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PubMed2006

Inhaled azithromycin therapy.

The treatment of pulmonary infectious diseases with pharmaceutical aerosols is an attractive option considering the accessibility of the lungs for topical drug delivery. Aerosols have been targeted to the lungs for the treatment of asthma with great success. Current therapies for other diseases, including Pseudomonas aeruginosa, Pneumocystis jirovecii (formerly Pneumocystis carinii), and mycobacterial infections, remain suboptimal due to the efficacy/safety profile. This may be improved by aerosol targeted pulmonary drug delivery. Azithromycin is a broad spectrum antibiotic that acts by inhibiting protein synthesis. It is associated with side effects that might be avoided by aerosol delivery to the lungs. In the present study three concentrations of azithromycin (10, 50, and 100 mg/mL) were delivered from three nebulizers (Acorn II, Updraft, and LC Plus) operated at 8 L/min. Particles size analyses were conducted by inertial impaction and laser diffraction. In addition, emitted doses were determined. A linear proportionality existed across the concentration range between nominal dose and both fine particle dose/fraction and emitted dose, with R2 > 0.999 in all cases. The mass median aerodynamic diameter increased from 1.4 to 1.9 microm between 10 and 100 mg/mL of azithromycin solution concentration for the Acorn II. The particle size distributions were not all log-normally distributed. The median particle size delivered from the devices was largest for the Updraft (2.8 microm) and smallest for the Acorn II (1.9 microm) for 100 mg/mL azithromycin solution concentrations. The efficiencies of small particle delivery (%<4.7 microm) were as follows, LC Plus = Acorn II (85%) > UpDraft (75%). However, the emitted dose from the LC Plus (55 mg/min) was higher than the Acorn II (31 mg/min) to maximize lung exposure to the aerosol, small median diameters and broad particle size distributions would be most effective. This study demonstrates that the dose delivered to the lungs will be maximized, under the current operating conditions by adopting the LC Plus, and high (100 mg/mL) azithromycin concentrations.

Administration, Inhalation↗
PubMed1995

Comparison of azithromycin and ceftriaxone for the treatment of chancroid.

We conducted a randomized, unblinded, prospective study designed to determine the efficacy of single-dose azithromycin for the treatment of chancroid. Men and women 16 years of age and older who had darkfield-negative genital ulcers that were clinically suspected to be caused by Haemophilus ducreyi and who attended urban sexually transmitted disease clinics or presented to hospital emergency departments were enrolled in the study. Patients were randomized to receive 250 mg of ceftriaxone im or 1 g of azithromycin orally, both given as a single dose. They were followed for up to 23 days after treatment. For 65 patients, cultures were positive for H. ducreyi; there were 68 patients whose cultures were negative for both H. ducreyi and herpes simplex virus and who had no evidence of syphilis. All 133 patients returned for at least one follow-up visit. At the time of the last follow-up visit, all 32 patients whose cultures were positive for H. ducreyi and who were treated with azithromycin were clinically cured. In all 33 culture-positive cases in which ceftriaxone was used, there was either clinical improvement or cure at the time of the patient's last follow-up visit. In addition, azithromycin and ceftriaxone were equally effective in healing ulcers for which cultures were negative. We conclude that a single 1-g oral dose of azithromycin is as effective as a 250-mg im dose of ceftriaxone for the treatment of chancroid.

Administration, Oral↗
PubMed1993

Efficacy of azithromycin for treating Babesia microti infection in the hamster model.

Because of its prevalence and severity, Babesia microti infection is an important public health problem. The current treatment of choice is clindamycin plus quinine. However, in some cases other treatments are needed because of drug intolerance or relapse. The activity of azithromycin was investigated for treatment of babesiosis in the hamster model. All animals received vancomycin to prevent antibiotic-associated colitis. Quinine (250 mg/kg/day), azithromycin (150 mg/kg/day), and the combination of azithromycin and quinine were compared. A significant suppression of parasitemia was found in all treatment groups (combination had the greatest effect, followed by azithromycin, then quinine; P < .05). The mean survival was significantly prolonged in the combination group (P < .05). Azithromycin as monotherapy in a higher dose (300 mg/kg/day) also resulted in a significant prolongation of survival (P < .05). Spirogermanium and ciprofloxacin, which have been reported to have antimalarial activity, had no effect on parasitemia or survival in this experimental babesiosis model.

Animals↗
PubMed1990

Comparison of azithromycin and erythromycin in the treatment of atypical pneumonias.

An open, randomized, multicentre study compared the efficacy and safety of the prototype, azalide, azithromycin, and erythromycin in the treatment of atypical pneumonias. Azithromycin was administered for five days at a dosage of 250 mg bd on day 1 and 250 mg once daily on days 2 to 5. Erythromycin was given for ten days at 500 mg qid. Causative pathogens were identified by serological methods. Of 57 patients treated with azithromycin, Mycoplasma pneumoniae and Chlamydia psittaci were identified in 31 and eight patients, respectively. Of 44 patients treated with erythromycin, M. pneumoniae and C. psittaci were identified in 24 and eight patients, respectively. There were no therapeutic failures in either treatment group. Side effects were observed in one of 57 patients on azithromycin and in six of 44 patients on erythromycin. Azithromycin appears to be as effective as erythromycin in the treatment of atypical pneumonias and better tolerated.

Adolescent↗
PubMed1990

Pharmacokinetics of azithromycin in rats and dogs.

After intravenous or oral administration to rats and dogs, azithromycin was rapidly distributed into the tissues, where concentrations frequently exceeded those in serum by 100-fold or more within 24 h of a single dose. Tissue concentrations were proportional to the dose following single administrations of 10 to 40 mg/kg in rats and dogs. Tissue concentrations were higher after multiple dosing and became greater as the dose was increased from 10 to 40 mg/kg. Elimination half-lives were similar in most tissues and were about 40 h in rats after seven doses of 20 mg/kg and about 90 h in dogs after five doses of 30 mg/kg. Serum concentrations declined in a multi-exponential manner, reflecting initial rapid distribution into tissues and then slow return to serum from tissues. Azithromycin had good oral bioavailability in rats and dogs (46% and 97%, respectively). Rapid uptake of azithromycin by tissues from serum and slow redistribution from tissues to serum are apparently factors governing the pharmacokinetics of azithromycin in rats and dogs. Serum concentrations do not reflect the availability of azithromycin in tissues.

Administration, Oral↗
PubMed1991

The effect of a single oral dose of azithromycin on chlamydial salpingitis in mice.

Progesterone-treated C3H mice were inoculated under the ovarian bursa with a human Chlamydia trachomatis strain, serovar E, and treated variously from one week before inoculation to two weeks afterwards with a single oral dose of azithromycin. At autopsy, all 27 control mice, not given azithromycin, had histological evidence of salpingitis. Any tubal inflammation in the 139 mice which had received greater than or equal to 60 mg azithromycin/kg was always less severe than that in control mice killed on the same day. This was true also for three of the six mice given azithromycin 25 mg/kg. Salpingitis was prevented in all 38 mice given greater than or equal to 60 mg of azithromycin on the day chlamydiae were inoculated. Inflammation was found in only 35% of mice given 60-80 mg/kg of drug from two to ten days after inoculation and was less severe than in untreated control mice. This dose given later was not as effective in preventing disease. Doses of 200-240 and 100-180 mg/kg given up to a week before inoculation reduced the proportion of mice with salpingitis to 33% and 77%, respectively, while no reduction occurred with 60-80 mg/kg, although lesions were less severe than in control mice. Chlamydiae were not detected in any part of the genital tract when greater than or equal to 60 mg/kg of azithromycin were given on the day of inoculation and were rarely detected when the drug was given a week before or up to 12 days after inoculation. Re-isolation of organisms was not always associated with histological evidence of disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A comparative study of the efficacy, safety and tolerance of azithromycin, dicloxacillin and flucloxacillin in the treatment of children with acute skin and skin-structure infections.

An open, randomized, multicentre study was undertaken to compare a three-day regimen of azithromycin with a seven-day course of dicloxacillin or flucloxacillin in the treatment of 118 children (aged 2-12 years) with clinically diagnosed acute skin and skin-structure infections. Sixty patients received a single daily dose of azithromycin of 10 mg/kg for three days, whilst 58 received a cloxacillin ester: either dicloxacillin (n = 49) at a daily dose of 12.5-25 mg/kg (depending on severity of infection); or flucloxacillin (n = 9) at 250-2000 mg/day (depending on age). Both cloxacillin esters were administered in four divided doses for seven days. Clinical, safety and, where possible, bacteriological assessments were made before therapy and after 3 to 5 and 7 to 10 days of treatment. A successful clinical response (cure and improvement) was recorded in 57 of 59 (97%) of evaluable azithromycin patients, and in 57 of 58 (98%) of cloxacillin ester patients. Eradication of the key pathogens was 31 of 34 (91%) and 34 of 35 (97%) for Staphylococcus aureus, and 5 of 5 and 4 of 4 for Streptococcus pyogenes in the azithromycin and cloxacillin ester groups, respectively. Both medications were well tolerated, with mild to moderate side-effects (abdominal pain and vomiting) occurring in two patients in each group, and laboratory abnormalities (elevated eosinophil count) in one patient in each group. There were no withdrawals from therapy. The results of this study suggest that azithromycin is as effective and as well tolerated as a cloxacillin ester antibiotic in the treatment of children with acute skin and skin-structure infections.

Azithromycin↗
PubMed1993

Single-dose oral azithromycin versus seven-day doxycycline in the treatment of non-gonococcal urethritis in males.

One hundred and twenty male patients with signs and symptoms compatible with non-gonococcal urethritis were enrolled in a prospective-randomized study to compare the efficacy and safety of a single oral-dose of 1 g azithromycin and a seven-day course of 100 mg doxycycline twice-daily. Clinical examination and culture samples for Chlamydia trachomatis were performed before and approximately 8, 15 and 35 days after starting treatment. Both treatment groups were comprised of 30 chlamydia-positive patients evaluable for efficacy. The eradication rate of C. trachomatis in baseline-positive patients at the first follow-up visit in the azithromycin group was 96% with one persistent case, and 100% in the doxycycline group. After about two weeks, there were two re-occurrences in the azithromycin group, resulting in a cumulative eradication rate of 90% with three culture-positive cases. The corresponding figure in the doxycycline group was still 100%, but there were leucocytes present in the urethral smear of two patients who later proved to be true culture-positive re-occurrences. After about five weeks, there was an additional re-occurrence in the azithromycin group leading to a cumulative eradication rate of 87%, while two re-occurrences in the doxycycline group gave a cumulative eradication rate of 93%. There was no statistically significant difference in efficacy between the single-dose azithromycin and seven-day course of doxycycline in the treatment of patients with chlamydial urethritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

A comparative study of azithromycin and amoxycillin in paediatric patients with acute otitis media.

In this open study, a three-day regimen of azithromycin (single daily dose of 10 mg/kg) was compared with a ten-day regimen of amoxycillin paediatric suspension (30 mg/kg/day in three divided doses; children > 20 kg received 250 mg tid daily) in 154 children (aged 2-12 years) with a clinical diagnosis of acute otitis media (13 recurrent). Full clinical, bacteriological and laboratory safety assessments were performed during and after the study. Of the 77 azithromycin patients, 61 (79%) were considered cured, 15 (19%) improved and one (1%) failed, compared with 45 (58%) cured, 28 (36%) improved and four (5%) failed among the 77 amoxycillin patients. Excluding from analysis the 13 patients with recurrent otitis media, azithromycin was found to be significantly superior to amoxycillin (P = 0.003). The incidence of side-effects was low, with only two (3%) and three (4%) patients reporting adverse events with azithromycin and amoxycillin, respectively. These were gastrointestinal in nature and of mild or moderate severity, except for one case of severe diarrhoea in the amoxycillin group. No treatment-related abnormalities in the laboratory safety tests were observed, and no patients withdrew from therapy. A three-day regimen of azithromycin was therefore shown to be more effective than, and as well tolerated as, amoxycillin in the treatment of children with acute otitis media.

Acute Disease↗
PubMed1994

The effect of a single oral dose of azithromycin on chlamydial infertility and oviduct ultrastructure in mice.

Azithromycin has been recommended for the treatment of human chlamydial genital tract infections because of the sustained, chlamydicidal levels of the antibiotic which can be achieved after a single dose. The effect of single dose azithromycin on the prevention or reversal of chlamydial-induced damage to the oviduct or to fertility was assessed in a mouse model of chlamydial salpingitis which closely mimics the human disease. C3H mice were treated with progesterone and then inoculated under the ovarian bursa with a human genital tract isolate of Chlamydia trachomatis, serovar F. Azithromycin at doses from 135-250 mg/kg was administered by oral intubation. Morphological damage to the oviduct lumen was assessed by scanning electron microscopy, while fertility was assessed by breeding experiments. Treatment of mice two or seven days after infection with 135 mg/kg azithromycin completely reversed chlamydial-induced ultrastructural changes and infertility. Treatment 12 or more days after infection, at doses as high as 250 mg/kg, failed to prevent infertility. The onset of fertility correlated with the loss of ciliated epithelia from the oviduct. However, the regeneration of ciliated epithelia following azithromycin treatment did not necessarily restore tubal patency. These results, if true for women also, indicate the need for rapid, effective antibiotic therapy for chlamydial salpingitis to prevent infertility and other sequelae of tubal damage.

Administration, Oral↗
PubMed1995

Efficacy of azithromycin and rifabutin in preventing infection by Mycobacterium avium complex in beige mice.

We investigated the potential of the azalide, azithromycin, and rifabutin in preventing disseminated infection due to Mycobacterium avium complex (MAC) in beige mice. Azithromycin 200 mg/kg, rifabutin (30 mg/kg or 60 mg/kg) were administered by gavage 6 days before mice were challenged orally with 10(8) cfu MAC and daily for 10 days thereafter during which time the mice were again challenged with the same inoculum on alternate days (days +1, +3, +5, +7, and +9). Sixty-four days later, the presence of bacteria in the blood and the number of viable bacteria in liver, spleen and appendix were estimated. Treatment with azithromycin and 60 mg/kg/day rifabutin but not 30 mg/kg/day, significantly decreased the incidence of bacteraemia and the number of bacteria in the appendix. The administration of azithromycin resulted in significantly fewer MAC in the liver and spleen but not in the appendix whereas the converse was true of 60 mg/kg rifabutin. Our results indicate that both azithromycin and rifabutin can prevent MAC disseminated infection, but that the azalide is more effective than the rifamycin in reducing the burden of infection.

Animals↗
PubMed1995

Comparative activity of azithromycin and doxycycline against Brucella spp. infection in mice.

The activities of a short therapeutic regimen with azithromycin and the classic treatment doxycycline with streptomycin were compared and evaluated in mice infected with Brucella melitensis. In a chronic model, starting therapy 31 days after challenge, azithromycin (10 days, 50 mg/kg/day) significantly reduced the infection (2.9 logs, day 48 post-infection). The effectiveness of doxycycline (21 days, 50 mg/kg/12 hourly) was greater than azithromycin (4.1 logs of reduction, day 48 post-infection), and when doxycycline was administered for a period of 45 days, all the animals were bacteriologically cured from day 78. The combination with streptomycin (14 days, 10 mg/kg/day) did not improve the effect of any of the regimens. In an acute model infection, treatments with doxycycline or doxycycline-streptomycin, for a period of 3 days, starting 1 day after lethal challenge, were able to protect all the mice. In contrast, only 50% of the mice treated with azithromycin survived the challenge. In conclusion, although a short oral treatment with azithromycin was able to reduce the infection significantly, it was not able to cure the animals as effectively as the classic regimen with doxycycline administered for a longer period of time.

Acute Disease↗
PubMed1996

In-vitro activity of azithromycin in against intracellular Helicobacter pylori.

We studied the effect in vitro of azithromycin on the clinical strain Helicobacter pylori H:72 growing intracellularly in monolayers of HEp-2 epithelial cells. After using gentamicin to eradicate extracellular bacteria, different concentrations of azithromycin were added to the infected cells and samples were taken after 0, 4, 8 and 24 h. Infected cells not exposed to antibiotic were included as controls. The MIC of azithromycin to the H. pylori was 0.25 mg/L and the MBC 0.5 mg/L in a broth dilution plate count method. A bactericidal effect was observed on intracellular H. pylori, with inhibition increasing with increasing azithromycin concentrations. However, extracellular concentrations of 200 x MBC were necessary to achieve intracellular killing. Our results show that azithromycin is active against intracellular H. pylori suggesting that it might be possible to exploit this activity when treating infections due to the organism.

Anti-Bacterial Agents↗
PubMed1999

Safety and effect on anti-Chlamydia pneumoniae antibody titres of a 1 month course of daily azithromycin in adults with coronary artery disease.

A pilot study of azithromycin treatment following percutaneous coronary revascularization procedures was performed to assess safety and the effect of azithromycin treatment on anti-Chlamydia pneumoniae antibody titres. Patients were randomized to a 1 month course of azithromycin (total dose of 8.0 g) or placebo. Safety and compliance were assessed at 2 and 4 weeks and serological testing was performed on samples obtained at enrolment and at 6 months post-enrolment. Azithromycin was well tolerated at this dose. No effect of treatment on antibody titres was demonstrated. These results support further clinical trials to assess the effect of azithromycin treatment on cardiovascular disease outcomes.

Adult↗
PubMed2001

Meta-analysis of randomized controlled trials on the comparative efficacy and safety of azithromycin against other antibiotics for lower respiratory tract infections.

We carried out a meta-analysis of randomized controlled trials of azithromycin compared with other antibiotics in the treatment of lower respiratory tract infections, including acute bronchitis (five comparisons including 1372 patients), acute exacerbations of chronic bronchitis (13 comparisons including 1342 patients) and community-acquired pneumonia (18 comparisons with 1664 patients). For the first two indications, azithromycin did not offer any statistically significant reduction in clinical failures [random effects odds ratios 0.84, 95% confidence interval (CI) 0.54-1.31 and 0.64, 95% CI 0.31-1.32, respectively] and absolute risk differences were small. For community-acquired pneumonia, azithromycin significantly reduced clinical failures by about one-third (random effects odds ratio 0.63, 95% CI 0.41-0.95). The absolute incremental benefit was approximately one clinical failure prevented per 50 treated patients with community-acquired pneumonia. There was no significant heterogeneity for different comparators and for bacterial versus atypical pneumonias. Azithromycin was discontinued because of adverse events in only 23 of 3487 patients (0.7%). Although results should be interpreted cautiously as most trials were open-label and susceptible to bias, the meta-analysis indicates that, compared with antibiotics with traditional pharmacokinetics that require more prolonged courses, azithromycin offers no significant advantage for bronchitis, but may be more effective in community-acquired pneumonia.

Anti-Bacterial Agents↗
PubMed2002

Pharmacokinetics of intravenous azithromycin and ceftriaxone when administered alone and concurrently to healthy volunteers.

This study was conducted to identify whether or not a pharmacokinetic interaction existed when azithromycin and ceftriaxone were administered concurrently. This randomized, open-label, three-way crossover study in 12 healthy volunteers characterized the plasma pharmacokinetic parameter profiles of both drugs, as well as the white blood cell uptake and exposure to azithromycin, when the drugs were administered alone and together. The plasma pharmacokinetic parameters for azithromycin and ceftriaxone did not differ significantly either after a single dose or at steady state when the two were co-administered as opposed to being administered alone. Moreover, the neutrophil and monocyte/lymphocyte peak azithromycin concentrations and sampling period exposures also did not differ significantly between the study arm and the control arm. This study confirms that there is no interaction between azithromycin and ceftriaxone when they are administered concurrently.

Adult↗
PubMed2003

Influence of P-glycoprotein and MRP efflux pump inhibitors on the intracellular activity of azithromycin and ciprofloxacin in macrophages infected by Listeria monocytogenes or Staphylococcus aureus.

Antibiotic efflux pumps expressed in eukaryotic cells can decrease the intracellular accumulation of the corresponding drugs and therefore impair their activity against intracellular bacteria. We have investigated whether verapamil (an inhibitor of P-glycoprotein) and gemfibrozil (an inhibitor of multidrug resistance proteins (MRP) and other organic anion transporters), can modulate the intracellular activity of azithromycin and ciprofloxacin against Listeria monocytogenes and Staphylococcus aureus in J774 macrophages. In parallel, we have measured the cell accumulation and subcellular distribution of both drugs. Antibiotics were used at equipotent extracellular concentrations (from 0.5 x to 10 x MIC) to allow for pharmacological comparisons. Azithromycin was bacteriostatic against L. monocytogenes and slightly bactericidal against S. aureus. Verapamil did not improve the maximal activity of azithromycin but allowed it to reach a similar effect at extracellular concentrations about seven-fold lower in both models. Azithromycin was predominantly localized in cell granules (66%), the remainder being in the cytosol and in the 'nuclei/unbroken cells' fraction. Verapamil increased the cellular accumulation of azithromycin by almost 2.4-fold without modifying its subcellular distribution. Ciprofloxacin displayed a strong concentration-dependent bactericidal activity in both models. Gemfibrozil increased ciprofloxacin activity almost 2.5-fold against L. monocytogenes, but not against S. aureus. Ciprofloxacin was predominantly (65%) distributed in the cytosol. Gemfibrozil increased ciprofloxacin total accumulation by approximately 2.4-fold, but the excess was only found in the cytosol. Inhibition of efflux pumps may be a useful strategy to improve antibiotic efficacy against intracellular bacteria when increased accumulation can be obtained in the compartment where bacteria sojourn.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2004

Pre-exposure of infected human endometrial epithelial cells to penicillin in vitro renders Chlamydia trachomatis refractory to azithromycin.

OBJECTIVE: The clinical significance of the potential for persistent human chlamydial infections in vivo is being actively reassessed because of the increased frequency of recurrent infection with the same serovar despite compliance with an effective antibiotic regimen. The ability to extend the length of time of in vitro cultivation of polarized human endometrial epithelial cells (HEC-1B) provided the opportunity to establish a model system to determine if a persistent form of Chlamydia trachomatis had the same susceptibility as the actively growing form to a cidal concentration of azithromycin. METHODS: Polarized HEC-1B cells cultivated on extracellular matrix were infected with C. trachomatis serovar E and exposed to penicillin at 24 h post-infection (hpi) to induce a persistent infection characterized by slowly metabolizing but non-dividing, ultrastructurally aberrant reticulate bodies within the chlamydial inclusion; at 48 hpi, infected cultures were exposed to a bactericidal concentration of azithromycin for 72 h. RESULTS: Persistent chlamydiae were phenotypically resistant to azithromycin; the number of chlamydial inclusions on subpassage of progeny from persistent chlamydiae following removal of penicillin and recovery was essentially the same as from progeny from persistent chlamydiae following removal of penicillin and azithromycin and recovery. Neutrophils were attracted in vitro to persistently infected HEC-1B cells that had been exposed to penicillin and azithromycin. CONCLUSIONS: Thus, this study provides evidence at the cellular microbiology level in vitro for mechanisms that could exist in vivo to create sustained, but perhaps clinically inapparent inflammation, which might eventually lead to conditions such as silent pelvic inflammatory disease.

Anti-Bacterial Agents↗