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PubMed1997

Azithromycin: 3-day versus 5-day course in the treatment of respiratory tract infections in children. Croatian Azithromycin Study Group.

A total of 371 children, aged 6 months to 12 years, with acute otitis media, acute sinusitis, streptococcal tonsillitis/pharyngitis, or pneumonia were included in an open, multicenter study. Among them, 192 children were randomized to receive azithromycin for 3 days (10 mg/kg daily), and 179 for 5 days (10 mg/kg on day 1 and 5 mg/kg on days 2-5). The overall clinical cure rate was 95.7% and 96.1%, and bacteriological eradication rate 90.1% and 94.2% in the 3-day and 5-day groups, respectively. Side effects, mostly mild gastrointestinal disturbances, were observed in 5.3% of children from the 3-day, and 6.7% from the 5-day group. Only in one child (0.3%) was therapy discontinued due to vomiting. The results of this study demonstrate that 3-day and 5-day azithromycin courses have comparable efficacy and tolerability in children with respiratory infections.

Anti-Bacterial Agents↗
PubMed1998

[Inhibitory activity of azithromycin on biofilm synthesis and synergism between azithromycin and fleroxacin on Pseudomonas aeruginosa in biofilms].

OBJECTIVE: The influence of azithromycin (AZT) on the production of glycocalyx (GLX) from P. aeruginosa biofilms and synergism of antibacterial activities between AZT and fleroxacin (FLX) on P. aeruginosa were investigated. METHOD: GLX production was measured by using a L-tryptophan method and viable counts in biofilms was determined by using a methylthiazolyldiphenyltetrazolium(MTT) method. RESULT: GLX production was reduced significantly from 28.0 +/- 8.1 micrograms/ml at 0MIC to 21.8 +/- 8.2 micrograms/ml at 1/16MIC and 16.7 +/- 7.9 micrograms/ml at 1/4MIC respectively (P = 0.0002). 1/16MIC and 1/4MIC AZT showed no bactericidal activities to P. Aeruginosa in biofilms. Viable counts in biofilms were 6.2 +/- 0.61 Lg/cm2 at 0MIC, 6.1 +/- 0.4 Lg/cm2 at 1/16MIC and 6.2 +/- 0.4 Lg CFU/cm2 at 1/4 MIC respectively (P = 0.63). However, AZT could enhance bactericidal activity of FLX on P. aeruginosa in biofilms. When 1/4MIC FLX was combined with 1/16MIC and 1/4 MIC AZT, viable counts were reduced significantly from 6.1 +/- 0.5 Lg CFU/cm2 to 5.9 +/- 0.3 Lg CFU/cm2 and 5.8 +/- 0.4 Lg CFU/cm2 respectively (P = 0.02). When 1/2MIC FLX was combined with 1/16MIC and 1/4MICAZT, viable counts were reduced significantly from 6.3 +/- 0.7 Lg CFU/cm2 to 5.8 +/- 0.5 LgCFU/cm2 and 5.7 +/- 0.6 Lg CFU/cm2 respectively (P = 0.03). CONCLUSION: Because AZT did not have direct bactericidal activities on P. aeruginosa in biofilms but could inhibit GLX production, We considered that AZT could enhance antibacterial activities of FLX by enhancing permeability of FLX into biofilms.

Anti-Bacterial Agents↗
PubMed1995

[Pharmacokinetic and clinical studies with azithromycin (fine granule) in the pediatric field. Pediatric Study Group of Azithromycin].

Azithromycin (AZM) in 10% fine granules, a newly developed azalide antibiotic, was administered at a standard dose of 10 mg/kg once daily for 3 to 5 days (89.5% received 3 day administration) to children with infectious diseases and the efficacy and the safety of AZM were investigated. In addition AZM concentrations were determined in blood samples from 18 patients and in urine samples from 17 patients to examine o pharmacokinetic characteristics of AZM. 1. Absorption and excretion: Cmax's in 16 patients who received 10 mg/kg and 2 patients who received 20 mg/kg were 0.29 +/- 0.24 micrograms/ml and 0.75 micrograms/ml, respectively, while T 1/2's were 42.0 +/- 11.8 hours for the former and 51.3 hours for the latter. AUC(0 to approximately infinity)'s were 10.72 +/- 5.00 micrograms x hr/ml in the former and 28.83 micrograms x hr/ml in the latter. Urinary concentrations of AZM peaked at 48 to 72 hours after the administration of 10 mg/kg AZM in 14 patients, while it peaked at 24 to 48 hours in the patients who received 20 mg/kg. Urinary recovery rates in the first 120 hours after the start were 9.1 +/- 2.6% for 10 mg/kg and 10.8 +/- 3.4% for 20mg/kg. 2. Clinical efficacy: The study received 619 entries and 564 cases were evaluated for drug efficacy. The remaining were not evaluated because of dropout or exclusion. The efficacy rate, combining both "Excellent" and "Good" cases was 94.3% in 246 cases where pathogens were identified, classified as Group A. The efficacy rate was 90.7% for the remaining 321 cases, classified as Group B, where causative pathogens were unidentified. The difference between the two groups was no statistical significance. The combined efficacy rate was 92.2%. For the 116 cases where the patients had failed to respond to previous chemotherapies instituted for 3 days or longer, the efficacy rate for AZM was 94.0%. 3. Adverse reactions and abnormal laboratory tests: Incidents of diarrhea, soft stool, skin rashes, or vomiting were found in 15 patients (2.5%) of 596 cases eligible for evaluation. These reactions, however, were all transient and mild to moderate in severity in the 15 patients including 4 patients for whom the treatment was discontinued, all resolved in time. Abnormal changes in laboratory tests were found as follows: decrease in WBC in 23 patients (5.6%), increase in eosinophils in 28 (7.1%), increase in platelet count in 2 (0.5%), decrease in platelet count in 1 (0.3%), elevation of GOT in 3 (0.8%), and elevation of GPT in 6 (1.6%).(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗
PubMed1995

[Pharmacokinetic and clinical studies with azithromycin (capsule) in the pediatric field. Pediatric Study Group of Azithromycin].

Azithromycin (AZM) in 100 mg capsules, a newly developed azalide antibiotic, was administered at a standard dose of 10 mg/kg once daily for 3 to 5 days (89.9% received 3 day administration) to children with infectious diseases and the efficacy and the safety of AZM were investigated. In addition, AZM concentrations were determined in blood samples from 9 patients and in urine samples from 12 patients to examine pharmacokinetic characteristics of AZM. 1. Absorption and excretion: Cmax was 0.45 +/- 0.28 micrograms/ml, T 1/2 was 52.7 +/- 20.2 hours, and AUC(0 approximately to infinity) was 12.09 +/- 4.93 micrograms.hr/ml in the 9 patients each of whom received 8.5 to 14.3 mg/kg AZM. Urinary concentrations of AZM peaked at 48 to 72 hours after the administration of 8.5 to 14.7 mg/kg AZM in 12 patients and the average urinary recovery rate in 120 hours was 7.3 +/- 2.8%. 2. Clinical efficacy: The study received 139 entries and 119 cases were evaluated for drug efficacy. The remaining were not evaluated because of dropout or exclusion. The efficacy rate combining both "Excellent" and "Good" cases, was 100% for 40 cases in which pathogens were identified, classified as Group A. The efficacy rate was 97.5% for the remaining 79 cases, classified as Group B, where causative pathogens were unidentified. The difference between the two groups was no statistical significance. The combined efficacy rate was 98.3%. For the 31 cases where the patients had failed to respond to the previous chemotherapies instituted for 3 days or longer, the efficacy rate for AZM was 93.5%. 3. Adverse reactions and abnormal laboratory tests: 8 incidents of diarrhea, skin rashes, urticaria, or vomiting were found in 7 patients (5.4%) of 130 cases eligible for evaluation. These reactions, however, were all transient and mild to moderate in severity in the 7 patients including 2 patients for whom the treatment was discontinued, all resolved in time. Abnormal changes in laboratory tests were found as follows: decrease in WBC in 10 patients (9.3%), an increase in eosinophils in 12 (11.4%), an increase in platelet count in 1 (1.0%), an elevation of GOT in 3 (3.1%), an elevation of GPT in 6 (6.2%), and an elevation of LDH in 1 (1.1%). The abnormalities were transient and did not require particular intervention. Moreover, none of the patients indicated clinical signs associated with the abnormal changes of laboratory tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed2003

Azithromycin metabolite identification in plasma, bile, and tissues of the ball python (Python regius).

Azithromycin is the first of a class of antibiotics classified as azalides. Six ball pythons (Python regius) were given a single dose of azithromycin at 10 mg/kg p.o. and i.v. in a crossover design. Serial blood samples were collected for unchanged azithromycin and to determine, if possible, the structure and number of circulating azithromycin metabolites. After a 4-month wash-out period, the snakes were given azithromycin p.o. as a single dose of 10 mg/kg for the study of azithromycin metabolism and metabolite tissue distribution. Bile, liver, lung, kidney, and skin samples were analyzed for the metabolites identified from the first experiment. Unchanged azithromycin accounted for 80, 68, and 60% of the total material at 12, 24, and 48 h postadministration in plasma, independent of route of administration. At both 24 and 72 h postadministration, azithromycin accounted for 70% of total azithromycin- associated material in bile. In liver and kidney, unchanged azithromycin accounted for 40% of the total azithromycin-associated material; this doubled in lung and skin. Fifteen metabolites were positively or tentatively identified in plasma, bile, or tissues of all snakes. Four of these possible metabolites: 3'-desamine-3-ene-azithromycin, descladinose dehydroxy-2-ene-azithromycin, 3'-desamine-3-ene descladinose-azithromycin, and 3'-N-nitroso,9a-N-desmethyl-azithromycin are unique to this species. Descladinose-azithromycin, 3'-N-desmethyl,9a-N-desmethyl-azithromycin, and 3'-N-desmethyl, 3'-O-desmethyl-azithromycin were the only metabolites identified in skin. Kidney tissue contained a greater number of metabolites than liver tissue, with 3'-N-didesmethyl-azithromycin being identified only in the kidney. Compared with the dog and cat, a greater number of metabolites were identified in ball python plasma. The percentage of unchanged azithromycin in bile is not different between the three species.

Administration, Oral↗
PubMed1992

Azithromycin. A review of its antimicrobial activity, pharmacokinetic properties and clinical efficacy.

Azithromycin is an acid stable orally administered macrolide antimicrobial drug, structurally related to erythromycin, with a similar spectrum of antimicrobial activity. Azithromycin is marginally less active than erythromycin in vitro against Gram-positive organisms, although this is of doubtful clinical significance as susceptibility concentrations fall within the range of achievable tissue azithromycin concentrations. In contrast, azithromycin appears to be more active than erythromycin against many Gram-negative pathogens and several other pathogens, notably Haemophilus influenzae, H. parainfluenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, Urea-plasma urealyticum and Borrelia burgdorferi. Like erythromycin and other macrolides, the activity of azithromycin is unaffected by the production of beta-lactamase. However, erythromycin-resistant organisms are also resistant to azithromycin. Following oral administration, serum concentrations of azithromycin are lower than those of erythromycin, but this reflects the rapid and extensive movement of the drug from the circulation into intracellular compartments resulting in tissue concentrations exceeding those commonly seen with erythromycin. Azithromycin is subsequently slowly released, reflecting its long terminal phase elimination half-life relative to that of erythromycin. These factors allow for a single dose or single daily dose regimen in most infections, with the potential for increased compliance among outpatients where a more frequent antimicrobial regimen might traditionally be indicated. The potential disadvantage of low azithromycin serum concentrations, however, is that breakthrough bacteraemia may occur in patients who are severely ill; nevertheless, animal studies suggest that tissue concentrations of azithromycin are more important than those in serum when treating respiratory and other infections. The clinical efficacy of azithromycin has been confirmed in the treatment of infections of the lower and upper respiratory tracts (the latter including paediatric patients), skin and soft tissues (again including paediatric patients), in uncomplicated urethritis/cervicitis associated with N. gonorrhoeae, Chlamydia trachomatis or U. urealyticum and in the treatment of early Lyme disease. Azithromycin was as effective as erythromycin and other commonly used drugs including clarithromycin, beta-lactams (penicillins and cephalosporins), and quinolone and tetracycline antibiotics in some of the above infections. Some patients with acute exacerbations of chronic bronchitis due to H. influenzae may be refractory to therapy with azithromycin (as is the case with erythromycin) indicating the need for physician vigilance, although it should be noted that azithromycin is of equivalent efficacy to amoxicillin in the treatment of such patients. In the therapy of urethritis/cervicitis associated with C. trachomatis, N. gonorrhoea or U. urealyticum, a single dose azithromycin regimen offers a distinct advantage over currently available pharmacological options, while providing effective therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2001

Pharmacokinetic and safety profile of desloratadine and fexofenadine when coadministered with azithromycin: a randomized, placebo-controlled, parallel-group study.

BACKGROUND: Significant cardiac toxicity has been associated with some older antihistamines (eg, terfenadine and astemizole) when their plasma concentrations are increased. There is thus a need for a thorough assessment of the cardiac safety of newer antihistamine compounds. OBJECTIVE: This study was undertaken to assess the effects of coadministration of desloratadine or fexofenadine with azithromycin on pharmacokinetic parameters, tolerability, and electrocardiographic (ECG) findings. METHODS: Healthy volunteers aged 19 to 46 years participated in this randomized, placebo-controlled, parallel-group, third-party-blind, multiple-dose study. Subjects received desloratadine 5 mg once daily, fexofenadine 60 mg twice daily, or placebo for 7 days. An azithromycin loading dose (500 mg) followed by azithromycin 250 mg once daily for 4 days was administered concomitantly starting on day 3. Group 1 received desloratadine and azithromycin, group 2 received desloratadine and placebo, group 3 received placebo and azithromycin, group 4 received fexofenadine and azithromycin, and group 5 received fexofenadine and placebo. RESULTS: The results of the pharmacokinetic analysis revealed little change in mean maximum concentration (Cmax) and area under the concentration-time curve (AUC) values for desloratadine with concomitant administration of azithromycin: Cmax ratio, 115% (90% CI, 92-144); AUC, ratio 105% (90% CI, 82-134). The corresponding ratios for 3-hydroxydesloratadine were 115% (90% CI, 98-136) and 104% (90% CI, 88-122), respectively. A substantial increase was observed in mean Cmax and AUC values for fexofenadine when administered with azithromycin: Cmax, ratio, 169% (90% CI, 120-237); AUC ratio, 167% (90% CI, 122-229). Compared with the group receiving desloratadine and azithromycin, subjects receiving fexofenadine and azithromycin also displayed greater variability in pharmacokinetic parameters for the antihistamine. Mean Cmax and AUC values of azithromycin were slightly higher when administered with desloratadine (Cmax ratio, 131% [90% CI, 92-187]; AUC ratio, 112% [90% CI, 83-153]) but were lower when given in combination with fexofenadine (Cmax ratio, 87% [90% CI, 61-124]; AUC ratio, 88% [90% CI, 65-1201). The most common adverse event for all regimens was headache, reported in 20 (22%) subjects. All combinations of desloratadine or fexofenadine with and without azithromycin were well tolerated, and no statistically significant changes in PR, QT, or QT, interval, QRS complex, or ventricular rate were observed. CONCLUSIONS: Small increases (<15%) in mean pharmacokinetics of desloratadine were observed with coadministration of azithromycin. By contrast, peak fexofenadine concentrations were increased by 69% and the AUC was increased by 67% in the presence of the azalide antibiotic. Based on the reported adverse-events profile and the absence of changes in ECG parameters, the combination of desloratadine and azithromycin was well tolerated. This study suggests that desloratadine has a more favorable drug-interaction potential than does fexofenadine.

Adolescent↗
PubMed2004

A topical azithromycin preparation for the treatment of acne vulgaris and rosacea.

BACKGROUND: Erythromycin is a common therapy for acne and rosacea. A newer macrolide, azithromycin, offers superior tissue distribution and cellular concentration and is an effective oral anti-acne agent. Topical formulations such as erythromycin have been a major clinical therapy for acne. To date, no topical solution of azithromycin is available for the treatment of acne. OBJECTIVE: To prepare a stable topical 2% azithromycin formulation that could be used in an acne clinical trial to determine the efficacy of topical azithromycin in treating subjects with acne vulgaris and acne rosacea. METHODS: The study was divided into two phases. In phase I, azithromycin was prepared over a range of ethanol/water concentrations to determine solubility. The stability of a 2% azithromycin in 60% ethanol/water preparation was assessed by high-pressure liquid chromatography. The temperature, light, and pH dependence of the stability was also assessed. In phase II, a single center, randomized, double-blind, treatment-controlled study compared once-nightly application of topical 2% azithromycin versus 2% erythromycin. A total of 20 subjects with moderate inflammatory acne and 20 with rosacea were examined clinically at 0, 2, 4, 8, and 12 weeks for a 12-week period. Efficacy was evaluated with the Physician's Visual Analog Scale evaluation (PVAS), the papulopustule count, and acne severity rating (in subjects with acne). RESULTS: In phase I, azithromycin was soluble in 60% ethanol/water. A 2% azithromycin in 60% ethanol/water solution maintained stability at room temperature for up to 26 weeks but at 37 degrees C there was some decay (16%) at 26 weeks. The stability was greatest at pH 6.8 and was unaffected by ambient light exposure. In phase II, the number of inflammatory lesions decreased in both acne and rosacea subjects treated with 2% erythromycin (7.56, p=0.03 and 4.4, p=0.01, respectively). Azithromycin was not as effective for the treatment of rosacea. Both azithromycin (p=0.01) and erythromycin (p=0.03) treatment significantly reduced the inflammatory lesion count in acne vulgaris. No significant adverse events were identified in the acne group. In patients with rosacea, transient irritation occurred in five patients. CONCLUSIONS: A 2% azithromycin in 60% ethanol/water solution can be prepared and is stable for at least 6 months at room temperature. The methodology and power of the study were adequate to identify improvement in acne vulgaris and rosacea. Though it appears the formulation of topical azithromycin was at least comparable with topical erythromycin, larger studies would be needed to determine whether topical azithromycin has any significant advantage over topical erythromycin.

Acne Vulgaris↗
PubMed1992

Azithromycin: the first azalide antibiotic.

OBJECTIVE: To discuss the chemistry, mechanism of action, spectrum of activity, pharmacokinetics, clinical trials, adverse-effect profile, drug interactions, and dosage guidelines of azithromycin, the first azalide antibiotic. DATA SOURCES: Pertinent literature published between 1988 and the present was identified via a MEDLINE search. Of 77 articles retrieved, 37 have been referenced. STUDY SELECTION: Azithromycin is a new agent, and as such, limited data regarding this drug are available in the literature. We evaluated all pharmacokinetic, microbiologic, and basic science articles pertaining to azithromycin, and reviewed the clinical efficacy trials that we believed were of good quality for each indication for which azithromycin has received approval to date. Comparative clinical trials involving large numbers of patients, clinical outcome assessments, and recommendations for azithromycin use are included. DATA SYNTHESIS: Azithromycin is a macrolide derivative and the first of the 15-membered ring azalide class of antimicrobials. Although its mechanism of action and susceptibility to resistance are similar to those of the macrolide antibiotics, azithromycin's extended spectrum of activity includes gram-positive and gram-negative organisms, as well as atypical pathogens. Azithromycin is stable at gastric pH and has an absolute bioavailability of approximately 37 percent following oral administration. Although its serum concentrations are typically low, the drug concentrates to a high degree in tissue. Azithromycin is cleared primarily by the biliary and fecal routes; its serum half-life is in excess of 60 hours. Several clinical trials have proven that a 5-day course of azithromycin administered once a day is equally efficacious to a 7- to 14-day course of other commonly used oral antimicrobials, administered two to four times a day, for the treatment of upper and lower respiratory tract and skin and skin-structure infections. Urethritis and cervicitis caused by chlamydia are treated with a single 1-g dose. Trials have shown azithromycin's adverse-effect profile to be equal or even superior to that of other agents, with only 0.7 percent of patients discontinuing therapy versus 2.6 percent for comparable drugs. CONCLUSIONS: Azithromycin represents a significant improvement in the treatment of selected community-acquired infections. Although this agent may revolutionize the treatment of sexually transmitted diseases caused by chlamydia, it also should impact the management of respiratory tract and skin and skin-structure infections. Because of its unique pharmacokinetics and excellent adverse-effect profile, patient compliance should be greatly enhanced compared with other commonly used oral antimicrobials. Azithromycin's primary role in the near future will be in the community setting. Although its use in the hospital may be limited, this drug will be a convenient therapeutic option to have on hand in the emergency room and outpatient clinic. Azithromycin may also be used in the future to treat opportunistic infections in immunocompromised patients.

Azithromycin↗
PubMed2004

Possible involvement of the drug transporters P glycoprotein and multidrug resistance-associated protein Mrp2 in disposition of azithromycin.

P glycoprotein and multidrug resistance-associated protein 2 (Mrp2), ATP-dependent membrane transporters, exist in a variety of normal tissues and play important roles in the disposition of various drugs. The present study seeks to clarify the contribution of P glycoprotein and/or Mrp2 to the disposition of azithromycin in rats. The disappearance of azithromycin from plasma after intravenous administration was significantly delayed in rats treated with intravenous injection of cyclosporine, a P-glycoprotein inhibitor, but was normal in rats pretreated with intraperitoneal injection erythromycin, a CYP3A4 inhibitor. When rats received an infusion of azithromycin, cyclosporine and probenecid, a validated Mrp2 inhibitor, significantly decreased the steady-state biliary clearance of azithromycin to 5 and 40% of the corresponding control values, respectively. However, both inhibitors did not alter the renal clearance of azithromycin, suggesting the lack of renal tubular secretion of azithromycin. Tissue distribution experiments showed that azithromycin is distributed largely into the liver, kidney, and lung, whereas both inhibitors did not alter the tissue-to-plasma concentration ratio of azithromycin. Significant reduction in the biliary excretion of azithromycin was observed in Eisai hyperbilirubinemic rats, which have a hereditary deficiency in Mrp2. An in situ closed-loop experiment showed that azithromycin was excreted from the blood into the gut lumen, and the intestinal clearance of azithromycin was significantly decreased by the presence of cyclosporine in the loop. These results suggest that azithromycin is a substrate for both P glycoprotein and Mrp2 and that the biliary and intestinal excretion of azithromycin is mediated via these two drug transporters.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Azithromycin is as effective as and better tolerated than erythromycin estolate for the treatment of pertussis.

OBJECTIVE: Although universal immunization against Bordetella pertussis (whooping cough) infection has resulted in dramatic reductions in the incidence of pertussis, outbreaks continue to occur in countries with excellent vaccine coverage. Treatment of infection may ameliorate symptom severity during the catarrhal phase of pertussis but has no effect on established paroxysms, emesis, or apnea if given during the paroxysmal or convalescent phases. Erythromycin, recommended for treatment of pertussis to prevent transmission of infection, is poorly tolerated because of gastrointestinal side effects. We compared the safety and efficacy of erythromycin with azithromycin for treatment of pertussis in a large, randomized, controlled trial that enrolled children from primary care practices in 1 American and 11 Canadian urban centers. METHODS: Children who were 6 months to 16 years of age and had cough illness that was suspected to be or was culture confirmed as pertussis were randomized to azithromycin (10 mg/kg on day 1 and 5 mg/kg on days 2-5 as a single dose) or erythromycin estolate (40 mg/kg/day in 3 divided doses for 10 days) with stratification by center. The primary outcome measure was bacteriologic cure of infection as determined by cultures of nasopharyngeal aspirates. Culture-positive participants had a second aspirate collected at the end of therapy (days 5-7 for azithromycin, days 10-12 for erythromycin) and 1 week after therapy. Bacteriologic cure was defined as negative cultures at the end of therapy. Bacteriologic relapse was defined as a positive culture 1 week after completion of therapy and after a negative end-of-therapy culture. Secondary outcomes were pertussis diagnosed by serology and polymerase chain reaction (PCR), treatment-associated adverse events, compliance, and presence of clinical symptoms at the end of the treatment course. Serology was performed using standard enzyme-linked immunosorbent assay methods. A participant was considered to have pertussis when the PCR was positive or a 4-fold increase in pertussis toxin antibody between baseline and follow-up visits was observed. PCR was performed using a 1046-bp ClaI DNA fragment from B pertussis. Adverse events (nausea, vomiting, diarrhea, any gastrointestinal complaint, or other) were determined by a parent-completed diary that was reviewed with study personnel during study visits. Compliance was measured by review of the parent medication diary during study visits and observation of medication containers by the pharmacist at study completion. Symptoms were determined by history collected by study personnel at enrollment and subsequently from the diary. The design of the study was an equivalence trial, aimed at demonstrating that the bacteriologic failure rates with the 2 therapies did not differ by >8%. For the safety analysis, all participants who received at least 1 dose of study drug were included. In the per-protocol efficacy analysis, all culture-positive participants with end-of-treatment cultures were considered. RESULTS: A total of 477 children were enrolled and randomly assigned to either azithromycin (n = 239) or erythromycin (n = 238). Of these children, 114 (24%) grew B pertussis from nasopharyngeal specimens (azithromycin group: 58 of 239 [24%]; erythromycin group: 56 of 238 [23%]); these children composed the efficacy cohort for the per-protocol and intention-to-treat analyses. Serology and PCR added 52 children to the number considered to have pertussis for a total of 35% (166 of 477) of all children who presented with cough illness. In the safety analysis (antibiotic side effects, compliance) and comparison of cough symptoms after treatment, all randomized children are reported in their assigned treatment group. At end of therapy, bacterial eradication was demonstrated in all 53 patients in the azithromycin group and all 53 patients in the erythromycin group with follow-up cultures available (eradication 100%; 95% confidence interval [CI]: 93.3-100). No bacterial recurrence was demonstrated in children with 1 week posttreatment nasopharyngeal cultures available (51 and 53 participants in the azithromycin and erythromycin arms, respectively [0%, 95% CI: 0-7.0; and 0%, 95% CI: 0-6.7]). No serious adverse events attributable to study drug were observed. Gastrointestinal adverse events were reported less frequently in azithromycin (18.8%; 45 of 239) than in erythromycin estolate (41.2%; 98 of 238) recipients (90% CI on difference: -29.0% to -15.7%) as a result of less nausea (2.9% vs 8.4%; 95% CI: -8.9% to -2.0%), less vomiting (5.0% vs 13.0%; 95% CI: -4.9% to -1.4%), and less diarrhea (7.1% vs 11.8%; 95% CI: -9.0% to -0.3%). Children who were randomized to azithromycin were much more likely to have complied with antimicrobial therapy over the treatment period. In the azithromycin group, 90% of children took 100% of prescribed doses, whereas only 55% of children in the erythromycin group took 100% of prescribed doses. CONCLUSIONS: In this large, multicenter, randomized trial, we found that azithromycin is as effective as erythromycin estolate for the treatment of pertussis in children. Gastrointestinal adverse events were much more common with erythromycin treatment than azithromycin. Compliance with therapy was markedly better with azithromycin than with erythromycin in this study.

Adolescent↗
PubMed1998

Azithromycin. A review of its use in paediatric infectious diseases.

UNLABELLED: Azithromycin is an azalide antimicrobial agent active in vitro against major pathogens responsible for infections of the respiratory tract, skin and soft tissues in children. Pathogens that are generally susceptible to azithromycin include Haemophilus influenzae (including ampicillin-resistant strains), Moraxella catarrhalis, Chlamydia pneumoniae, Chlamydia trachomatis, Mycoplasma pneumoniae, Legionella spp., Streptococcus pyogenes and Streptococcus agalactiae. Azithromycin is also generally active against erythromycin- and penicillin-susceptible Streptococcus pneumoniae and methicillin-susceptible Staphylococcus aureus. Azithromycin is administered once daily, achieves clinically relevant concentrations at sites of infection, is slowly eliminated from the body and has few drug interactions. In children, azithromycin is usually given as either a 3-day course of 10 mg/kg/day or a 5-day course with 10 mg/kg on the first day, followed by 5 mg/kg/day for a further 4 days. These standard regimens were as effective as amoxicillin/clavulanic acid, clarithromycin, cefaclor and amoxicillin in the treatment of children with otitis media. Azithromycin was also as effective as either phenoxymethylpenicillin (penicillin V), erythromycin, clarithromycin or cefaclor against streptococcal pharyngitis or tonsillitis in children, but appears to result in more recurrence of infection than phenoxymethylpenicillin in this indication, necessitating a dosage of 12 mg/kg/day for 5 days. Community-acquired pneumonia, bronchitis and other respiratory tract infections in children responded as well to azithromycin as to amoxicillin/clavulanic acid, cefaclor, erythromycin or josamycin. Azithromycin was similar or superior to ceftibuten in mixed general practice populations of patients. However, symptoms of lower respiratory tract infections resolved more rapidly with azithromycin than with erythromycin, josamycin or cefaclor. Skin and soft tissue infections responded as well to azithromycin as to cefaclor, dicloxacillin or flucloxacillin, and oral azithromycin was as effective as ocular tetracycline in treating trachoma. Although not as well tolerated as phenoxymethylpenicillin in the treatment of streptococcal pharyngitis, azithromycin is at least as well tolerated as most other agents used to treat respiratory tract and other infections in children and was better tolerated than amoxicillin/clavulanic acid. Adverse events that do occur are mostly gastrointestinal and tend to be mild to moderate in severity. CONCLUSIONS: Azithromycin is an effective and well tolerated alternative to first-line agents in the treatment of respiratory tract, skin and soft tissue infections in children, offerring the convenience of a short, once-daily regimen.

Anti-Bacterial Agents↗
PubMed2003

Maternal and transplacental pharmacokinetics of azithromycin.

OBJECTIVE: The purpose of this study was to characterize the pharmacokinetics of orally administered azithromycin in the term gravid woman. STUDY DESIGN: Twenty women who were scheduled for elective cesarean delivery were enrolled prospectively and received 1 g of oral azithromycin at either 6, 12, 24, 72, or 168 hours before the operation. All women received spinal anesthesia, at which time a sample of cerebrospinal fluid was obtained for analysis. Maternal serum and urine were obtained immediately before the operation. Intraoperatively, samples of myometrium, maternal adipose tissue, placenta, amniotic fluid, and umbilical arterial and venous cord blood were obtained. Azithromycin levels were determined quantitatively with high-pressure liquid chromatography with electrochemical detection. RESULTS: All participants tolerated the preoperative azithromycin without significant adverse reactions. Peak maternal serum azithromycin levels occurred within 6 hours of drug administration. Although high serum levels of azithromycin were reached early, a rapid decline in drug concentration was noted over the initial 24 hours after the drug administration (6-hour: 311 ng/mL; 24-hour: 63 ng/mL). In contrast, azithromycin levels in myometrial, adipose, and placental tissue were higher (>500 ng/mL) and sustained for up to 72 hours after administration. High urine levels of azithromycin (>5000 ng/mL) were noted similarly during the initial 72 hours after drug administration. Umbilical arterial and venous serum azithromycin levels were low (19-38 ng/mL) during the first 72 hours. Amniotic fluid levels were highest at 6 hours (151 ng/mL) and declined rapidly. Maternal cerebrospinal azithromycin concentrations were undetectable for all time points. CONCLUSION: Azithromycin has a rapid serum half-life in the term gravid woman with a prolonged half-life and high-sustained antibiotic levels noted within myometrium, adipose, and placental tissue. Given the broad antimicrobial spectrum and placental penetration, azithromycin may have potential use for the treatment of perinatal infections.

Adipose Tissue↗
PubMed2005

Azithromycin-resistant syphilis infection: San Francisco, California, 2000-2004.

BACKGROUND: The incidence of syphilis has been increasing in the United States since reaching a nadir in 2000. Several clinical trials have demonstrated that treatment with oral azithromycin may be useful for syphilis control. After reports of azithromycin treatment failures in San Francisco, we investigated the clinical and epidemiologic characteristics of patients with syphilis due to azithromycin-resistant Treponema pallidum infection. METHODS: We reviewed city-wide case reports and conducted molecular screening for patients seen at the San Francisco metropolitan STD clinic (San Francisco City Clinic) to identify patients who did not respond to azithromycin treatment for syphilis or who were infected with azithromycin-resistant T. pallidum. We conducted an epidemiologic investigation and retrospective case-control study to identify risk factors for acquiring syphilis due to azithromycin-resistant T. pallidum. RESULTS: From January 2000 through December 2004, molecular screening of 124 samples identified 46 azithromycin-resistant T. pallidum isolates and 72 wild-type T. pallidum isolates. Six instances of treatment failure were identified through record review. In total, we identified 52 case patients (one of whom had 2 episodes) and 72 control patients. All case patients were male and either gay or bisexual, and 31% (16 of 52) were infected with human immunodeficiency virus. Investigation of patient-partner links and a retrospective case-control study did not reveal a sexual network or demographic differences between cases and controls. However, 7 case patients had recently used azithromycin, compared with 1 control patient. Surveillance data demonstrated that azithromycin-resistant T. pallidum prevalence increased from 0% in 2000 to 56% in 2004 among syphilis cases observed at the San Francisco City Clinic. CONCLUSIONS: Azithromycin-resistant T. pallidum is widespread in San Francisco. We recommend against using azithromycin for the management of syphilis in communities where macrolide-resistant T. pallidum is present and recommend active surveillance for resistance in sites where azithromycin is used.

Anti-Bacterial Agents↗
PubMed2003

Comparative randomized trial of azithromycin versus erythromycin and amoxicillin for treatment of community-acquired pneumonia in children.

Our objective was to compare the clinical efficacy of azithromycin vs. erythromycin and amoxicillin in the treatment of presumed bacterial community-acquired pneumonia in ambulatory children, and to evaluate the etiologies of these illnesses. One hundred and ten children, aged 1 month to 14 years, were enrolled between January 1996-January 1999. Children were distributed into two groups according to clinical and radiological patterns: classic or atypical pneumonia. Patients with classic pneumonia were randomly assigned to receive oral amoxicillin 75 mg/kg/day for 7 days, or azithromycin 10 mg/kg/day for 3 days; patients with atypical pneumonia received azithromycin 10 mg/kg/day for 3 days, or erythromycin 50 mg/kg/day for 14 days. Chest X-ray, clinical, and laboratory parameters were obtained on enrollment. Clinic visits were performed on days 3, 7, and 14, and chest X-ray follow-up on days 7 and 14. Microbiological diagnosis of classic pathogens was based on blood and bronchial secretion cultures. The diagnosis of atypical pathogens C. pneumoniae, C. trachomatis, and M. pneumoniae was based on PCR and serologic tests.Forty-seven children met the criteria for classic pneumonia (23 children received azithromycin, and 24 received amoxicillin), and 59 children had atypical pneumonia (33 children were treated with azithromycin, and 26 with erythromycin). Demographic characteristics at enrollment were similar between children with classic pneumonia treated with azithromycin and erythromycin and children treated with azithromycin and erythromycin for atypical pneumonia. However, on day 7, children with classic pneumonia who received azithromycin normalized their chest X-ray more often than those who received amoxicillin (81.0% vs. 60.9%, respectively, P = 0.009). The same was true for children with atypical pneumonia; their chest X-rays had normalized by day 14 (100% in those with azithromycin vs. 81% in those with erythromycin, P = 0.059). Also, children with atypical pneumonia treated with azithromycin had earlier cessation of cough than children treated with erythromycin (3.6 +/- 1.9 vs. 5.5 +/- 3.6 days respectively, P = 0.02). There were only three children with side effects (mild diarrhea, all in the erythromycin group). Etiological agents were identified in 41% of children. In conclusion, azithromycin is an effective therapeutic option for the treatment of community-acquired classic and atypical pneumonia in children.

Adolescent↗
PubMed1991

Lack of emergence of significant resistance in vitro and in vivo to the new azalide antibiotic azithromycin.

In vitro experiments were performed in which 6 to 12 strains of Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae and Enterobacteriaceae were passaged nine times in sub-lethal concentrations of azithromycin or control antibiotics. Streptococcus pyogenes and Staphylococcus aureus quickly became resistant to rifampin as the MIC90 increased from 0.1 to greater than 50 micrograms/ml for both species. The MIC90 of azithromycin, erythromycin, amoxicillin and cefaclor increased by three dilutions for Staphylococcus aureus. The MIC values of azithromycin for Streptococcus pyogenes, Haemophilus influenzae and Enterobacteriaceae strains did not change significantly. However, for Haemophilus influenzae and the Enterobacteriaceae strains, the MIC values of erythromycin and oral cephalosporins increased four-fold. In the in vivo experiments, mice infected with Staphylococcus aureus or Escherichia coli contaminated sutures were administered azithromycin for three days, and on day 6 viable bacterial cells were recovered from the infection site. The sustained tissue concentrations of azithromycin indicated that the organisms would have been continuously exposed to azithromycin at the site of infection. Colonies isolated from azithromycin-treated and non-treated mice were cultured and their susceptibility to azithromycin compared. The azithromycin MIC values for Staphylococcus aureus cultures from treated and non-treated animals were identical. The azithromycin MICs for Escherichia coli recovered from treated animals were on average, less than one dilution higher than for control cultures. Emergence of significant resistance to azithromycin in the laboratory was not observed with the pathogens tested.

Animals↗
PubMed2006

Activity of azithromycin or erythromycin in combination with antimalarial drugs against multidrug-resistant Plasmodium falciparum in vitro.

Azithromycin, an azalide analog of erythromycin was assayed for its in vitro activity against multidrug-resistant Plasmodium falciparum K1 strain by measuring the 3H-hypoxanthine incorporation. Azithromycin caused inhibitory effects on the parasite growth with IC50 and IC90 values of 8.4+/-1.2 microM and 26.0+/-0.9 microM, respectively. Erythromycin inhibited growth of P. falciparum with IC50 and IC90 values of 58.2+/-7.7 microM and 104.0+/-10.8 microM, respectively. The activity of antimalarial drugs in combination with azithromycin or erythromycin against P. falciparum K1 were compared. Combinations of chloroquine with azithromycin or erythromycin showed synergistic effects against parasite growth in vitro. Combinations of quinine-azithromycin and quinine-erythromycin showed potentiation. Additive effects were observed in mefloquine-azithromycin and mefloquine-erythromycin combinations. Similar results were also produced by pyronaridine in combination with azithromycin or erythromycin. However, artesunate-azithromycin and artesunate-erythromycin combinations had antagonistic effects. The in vitro data suggest that azithromycin and erythromycin will have clinical utility in combination with chloroquine and quinine. The worldwide spread of chloroquine-resistant P. falciparum might inhibit the ability to treat malaria patients with chloroquine-azithromycin and chloroquine-erythromycin in areas of drug-resistant. The best drug combinations against multidrug-resistant P. falciparum are quinine-azithromycin and quinine-erythromycin.

Animals↗