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Assessment of the bioequivalence of different formulations containing azithromycin (tablets and suspension).

Azithromycin (CAS 11772-70-0) is an orally administered macrolide antimicrobial drug, structurally related to erythromycin, with a similar spectrum of antimicrobial activity. The aim of the present studies, performed in two different groups of volunteers, was to compare the bioavailability of azithromycin (Azro) 500 mg tablets (study 1) and azithromycin (Azro) 200 mg/5 mL suspensions (study 2) with originator products. Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in 24 healthy volunteers with a wash-out period from 14 to 21 days. Blood samples were taken up to 96 h post dosing, and concentrations of azithromycin were determined by HPLC method. In the first study, the 90% confidence interval for intra-individual ratios (test vs. reference) of AUC0-t and Cmax of azithromycin were between 0.82 and 1.04 for AUC0-t and 0.81 and 1.11 for Cmax, and thus within the acceptance ranges for bioequivalence trials. The 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of azithromycin administered as suspension were between 0.89 and 1.22 and 0.91 and 1.23, respectively. These values were also within the acceptance range. Concerning the secondary parameter tmax the 90% confidence interval for the intra-individual differences for azithromycin were between -0.49 - 0.50 in the first and between -0.50 - 0.25 in the second study, respectively. In the light of the results of the studies reported here it can be concluded that azithromycin test formulations, i.e. tablet and suspension are bioequivalent to the respective reference formulations.

Adolescent↗

Once weekly azithromycin therapy for prevention of Mycobacterium avium complex infection in patients with AIDS: a randomized, double-blind, placebo-controlled multicenter trial.

We conducted a randomized, double-blind, placebo-controlled multicenter trial of azithromycin (1,200 mg once weekly) for the prevention of Mycobacterium avium complex (MAC) infection in patients with AIDS and a CD4 cell count of < 100/mm3. In an intent-to-treat analysis through the end of therapy plus 30 days, nine (10.6%) of 85 azithromycin recipients and 22 (24.7%) of 89 placebo recipients developed MAC infection (hazard ratio, 0.34; P = .004). There was no difference in the ranges of minimal inhibitory concentrations of either clarithromycin or azithromycin for the five breakthrough (first) MAC isolates from the azithromycin group and the 18 breakthrough MAC isolates from the placebo group. Of the 76 patients who died during the study, four (10.5%) of 38 azithromycin recipients and 12 (31.6%) of 38 placebo recipients had a MAC infection followed by death (P = .025). For deaths due to all causes, there was no difference in time to death or number of deaths between the two groups. Episodes of non-MAC bacterial infection per 100 patient years occurred in 43 azithromycin recipients and 88 placebo recipients (relative risk, 0.49; 95% confidence interval, 0.33-0.73). The most common toxic effect noted during the study was gastrointestinal, reported by 78.9% of azithromycin recipients and 27.5% of placebo recipients. Azithromycin given once weekly is safe and effective in preventing disseminated MAC infection, death due to MAC infection, and respiratory tract infections in patients with AIDS and CD4 cell counts of < 100/mm3.

AIDS-Related Opportunistic Infections↗

In-vitro activity of azithromycin, erythromycin, ciprofloxacin and norfloxacin against Neisseria gonorrhoeae, Haemophilus ducreyi, and Chlamydia trachomatis.

The minimum inhibitory concentrations (MICs) of azithromycin, erythromycin, ciprofloxacin and norfloxacin for 300 strains of Neisseria gonorrhoeae, 100 strains of Haemophilus ducreyi and six strains of Chlamydia trachomatis were determined. The two quinolones were more active against gonococcal strains than were the two macrolides. Azithromycin was approximately eight-fold more active against N. gonorrhoeae than was erythromycin (MIC90: 0.25 mg/l azithromycin, 2.0 mg/l erythromycin). The Mtr phenotype of gonococci increased azithromycin MICs approximately four fold. Azithromycin was less active than erythromycin against C. trachomatis. Azithromycin had considerable activity against H. ducreyi and was ten-fold more active than was erythromycin (MIC90: 0.004 mg/l azithromycin, 0.03 mg/l erythromycin). Clinical trials of azithromycin in the treatment of chlamydial infection and genital ulcer disease are indicated.

Azithromycin↗

Comparative in-vitro activity of azithromycin and erythromycin against Gram-positive cocci, Haemophilus influenzae and anaerobes.

The in-vitro activities of azithromycin and erythromycin were compared against 689 clinical isolates, including Gram-positive cocci, Haemophilus influenzae, and anaerobes. Of the 100 methicillin-susceptible isolates of Staphylococcus aureus tested, 77% were susceptible to 1 mg/l azithromycin and 0.5 mg/l erythromycin, whereas 22% were resistant to 32 mg/l of both compounds. All methicillin-resistant S. aureus isolates were highly resistant to both macrolides (MIC greater than 64 mg/l). Coagulase-negative staphylococci showed a wide range of susceptibilities to both compounds; MIC50 values for azithromycin and erythromycin for all isolates were 0.5 and 0.25 mg/l, respectively. With the exception of enterococci, both macrolides showed similar activity against streptococci; MIC90 values for both group A and group B streptococci were 0.03 and 0.06 mg/l for erythromycin and azithromycin, respectively. Azithromycin was less active than erythromycin against enterococci, with mode MICs of 4.0 and 1.0 mg/l, respectively; about 20% of isolates were highly resistant to both compounds. Azithromycin was substantially more active than erythromycin against H. influenzae; 41% of isolates were inhibited by 0.5 mg/l azithromycin and all isolates were inhibited by 2 mg/l. The MIC90 for erythromycin was 8 mg/l; 36% of isolates required concentrations of greater than or equal to 4 mg/l for inhibition. The anaerobic bacteria tested showed similar susceptibility to both azithromycin and erythromycin.

Azithromycin↗

Influence of outer membrane mutations on susceptibility of Escherichia coli to the dibasic macrolide azithromycin.

Azithromycin differs chemically from erythromycin by having an extra positive charge created by the presence of a methyl-substituted nitrogen in the 15-membered macrolide ring. This results in substantially increased potency against Gram-negative bacteria. Therefore, the possibility was considered that azithromycin was taken across the outer membrane of Escherichia coli by the self-promoted uptake route, which is utilized by other cationic antibiotics including polymyxins and aminoglycosides. Azithromycin, like polymyxin B and gentamicin, demonstrated equal activity against porin-sufficient and porin-deficient E. coli strains but its MIC was increased eight-fold by magnesium supplementation. Nevertheless, an outer membrane-altered mutant DC2 was eight-fold more susceptible than its parent strain UB1005 to azithromycin, indicating that the outer membrane was a permeability barrier to this macrolide. A mutant SC9252 which had an alteration in the self-promoted uptake of polymyxin and gentamicin, was more resistant to azithromycin, polymyxin and gentamicin compared to its parent SC9251. Further azithromycin, like polymyxin B and gentamicin, was capable of weakly permeabilizing cells to the hydrophobic fluorophor 1-N-phenyl-naphthylamine, a process antagonized by Mg2+. The monobasic macrolide erythromycin on the other hand was less affected by the SC9252 mutation, less effectively antagonized by Mg2+, and was a far less effective permeabilizer than dibasic azithromycin. These data are consistent with the hypothesis that the improved efficacy of azithromycin compared to erythromycin against E. coli reflects its better access to the self-promoted uptake pathway due to its additional positive charge.

Azithromycin↗

Comparison of azithromycin versus clarithromycin in the treatment of patients with lower respiratory tract infection.

The efficacy and safety of azithromycin and clarithromycin in lower respiratory tract infection (LRTI) were compared in an open, multicentre study. Five hundred and ten adult patients with a diagnosis of LRTI, including acute bronchitis, acute infective exacerbations of chronic bronchitis (AIECB) or pneumonia were enrolled. The patients were randomly assigned to receive either azithromycin (n = 252) as a single daily dose of 500 mg for three days, or clarithromycin (n = 258) 250 mg twice daily for ten days. In AIECB patients, baseline comparisons of the two treatment groups showed that there were no differences in the number of previous episodes of infection or in the incidence of current or past smokers. The overall clinical efficacy was found to be similar in each treatment group on day 10 to 14, with a satisfactory response (cured or improved) in 94% of azithromycin- and 97% of clarithromycin-treated patients. At follow-up evaluation (day 18 to 22), 97% of azithromycin- and 100% of clarithromycin-treated patients who had improved at day 10 to 14, showed satisfactory outcomes. Bacteriological efficacy was similar in both treatment groups, with eradication of 100% vs 95% of isolates in the azithromycin and clarithromycin groups, respectively. In AIECB, 100% of pathogens were eradicated by azithromycin, although one patient was clinically assessed as failed. Clarithromycin eradicated 93% of pathogens in this group; all patients being assessed as cured or improved. Both drugs were well tolerated, with 9% and 6% of patients reporting adverse events with azithromycin and clarithromycin, respectively. These adverse events were largely gastrointestinal in origin. It was concluded that a three-day course of azithromycin is as effective and well tolerated as a ten-day course of clarithromycin in adults with acute LRTIs.

Acute Disease↗

Comparison of azithromycin and co-amoxiclav in the treatment of otitis media in children.

An open randomized trial was conducted in 159 children (aged 1 to 8 years) with acute otitis media to compare the clinical efficacy of azithromycin (n = 105) and co-amoxiclav (n = 54). Azithromycin (10 mg/kg/day) was administered as a single dose for three days and co-amoxiclav was given tid for ten days at a dosage according to the manufacturer's instructions for the country. Of 103 evaluable azithromycin patients on day 3 to 5 after the start of therapy, 31 (30%) were considered cured, 67 (65%) improved and five (5%) failed compared with eight (15%) cured, 45 (83%) improved and one (2%) failed among the 54 evaluable co-amoxiclav treated patients. There was a higher number of azithromycin patients with complete resolution of symptoms at this first visit (P = 0.056). By day 10 to 12, clinical equivalence between the two treatment groups was observed with clinical cure in 86 (88%), improvement in 11 (11%) and failure in one (1%) of the 98 azithromycin patients, and in the 54 patients treated with co-amoxiclav, clinical cure was observed in 45 (83%), and improvement in nine (17%) patients. Both drugs were well tolerated and treatment related side-effects were reported in 8/105 (8%) azithromycin and 2/54 (4%) co-amoxiclav patients. In the azithromycin treatment group, these were predominantly mild to moderate gastrointestinal effects, whilst in the co-amoxiclav treatment group, both reports were of mild erythematous rash. One patient from each treatment group was withdrawn due to side-effects (azithromycin--diarrhoea and vomiting; co-amoxiclav--erythematous pruritic rash).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

Factors affecting the intracellular accumulation and activity of azithromycin.

Azithromycin is a new macrolide which accumulates in high concentrations in human phagocytes. The cellular to extracellular ratio (C/E) of azithromycin concentrations (fixed extracellular concentration 1 mg/L) in human polymorphonuclear leucocytes (PMN) were significantly affected by small increases in the environmental temperature (C/E 20.3 +/- 2 and 59.4 +/- 6 at 37 degrees C and 40 degrees C, respectively). PMN-associated azithromycin was not affected by the presence of different concentrations of human serum. The intracellular accumulation of azithromycin decreased slightly (C/E approximately 5) when cells were activated with PMA or opsonized with zymosan. The phagocytosis of opsonized Staphylococcus aureus or Haemophilus influenzae, however, slightly increased the intracellular concentrations of azithromycin. At different extracellular concentrations, azithromycin did not affect the production of hydrogen peroxide and superoxide radicals by PMN. The intracellular survival of H. influenzae in human PMN was abolished in the presence of concentrations higher than 0.125 mg/L of azithromycin. Under the same experimental conditions, however, azithromycin did not show any intracellular activity against S. aureus.

Azithromycin↗

Economic analysis of antibiotic regimens used in the treatment pharyngitis: a prospective comparison of azithromycin versus roxithromycin.

The economic impacts in terms of cost and effectiveness (speed of resolution of symptoms) of 3- and 5-day courses of azithromycin and a 10-day course of roxithromycin were compared in a randomized, open study in patients with symptoms suggestive of beta-haemolytic streptococcal pharyngitis. Direct medical costs and absence from work were recorded and symptom scores and compliance were used to assess the effectiveness of therapies. Although no differences between treatment groups in terms of overall clinical response rates were detected 2 and 4 weeks after the start of treatment, more rapid resolution of symptoms was achieved with 3- and 5-day courses of azithromycin than with a 10-day course of roxithromycin. There was also a significant reduction in the time absent from work in the azithromycin treatment groups. The total costs of care over the 4-week evaluation period were lower for the 3- and 5-day azithromycin courses (US$193.60 and US$195.30 respectively) than for roxithromycin (US$202.10). The major cost components were absence from work (58.6%), visits to the physician (15.3%) and utilization of antibiotics (14.9%). Compliance was significantly better (P < 0.01) in patients prescribed azithromycin for 3 and 5 days (58.0% and 42.9% respectively) than in those who received roxithromycin (20.3%) and a significantly longer symptom-free period (P < 0.01) was reported in azithromycin- compared with roxithromycin-treated patients. These findings support the hypothesis that a 3- or 5-day course of azithromycin is as effective as a 10 day course of roxithromycin in the treatment of patients with pharyngitis and is associated with lower costs. Furthermore, azithromycin is associated with faster resolution of symptoms and improved patient compliance.

Acute Disease↗

Influence of immunosuppression on the pharmacokinetics and pharmacodynamics of azithromycin in infected mouse tissues.

Azithromycin has been shown to preferentially distribute to infection loci. Due to the potential contribution of phagocytes as transporters of drug to these sites, there has been some concern that immunosuppression of the cellular arm of the host defence system would greatly reduce the delivery of azithromycin to sites of infection and hence impair efficacy. Therefore, we evaluated the pharmacokinetics and pharmacodynamics of azithromycin in a Staphylococcus aureus intramuscular infection model in normal and immunosuppressed mice, employing therapeutic and prophylactic regimens. Immunosuppression was induced by daily doses of cyclophosphamide that culminated in leucopenia with an underlying granulocytopenic condition, with circulating peripheral granulocytes numbering from < or = 0.1-0.3 x 10(9)/L. Azithromycin tissue levels were not reduced in infection loci in granulocytopenic mice but moderate increases in Cmax and AUC values were observed, relative to similar tissues from normal mice. The tissue half-life of azithromycin in infected tissues in a therapeutic mode (75 h) was three-fold longer than in a prophylactic mode (25 h); this correlated with the degree of inflammation (therapy was withheld until inflammation was evident; i.e., prophylaxis reduced inflammation). Histological examination of infected tissues from normal and leucopenic mice was indistinguishable despite a 70%-85% reduction in circulating granulocytes. Compared with untreated infected controls, bactericidal activity was noted following prophylaxis with azithromycin and bacteraemia was suppressed in mice receiving azithromycin therapeutically. In summary, these data indicate that azithromycin delivery and efficacy in a moderately immunosuppressed animal model are unimpaired.

Agranulocytosis↗

Concentrations of azithromycin in tonsilar and/or adenoid tissue from paediatric patients.

Azithromycin levels in tonsillar and/or adenoid tissue were determined in children (1.6-7.5 years old) who were scheduled for surgical removal of their tonsils and/or adenoids. The children received azithromycin oral suspension 10 mg/kg once daily for 3 days. Tissue samples were obtained during surgery 1 (n = 4), 2 (n = 5), 4 (n = 6), or 8 (n = 5) days after the last dose of azithromycin. Serum samples were also obtained from four children in each of these groups at the time of surgery. Mean tissue concentrations of azithromycin were 10.33 +/- 3.01, 7.21 +/- 4.04, 9.30 +/- 3.74 and 1.49 +/- 0.48 mg/kg, respectively, 1, 2, 4 and 8 days after the last dose. At the corresponding times, serum concentrations were markedly lower: 47.25 +/- 19. 19, 14.00 +/- 8.45, 8.00 +/- 2.16 and < 4 micrograms/L, respectively. The mean tissue:serum concentration ratios were, 227 +/- 54, 547 +/- 184 and 956 +/- 355, respectively, 1, 2 and 4 days after treatment. No adverse events attributable to azithromycin were observed in any of the 23 children who had received at least one dose of azithromycin. The study shows that levels of azithromycin in tonsillar and adenoid tissue were consistently higher than in serum and remained elevated up to 8 days after the end of dosing, supporting the use of a short-course (3-day), once-daily regimen of azithromycin in the treatment of upper respiratory tract infections.

Adenoids↗

An open comparative study of azithromycin versus cefaclor in the treatment of patients with upper respiratory tract infections.

Azithromycin and cefaclor were compared for the treatment of acute otitis media, streptococcal pharyngitis/tonsillitis, or sinusitis in an open multicentre study conducted in 530 adults. At the end of therapy (day 11-15), 228/245 (93%) patients treated with azithromycin 500 mg once daily for 3 days and 233/241 (97%) treated with cefaclor 250 mg given three times daily for 10 days were considered to have responded satisfactorily (cured or improved). In bacteriologically evaluable patients with pharyngitis/ tonsillitis, Streptococcus pyogenes was eradicated in 116/117 (99%) azithromycin- and in 115/119 (97%) cefaclor-treated patients at day 11-15; one patient in each group had become reinfected after initial eradication of the pathogen. When followed up on day 25-30, S. pyogenes infection had recurred in 5/105 (5%) azithromycin and 4/108 (3%) cefaclor patients who had responded satisfactorily at day 11-15, and whose baseline pathogen had been eradicated. Of these patients, two in the azithromycin and one in the cefaclor group also relapsed clinically; the others remained asymptomatic. Patients tolerated both treatments well; treatment-related adverse events were recorded in 11% of the 267 azithromycin- and 10% of the 263 cefaclor-treated patients assessed for safety. One azithromycin patient and five cefaclor patients withdrew because of adverse events. The results of the study show that a 3-day regimen of azithromycin, given once daily, is as effective and well tolerated as a multiple-daily, 10-day cefaclor regimen for the treatment of upper respiratory tract infections in adults.

Acute Disease↗

Gastric mucosal distribution and clinical efficacy of azithromycin in patients with Helicobacter pylori related gastritis.

The gastric mucosal distribution of azithromycin, the prototype of a new class of macrolide antibiotics named azalides, was studied in patients with duodenal ulcer and Helicobacter pylori-related gastritis. The time course of ulcer healing, H. pylori infection, and gastritis activity was also evaluated. Twenty patients (median age 50 years) received the following treatment for 1 month: three cycles of azithromycin (500 mg/day for 3 consecutive days) on days 1-3, 11-13 and 21-23 plus omeprazole (40 mg/day) for 30 consecutive days. Endoscopic biopsy specimens of gastric mucosa and blood samples were collected on days 0, 4, 7, 10, 20 and 30. An additional follow-up endoscopy was carried out on day 60. H. pylori infection was determined by both histology and rapid urease test. Azithromycin concentrations in both plasma and gastric mucosa were measured by a microbiological plate assay, using Micrococcus luteus NCTC 8440 as the reference organism. Azithromycin concentrations in plasma ranged between 0.17 mg/L (95% CI: 0.08-0.26; n = 5) and 0.32 mg/L (95% CI: 0.21-0.43; n = 5) throughout the treatment period. In addition, azithromycin concentrations in gastric mucosa were significantly higher than plasma concentrations at all times examined and ranged from 18.5 mg/kg (95% CI: 15-20; n = 20) to 24.6 mg/kg (95% CI: 16.8-32.4; n = 5), Indicating that the drug was highly retained in the target tissue. Accordingly, the ratio of azithromycin mucosal level to plasma concentration varied between 77.9 (95% CI: 56.5-99.3; n = 5) and 112.7 (95% CI: 100.2-125.2; n = 5). At the end of treatment (day 30) H. pylori was no longer detected in 16 of 20 patients (80%), and this finding was consistent with a marked decrease in the grading of gastritis activity. At the follow-up endoscopy (day 60) the infection was eradicated in only four patients (20%). These data indicate a favourable distribution of azithromycin into gastric mucosa of patients with H. pylori infection and suggest that this new macrolide antibiotic represents a valuable option for treatment regimens against H. pylori. However, the low eradication rate achieved with azithromycin plus omeprazole is a source of concern and requires further investigation.

Adult↗

Randomized, double-blind study of the clinical efficacy of 3 days of azithromycin compared with co-amoxiclav for the treatment of acute otitis media.

BACKGROUND: Compared with 5 days of dosing, a 3 day dosing regimen of azithromycin for treatment of acute otitis media (AOM) may improve compliance, will simplify therapy for the caregiver and, by giving the same total dose as the 5 day regimen, provide more drug when the bacterial burden is highest. METHODS: Children of 6 months-12 years were enrolled if they had had symptoms and signs of AOM for <4 weeks and tympanic membrane effusion by acoustic reflectometry. Eligible children were randomized to azithromycin 10 mg/kg/day x 3 days or co-amoxiclav 45 mg/kg/day x 10 days. The primary endpoint was clinical response at day 28. RESULTS: One hundred and eighty-eight children (mean age 3.5 years) were randomized to azithromycin and 185 to co-amoxiclav. At day 10, the clinical success rate was 153/185 (83%) in children treated with azithromycin and 159/181 (88%) in children treated with co-amoxiclav. At day 28, 134/182 (74%) of the children were cured on azithromycin compared with 124/180 (69%) on co-amoxiclav. Also at day 28, signs of AOM, such as abnormal reflectometry (45% versus 59%; P = 0.017), bulging of the eardrum (10% versus 16%; P = 0.059) and loss of tympanic membrane landmarks (11% versus 22%; P = 0.010) were seen less frequently in azithromycin- than co-amoxiclav-treated children, respectively. Adverse events related to therapy were seen in 11% of azithromycin patients compared with 20% on co-amoxiclav (P = 0.014). CONCLUSIONS: Azithromycin given over 3 days is as effective as co-amoxiclav for treatment of AOM, may result in more complete resolution of tympanic membrane disease, and is better tolerated.

Acute Disease↗

Enhanced efficacy of single-dose versus multi-dose azithromycin regimens in preclinical infection models.

OBJECTIVES: As a result of the prolonged half-life and unique pharmacokinetic and pharmacodynamic (PK-PD) characteristics of azithromycin, shorter dosing regimens are being evaluated for the treatment of community-acquired infections. To provide further support for a shorter dosing regimen, the efficacy of azithromycin was determined in preclinical infection models comparing single- versus multi-dose regimens. METHODS: The efficacy of single versus multi-dose regimens of azithromycin was compared in mouse pneumonia, acute peritonitis, and neutropenic thigh infection models and in a gerbil model of Haemophilus influenzae acute otitis media. Azithromycin was administered as a single oral dose on the first treatment day, or as two divided doses over 2 treatment days, or as three divided doses over 3 treatment days. The pharmacokinetics of azithromycin was profiled following single and multi-dose regimens with the single dose data fit to an Emax model to characterize the PK-PD of azithromycin. RESULTS: In the mouse efficacy models, administration of single-dose azithromycin produced superior rates of survival and bacterial clearance compared with the same total dose divided over 2 or 3 days. In the gerbil model, a single dose sterilized the middle ear and more rapidly cleared H. influenzae. The pharmacokinetic evaluation confirmed similar total exposure (AUC) in serum and pulmonary tissue for the three regimens. Correlation of PK-PD parameters and antimicrobial efficacy confirmed a concentration-dependent and dosing-independent relationship for azithromycin. CONCLUSIONS: These data are consistent with data reported from clinical studies and indicate that a single-dose regimen would be at least as effective as the same dose administered over several days.

Animals↗

A multicenter, double blind comparison of azithromycin and amoxicillin/ clavulanate for the treatment of acute otitis media in children.

OBJECTIVE: To compare the efficacy and safety of azithromycin and amoxicillin/clavulanate in pediatric acute otitis media. METHODS: Investigators from 12 US centers recruited 677 children. In a randomized, double blind, double dummy fashion, participants received either azithromycin suspension (n = 341) once daily for 5 days or amoxicillin/clavulanate suspension (n = 336) in three divided doses daily for 10 days. RESULTS: Among evaluable patients satisfactory clinical response rates (cured and improved) measured 11 days after therapy began were 87.5% in the azithromycin group and 87.9% in the amoxicillin/clavulanate group; corresponding rates at 30 days were 73.5% in the azithromycin and 71.2% in the amoxicillin/clavulanate groups. Relapse rates were comparable for the treatment groups. Treatment-related side effects, primarily gastrointestinal, were reported significantly less frequently with azithromycin (8.8%) than with amoxicillin/clavulanate (30.8%) (P < 0.0001). Two (0.6%) azithromycin patients and 12 (3.6%) amoxicillin/ clavulanate patients discontinued therapy because of treatment-related side effects (P < 0.006 between groups). CONCLUSIONS: In these children with acute otitis media, azithromycin given once daily for 5 days and amoxicillin/clavulanate given three times daily for 10 days had similar efficacy; however, azithromycin was significantly better tolerated.

Acute Disease↗

Short course therapy with cefitbuten versus azithromycin in pediatric streptococcal pharyngitis.

OBJECTIVE: To compare the safety and efficacy of a short course (5 days) of ceftibuten vs. azithromycin for 3 days for treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis in children. METHODS: A multicenter, open label, prospective, randomized trial in which patients > or =3 to < or =16 years of age with proven GABHS pharyngitis were randomized to receive either once daily ceftibuten for 5 days or azithromycin for 3 days. Patients were evaluated for clinical outcomes and/or for adverse events at days 6 to 8, 13 to 15 and 33 to 35 posttherapy. Microbiologic assessments (pharyngeal cultures) were conducted at baseline and at each follow-up visit. RESULTS: A total of 132 patients in the ceftibuten arm and 116 in the azithromycin arm were enrolled in the safety analysis, whereas 126 and 101, respectively, were enrolled for ceftibuten and azithromycin efficacy evaluation. Clinical success (cure or marked amelioration) at days 6 to 8 was recorded in 98 and 94% in the 2 groups, respectively. In the bacteriologic efficacy analysis at 6 to 8 days, the GABHS strain was eradicated in 76% of the patients treated with ceftibuten and in 76% of those receiving azithromycin. At 33 to 35 days, 84% of the patients in the ceftibuten arm and 71% in the azithromycin arm were GABHS-negative, and bacteriologic relapse was observed in 4 and 7% of the ceftibuten and azithromycin cases, respectively. Both treatments were well-tolerated by all patients. CONCLUSIONS: Ceftibuten and azithromycin allow simple treatment schedules (i.e. once daily administration, short duration of treatment). The somewhat higher eradication rate recorded after ceftibuten administration is consistent with the overall superior bactericidal activity of beta-lactams compared with macrolides vs. GABHS in vitro.

Adolescent↗

Azithromycin compared with beta-lactam antibiotic treatment failures in pneumococcal infections of children.

OBJECTIVE: To determine whether treatment failures occurred more commonly with azithromycin than with beta-lactam antibiotics in children who developed invasive pneumococcal disease within 30 days of receiving prior antimicrobial therapy. METHODS: Retrospective review of medical records of children evaluated at Texas Children's Hospital between 1996 and 2002 who had received antimicrobials (azithromycin or a beta-lactam antibiotic) and developed invasive pneumococcal disease within 30 days. Treatment failure was defined as invasive pneumococcal infection that occurred while taking antimicrobials or within 3 days of stopping azithromycin treatment or 1 day of stopping beta-lactam treatment. Penicillin and azithromycin susceptibilities were determined and categorized according to National Committee for Clinical Laboratory Standards guidelines. RESULTS: We identified 21 and 33 children with similar demographic features who had developed invasive pneumococcal disease within 1 month of receiving azithromycin or a beta-lactam antibiotic, respectively. Eleven (52%) children in the azithromycin group and 11 (33%) in the beta-lactam group met the definition for treatment failures (P = 0.34). Eight treatment failures while receiving azithromycin were caused by pneumococci with the macrolide-resistant (M) phenotype, 2 with the macrolide-, lincosamide- and streptogramin B-resistant (MLSB) phenotype and 1 by a macrolide-susceptible organism. In the beta-lactam group 7 had a penicillin-resistant isolate, 3 had an intermediately susceptible isolate and 1 had a susceptible isolate. CONCLUSIONS: Our study suggests that treatment failures among patients who developed invasive disease within 30 days of receiving an antimicrobial occur as frequently in patients who receive beta-lactam antibiotics as in those who receive azithromycin. Furthermore macrolide resistant organisms are not more likely to be recovered after a macrolide treatment failure than a penicillin-nonsusceptible isolate being recovered after a beta-lactam treatment failure (P = 1.0).

Anti-Bacterial Agents↗