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PubMed1995

In vitro effectiveness of azithromycin against doxycycline-resistant and -susceptible strains of Rickettsia tsutsugamushi, etiologic agent of scrub typhus.

In an effort to find a potential alternative treatment for scrub typhus, we evaluated the effectiveness of the standard drug doxycycline and the new macrolide azithromycin against a doxycycline-susceptible strain (Karp) and a doxycycline-resistant strain (AFSC-4) of Rickettsia tsutsugamushi. The antibiotics were tested in an in vitro assay system in which infected mouse fibroblast cells (L929) were incubated for 3 days in various concentrations of the drugs. Rickettsial growth was evaluated by direct visual counts of rickettsiae in Giemsastained cells or by flow cytometry. Initial tests were conducted at the concentration of each antibiotic considered to be the upper breakpoint for susceptibility (16 micrograms/ml for doxycycline and 8 micrograms/ml for azithromycin). Growth of both Karp and AFSC-4 was strongly inhibited with both antibiotics, as measured by visual counts, although the percentage of cells infected with AFSC-4 in the presence of doxycycline was three times greater than the percentage of cells infected with Karp but was only 60% as great as the percentage of cells infected with Karp in the presence of azithromycin. Flow cytometry confirmed that rickettsial growth occurred in the absence of antibiotics, but it failed to detect it in the presence of high concentrations of either drug. Visual counts of rickettsial growth at lower concentrations of the antibiotics (0.25 to 0.0078 microgram/ml) showed that the Karp strain was 16 times more susceptible that the AFSC-4 strain to doxycycline. Azithromycin was much more effective than doxycycline against AFSC-4, inhibiting rickettsial growth at 0.0156 microgram/ml to levels below that achieved by 0.25 microgram of doxycycline per ml. Azithromycin was also more effective than doxycycline against the Karp strain, causing greater reductions in the number of rickettsiae per cell at lower concentrations. If in vivo testing confirms the in vitro effectiveness of azithromycin, it may prove to be the drug of choice for the treatment of scrub typhus in children and pregnant women, who should not take doxycycline, and in patients with refractory disease from locations where doxycycline-resistant strains of R. tsutsugamushi have been found. When tested in an in vitro assay system, azithromycin was more effective than doxycycline against doxycycline-susceptible and -resistant strains of R. tsutsugamushi.

Animals↗
PubMed1995

In vivo efficacy of azithromycin in treatment of systemic infection and septic arthritis induced by type IV group B Streptococcus strains in mice: comparative study with erythromycin and penicillin G.

We compared the activities of azithromycin, erythromycin, and penicillin G in a mouse model of systemic infection and septic arthritis induced by type IV group B streptococci (GBS). The in vitro and in vivo efficacy data for these drugs were analyzed relative to the pharmacokinetics of the drugs in sera, joints, and kidneys. Adult CD-1 mice were infected intravenously with 10(7) CFU of type IV GBS. Intraperitoneal drug administration was initiated with different dose regimens at different times after infection. A single dose of azithromycin (100 mg/kg) strongly reduced the incidence of articular lesions with respect to that with erythromycin or penicillin G. Treatment with azithromycin (three intraperitoneal administrations of 50 mg/kg at 12-h intervals) resulted in the complete prevention of arthritis. In contrast, erythromycin was poorly effective and penicillin G was effective only if inoculated 30 min after infection and at high doses (400,000 or 600,000 IU/kg). Furthermore, azithromycin was able to cure about 70% of the mice when administered 7, 8, and 9 days after GBS infection. Azithromycin was much more active than erythromycin and penicillin G with respect to bacterial killing in the joints and kidneys. In fact, cultures from these tissues were always negative no matter what treatment schedule was employed. The pharmacokinetics of azithromycin account for its superior in vivo efficacy against type IV GBS. A longer half-life and higher levels of this drug in serum and tissues with respect to those for erythromycin or penicillin G were achieved. The high affinity of azithromycin for the joints strongly supports its potential value for therapy of septic arthritis, which is a severe and frequent clinical manifestation of GBS infection.

Animals↗
PubMed1996

Safety, toleration, and pharmacokinetics of intravenous azithromycin.

To date, the clinical pharmacology of large intravenous doses of azithromycin has not been described. In the present study, single 2-h intravenous infusions of 1, 2, and 4 g of azithromycin were administered to three parallel groups (in each group, six received active drug and two received placebo) of healthy male subjects. Toleration (assessed by scores of subject-administered visual analog scale tests spanning 0 [good] to 10 [poor]), safety, pharmacokinetics, and serum motilin levels were monitored for up to 240 h after the start of each intravenous infusion. Mean nausea scores of 0.0, 0.0, 1.0, and 0.5 and abdominal cramping scores of 0.0, 0.0, 0.4, and 0.4 for 12-h periods after doses of 0, 1, 2, and 4 g of azithromycin, respectively, suggested that azithromycin was well tolerated. Because of the standardized 1-mg/ml infusates, all subjects in the 4-g dosing group complained of an urgent need to urinate. There were no consistent trends in endogenous motilin levels throughout the study. The maximum concentration of azithromycin in serum (10 micrograms/ml after a 4-g dose) and the area under the concentration-time curve (82 micrograms.h/ml after a 4-g dose) were dose related. The mean pharmacokinetic parameters were an elimination half-life of 69 h, total systemic clearance of 10 ml/min/kg, and a volume of distribution at steady state of 33.3 liters/kg. The pharmacokinetic results suggest that the long half-life of azithromycin is due to extensive uptake and slow release of the drug from tissues rather than an inability to clear the drug. Single intravenous doses of up to 4 g of azithromycin in healthy subjects are generally well tolerated, and quantifiable concentrations may persist in serum for 10 days or more.

Adolescent↗
PubMed1996

Distribution of azithromycin into brain tissue, cerebrospinal fluid, and aqueous humor of the eye.

To measure the concentrations of azithromycin in the central nervous system, 20 patients with brain tumors (group I) received a single 500-mg oral dose of azithromycin either 24, 48, 72, or 96 h prior to the tumor removal operation and 10 patients with cataracts undergoing surgery (group II) and 7 patients scheduled to undergo lumbar puncture (group III) received the same dose of azithromycin 24 h prior to the operation or procedure. Serum from all patients, brain tissue from group I, aqueous humor from group II, and cerebrospinal fluid from group III were assayed for azithromycin concentration. The mean concentrations of azithromycin in brain tissue 24, 48, 72, and 96 h after administration were 2.63 +/- 2.58, 3.64 +/- 3.81, 0.74 +/- 0.37, and 0.41 micrograms/g, respectively. In contrast, the concentrations of azithromycin in cerebrospinal fluid and aqueous humor of the eye were very low or undetectable. Therefore, these data show that azithromycin appears to be widely distributed into brain tissue but not into cerebrospinal fluid or aqueous humor of the eye.

Adolescent↗
PubMed1996

Single-dose intrapulmonary pharmacokinetics of azithromycin, clarithromycin, ciprofloxacin, and cefuroxime in volunteer subjects.

The intrapulmonary pharmacokinetics of azithromycin, clarithromycin, ciprofloxacin, and cefuroxime were studied in 68 volunteers who received single, oral doses of azithromycin (0.5 g), clarithormycin (0.5 g), ciprofloxacin (0.5 g), or cefuroxime (0.5 g). In subgroups of four subjects each, the subjects underwent bronchoscopy and bronchoalveolar lavage at timed intervals following drug administration. Drug concentrations, including those of 14-hydroxyclarithromycin (14H), were determined in serum, bronchoalveolar lavage fluid, and alveolar cells (ACs) by high-pressure liquid chromatography. Concentrations in epithelial lining fluid (ELF) were calculated by the urea diffusion method. The maximum observed concentrations (mean +/- standard deviation) of azithromycin, clarithromycin, 14H, ciprofloxacin, and cefuroxime in serum were 0.13 +/- 0.07, 1.0 +/- 0.6, 0.60 +/- 0.41, 0.95 +/- 0.32, and 1.1 +/- 0.3 microgram/ml, respectively (all at 6 h). None of the antibiotics except clarithromycin (39.6 +/- 41.1 micrograms/ml) was detectable in ELF at the 6-h bronchoscopy. The movement into and persistence in cells was different for azithromycin and clarithromycin. In ACs azithromycin was not detectable at 6 h, reached its highest concentration at 120 h, and exhibited the greatest area under the curve (7,403 micrograms.hr ml-1). The peak concentration of clarithromycin (181 +/- 94.1 micrograms/ml) was greater and occurred earlier (6 h), but the area under the curve (2,006 micrograms.hr ml-1) was less than that observed for azithromycin. 14H was detectable in ACs at 6 h (40.3 +/- 5.2 micrograms/ml) and 12 h (32.8 +/- 57.2 micrograms/ml). The peak concentration of ciprofloxacin occurred at 6 h (4.3 +/- 5.2 micrograms/ml), and the area under the curve was 35.0 micrograms.hr ml-1. The data indicate that after the administration of a single dose, azithromycin, clarithromycin, and ciprofloxacin penetrated into ACs in therapeutic concentrations and that only clarithromycin was present in ELF. The correlation of these kinetic observations with clinical efficacy or toxicity was not investigated and is unclear, but the data provide a basis for further kinetic and clinical studies.

Administration, Oral↗
PubMed2000

A randomized controlled comparison of azithromycin and ofloxacin for treatment of multidrug-resistant or nalidixic acid-resistant enteric fever.

To examine the efficacy and safety of short courses of azithromycin and ofloxacin for treating multidrug-resistant (MDR, i.e., resistant to chloramphenicol, ampicillin, and cotrimoxazole) and nalidixic acid-resistant enteric fever, azithromycin (1 g once daily for 5 days at 20 mg/kg/day) and ofloxacin (200 mg orally twice a day for 5 days at 8 mg/kg/day) were compared in an open randomized study in adults admitted to a hospital with uncomplicated enteric fever. A total of 88 blood culture-confirmed patients were enrolled in the study (86 with Salmonella enterica serovar Typhi and 2 with S. enterica serovar Paratyphi A). Of these, 44 received azithromycin and 44 ofloxacin. A total of 68 of 87 (78%) isolates were MDR serovar Typhi, and 46 of 87 (53%) were nalidixic acid resistant. The MIC(90) (range) of azithromycin was 8 (4 to 16) microgram/ml for the isolates. The MIC(90) (range) of ofloxacin for the nalidixic acid-sensitive isolates was 0.03 (0.015 to 0.06) microgram/ml and for the nalidixic acid-resistant isolates it was 0.5 (0.25 to 1.0) microgram/ml. There was no significant difference in the overall clinical cure rate with ofloxacin and azithromycin (38 of 44 [86.4%] versus 42 of 44 [95.5%]; P = 0.27) or in the patients infected with nalidixic acid-resistant typhoid (17 of 21 [81.0%] versus 24 of 25 [96.0%]; P = 0.16). However, patients with nalidixic acid-resistant typhoid treated with ofloxacin had a longer fever clearance time compared with those treated with azithromycin (174 [60 to 264] versus 135 [72 to 186] h; P = 0.004) and had positive fecal cultures after the end of treatment (7 of 17 [41%] versus 0 of 19 [0%]; P = 0.002). Both antibiotics were well tolerated. A 5-day course of azithromycin was effective for the treatment of enteric fever due to MDR and nalidixic-acid-resistant serovar Typhi, whereas the ofloxacin regimen chosen was less satisfactory for these strains.

Adolescent↗
PubMed2001

A randomized trial of azithromycin versus amoxicillin for the treatment of Chlamydia trachomatis in pregnancy.

OBJECTIVE: To compare the compliance, side effects and efficacy of amoxicillin and azithromycin for the treatment of Chlamydia trachomatis infection in pregnancy. METHODS: This is a randomized single-blind trial of women diagnosed with C. trachomatis before 33 weeks gestation. Women were randomlyassigned either 500 mg amoxicillin orally three times per dayfor 7 days or a single dose of 1 g azithromycin orally. Patients were interviewed by telephone approximately 3-7 days following therapy to assess compliance and side effects. Test of cure was performed at a follow-up visit 4-6 weeks following completion of therapy. RESULTS: Thirty-nine patients were randomized with 19 receiving amoxicillin and 20 receiving azithromycin. There were no differences in baseline data between the two groups, and there were no statistically significant differences in side effects, compliance or efficacy. In the amoxicillin group 84% of women took all pills, while 100% completed the single 1 g dose of azithromycin. Side effects were common in both groups (38% overall), with 40% of the azithromycin group reporting moderate to severe gastrointestinal side effects compared to 17% in the amoxicillin group (p = 0.11). Of patients who returned for follow-up test of cure, 3 of 15 (20%) in the amoxicillin group were positive compared with 1 of 19 (5%) in the azithromycin group (p = 0.3). CONCLUSIONS: Side effects of therapy for C. trachomatis in pregnancy are common. Amoxicillin was slightly better tolerated than azithromycin. Compliance and cure rates with both regimens was high.

Adult↗
PubMed2000

Randomized secondary prevention trial of azithromycin in patients with coronary artery disease: primary clinical results of the ACADEMIC study.

BACKGROUND: Chlamydia pneumoniae is associated with coronary artery disease (CAD), although its causal role is uncertain. A small preliminary study reported a >50% reduction in ischemic events by azithromycin, an antibiotic effective against C pneumoniae, in seropositive CAD patients. We tested this prospectively in a larger, randomized, double-blind study. METHODS AND RESULTS: CAD patients (n=302) seropositive to C pneumoniae (IgG titers >/=1:16) were randomized to placebo or azithromycin 500 mg/d for 3 days and then 500 mg/wk for 3 months. The primary clinical end point included cardiovascular death, resuscitated cardiac arrest, nonfatal myocardial infarction (MI), stroke, unstable angina, and unplanned coronary revascularization at 2 years. Treatment groups were balanced, and azithromycin was generally well tolerated. During the trial, 47 first primary events occurred (cardiovascular death, 9; resuscitated cardiac arrest, 1; MI, 11; stroke, 3; unstable angina, 4; and unplanned coronary revascularization, 19), with 22 events in the azithromycin group and 25 in the placebo group. There was no significant difference in the 1 primary end point between the 2 groups (hazard ratio for azithromycin, 0.89; 95% CI, 0.51 to 1.61; P:=0.74). Events included 9 versus 7 occurring within 6 months and 13 versus 18 between 6 and 24 months in the azithromycin and placebo groups, respectively. CONCLUSIONS: This study suggests that antibiotic therapy with azithromycin is not associated with marked early reductions (>/=50%) in ischemic events as suggested by an initial published report. However, a clinically worthwhile benefit (ie, 20% to 30%) is still possible, although it may be delayed. Larger (several thousand patient), longer-term (>/=3 to 5 years) antibiotic studies are therefore indicated.

Adult↗
PubMed2002

Effect of azithromycin treatment on endothelial function in patients with coronary artery disease and evidence of Chlamydia pneumoniae infection.

BACKGROUND: It has been suggested that infection with Chlamydia pneumoniae(CPn) can trigger inflammatory mechanisms that may in turn impair vascular endothelial function. The aim of the present study was to assess whether treatment with the macrolide antibiotic azithromycin improves endothelial function in patients with coronary artery disease and antibodies positive to CPn. METHODS AND RESULTS: We carried out a randomized, prospective, double-blind, placebo-controlled trial in 40 male patients (mean age, 55+/-9 years) with documented coronary artery disease and positive CPn-IgG antibody titers. After baseline evaluation, patients were randomized to receive either azithromycin or placebo for 5 weeks. Flow-mediated dilation (FMD) of the brachial artery and E-selectin, von Willebrand factor, and C-reactive protein (CRP) levels were assessed at study entry and at the end of the treatment period. Our results showed that patients who received azithromycin had a significant improvement in FMD (mean change, 2.1+/-1.1%; P<0.005). In contrast, FMD was not significantly changed in the placebo group (mean change, -0.02+/-0.2%, P=0.64). Azithromycin therapy also resulted in a significant decrease of E-selectin and von Willebrand factor levels. CRP levels were not significantly altered by treatment with either azithromycin or placebo. Beneficial effects of azithromycin treatment were independent from the presence of low (<1:32) or high (> or =1:32) CPn antibody titers. CONCLUSIONS: Our findings indicate that treatment with azithromycin has a favorable effect on endothelial function in patients with documented coronary artery disease and evidence of CPn infection irrespective of antibody titer levels. Whether these favorable actions of antibiotic treatment will translate into a beneficial effect on atherogenesis and cardiac events needs further investigation.

Anti-Bacterial Agents↗
PubMed2005

Heterogeneity of treatment response to azithromycin in patients with cystic fibrosis.

RATIONALE: We recently reported a randomized, placebo-controlled trial of azithromycin in patients with cystic fibrosis (CF) that demonstrated a 6.2% improvement in the 168-d relative change in FEV1 among azithromycin participants compared with placebo participants. OBJECTIVES: In the current analyses, heterogeneity of treatment response and the association between FEV1 and the risk of pulmonary exacerbations were investigated. METHODS: The time to first pulmonary exacerbation, hospitalization rates, and antibiotic use were compared between participants categorized by their relative change in FEV1 % predicted (>or= 5 vs. < 5% improvement) at Day 168. Pulmonary function and exacerbation responses were compared in subgroups of participants characterized by long-term concomitant medications and baseline lung function. MEASUREMENTS: All available data from the 185 randomized participants in the azithromycin trial were included in these analyses. MAIN RESULTS: Compared with placebo participants, a reduced risk of pulmonary exacerbations was observed both among azithromycin participants with >or= 5% and those with < 5% relative improvement in FEV1. Similarly, decreased hospitalization rates and decreased use of oral quinolone and nonquinolone antibiotics were observed in azithromycin participants regardless of improvement in FEV1. Subgroup analyses demonstrated that overall, participants on long-term aerosolized tobramycin and/or rhDNase had worse baseline lung function, but still benefited from azithromycin, as evidenced by a lower risk of exacerbations. CONCLUSIONS: Azithromycin participants experienced benefits in exacerbation parameters regardless of FEV1 response or subgroup. These data have implications for clinical practice and the design of clinical trials.

Anti-Bacterial Agents↗
PubMed2005

Clinical efficacy and safety of a short regimen of azithromycin sequential therapy vs standard cefuroxime sequential therapy in the treatment of community-acquired pneumonia: an international, randomized, open-label study.

An international, randomized, open-label, comparative study was undertaken in order to assess the efficacy and safety of azithromycin and cefuroxime, short sequential vs standard sequential therapy, respectively, in the treatment of patients with community-acquired pneumonia (CAP). 180 adult patients were included in the study. 89 patients received azithromycin 500 mg intravenously (i.v.) once daily for 1-4 days followed by azithromycin 500 mg orally once daily for 3 days. 91 patients received cefuroxime 1.5 g i.v. three times daily for 1-4 days followed by cefuroxime axetil 500 mg orally twice daily for 7 days. Clinical efficacy was achieved in 67/82 (81.7%) patients treated with azithromycin, and in 73/89 (82.0%) patients treated with cefuroxime. The mean duration of total (i.v. and oral) therapy was significantly shorter for the azithromycin group than for the cefuroxime group (6.2 days vs 10.1 days). Adverse events were recorded in 38.2% of patients treated with azithromycin, and in 29.7% of patients treated with cefuroxime (p = 0.20). Shorter sequential i.v.-to-oral azithromycin therapy of patients with CAP was as effective as standard sequential i.v.-to-oral cefuroxime therapy.

Anti-Bacterial Agents↗
PubMed2006

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.

Anti-Bacterial Agents↗
PubMed2002

Cost-effectiveness of IV-to-oral switch therapy: azithromycin vs cefuroxime with or without erythromycin for the treatment of community-acquired pneumonia.

STUDY OBJECTIVE: To conduct a cost-effectiveness analysis of IV-to-oral regimens of azithromycin vs cefuroxime with or without erythromycin in the treatment of patients hospitalized with community-acquired pneumonia (CAP). PATIENTS: Of the 268 evaluable patients enrolled into a randomized, multicenter clinical trial of adults, 266 patients had sufficient data to be included in this cost-effectiveness analysis. One hundred thirty-six patients received azithromycin, and 130 patients received cefuroxime with or without erythromycin. METHODS: A pharmacoeconomic analysis from the hospital provider perspective was conducted. Health-care resource utilization was extracted from the clinical database and converted to national reference costs. Decision analysis was used to structure and characterize outcomes. Sensitivity analyses were performed, and statistics were applied to the cost-effectiveness ratios. RESULTS: The clinical success and adverse event rates and antibiotic-related length of stay were 78%, 11.8%, and 5.8 days for the azithromycin group and 75%, 20.7%, and 6.4 days for the group receiving cefuroxime with or without erythromycin, respectively. Geometric mean treatment costs were 4,104 US dollars (95% confidence interval [CI], 3,874 to 4,334 US dollars) for the azithromycin group, and 4,578 US dollars (95% CI, 4,319 to 4,837 US dollars) for the group receiving cefuroxime with or without erythromycin (p = 0.06). The cost-effectiveness ratios were 5,265 US dollars per expected cure for the azithromycin group, and 6,145 US dollars per expected cure for group receiving cefuroxime with or without erythromycin (p = 0.05). CONCLUSIONS: Despite a higher per-dose purchase price, overall costs with azithromycin tended to be lower due to decreased duration of therapy, lower preparation and administration costs, and reduced hospital length of stay. As empiric therapy, azithromycin monotherapy was cost-effective compared to cefuroxime with or without erythromycin for patients hospitalized with CAP who have no underlying cardiopulmonary disease, and no risk factors for either drug-resistant pneumococci or enteric Gram-negative pathogens.

Administration, Oral↗
PubMed2005

Single-dose azithromycin microspheres vs clarithromycin extended release for the treatment of mild-to-moderate community-acquired pneumonia in adults.

BACKGROUND: Community-acquired pneumonia (CAP) is a major cause of morbidity and mortality worldwide. The inability or failure of many subjects to adhere to standard antibiotic regimens, which may last up to 10 days, results in suboptimal antibiotic treatment. Treatment with a single-dose antibiotic regimen may improve compliance with prescribed therapy. A novel microsphere formulation of azithromycin provides a single-dose regimen while maintaining tolerability. STUDY OBJECTIVE: To compare the efficacy and safety of a single 2.0-g dose of azithromycin microspheres to that of an extended-release formulation of clarithromycin (1.0 g/d for 7 days) for the treatment of adults with mild-to-moderate CAP. DESIGN: A phase III, multinational, multicenter, randomized, double-blind, double-dummy study, comparing single-dose azithromycin microspheres to extended-release clarithromycin, both administered orally. METHODS: Subjects with mild-to-moderate CAP (Fine class I and II) were included. The primary end point was clinical response at the test-of-cure (TOC) visit (days 14 to 21) in the clinical per protocol (CPP) population. The bacteriologic response at the TOC visit was assessed in subjects with a baseline pathogen. RESULTS: A total of 501 subjects were randomized, and 499 were treated. Clinical cure rates at the TOC visit in the CPP population were 92.6% (187 of 202 subjects) for azithromycin microspheres and 94.7% (198 of 209 subjects) for extended-release clarithromycin. Overall pathogen eradication rates were 91.8% (123 of 134 subjects) for azithromycin microspheres and 90.5% (153 of 169 subjects) for extended-release clarithromycin. Both agents were well tolerated. The incidence of treatment-related adverse events was 26.3% with azithromycin microspheres and 24.6% with extended-release clarithromycin. Most adverse events were mild to moderate in severity. CONCLUSION: A single 2.0-g dose of azithromycin microspheres was as effective and well tolerated as a 7-day course of extended-release clarithromycin in the treatment of adults with mild-to-moderate CAP.

Adult↗
PubMed2003

In vitro susceptibility of gram-positive cocci isolated from skin and respiratory tract to azithromycin and twelve other antimicrobial agents.

This study was conducted to evaluate the activity of azithromycin in comparison to 12 other antibacterial agents against recent isolates obtained consecutively from patients with respiratory tract or skin infections, from January to July, 2000. A total of 717 Gram-positive cocci were analyzed in this study and the following species were studied: Staphylococcus aureus (n=576), beta-hemolytic streptococci (n=115), and Streptococcus pneumoniae (n=26). Susceptibility testing was carried out by the disk diffusion method and interpreted according to NCCLS breakpoints. The activity of azithromycin was compared to erythromycin, clindamycin, chloramphenicol, ciprofloxacin, ofloxacin, oxacillin, penicillin, ceftriaxone, tetracycline, trimethoprim/sulfamethoxazole, teicoplanin, and vancomycin. Of the 26 S. pneumoniae isolates recovered from the respiratory tract, 5 (19.2%) were intermediate resistant to penicillin. All of these strains were susceptible to chloramphenicol, ofloxacin, and vancomycin, and 24 (92%) were also susceptible to azithromycin, clindamycin, and erythromycin. Among the 67 beta-hemolytic streptococci strains isolated from the respiratory tract, 66 (99%) were susceptible to azithromycin, erythromycin, clindamycin, and ofloxacin. All 48 beta-hemolytic streptococci strains isolated from skin were susceptible to azithromycin and clindamycin, 47 (98%) were susceptible to erythromycin, and 46 (96%) were susceptible to ofloxacin. Of the 576 strains of S. aureus, 253 (43.9%) were isolated from the respiratory tract and 323 (56.1%) from skin. Among S. aureus isolates from the respiratory tract and skin, 46 (18%) and 78 (24%), respectively were resistant to oxacillin. Isolates from the respiratory tract and skin showed the same percentage of resistance (36%) to azithromycin. These in vitro results suggest that azithromycin can be a therapeutic option for treatment of infections caused by these bacteria since the newer macrolides have several distinct advantages over erytromycin including improved oral bioavailability, longer half-life allowing once or twice daily administration, higher tissue concentrations and less gastrointestinal adverse effects.

Anti-Bacterial Agents↗
PubMed1997

Periodontal tissue disposition of azithromycin.

The tissue penetration of azithromycin, the prototype of a new class of macrolide antibiotics named azalides, was studied in patients undergoing surgery for third-molar removal. Drug concentrations in plasma, saliva, and periodontal tissues were evaluated in 28 patients treated with azithromycin 500 mg/day per os for 3 consecutive days. Samples of blood, saliva, gingiva, and alveolar bone were collected during oral surgery, 12 hours, and 2.5, 4.5, and 6.5 days after the last dosing, and the azithromycin concentration was measured microbiologically by using Micrococcus luteus NCTC 8440 as the reference organism. The highest concentrations of azithromycin were observed 12 hours after the last dose in plasma, saliva, gingiva, and bone (0.33 +/- 0.04 mg/l, 2.14 +/- 0.30 mg/l, 6.47 +/- 0.57 mg/kg, and 1.86 +/- 0.15 mg/kg, respectively) and then declined gradually. However, consistent levels of the drug in saliva and periodontal tissues could be detected up to 6.5 days, indicating that azithromycin was retained in target tissues and fluids for a long time after the end of treatment. Among the samples examined, the highest concentration of azithromycin was found in the gingiva at each time studied. Moreover, the ratios of salivary or periodontal tissue levels versus plasma concentrations remained nearly unmodified from 12 hours up to 6.5 days. Overall, these results indicate a favorable disposition of azithromycin into saliva and periodontal tissues and suggest that this macrolide antibiotic represents a valuable option in the pharmacologic treatment of odontogenic infections.

Adult↗
PubMed1994

Three-day azithromycin compared with ten-day roxithromycin treatment of atypical pneumonia.

An open, randomized, multicentre study compared the efficacy and safety of 3-day azithromycin with 10-day roxithromycin for the treatment of atypical pneumonia. Azithromycin was administered 500 mg once daily to 90 and roxithromycin 150 mg bid to 60 patients. Causative pathogens were identified by serological methods. In the azithromycin treatment group, Mycoplasma pneumoniae was identified in 65, Chlamydia spp. in 9 and Coxiella burnetti in 1 patient. In the roxithromycin treatment group, M. pneumoniae was identified in 39, Chlamydia spp. in 9 and C. burnetti in 3 patients. 89 azithromycin and 53 roxithromycin patients were eligible for efficacy analysis. Clinical cure rate was 98.9% in the azithromycin and 94.3% in the roxithromycin treatment group. Adverse events were observed in 3 patients in each group. Azithromycin appears to be as effective as roxithromycin for the treatment of atypical pneumonia. The 3-day azithromycin regimen may offer an additional advantage over 10-day roxithromycin by virtue of its more convenient administration.

Adolescent↗
PubMed1999

The macrolides: erythromycin, clarithromycin, and azithromycin.

In addition to erythromycin, macrolides now available in the United States include azithromycin and clarithromycin. These two new macrolides are more chemically stable and better tolerated than erythromycin, and they have a broader antimicrobial spectrum than erythromycin against Mycobacterium avium complex (MAC), Haemophilus influenzae, nontuberculous mycobacteria, and Chlamydia trachomatis. All three macrolides have excellent activity against the atypical respiratory pathogens (C. pneumoniae and Mycoplasma species) and the Legionella species. Azithromycin and clarithromycin have pharmacokinetics that allow shorter dosing schedules because of prolonged tissue levels. Both azithromycin and clarithromycin are active agents for MAC prophylaxis in patients with late-stage acquired immunodeficiency syndrome (AIDS), although azithromycin may be the preferable agent because of fewer drug-drug interactions. Clarithromycin is the most active MAC antimicrobial agent and should be part of any drug regimen for treating active MAC disease in patients with or without AIDS. Although both azithromycin and clarithromycin are well tolerated by children, azithromycin has the advantage of shorter treatment regimens and improved tolerance, potentially improving compliance in the treatment of respiratory tract and skin or soft tissue infections. Intravenously administered azithromycin has been approved for treatment of adults with mild to moderate community-acquired pneumonia or pelvic inflammatory diseases. An area of concern is the increasing macrolide resistance that is being reported with some of the common pathogens, particularly Streptococcus pneumoniae, group A streptococci, and H. influenzae. The emergence of macrolide resistance with these common pathogens may limit the clinical usefulness of this class of antimicrobial agents in the future.

Adult↗