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PubMed1994

Evaluation of lung tissue and hilar lymph node concentrations of azithromycin.

Since it is believed that most infections occur in the interstitial fluid, it has been suggested to measure the concentration of antimicrobial agents in pulmonary lymph that reflects the extracellular, extra-blood-vascular milieu in the lung. The aim of this study was to investigate the lung tissue and pulmonary lymph node penetration of azithromycin after 500 mg daily oral administration for three days in patients undergoing open thoracotomy. At the end of the treatment, each subject was assigned for 5 groups of 5 patients each according to thoracotomy time after the last dose (24, 48, 96, 120 and 144 h). Azithromycin was assayed by an agar diffusion method with Sarcina lutea Z114 (DRH) used as the test organism and the Antibiotic Assay Medium 1, pH 8.5 used as the medium. All patients had a detectable concentration of azithromycin in serum 24 h after the last dose (72 h after the first dose); the concentration fell below the detection limit (0.01 mg/l-1) after 96 h (168 h after the first dose). Peak concentrations in lung tissue and lymph nodes were found after 48 h (96 h after the first dose). Tissue and lymph node concentrations of azithromycin were much greater than serum concentrations and these tissue and lymph node concentrations persisted after serum concentrations declined. The concentrations in lung tissue of azithromycin were always higher than corresponding concentrations in hilar lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMedDate not supplied

Single oral dose of azithromycin for therapy of susceptible sexually transmitted diseases: a multicenter open evaluation.

In three randomised, multicentre studies, azithromycin treatment (1g) as a single dose was administered to patients with uncomplicated gonococcal and non-gonococcal urethritis attending STD Research Laboratories in Lagos, Jos and Ibadan; between January 1989 and December, 1990. One hundred and eighty three patients, comprising 106 males and 77 females who had infections were evaluable at the end of the treatment. Of these 71% of the N. gonorrhoeae isolates were penicillinase producers (PPNG), while 39% were non-PPNG. One hundred and fourteen (95%) of 120 patients with gonococcal urethritis including 104 cases due to penicillinase producing Neiserria gonorrhoeae (PPNG) were clinically and bacteriologically cured with a single 1g dose of azithromycin. Fifty-four (90%) out of 60 patients with non-gonococcal urethritis were cured whilst administered the same dose of azithromycin. The side effects reported for azithromycin were mainly mild and moderate gastro-intestinal complaints and there were no major abnormalities in laboratory parameters. It is concluded that azithromycin was efficacious and safe for the treatment of uncomplicated gonococcal and non-gonococcal infections and may improve patient compliance.

Administration, Oral↗
PubMed1995

[Clinical pharmacokinetics of azithromycin].

The bioavailability of azithromycin is approximately 37%. Concomitant administration of oral azithromycin with food significantly decreases by 50% drug bioavailability. Following a single oral 500 mg dose, peak plasma concentrations of about 0.35-0.45 mg/l are attained within approximately 2 hours. With a 500 mg oral dose on day 1, followed by 250 mg daily on days 2 to 5, peak and through plasma concentrations on day 5 are around 0.25 and 0.05 mg/l respectively. These low plasma concentrations are the consequence of extensive and rapid distribution from plasma to tissues. Plasma protein binding is low, less than 50% at plasma concentrations obtained with the usual dosage regimen. Apparent volume of distribution is very large, 25 to 35 l/kg. Azithromycin is mainly eliminated unchanged in the faeces via biliary excretion and transintestinal secretion. Urinary excretion is a minor elimination route: about 6% and an oral dose and 12% of an intravenous dose are recovered unchanged in urine. The mean terminal elimination half-life of azithromycin is 2 to 4 days. The pharmacokinetics of azithromycin is not significantly altered in elderly subjects and in patients with mild to moderate renal or hepatic insufficiency.

Administration, Oral↗
PubMed1996

Azithromycin for the cure of Helicobacter pylori infection.

OBJECTIVES: Azithromycin, a new antibiotic chemically related to erythromycin, has been proposed for the cure of Helicobacter pylori, achieving high gastric tissue levels (above the MIC for H. pylori) after oral administration. The aim of the study was to establish whether azithromycin plus metronidazole in association with either omeprazole or bismuth subcitrate is useful in curing H. pylori infection of the stomach. PATIENTS AND METHODS: The study involved 132 dispeptic patients who proved to be H. pylori infected by antral and corpus histology (Giemsa, modified) and rapid urease test (CLOtest); the Sydney system was used to classify the gastritis. Sixty-three patients received bismuth subcitrate 120 mg q.i.d. for 14 days plus azithromycin 500 mg o.d. for the first 3 days plus metronidazole 250 mg q.i.d. for the first 7 days; 69 patients received omeprazole 40 mg for 14 days plus azithromycin 500 mg o.d. for the first 3 days plus metronidazole 250 mg q.i.d. for the first 7 days. Patients were well matched for common clinical variables. Cure of H. pylori infection was assessed by the same methods 2 months after completion of treatment. RESULTS: Eleven patients dropped out of the study, only one reporting side effects (nausea, vomiting, and epigastric pain). Cumulative "per protocol" cure rate was 66.1% (CI 95%, 58.5-75.3%). There was no statistically significant difference between the two treatment groups: 58.9% (CI 95% 48.4-74.6%) versus 72.3% (CI 95%, 60.7-82.5%). Intention to treat does not substantially modify results. Few side effects were recorded. Cured patients showed a significant reduction in the activity of gastritis. CONCLUSION: Azithromycin, combined with omeprazole and metronidazole, the cure rate of H. pylori was about 70%. The cure of H. pylori infection improves the activity of gastritis.

Adult↗
PubMed1996

[Exacerbation of pseudoparalytic myasthenia gravis following azithromycin (Zithromax)].

We report the case of a 25-year-old female patient with severe aggravation of myasthenia gravis due to azithromycin which was prescribed for an influenza syndrome. One hour after the intake of 500 mg azithromycin the patient developed weakness of the legs and respiratory distress due to respiratory muscle failure. She was hospitalized in a comatose state and required intubation and mechanical ventilation for six days. Acute worsening of myasthenia gravis was observed in this patient in 1986 after parenteral administration of erythromycin. Erythromycin causing aggravation of myasthenia gravis by interfering with neuromuscular transmission is reported in the literature. The close temporal relationship between the intake of azithromycin and severe worsening of myasthenia gravis in our patient suggests that azithromycin, a new azalid-antibiotic of the macrolid group, can exacerbate myasthenia gravis. We conclude that azithromycin should be added to the list of drugs to be used with caution in patients with myasthenia gravis.

Adult↗
PubMed1996

Influence of the antibiotics erythromycin and azithromycin on the pharmacokinetics and pharmacodynamics of midazolam.

The pharmacokinetic and pharmacodynamic interaction between azithromycin (CAS 83905-01-5), an azalide antibiotic, and midazolam (CAS 59467-70-8), a short-acting hypnotic agent, was investigated in an open, three-way cross-over study, including erythromycin (CAS 114-07-8) as a positive control. Twelve healthy male and female subjects had standard doses of azithromycin (500 mg o.d. over 3 days), or erythromycin (500 mg t.i.d. over 5 days), or no pretreatment. On the day of the last dose, they ingested 15 mg midazolam. Blood samples were collected and psychometric tests performed. Erythromycin pretreatment (E) significantly changed the pharmacokinetics of midazolam compared to control (C), whereas azithromycin (A) had no such effect. The parameters are summarized as follows: area under the concentration-time curve, AUC (C) 173.8 h.ng.ml-1 vs. (E) 662.7 h.ng.ml-1*+ and (A) 220.0 h.ng.ml-1; concentration maxima (C) 67.2 ng.ml-1 vs. (E) 182.3 ng.ml-1*+ and (A) 86.7 ng.ml-1; elimination half-life (C) 2.21 h vs. (E) 4.85 h* and (A) 2.41 h (* p < 0.05 vs. (C), +p < 0.05 vs. (A)). Pharmacodynamic tests (digit symbol substitution test; critical flicker fusion test; subjective analog scale for rating of alertness; duration of sleep) consistently showed significant differences after erythromycin pretreatment compared to control, but not after azithromycin. Erythromycin, but not azithromycin, causes clinically significant changes in the pharmacokinetics and pharmacodynamics of midazolam.

Adult↗
PubMedDate not supplied

[The postantibiotic effect of azithromycin on respiratory pathogens].

Azithromycin has in vitro activity which includes important respiratory pathogens and is successful in treatment of respiratory tract infections. We assessed postantibiotic effect (PAE) of azithromycin against 3 stains of Streptococcus pneumoniae, 2 strains of Haemophilus influenzae and 2 strains of Moraxella catarrhalis. The strains were exposed for 2 hours to an azithromycin concentration of 0.5 mg/L (maximum serum concentration achieved by azithromycin after the usual dosing regimen). A stationary phase inoculum of 1 x 10(6)-5 x 10(6) UFC/ml in IsoSensitest Broth with 5% lysed horse blood and 20 mg/L NAD was used and shaken for the duration of the experiment. Antibiotic was neutralised by dilution 1:1000 into pre-warmed medium. Viable counts were determined before and after antibiotic exposure and then hourly for 7 hours by Miles and Misra method. The experiment was performed in triplicate. Even at such low concentration as that achieved in serum, azithromycin exhibits a PAE of 119 min for pneumococci, 130 min for haemophili and 155 min for moraxellae, fact which could allow the use of usual oral regimen in bacteraemic respiratory infection, as well.

Anti-Bacterial Agents↗
PubMed1998

Comparison of azithromycin and clarithromycin in their interactions with rifabutin in healthy volunteers.

A 14-day, randomized, open, phase I clinical trial was designed to examine possible pharmacokinetic interactions between rifabutin and two other antibiotics, azithromycin and clarithromycin, used in the treatment of Mycobacterium avium complex infections. Thirty healthy male and female volunteers were divided into five groups of six participants each: 18 received 300 mg/day of rifabutin, 12 in combination with therapeutic doses of either azithromycin or clarithromycin; the remaining 12 received azithromycin or clarithromycin alone. On day 10 the study was terminated because of adverse events, including severe neutropenia. Fourteen participants who received rifabutin developed neutropenia, including all 12 participants who received azithromycin or clarithromycin concomitantly. Analyses of serum revealed no apparent pharmacokinetic interaction between azithromycin and rifabutin. However, the mean concentrations of rifabutin and 25-O-desacetyl-rifabutin (an active metabolite) in participants who received clarithromycin and rifabutin concomitantly were more than 400% and 3,700%, respectively, of concentrations in those who received rifabutin alone. Physicians should be aware that recommended prophylactic doses of rifabutin may be associated with severe neutropenia within 2 weeks after initiation of therapy, and all patients receiving rifabutin, especially with clarithromycin, should be monitored carefully for neutropenia.

Adolescent↗
PubMed1997

Comparative trial of 3 days of azithromycin versus 10 days of clarithromycin in the treatment of children with acute otitis media with effusion.

The authors compared the efficacy, safety and tolerance of azithromycin and clarithromycin in pediatric patients with acute otitis media. A randomized, open clinical trial was performed comparing azithromycin and clarithromycin in children aged 6 months to 12 years of age with acute otitis media with effusion. Patients were allocated to azithromycin at 10 mg/kg once daily for 3 days or to clarithromycin at 15 mg/kg day divided into two equal doses for 10 days. Clinical examinations and tympanometric evaluations were performed at baseline, day 3-5, day 10-14, day 28-30 and day 50-60. Tympanocentesis fluid cultures were collected at enrollment and urine and blood samples were obtained at baseline and day 10-14. Of 100 patients enrolled, 97 were considered evaluable. The most common middle ear pathogens were Streptococcus pneumoniae (60%), Haemophilus influenzae (15%) and Staphylococcus aureus (13%). Fifty patients (100%) treated with azithromycin and 45 (95.7%) patients treated with clarithromycin had a satisfactory clinical response. Rates of persistence of middle ear effusion and possible drug related side effects were comparable. Based on the efficacy and safety results, azithromycin for 3 days and clarithromycin for 10 days are considered to represent an attractive alternative for the treatment of children with acute otitis media.

Anti-Bacterial Agents↗
PubMed2006

Secondary outcomes of a pilot randomized trial of azithromycin treatment for asthma.

OBJECTIVES: The respiratory pathogen Chlamydia pneumoniae (C. pneumoniae) produces acute and chronic lung infections and is associated with asthma. Evidence for effectiveness of antichlamydial antibiotics in asthma is limited. The primary objective of this pilot study was to investigate the feasibility of performing an asthma clinical trial in practice settings where most asthma is encountered and managed. The secondary objectives were to investigate (1) whether azithromycin treatment would affect any asthma outcomes and (2) whether C. pneumoniae serology would be related to outcomes. This report presents the secondary results. DESIGN: Randomized, placebo-controlled, blinded (participants, physicians, study personnel, data analysts), allocation-concealed parallel group clinical trial. SETTING: Community-based health-care settings located in four states and one Canadian province. PARTICIPANTS: Adults with stable, persistent asthma. INTERVENTIONS: Azithromycin (six weekly doses) or identical matching placebo, plus usual community care. OUTCOME MEASURES: Juniper Asthma Quality of Life Questionnaire (Juniper AQLQ), symptom, and medication changes from baseline (pretreatment) to 3 mo posttreatment (follow-up); C. pneumoniae IgG and IgA antibodies at baseline and follow-up. RESULTS: Juniper AQLQ improved by 0.25 (95% confidence interval; -0.3, 0.8) units, overall asthma symptoms improved by 0.68 (0.1, 1.3) units, and rescue inhaler use decreased by 0.59 (-0.5, 1.6) daily administrations in azithromycin-treated compared to placebo-treated participants. Baseline IgA antibodies were positively associated with worsening overall asthma symptoms at follow-up (p = 0.04), but IgG was not (p = 0.63). Overall asthma symptom improvement attributable to azithromycin was 28% in high IgA participants versus 12% in low IgA participants (p for interaction = 0.27). CONCLUSIONS: Azithromycin did not improve Juniper AQLQ but appeared to improve overall asthma symptoms. Larger community-based trials of antichlamydial antibiotics for asthma are warranted.

Journal Article↗
PubMed1991

Pharmacokinetics of azithromycin after single oral dosing of experimental animals.

Azithromycin, a macrolide antibiotic with an enhanced antimicrobial spectrum, was found to have a longer half-life than erythromycin, with marked tissue penetration. The pharmacokinetics of azithromycin after oral administration were compared with those of erythromycin in rats (200 mg kg-1) and rabbits (80 mg kg-1). Concentrations of azithromycin in liver, lung, kidney, ileum, and brain were higher than serum concentrations. The slow decline in tissue concentrations was evident from the biphasic elimination profile. Thus, advantageous pharmacokinetic properties and the broader antimicrobial spectrum of azithromycin relative to erythromycin appear to further support its therapeutic potential.

Administration, Oral↗
PubMed1994

Azithromycin does not alter the effects of oral midazolam on human performance.

Since macrolide antibiotics inhibit the oxidative hepatic metabolism of various drugs, including midazolam, the present double blind studies were conducted to find out if azithromycin, a new macrolide of the azalide type, would inhibit the metabolism of midazolam and enhance the effects of midazolam on human performance. In Study I, 64 healthy medical students, divided in four parallel groups received placebo, midazolam (10 mg or 15 mg), and midazolam 10 mg combined with azithromycin (500 mg + 250 mg). In Study II, three males received oral midazolam 10 mg in combination with placebo, azithromycin or erythromycin 750 mg (as a positive control) in a cross-over trial. Objective and subjective tests were done before the intake of midazolam and 30 and 90 min after it, and venous blood was sampled for the assay of midazolam. In the placebo group in Study I, the mean numbers of letters cancelled (LC) at baseline, 30 min and 90 min were 21, 20 and 20, respectively, and the corresponding mean numbers of correct digit symbol substitutions (DSS) were 126, 137 and 140, indicating a practice effect. Midazolam 10 mg impaired these performances (21, 13 and 12 for LC, and 127, 113 and 111 for DSS). Either dose of midazolam produced clumsiness, mental slowness and poor subjective performance, midazolam 15 mg being slightly more active. The corresponding, scores in the azithromycin+midazolam group were 21, 16, 16 for LC, and 132, 121 and 119 for DSS, the only significant difference from placebo being the impairment of DSS at 90 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The pharmacokinetics of azithromycin and their clinical significance.

The usefulness of erythromycin is limited by its poor pharmacokinetic profile which is characterised by low blood levels and poor gastric acid stability. Erythromycin's short half-life means that a four-times daily dosage schedule is required for effective treatment. In comparison, the azalide structure of azithromycin confers a much improved pharmacokinetic profile. The bioavailability of azithromycin is approximately 37% in humans (25% for erythromycin). Serum concentrations decline in a polyphasic manner and the relatively short serum half-life (11-14 hours recorded 8-24 hours after last dose) is an indication of the initial rapid distribution of drug into the tissues. The low serum levels recorded 24 hours or more after the end of administration are thought to reflect the slow release of azithromycin from tissues. Tissue concentrations exceed serum concentrations by as much as 100-fold following a single 500 mg oral dose. Macrophages and polymorphonuclear leucocytes concentrate azithromycin at levels greater than those found in tissues themselves. During multiple dosing, tissue half-life increases with duration of administration and the tissue to serum ratio further increases. High concentrations of drug are found in tissues such as tonsil, lung, prostate, liver and lymph nodes with relatively low concentrations in fat and muscle. Significantly, the sustained high levels of drug in the tissues appears to correlate with good in vivo activity. Two 1.5 g regimens have been investigated in clinical trials: 500 mg on day 1, followed by 250 mg daily on days 2 to 5; or 500 mg daily for three days.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Effects of environmental factors on the in vitro potency of azithromycin.

The effects of media, pH, cations, serum, CO2 or anaerobic atmosphere, inoculum size and time of incubation on the in vitro potency of azithromycin were determined. The potency of azithromycin against all genera was particularly sensitive to changes in pH. The MIC for Staphylococcus aureus strains ranged from 50 micrograms/ml at pH 6 to less than or equal to 0.025 micrograms/ml at pH 8; for erythromycin the MIC change was less (1.6 to 0.05 micrograms/ml). Incubation for 18 h in 5% CO2 or an anaerobic atmosphere (10% CO2, 10% H2, 80% N2) lowered the pH by approximately 0.8 units with gram-negative organisms and 0.4 units with gram-positive organisms. This resulted in an MIC eight times greater than the aerobic MIC. In addition, the MIC100 for azithromycin and erythromycin against Bacteroides strains growing in Wilkins-Chalgren broth fell from 3.1 micrograms/ml in the anaerobic atmosphere to 0.2 and 0.4 micrograms/ml, respectively, when using the Oxyrase enzyme system to remove oxygen. With the Oxyrase system, the pH of the medium at the MIC remained at 7.2, while it fell to 6.7 in the anaerobic gas mixture. An increase in potency for both agents was also observed with other anaerobic species when using the Oxyrase system. The addition of serum produced an increase in potency of azithromycin and erythromycin that correlated with an increase in pH during incubation, despite the use of buffered media. Adding cations to Mueller-Hinton broth resulted in increased MICs for gram-negative organisms; the highest increases observed were four-fold for Escherichia coli.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobiosis↗
PubMed1991

Comparison of three-day and five-day courses of azithromycin in the treatment of atypical pneumonia.

This open, randomised clinical study, conducted from June 1988 to December 1989, included 84 patients with clinical and radiological findings of atypical pneumonia. All patients were treated with a total dose of 1.5 g azithromycin, a new azalide antibiotic. In Group I, azithromycin was administered for three days (500 mg once daily). In Group II, azithromycin was administered for five days (250 mg b.i.d. on day 1, followed by 250 mg once daily on days 2 to 5). Causative pathogens were identified by serological methods. Of the 41 patients in Group I, Mycoplasma pneumoniae, Chlamydia psittaci and Coxiella burnetti were identified in 19, 4 and 3 patients, respectively. In Group II there were 43 patients; Mycoplasma pneumoniae was identified in 24, Chlamydia psittaci in 4 and Coxiella burnetti in 3. Only patients with known causative pathogens were included in the evaluation of clinical efficacy. All patients were clinically cured by day 5; most of the patients became afebrile within 48 h of starting treatment. Side effects were observed in one patient in Group I and in one patient in Group II. The results suggest that a 1.5 g total dose of azithromycin is equally effective when administered as a three- or five-day regimen for the treatment of atypical pneumonia.

Adult↗
PubMed1992

Efficacy of single-dose azithromycin versus doxycycline in the treatment of cervical infections caused by Chlamydia trachomatis.

The efficacy of single-dose azithromycin therapy in the treatment of cervical Chlamydia trachomatis infections was compared to that of a standard seven-day course of treatment with doxycycline. Cervical samples from 60 patients reacted positively in an enzyme immunoassay for detection of Chlamydia trachomatis. In 31 patients Chlamydia trachomatis was isolated from the sample taken before treatment. Fourteen of the 31 patients were treated with doxycycline and 17 with azithromycin. All cultures of samples taken one and four weeks after the start of therapy were negative. All 31 isolates showed a similar pattern of MICs for the seven antibiotics tested, including azithromycin and doxycycline. No differences were observed between isolates of different serovars. In samples from four patients chlamydial DNA could be detected by PCR one week after the start of the therapy and in two patients also after four weeks. No difference in microbiological parameters could be observed between the two treatment groups. It is concluded that single-dose azithromycin is as effective as a seven-day course of doxycycline in the therapy of cervical Chlamydia trachomatis infections.

Azithromycin↗
PubMed1993

Pyrimethamine plus azithromycin for treatment of acute toxoplasmic encephalitis in patients with AIDS.

A prospective study was conducted to evaluate azithromycin in combination with pyrimethamine for treatment of acute Toxoplasma encephalitis in patients with AIDS. Of the 14 patients given 75 mg pyrimethamine and 500 mg azithromycin daily for four weeks, eight were evaluable for clinical response. Five responded favorably, one had an intermediate response and two an unfavorable response. Of the nine patients evaluable for radiological response, six responded favorably, and three had an intermediate response. Eleven adverse events occurred in nine patients: rash (n = 5), abnormal liver function (n = 2), vomiting (n = 3) and hypoacousia (n = 1). This pilot study suggests that the combination of pyrimethamine and azithromycin may be further investigated and that the optimal dosage of azithromycin has yet to be determined.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Azithromycin: single 1.5 g dose in the treatment of patients with atypical pneumonia syndrome--a randomized study.

An open comparative study was undertaken in order to assess the efficacy and safety of a single dose of azithromycin in the treatment of community-acquired atypical pneumonia. A total of 100 adult patients with atypical pneumonia syndrome were randomized to receive 1.5 g of azithromycin as a single dose, or 500 mg once daily for 3 days. The presence of Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, Coxiella burnetii, and Legionella pneumophila infection was diagnosed by serological tests. Control clinical examinations were performed 72 h, 10-12 days and 4 weeks after treatment initiation. Among 96 patients (48 in each group) who were evaluable for clinical efficacy M. pneumoniae infection was confirmed in 24, C. pneumoniae in nine, C. psittaci in five, C. burnetii in six, and L. pneumophila in five. Forty-seven patients (97.9%) in each group were cured. Side effects were observed in two patients in the single-dose group, and one patient in the 3-day group. In conclusion, a single 1.5 g dose of azithromycin may be an alternative to the standard 3-day azithromycin regimen in the treatment of outpatients with atypical pneumonia syndrome.

Adult↗