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Azithromycin compared with cephalexin in the treatment of skin and skin structure infections.

This randomized, third-party-blinded study compared short-course therapy of once-daily azithromycin (500 mg on day 1, followed by 250 mg/day on days 2-5) with cephalexin (500 mg twice daily for 10 days) in the treatment of patients with skin and skin structure infections. At 25 centers, a total of 361 patients were entered into the study and 148 were evaluable for efficacy. The main causative pathogens, Staphylococcus aureus and Streptococcus pyogenes, were responsible for approximately two thirds of the infections in the two treatment groups. Clinical cure and improvement rates for the two treatments were comparable; 99% with azithromycin and 96% with cephalexin. On completion of therapy, both treatments had eradicated approximately 98% of pathogens. In general, both agents were well-tolerated. The results of this study show that a 5-day course of once-daily treatment with azithromycin is as effective as a 10-day course of twice-daily treatment with cephalexin in the management of skin and skin structure infections.

Adolescent↗

Azithromycin for treatment of Mycobacterium avium-intracellulare complex infection in patients with AIDS.

Mycobacterium avium complex infection is common in patients with AIDS. Experimentally infected mice have been treated successfully with azithromycin, a macrolide antibiotic. We report an uncontrolled phase I study in which male homosexuals with AIDS and M avium complex disease were given 500 mg azithromycin per day orally for 10, 20, or 30 days. Quantitative blood cultures showed a mean reduction in mycobacteraemia from 118 colony forming units (cfu)/ml to 43 cfu/ml in 3 patients treated for 10 days, and from 2028 cfu/ml to 136 cfu/ml in 21 patients treated for 20 or 30 days. Of the patients treated for 20 or 30 days, 15 of 21 with fever pretreatment and 12 of 18 with night sweats pretreatment reported resolution of these symptoms. The principal side-effects were loose stools or diarrhoea, but these did not result in cessation of therapy. Azithromycin, as a single oral agent, safely reduced M avium complex bacteraemia and associated symptoms in almost 75% of patients treated for at least 20 days. Further studies are needed to assess emergence of resistance.

Acquired Immunodeficiency Syndrome↗

An open-label, noncomparative study to evaluate the efficacy, safety, and tolerability of azithromycin in the treatment of patients with acute sinusitis.

The efficacy, safety, and tolerability of a 5-day, once-daily course of azithromycin were assessed in patients with acute sinusitis. Patients received two 250-mg capsules of azithromycin on day 1 and one 250-mg capsule on days 2 through 5. Of 102 clinically assessable patients, 27 (26.5%) were cured and 69 (67.6%) were improved on days 5 to 7. At days 12 to 16, 88 (86.3%) had a favorable clinical response. A total of 64 patients experienced adverse events; in all but two patients, adverse events were of mild or moderate severity. Thus azithromycin given once daily for 5 days was an effective treatment for patients with acute sinusitis.

Acute Disease↗

Effect of azithromycin therapy on coronary circulation in patients with coronary artery disease.

This study examined the effect of azithromycin therapy on the coronary microcirculation using measurement of coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography in 35 patients with coronary artery disease. CFVR increased significantly after azithromycin therapy (3.0 +/- 0.7 vs 3.5 +/- 0.7, p <0.001). The changes in CFVR were negatively correlated with changes in high-sensitivity C-reactive protein levels in patients receiving azithromycin.

Aged↗

One-week once-daily triple therapy with esomeprazole, levofloxacin and azithromycin compared to a standard therapy for Helicobacter pylori eradication.

BACKGROUND: Primary antibiotic-resistance and poor compliance are the main causes of Helicobacter pylori eradication failure of standard regimens. AIM: To investigate eradication rate, patient compliance and tolerability of a 1-week once-daily levofloxacin plus azithromycin triple therapy versus the standard twice-daily triple therapy. PATIENTS AND METHODS: A total of 164 H. pylori-positive patients were randomised to either esomeprazole 20mg, levofloxacin 500 mg and azithromycin 500 mg once-daily (ELAz) or esomeprazole 20mg, clarithromycin 500 mg and amoxycillin 1g twice-daily (ECA) for 1 week. H. pylori infection was defined at entry by histology and urea breath test; cure of infection was determined both by negative urea breath test and H. pylori stool antigens. RESULTS: H. pylori eradication rates of ELAz and ECA were similar at intention-to-treat (both 65%) and per-protocol analyses (70% versus 76%, respectively). Incidence of poor compliance was lower, although not significantly, in patients randomised to ELAz than to ECA (4% versus 10%); tolerability was significantly higher for ELAz than for ECA (88% versus 70%; P=0.01). CONCLUSIONS: Once-daily levofloxacin plus azithromycin-based triple therapy achieves an H. pylori eradication rate comparable to that of standard twice-daily triple therapy, but is associated with higher patient compliance and might even be better tolerated.

Anti-Bacterial Agents↗

Azithromycin-sulfonamide conjugates as inhibitors of resistant Streptococcus pyogenes strains.

Novel hybrid compounds 6a-6d, conjugates of 15-membered azalides and sulfonamides, i.e. unsubstituted, 4-aryl- and 4-heteroaryl-aminosulfonyl derivatives of 9a-[N'-(phenylcarbamoyl)]-9-deoxo-9-dihydro-9a-aza-9a-homoerythromycin A were synthesized and characterized by IR, one- and two-dimensional NMR spectroscopies and MALDI-TOF and MS/MS mass spectrometry. The new compounds were evaluated in vitro against a panel of sensitive and resistant Gram-positive and Gram-negative bacterial strains. 9a-{N'-[4-(Aminosulfonyl)phenyl]carbamoyl}--(6a) and 9a-{N'-[4-(phenylaminosulfonyl)phenyl]carbamoyl}--(6b) derivatives showed improvements in activity against inducible resistant Streptococcus pyogenes in comparison with macrolide antibiotic azithromycin and starting material 9-deoxo-9-dihydro-9a-aza-9a-homoerythromycin A (2). In addition, the synthesized azithromycin-sulfonamide conjugates 6a-6d showed good antibacterial activity against sensitive S. pyogenes and Streptococcus pneumoniae strains. The kinetics of degradation in the artificial gastric juice showed that the most active compounds, 6a and 6b, exhibited azithromycin like stability. The cleavage of the cladinose sugar was found to be the main decomposition pathway leading to inactive 7a and 7b, prepared also as analytical standards by the alternative synthetic route together with 7c and 7d.

Acetaldehyde↗

Effect of azithromycin on bronchiectasis and pulmonary function in a heart-lung transplant patient with severe chronic allograft dysfunction: a case report.

Azithromycin has been shown to be beneficial in several diseases with chronic neutrophilic inflammation of the airways, such as cystic fibrosis and bronchiolitis obliterans syndrome (BOS) after lung transplantation. Up to now, however, its healing effect on bronchiectasis has never been demonstrated. We report a heart-lung transplant patient who developed chronic rejection (BOS stage 3) with the appearance of gross bronchiectasis on a spiral computed tomography (CT) chest scan. Within 2 weeks after starting azithromycin, the patient's forced expiratory volume in 1 second increased significantly and a repeat spiral CT chest scan 5 months later, showed a major improvement of the bronchiectasis. This case report illustrates that bronchiectasis may greatly improve after treatment with azithromycin and no longer needs to be considered an endstage finding in patients with severe BOS.

Adolescent↗

Streptococcus pneumoniae in vitro development of resistance to amoxicillin/clavulanic acid, cefaclor, levofloxacin and azithromycin.

The purpose of this study was to determine effect of repeated exposure to sub-inhibitory concentrations of amoxicillin/clavulanic acid on the development of resistance in Streptococcus pneumoniae. Other agents, azithromycin, cefaclor and levofloxacin, were also tested. Twenty S. pneumoniae were passaged for 9 days in the presence of sub-inhibitory concentrations of each antimicrobial agent and MICs determined by NCCLS macro-dilution method. There was a four-fold increase in amoxicillin/clavulanic acid MICs for 2 of 20 isolates. Three of 9 tested against cefaclor, 11 of 13 tested against azithromycin and 9 of 20 tested against levofloxacin showed > or =4-fold increase. Amoxicillin/clavulanic acid was the most stable of the agents tested. Cefaclor MICs were also fairly stable. Azithromycin and levofloxacin MICs were most affected.

Amoxicillin-Potassium Clavulanate Combination↗

Comparative randomized pilot study of azithromycin and doxycycline efficacy in the treatment of prostate infection caused by Chlamydia trachomatis.

The study included 125 adult patients (> 18years of age) who had symptoms of chronic prostatitis and proven presence of Chlamydia trachomatis. The presence of C. trachomatis was confirmed in expressed prostatic secretion or in voided bladder urine collected immediately after prostatic massage by a DNA/RNA hybridization method and/or by isolation on McCoy culture and then by immunofluorescent typing with monoclonal antibodies. The patients were randomized in the ratio 2/1; azithromycin/doxycycline, to receive a total of 4.0 g azithromycin over 4 weeks, given as a single dose of 1 x 1000 mg weekly for 4 weeks or doxycycline 100 mg b.i.d. for 28 days. Patients' sexual partners were treated at the same time. Clinical and bacteriological efficacy was evaluated 4-6 weeks after the end of therapy. In the group of patients with chlamydial infection of the prostate, there was no significant difference between the eradication rates (azithromycin 65/82, doxycycline 33/43; P = 0.82) and the clinical cure rates (azithromycin 56/82, doxycycline 30/43; P = 0.94) of the two antimicrobials.

Adult↗

Susceptibility of Streptococcus pneumoniae to penicillin, azithromycin and telithromycin (PROTEKT 1999-2003).

Isolates of Streptococcus pneumoniae collected over the first 4 years of the PROTEKT study were tested for susceptibility to penicillin, azithromycin and telithromycin. A total of 20,750 isolates were collected from 39 countries. Penicillin non-susceptibility rates were stable over the study period; overall, 21.8% of isolates were resistant. Azithromycin resistance increased from 31.0% in Year 1 to 36.3% in Year 4. Resistance rates for penicillin and azithromycin varied between countries and were highest in France, Spain, South Africa, USA and the Far East. Multidrug resistance in S. pneumoniae did not change significantly over the 4 years, with an overall rate of 38.6%. Telithromycin retained good activity against S. pneumoniae (0.1% of isolates resistant), including multidrug-resistant isolates.

Anti-Bacterial Agents↗

Bacterial etiology of acute otitis media and clinical efficacy of amoxicillin-clavulanate versus azithromycin.

BACKGROUND: Acute otitis media (AOM) is one of the most common acute bacterial infection in childhood and also the most frequent reason for outpatient antibiotic therapy. Little recent information about susceptibility patterns of AOM bacterial pathogens in Turkish children has been reported. OBJECTIVE: To determine the bacterial etiology of acute otitis media in children and to compare the efficiency of 3 days course of azithromycin with a 10 days course of amoxicillin-clavulanate. METHODS: This prospective, single blind, randomised comparative study was carried out in 180 children with AOM. Paracentesis was performed for middle ear fluid culture before the first dose antibiotic therapy. Children with acute otitis media were randomised to receive either low dose amoxicillin-clavulanate (45/6.4 mg/kg/day in two divided doses for 10 days) or low dose azithromycin (10mg/kg/day for 3 days). Clinical response was assessed on days 2-4, 11-13, 26-28. RESULTS: Bacterial pathogens were isolated from 108 (60%) of 180 children. Streptococcus pneumoniae was the most common isolated pathogen (39.7%), followed by Haemophilus influenzae (20.7%), Moraxella catarrhalis (15.5%), Staphylococcus aureus (13.8%), Group A beta-hemolytic streptococcus (5.1%), Escherichia coli (3.4%) and Enterococcus faecalis (1.7%). This study demonstrated low resistance rates compared to studies of different countries. Although clinical response rates were better in patients treated with amoxicillin-clavulanate, this was not statistically significant [86.6% (78 of 90)] versus [95.2% (80 of 84)]. Success rates of amoxicillin-clavulanate were high for both S. pneumoniae and H. influenzae. Difference between success rates was not statistically significant (P=0.144 and 0.352). CONCLUSIONS: Bacteria were isolated in 60% of AOM cases. The clinical efficiency of amoxicillin-clavulanate was found to be equal compared to azithromycin in children with acute otitis media.

Acute Disease↗

High performance liquid chromatographic determination of azithromycin in serum using fluorescence detection and its application in human pharmacokinetic studies.

A fast and sensitive high-performance liquid chromatographic method for determination of azithromycin in human serum using fluorescence detection was developed. The drug and an internal standard (clarithromycin) were extracted from serum using n-hexan and subjected to pre-column derivatization with 9-fluorenylmethyl chloroformate as labeling agent. Analysis was performed on a phenyl packing material column with sodium phosphate buffer containing 2 ml/l triethylamine (pH 5.9) and methanol (29:71, v/v) as the mobile phase. The standard curve was linear over the range of 10-500 ng/ml of azithromycin in human serum. The means between-days precision were from 13.3% (for 10 ng/ml) to 2% (500 ng/ml) and the within-day precision from 11.9 to 1.7% determined on spiked samples. The accuracy of the method was 100.7-107.2% (between days) and 100.3-107.8% (within day). The limit of quantification was 10 ng/ml. This method was applied in a bioequivalence study of four different azithromycin preparations in 12 healthy volunteers.

Anti-Bacterial Agents↗

Pharmacokinetics and tissue tolerance of azithromycin after intramuscular administration to rabbits.

The pharmacokinetics of azithromycin after intravenous and intramuscular injection at a single dose rate of 10mg/kg bodyweight were investigated in rabbits by using a modified agar diffusion bioassay for determining plasma concentrations. The plasma creatine kinase activity was determined after i.m. administration for the evaluation of the tissue tolerance. The elimination half-lives of azithromycin after intravenous and intramuscular administration were 24.1 and 25.1h, respectively. After intramuscular administration mean peak plasma concentration was 0.26+/-0.01 mg/L and bioavailability was 97.7%. Plasma CK activity rose sharply within 8h after i.m. injection of azithromycin; activity returned to pre-treatment level by 48-72 h post-treatment. The transient rise in serum CK activity indicates some degree of muscle tissue damage at the injection site.

Animals↗

Interaction of the macrolide azithromycin with phospholipids. I. Inhibition of lysosomal phospholipase A1 activity.

Azithromycin, the first clinically developed dicationic macrolide antibiotic, displays an exceptional accumulation in lysosomes of cultured cells. In fibroblasts incubated with 50 mg/l (66.6 microM), it induces a distinct phospholipidosis as evidenced by biochemical and ultrastructural criteria, which strikingly resembles alterations described previously with gentamicin, a pentacationic aminoglycoside antibiotic which inhibits the lysosomal catabolism of phospholipids. We show that both drugs inhibit, in an equimolar manner, the activity of phospholipase A1 (assayed for phosphatidylcholine, included in negatively charged liposomes), in a way consistent with the model of 'charge neutralization' proposed already for gentamicin (Mingeot-Leclercq et al., 1988, Biochem. Pharmacol. 37, 591). Both drugs bind to negatively charged liposomes. Yet, in spite of this binding, azithromycin does not induce aggregation or fusion of negatively charged vesicles, under conditions in which gentamicin (or spermine, a fully hydrophilic polycation) causes a massive aggregation, and bis(beta-diethylaminoethylether)hexestrol (a dicationic amphiphile) causes fusion. The molecular interactions of azithromycin with acidic phospholipids are further examined in a companion paper.

Animals↗

Depression of the N-demethylation of erythromycin, azithromycin, clarithromycin and clindamycin in murine Toxoplasma infection.

The N-demethylation of macrolides was studied in a murine model of infection. Mice were infected with a cystogenic strain of Toxoplasma gondii (20 or 40 cysts/mouse) and microsomes were prepared from liver homogenates and jejunum villus tip enterocytes on day 10 post-infection. The rate of N-demethylation of the anti-Toxoplasma macrolides azithromycin, clarithromycin and clindamycin was investigated and compared to that of the macrolide erythromycin, a marker of activity of the cytochrome P-450 3A (CYP3A) mono-oxygenases. In infected mice (20 cysts/mouse), the rate of N-demethylation fell in the liver and jejunum for erythromycin (-25% and -35%, respectively), azithromycin (-12% and -10%, respectively), clarithromycin (-23% and -21%, respectively) and clindamycin (-20% and -28%, respectively). The degree of hepatic depression was more marked in mice receiving a 40-cysts burden: for erythromycin (-54%), azithromycin (-29%), clarithromycin (-49%) and clindamycin (-47%).

Animals↗

Azithromycin and clarithromycin.

Azithromycin and clarithromycin are alternatives to conventional macrolides in the routine treatment of many dermatologic, upper respiratory, and lower respiratory tract infections. In this role as alternative therapy, they are better tolerated, less toxic, and more convenient to take, although at a greater cost to the patient. This dosing convenience is an important consideration for the clinician; as shown by Nelson, patient compliance ranges from 95% with once-daily dosing to 58% with four-times-a-day dosing. Thus, less frequent dosing with both drugs as well as the shorter course of therapy possible with azithromycin may be therapeutically advantageous. In addition to their role as alternatives to conventional macrolide therapy, azithromycin and clarithromycin extend the spectrum of macrolides and offer new therapeutic options for H. influenzae, MAC in AIDS, MOTT, and leprosy. Finally, experimental therapy may extend their use for additional opportunistic infections, such as toxoplasmosis and cryptosporidiosis.

Azithromycin↗

Microbiological assay for azithromycin in pharmaceutical formulations.

The validation of a microbiological assay, applying the cylinder-plate method, for the determination of the antibiotic azithromycin is described. Using a strain of Micrococcus luteus ATCC 9341 as the test organism, azithromycin at concentrations ranging from 0.1 to 0.4 microgml(-1) could be measured in capsules and suspensions. A prospective validation of the method showed that it was linear (r=0.998), precise (RSD=1.40-capsules; RSD=1.19-powder for suspension and RSD=1.73-oral suspension) and accurate (it measured the added quantities). We conclude that the microbiological assay is satisfactory for quantitation of in vitro antibacterial activity of azithromycin.

Anti-Bacterial Agents↗

Voltammetric assay of azithromycin in pharmaceutical dosage forms.

The oxidative behaviour of azithromycin was studied at s glassy carbon electrode in different buffer system using cyclic, linear sweep and differential pulse voltammetry. The oxidation process was shown to be irreversible over the entire pH range studied (5-11) and was diffusion-adsorption controlled. Analytical method with adequate precision and accuracy was developed for the determination of azithromycin in phosphate buffer at pH 7 as supporting electrolyte containing 10% methanol and 0.05 M ammonium acetate. The peak current varied linearly with azithromycin concentration in the range 1-15 microg/ml. The procedure was successfully applied for assay of the drug in the pharmaceutical dosage forms. The relative standard deviation (n = 5) of 2.18% was obtained.

Anti-Bacterial Agents↗