90 4 mg/L) and Moraxella catarrhalis (MIC90 8 mg/L) for up to 4 and 2 h, respectively; in AM the MIC90 was exceeded for up to 7 h. Furthermore, the MIC90 for methicillin-resistant Staphylococcus aureus of 0.12 mg/L was exceeded at all sites for up to 7 h. These data suggest that iclaprim reaches lung concentrations that should be effective in the treatment of community-acquired pneumonia.

Azithromycin increases phagocytosis of apoptotic bronchial epithelial cells by alveolar macrophages

Chronic obstructive pulmonary disease (COPD) is associated with increased apoptosis and defective phagocytosis in the airway. As uncleared cells can undergo secondary necrosis and perpetuate inflammation, strategies to improve clearance would have therapeutic significance. There is evidence that the 15-member macrolide antibiotic azithromycin has anti-inflammatory properties. Its effects may be increased in the lung due to its ability to reach high concentrations in alveolar macrophages (AMs). The present study investigated the effects of low-dose (500 ng x mL(-1)) azithromycin on the phagocytosis of apoptotic bronchial epithelial cells and neutrophils by AMs. Flow cytometry was applied to measure phagocytosis and receptors involved in AM recognition of apoptotic cells. Cytokines were investigated using cytometric bead array. Baseline phagocytosis was reduced in COPD subjects compared with controls. Azithromycin significantly improved the phagocytosis of epithelial cells or neutrophils by AMs from COPD subjects by 68 and 38%, respectively, often up to levels comparable with controls. The increase in phagocytosis was partially inhibited by phosphatidylserine, implicating the phosphatidylserine pathway in the pro-phagocytic effects of azithromycin. Azithromycin had no effect on other recognition molecules (granulocyte-macrophage colony-stimulating factor, CD44, CD31, CD36, CD91, alphavbeta3 integrin). At higher doses, azithromycin decreased levels of pro-inflammatory cytokines. Thus, low-dose azithromycin therapy could provide an adjunct therapeutic option in chronic obstructive pulmonary disease.

Intrapulmonary Concentrations of Telithromycin: Clinical Implications for Respiratory Tract Infections due to Streptococcus pneumoniae

Background: Antimicrobial efficacy is dependent on the ability of the agent to reach the site of infection. To assess the bronchopulmonary drug disposition of a novel ketolide, telithromycin (TEL), the epithelial lining fluid (ELF) and alveolar macrophage (AM) concentrations were utilized as a surrogate marker for lung penetration. Methods: Adult subjects scheduled for diagnostic bronchoscopy received oral TEL 800 mg once daily for 5 days. Plasma and bronchoalveolar lavage (BAL) samples were collected 2, 8, 12, or 24 h after the last TEL dose. TEL concentrations in the ELF and AM were determined using a validated HPLC assay. ELF drug concentrations were calculated using the urea dilution method. Results: Seventeen subjects with a mean age 65 ± 13 years and a mean weight of 81 ± 25 kg completed this open-label study. The median (range) TEL concentrations in plasma and ELF, respectively, were 1.09 mg/l (1.00–4.81) and 3.91 mg/l (2.64–9.59) at 2 h (n = 6), 0.48 and 1.09 mg/l at 8 h (n = 1), 0.65 mg/l (0.18–1.55) and 1.81 mg/l (0.61–10.0) at 12 h (n = 5), and 0.11 mg/l (0.09–0.24) and 0.69 mg/l (0.15–1.58) at 24 h (n = 5). The median AM concentrations obtained from these subjects were 53.35 mg/l at 2 h, 32.55 mg/l at 8 h, 65.96 mg/l at 12 h, and 26.43 mg/l at 24 h. Overall TEL was well tolerated. No discontinuation was required due to an adverse event. Conclusions: TEL displayed high intrapulmonary penetration with ELF concentrations exceeding that of plasma at all time points. AM intracellular concentrations were multiple times higher than in the ELF and plasma. These data support the clinical efficacy of TEL against intracellular and extracellular pathogens, particularly with Streptococcus pneumoniae having an MIC₉₀well below achievable concentrations at the site of infection.

Repeated Exposure to Ozone Increases Alveolar Macrophage Recruitment into Asthmatic Airways

Repeated, short-term exposures to ozone (O3) lead to attenuation of the acute lung function and airway inflammatory responses seen after a single exposure in healthy subjects, but it is unclear whether these acute responses also attenuate in subjects with asthma. To address this question by exposing 14 subjects with asthma to 0.2 ppm O3 for either 4 hours on a single day or 4 hours on 4 consecutive days (multiday [MD]). At least 3 weeks later, subjects underwent the alternate exposure. Spirometry was performed immediately pre- and postexposure and bronchoalveolar lavage (BAL) was obtained 18 hours after each exposure. The decrease in FEV1 was greatest across Day 2 of the MD (MD2) exposure and then gradually declined on successive days of the MD exposure (mean +/- SD decrease in FEV1 of 25.4 +/- 18.0% across MD2 compared with 4.2 +/- 6.5% across MD4). Respiratory symptoms followed a similar pattern to that of FEV1. Although the concentration of neutrophils in BAL after the MD4 exposure was not significantly different from that after the single-day exposure (1.7 +/- 1.3 x 10(4) cells/ml vs. 1.2 +/- 0.8 x 10(4) cells/ml, p = 0.20), the concentration of alveolar macrophages did significantly increase in BAL after the MD exposure (19.9 +/- 9.7 x 10(4) cells/ml after MD4 vs. 12.1 +/- 6.4 x 10(4) cells/ml after the single day). Alveolar macrophages are recruited to the airways of subjects with asthma with repeated short-term exposures to O3, suggesting a possible role for these cells in the chronic response to oxidant-induced injury.

Steady-State Plasma and Intrapulmonary Concentrations of Levofloxacin and Ciprofloxacin in Healthy Adult Subjects

To determine the steady-state plasma, epithelial lining fluid (ELF), and alveolar macrophage (AM) concentrations of levofloxacin and ciprofloxacin. Multiple-dose, open-label, randomized pharmacokinetic study. Thirty-six healthy, nonsmoking adult subjects were randomized either to oral levofloxacin, 500 or 750 mg once daily for five doses, or ciprofloxacin, 500 mg q12h for nine doses. Venipuncture, bronchoscopy, and BAL were performed in each subject at 4 h, 12 h, or 24 h after the last administered dose of antibiotic. Mean plasma concentrations of levofloxacin and ciprofloxacin were similar to those previously reported. For once-daily dosing of levofloxacin, 500 mg, the mean (+/- SD) steady-state concentrations at 4 h, 12 h, and 24 h in ELF were 9.9 +/- 2.7 microg/mL, 6.5 +/- 2.5 microg/mL, and 0.7 +/- 0.4 microg/mL, respectively; AM concentrations were 97.9 +/- 80.0 microg/mL, 36.7 +/- 23.4 microg/mL, and 13.8 +/- 16.0 microg/mL, respectively. For levofloxacin, 750 mg, the mean steady-state concentrations in ELF were 22.1 +/- 14.9 microg/mL, 9.2 +/- 5.3 microg/mL, and 1.5 +/- 0.8 microg/mL, respectively; AM concentrations were 105.1 +/- 65.5 microg/mL, 36.2 +/- 26.1 microg/mL, and 15.1 +/- 2.0 microg/mL, respectively. The concentrations of ciprofloxacin at 4 h and 12 h in ELF were 1.9 +/- 0.9 microg/mL and 0.4 +/- 0.1 microg/mL, respectively; AM concentrations were 34.9 +/- 23.2 microg/mL and 6.8 +/- 5.9 microg/mL, respectively. The differences in the ELF concentrations of the two levofloxacin groups vs those of the ciprofloxacin group were significant (p < 0.05) at each sampling time. Levofloxacin was more extensively distributed into intrapulmonary compartments than ciprofloxacin and achieved significantly higher steady-state concentrations in plasma and ELF during the 24 h after drug administration.

HIV-1 DNA and mRNA concentrations are similar in peripheral blood monocytes and alveolar macrophages in HIV-1-infected individuals.

To determine the relative contribution of alveolar macrophages, peripheral blood monocytes (PBM) and peripheral blood lymphocytes (PBL) from HIV-infected individuals to HIV-1 viral load. Alveolar macrophages were obtained by flexible bronchoscopy, and PBM and PBL by venipuncture from HIV-1-infected individuals. Alveolar macrophages and PBM were purified using immunomagnetic bead selection to deplete CD3+ and CD19+ cells from bronchoalveolar lavage and peripheral blood mononuclear cells, respectively. DNA and mRNA were extracted and gag copy number quantified using polymerase chain reaction (PCR) and reverse transcriptase PCR. The titres of infectious cell-associated HIV-1 in cells were determined by the endpoint dilution coculture technique for alveolar macrophages and PBM. Alveolar macrophages and PBM from HIV-1-infected subjects (n=11) contained equivalent concentrations of HIV-1 DNA and HIV-1 mRNA as determined by PCR and reverse transcriptase PCR, respectively. Antiretroviral therapy was associated with reduced viral DNA concentrations in alveolar macrophages but not in PBM. PBL had a significantly higher level of proviral DNA and mRNA than alveolar macrophages or PBM. Although alveolar macrophages infected in vitro are more permissive for HIV-1 replication than PBM, this difference could not be demonstrated in vivo.

Pharmacodynamics and pharmacokinetics of spiramycin and their clinical significance.

The absolute bioavailability of oral spiramycin is generally within the range of 30 to 40%. After a 1 g oral dose, the maximum serum drug concentration was found to be within the range 0.4 to 1.4 mg/L. The tissue distribution of spiramycin is extensive. The volume of distribution is in excess of 300 L, and concentrations achieved in bone, muscle, respiratory tract and saliva exceed those found in serum. The intracellular penetration of spiramycin is also rapid and extensive, with the concentrations in alveolar macrophages 10 to 20 times greater than simultaneous serum concentrations. Spiramycin is less metabolised than some of the other macrolides. The renal excretion of spiramycin is low, with 4 to 20% of the dose being excreted by this route. High concentrations of spiramycin are achieved in bile, which is an important route of elimination. The serum elimination half-life of spiramycin is between 6.2 and 7.7 hours. Of significance to clinicians may be the finding that spiramycin is highly concentrated in the respiratory tract and other tissues and macrophages. The post-antibiotic effect of spiramycin is significant and this effect is more prolonged than that of erythromycin against Staphylococcus aureus. Spiramycin has also been shown to greatly reduce the capacity of strains of Gram-positive cocci to adhere to human buccal cells.

Effect of Nedocromil Sodium on Sulfidopeptide Leukotrienes-stimulated Human Alveolar Macrophages in Asthma

Summary: Alveolar macrophages (AM) may take part in the amplification of the inflammatory mechanism involved in asthma. During an asthma attack, mast cells and eosinophils release arachidonic acid derivative mediators of inflammation such as sulfidopeptide leukotrienes. Among them, LTC 4 has been shown to be present in bronchoalveolar fluid. In asthmatic patients, we showed that the ability of AM to transform LTC 4 into its derivatives LTD 4 and LTE 4 was related to the intensity of the local inflammation observed during endoscopy. AM from asthmatics incubated in the presence of LTC 4 or LTE 4, generated LTB 4 and 5-HETE, which are potent chemoattractants. Nedocromil sodium (10 -4 M) decreased LTB 4 releasability and intracellular 5-HETE concentrations in zymosan-stimulated AM from asthmatic patients, and was shown to decrease the LTC 4 or LTE 4-promoted formation of LTB 4 and 5-HETE.

Haematological disorders and lung alveolar macrophage function following total parenteral nutrition in rats

Alterations in haematological parameters have been reported both clinically and experimentally following administration of total parenteral nutrition (TPN). Fat emulsions also affect function of the mononuclear phagocytic system. We have examined haematological parameters and pulmonary alveolar macrophages in rats fed intravenously with the individual components of TPN; a 20 % fat emulsion (Intralipid) and an amino acid solution (Vamin-Glucos), for 1, 3 and 7 days as a continuous infusion. The control groups were given saline infusion for the same periods of time. Haemoglobin, haematocrit, red blood cells, leukocytes, leukocyte superoxide anion production, leukocyte distribution, platelets and platelet aggregation were measured. Lung lavage fluid was examined for alveolar macrophage concentration and procoagulant activity of macrophages. Several of the animals in the experimental groups developed superior caval vein thrombosis. Both experimental groups developed anaemia after 7 days of infusion. Thrombocytopaenia occurred in both experimental groups after 3 and 7 days of infusion. Platelet aggregation decreased already after 1 day of infusion. We did not observe any alteration in counts, distribution in peripheral blood, or superoxide production of leukocytes. The concentration of alveolar macrophages in the lung lavage fluid increased in the experimental groups. The tissue factor activity of the alveolar macrophages increased in the group receiving Intralipid. Our observations are consistent with a granulomatous inflammation reaction.

Acute and Subacute Effects of Injury on the Canine Alveolar Septum

The effect of papain on the prevalence and distribution of alveolar macrophages, alveolar septal interstitial tissue gaps and epithelial cells in normal canine pulmonary alveoli was studied by light and electron microscopy. Serial sections of whole alveoli from control animals and from animals sacrificed 4 h, two weeks and one month after the instillation into one lung of crude papain in saline solution containing India ink as a marker were compared. In dogs, as in humans, there is normally a zonal distribution of alveolar macrophages and type 2 cells at alveolar junctional sites. We hypothesize that early alveolar septal injury takes place at these junctional sites, judging from concentration of alveolar macrophages and interstitial septal gaps at these sites following papain exposure, and also that septal repair activities are greatest at these sites, in view of the preponderance and high prevalence of type 2 cells occupying interstitial septal gaps in junctional zones. Consequently, the type 2 cell may play a role beyond that of merely replacing type 1 epithelial cells following alveolar septal injury.

The penetration of co-trimoxazole into alveolar macrophages and its effect on inflammatory and immunoregulatory functions

The pharmacokinetics of co-trimoxazole in serum, bronchoalveolar lavage-fluid (BAL-fluid) and alveolar macrophages (AM) of guinea pigs receiving sulphamethoxazole (100 mg/kg) and trimethoprim (20 mg/kg) were studied. HPLC showed that peak co-trimoxazole levels were obtained in serum at 30 min, in BAL-fluid at 1 h and in AM at 3 h. A comparison between mean concentrations in serum, BAL-fluid and AM showed a six-fold higher concentration of trimethoprim in cells than in serum, but only 0.25-fold of sulphamethoxazole. The BAL-fluid/serum ratio was four to ten times higher for trimethoprim than for sulphamethoxazole (0.6-to-one-fold). Sulphamethoxazole/trimethoprim ratios (30 min, 1 and 3 h) were lower in BAL-fluid (4.9 +/- 0.5) and in AM (1.4 +/- 0.5) than in serum (30.7 +/- 1.6). The influence of co-trimoxazole in vitro on microbicidal capacities (superoxide anion and hydrogen peroxide generations), immunoregulation (production of interleukin 1) and pro-inflammatory agent production (tumour necrosis factor) of guinea pigs' AM was also studied. No significant effect of co-trimoxazole on superoxide anion and hydrogen peroxide generations, or on interleukin 1 and TNF production, was demonstrable.