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PubMedDate not supplied

Comparative pharmacodynamics of clarithromycin and azithromycin against respiratory pathogens.

The differences between the antibacterial activities of new macrolides such as clarithromycin (CLA) and azithromycin (AZI) against common respiratory tract pathogens are only minor. However, CLA and AZI constitute macrolides with extremely different pharmacokinetic profiles. This constellation presents an opportunity to evaluate the effect of the pharmacokinetic profile on antibacterial kinetics comparatively. In a pharmacodynamic model simulating the dynamics of serum concentrations in bacterial cultures, both CLA and AZI demonstrate bactericidal activity at concentrations reached in human blood at recommended dosages (CLA 250 mg b.i.d., AZI 500 mg o.i.d.). Bactericidal activity of CLA against the variety of pathogens included is superior to that of AZI in the rate and the extent of killing in this model. These results are considered to correlate with the antibacterial effect of macrolides in vivo in cases where pathogens enter the blood stream. Furthermore, mutants with susceptibility reduced between 8 and 16 times in relation to the initial strain of all strains having an initial minimal inhibitory concentration (MIC) < or = 0.25 mg/l, are selected during exposure to AZI, but not to CLA. The pharmacokinetic profiles of CLA and AZI thus strongly influence their antibacterial effect in the pharmacodynamic model, allowing both higher bactericidal activity and greater reduction of the risk of selection of resistant mutants with CLA than with AZI. As a whole, the pharmacodynamics of these macrolides are determined more by the proportion of the MICs to the maximum serum concentration than by the relation of the MICs to the area under the curve.

Anti-Bacterial Agents↗
PubMed1991

Comparative study of azithromycin and amoxicillin/clavulanic acid in the treatment of lower respiratory tract infections.

Forty-eight patients with acute bronchitis and four with pneumonia were randomly assigned to receive five doses (500 mg on day 1, plus 250 mg/day on days 2-5) of azithromycin; 54 patients with acute bronchitis and four with pneumonia were assigned 30 doses (625 mg every eight hours for ten days) of amoxicillin/clavulanic acid (CA). The two regimens were equally effective, with clinical improvement or cure in 92% and 87% of patients respectively, bacteriological cure in 89% and 86%, with 91% and 89% of pathogens eliminated. Minor side effects occurred in 6% and 12% of patients in the two groups, respectively. No major abnormalities in laboratory safety parameters were seen in either group.

Acute Disease↗
PubMed1992

Synergistic combination of azithromycin and sulfadiazine for treatment of toxoplasmosis in mice.

Experiments were performed in vivo in a mouse model of acute toxoplasmosis to evaluate the effectiveness of the combination azithromycin/sulfadiazine. Azithromycin alone or sulfadiazine alone, at doses that did not provide any protection against death due to toxoplasmosis, were remarkably and significantly synergistic against murine toxoplasmosis when administered in combination.

Animals↗
PubMed1991

Influence of the test medium on azithromycin and erythromycin regression statistics.

Azithromycin and erythromycin disk test results were compared to MIC values obtained in six different media. One hundred isolates were tested in triplicate, and geometric mean MICs were plotted against arithmetic mean zone diameters and regression statistics calculated. The test media evaluated did not markedly influence MIC values, but incubation in 5-7% CO2 resulted in a two- to four-fold decrease in the activity of both drugs. For testing Haemophilus influenzae and other species that need to be tested in 5-7% CO2, interpretive breakpoints for the macrolides and azalides should be modified to compensate for the anticipated decrease in activity.

Azithromycin↗
PubMed2005

Validated HPLC-MS-MS method for determination of azithromycin in human plasma.

A validated, highly sensitive, and selective HPLC method with MS-MS detection has been developed for quantitative determination of azithromycin (AZI) in human Na2EDTA plasma. Roxithromycin (ROX) was used as internal standard. Human plasma containing AZI and internal standard was ultrafiltered through Centrifree Micropartition devices and the concentration of AZI was determined by isocratic HPLC-MS-MS. Multiple reaction monitoring mode (MRM) was used for MS-MS detection. The calibration plot was linear in the concentration range 2.55-551.43 ng mL(-1). Inter-day and Intra-day precision and accuracy of the proposed method were characterized by R.S.D and percentage deviation, respectively; both were less than 8%. Limit of quantification was 2.55 ng mL(-1). The proposed method was used to determine the pharmacokinetic profile of AZI (250-mg tablets).

Anti-Bacterial Agents↗
PubMed2006

Cryptosporidium parvum bovine genotype oocysts in the respiratory samples of an AIDS patient: efficacy of treatment with a combination of azithromycin and paromomycin.

Cryptosporidium has been recognized as an emerging zoonotic agent of intestinal cryptosporidiosis leading to diarrhea, malabsorption syndrome, and weight loss in AIDS patients. In the present case, oocysts of zoonotic Cryptosporidium parvum were detected in the sputum and stool samples of an AIDS patient with a 3-month history of intestinal cryptosporidiosis. The oocysts were detected by modified Ziehl-Neelsen staining; confirmation was achieved by nested polymerase chain reaction (PCR), targeting the most polymorphic region of the 18S rRNA gene. Genotyping was done by restriction endonuclease digestion of the PCR product. The zoonotic C. parvum bovine genotype was identified in both intestinal and respiratory samples. Treatment with both azithromycin and paromomycin resulted in improvement of both intestinal and respiratory symptoms, as well as the elimination of the parasite. This is the first report of the identification of Cryptosporidium sp. oocysts in the respiratory samples obtained from an AIDS patient in Iran. Pulmonary cryptosporidiosis should be considered whenever an AIDS patient with intestinal cryptosporidiosis develops respiratory symptoms.

AIDS-Related Opportunistic Infections↗
PubMed2006

In vitro synergistic effects of double combinations of beta-lactams and azithromycin against clinical isolates of Neisseria gonorrhoeae.

In Japan, Neisseria gonorrhoeae, a sexually transmitted pathogen, has recently shown significant resistance to various antimicrobial agents. In this study, a checkerboard method was utilized to investigate the in vitro activities of cefixime (CFIX), cefteram (CFTM), or amoxicillin (AMPC) in combination with azithromycin (AZM) against 25 clinical isolates of N. gonorrhoeae. Synergy, defined as a fractional inhibitory concentration (FIC) index of less than or equal to 0.50, was observed in 32% of isolates with CFIX+AZM, 12% of isolates with CFTM+AZM, and 4% of isolates with AMPC+AZM. Moreover, partial synergy, defined as an FIC index of greater than 0.50 and less than 1, was observed in 44% of isolates with CFIX+AZM, 68% of isolates with CFTM+AZM, and 52% of isolates with AMPC+AZM. In particular, as a result of the combination of CFIX and AZM, for all isolates, significant reductions were observed in the median CFIX minimum inhibitory concentration (MIC; from 0.25 to 0.008 microg/ml; P < 0.0001) and the median AZM MIC (from 0.12 to 0.03 microg/ml; P < 0.0001). However, antagonism, defined as an FIC index of greater than 1, was observed in only 4% of the isolates with both CFIX+AZM and CFTM+AZM, while it was seen in 12% of the isolates with AMPC+AZM. To our knowledge, this is the first study to demonstrate that the in vitro activity of CFIX against N. gonorrhoeae can be significantly enhanced in combination with AZM.

Amoxicillin↗
PubMed2006

Enhancement of antimicrobial activities of cefteram or clavulanic acid/amoxicillin against cefixime-resistant Neisseria gonorrhoeae in the presence of clarithromycin or azithromycin.

We investigated the enhancement of the antimicrobial activities of beta-lactams against cefixime (CFIX)-resistant Neisseria gonorrhoeae in the presence of macrolides. Ten strains of CFIX-resistant N. gonorrhoeae, isolated between 2000 and 2003 from male patients with urethritis at Jikei University Affiliated Hospital and its related clinics in the Tokyo metropolitan area, were tested. The fractional inhibitory concentrations of clavulanic acid/amoxicillin (CVA/AMPC), CFIX, or cefteram (CFTM), in the presence of clarithromycin (CAM) or azithromycin (AZM), against these strains were determined. Synergism, partial synergism, or additivity was recognized between CVA/AMPC or CFTM and macrolides against nine strains. Additivity and partial synergism between CFTM and macrolides against nine and ten strains, respectively, were also recognized. On the other hand, antagonism between CFIX and macrolides was recognized. These results indicate that combination antimicrobial chemotherapy, using CFTM or CVA/AMPC with macrolides, is a possible alternative treatment for CFIX-resistant N. gonorrhoeae infections.

Amoxicillin↗
PubMed2005

Autoantibodies against bactericidal/permeability-increasing protein (BPI-ANCA) in cystic fibrosis patients treated with azithromycin.

Autoantibodies against bactericidal/permeability-increasing protein (BPI-ANCA) were found in patients with cystic fibrosis (CF). It is speculated that they represent a marker of the chronic endobronchial infection and sustained inflammatory response in CF. Our aim was to evaluate whether azithromycin (AZM), through its antiinflammatory effect, could affect the level of BPI-ANCA in CF patients. Eighteen patients with CF aged 5.5-36.3 years (median 15.1) were enrolled in a randomised, double-blind, placebo-controlled trial of AZM (250 mg twice a week to 10 patients) or placebo (8 patients) for 12 weeks. BPI-ANCA levels were recorded pre- and post-treatment and compared to a group of 18 matched healthy controls. Chi-square analysis, Kruskal-Wallis and Mann-Whitney tests were used to compare between the groups. Pre- and post-treatment values were compared using the Wilcoxon Signed-Ranked test. BPI-ANCA was found in 12 CF patients (67%) and four (22%) healthy subjects (P<0.001). The mean BPI-ANCA level was 3.94+/-6.15 U/ml (mean+/-SD) in healthy subjects and 38.11+/-42.34 U/ml in CF patients (P=0.023). The mean BPI-ANCA level was higher in patients with Pseudomonas aeruginosa compared to those without (64+/-35 U/ml and 25+/-41 U/ml respectively, P=0.032). No change in BPI-ANCA levels occurred in the AZM-treated patients [35 (0-127) U/ml (median (range) and 30 (0-120) U/ml, respectively] or in the placebo group [10 (0-66) U/ml and 13 (0-83) U/ml, respectively]. BPI-ANCA levels are significantly higher in patients with CF compared to healthy controls. BPIANCA levels are higher among patients colonised with P. aeruginosa. Twelve weeks of AZM therapy did not lower the BPI-ANCA level in patients with CF.

Adolescent↗
PubMedDate not supplied

Buccal adherence of Pseudomonas aeruginosa in patients with cystic fibrosis under long-term therapy with azithromycin.

BACKGROUND: The oropharyngeal barrier is an innate host defence mechanism to prevent bacterial Lung infection. A compromised barrier function is observed in patients with cystic fibrosis (CF) who are chronically infected with Pseudomonas aeruginosa. Macrolides are assumed to modify host defence. We investigated the oropharyngeaL barrier function in CF patients treated with azithromycin (AZM). PATIENTS AND METHODS: In a prospective study, eleven chronically infected children with CF were treated with longterm low-dose AZM. The oropharyngeal barrier function was assessed by adherence of P. aeruginosa (strain PACF 12-1) to buccal epithelial cells of the patients before and after therapy. RESULTS: The mean (standard deviation, SD) buccaL adherence before therapy was markedly high with 8.0 (4.8) bacteria/cell. Following therapy with AZM adherence decreased in all patients by 70% or 5.6 to 2.4 (1.1) bacteria/cell (p = 0.007), representing close to normal LeveLs (1.2 +/- 0.6). CONCLUSION: Long-term low-dose AZM therapy may improve the compromised oropharyngeaL barrier function in patients with CF, opening new perspectives for early treatment of P. aeruginosa infection in CF.

Adolescent↗
PubMed1995

Increased antimalarial activity of azithromycin during prolonged exposure of Plasmodium falciparum in vitro.

The minimum inhibitory concentration, MIC, of azithromycin was determined for 2 isolates of Plasmodium falciparum at 48 and 96 h. The MIC at 48 h for the K1 and FC isolates were 6.2 and 8.7 micrograms/ml, respectively. At 96 h, the MIC decreased to 0.08 microgram/ml for the K1 isolate and 0.04 microgram/ml for the FC isolate. The marked reduction in the MIC values between the first and second asexual erythrocytic cycles suggests that the drug acts slowly and that it may have to be used in combination with a faster acting drug.

Animals↗
PubMed1996

Quality control guidelines for amoxicillin, amoxicillin-clavulanate, azithromycin, piperacillin-tazobactam, roxithromycin, ticarcillin, ticarcillin-clavulanate, trovafloxacin (CP 99,219), U-100592, and U-100766 for various National Committee for Clinical Laboratory Standards susceptibility testing methods. Results from multicenter trials.

Quality control guidelines for standardized antimicrobial susceptibility test methods are critical to the continuing accuracy of the tests. In this report, quality control limits were proposed for 22 organism-antimicrobial combinations with minimum inhibitory concentration (MIC) ranges of three or four log2 dilution steps. Disk diffusion zone diameter ranges were proposed for azithromycin compared with Neisseria gonorrhoeae ATCC 49226 and ticarcillin with and without clavulanic acid tested against Staphylococcus aureus ATCC 25923. The data from five or six participating laboratories produced > or = 94.7% of results within proposed MIC limits, and 94.3%-99.0% of zones were found within suggested zone guidelines. These proposed quality control ranges should be validated by in-use results from clinical laboratories.

Acetamides↗
PubMed2006

Anti-inflammatory effects of azithromycin in cystic fibrosis airway epithelial cells.

We aimed at identifying molecular mechanisms for anti-inflammatory effects of azithromycin (AZM) suggested by clinical evidences. IL-8 expression and DNA binding activity of two key pro-inflammatory transcription factors (TF), NF-kappaB and AP-1, were investigated in cystic fibrosis (CF) and isogenic non-CF airway epithelial cell lines. AZM reduced about 40% of IL-8 mRNA and protein expression (n=9, p=0.02, and n=4, p=0.00011) in CF cells reaching the levels of non-CF cells. In the presence of AZM we found about 50% and 70% reduction of NF-kappaB and AP-1 DNA binding, respectively (n=3, p=0.01, and n=3, p=0.0017), leading to levels of non-CF cells. The relevance of NF-kappaB and AP-1 in regulating IL-8 promoter transcriptional activity was demonstrated by gene reporter assays (n=4, p=8.54x10(-7), and n=4, p=6.45x10(-6)). Our data support the anti-inflammatory effects of AZM in CF cells, indicating inhibition of transcription of pro-inflammatory genes as possible mechanism, thus providing a rationale for the possible use of specific TF inhibitors for therapy.

Anti-Bacterial Agents↗
PubMed2005

Prospective observational study of patient-reported outcomes for azithromycin versus usual care in the treatment of bacterial acute exacerbation of chronic bronchitis.

BACKGROUND: The 3-day course of azithromycin (AZM) 500 mg/d was introduced to the US market in June 2002. OBJECTIVE: The objective of this study was to evaluate changes in health-related quality of life (HRQOL) as measured by the St. George's Respiratory Questionnaire (SGRQ) over a 1-month period in patients receiving a 3-day course of AZM for bacterial acute exacerbation of chronic bronchitis (AECB). METHODS: This was a prospective, multicenter, observational study evaluating outpatient adults with AECB who received either 3 days of AZM 500 mg/d or 5- to 14-day courses of other antibiotics (usual care [UC]) as directed by the clinician. Patients completed 2 HRQOL instruments-the SGRQ and Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36)-at baseline, day 14, and end of study (EOS) at days 24 to 28. In addition, patients kept a diary for the first 14 days after initiating antibiotic therapy. RESULTS: One hundred twenty-eight patients (57 AZM, 71 UC) were clinically evaluable. There were no significant differences between treatment groups in clinical presentation or baseline demographics, with the exception of a higher percentage of patients with diabetes mellitus in the UC group compared with the AZM group (16.9% vs 3.5%; P = 0.02). Both groups reported similar improvements in signs and symptoms, absenteeism, concomitant respiratory medication use, resource utilization, compliance, and treatment satisfaction as reported in the patient diary. The AZM group reported statistically significant improvement (simple contrasts for end of study vs baseline) in SGRQ measures (total score, P < 0.001; symptoms, P = 0.031; activity, P < 0.001; impacts, P < 0.001) and the SF-36 mental and physical summary components, compared with baseline (both, P < 0.001). Similarly, the UC group reported significant improvement in all SGRQ measures and in the SF-36 physical component score (P < 0.01), but not in the SF-36 mental component score, compared with baseline. At EOS, 80.0% of AZM patients and 59.0% of UC patients had a > or =4-point improvement on the SGRQ total score; however, this difference was not statistically significant in the multivariate analysis. In addition, 89.5% of AZM patients and 89.9% of UC patients were satisfied or very satisfied with their treatment (P = NS). Resource utilization was similar between the groups. CONCLUSIONS: In this observational study, patients with AECB treated with a 3-day course of AZM experienced significant improvements in HRQOL as measured by a change of > or =4 points on the SGRQ and SF-36 physical and mental component scores versus baseline.

Acute Disease↗
PubMed2004

Macrolides and ketolides: azithromycin, clarithromycin, telithromycin.

The advanced macrolides, azithromycin and clarithromycin, and the ketolide telithromycin are structural analogues of erythromycin. They have several distinct advantages when compared with erythromycin including enhanced spectrum of activity, more favorable pharmacokinetics and pharmacodynamics, once daily administration, and improved tolerability. This article reviews the pharmacokinetics, antimicrobial activity, clinical use, and adverse effects of these antimicrobial agents.

Anti-Bacterial Agents↗
PubMed2004

Pharmacokinetic evaluation of an azithromycin controlled release dosage form in healthy human volunteers: a single dose study.

Azithromycin (AZI) follows a two-compartment model pharmacokinetically. The purpose of this study was to evaluate the in vivo performance of a controlled release (CR) formulation of AZI, which would eliminate the risk of high peak plasma concentrations obtained within 2-3 h after peroral administration of immediate release (IR) products. The study was conducted in twelve healthy male human volunteers to compare an experimental NIPER product (CR tablets) with Vicon (IR tablets) at the same dose level as a single-dose, randomized, one-period, two-treatment, and parallel-study. Concentrations of AZI in serum samples were assessed using the validated HPLC method. From the serum concentration-time profiles various pharmacokinetic parameters (AUC(0-96), AUC(0-inf), C(max) and T(max)) were calculated for both products. Results showed that the high peak concentration obtained by administration of a conventional IR formulation were eliminated with the CR product. A mean dosage form index (DI) of 1.17 with fluctuations of 7.57% was obtained with the CR product at steady state level, indicating reduced fluctuations at the steady state serum concentrations. Elimination of the pronounced peak as well as fluctuations reduced or minimized AZI adverse effects associated with the IR product.

Administration, Oral↗
PubMed2004

Clarithromycin and azithromycin induce apoptosis of activated lymphocytes via down-regulation of Bcl-xL.

To evaluate the anti-inflammatory action of macrolide antibiotics, we examined whether macrolide antibiotics could induce apoptosis of activated lymphocytes. The proportion of apoptotic cells was augmented by clarithromycin (CLR) and azithromycin (AZM) compared with control. There was no significant difference in Fas and Fas-ligand expression between the control and macrolide-treated groups. CLR and AZM inhibited the expression of Bcl-xL compared with that of control. Our results suggest that CLR and AZM enhance apoptosis of activated lymphocytes by down-regulation of Bcl-xL.

Adult↗
PubMed2005

Rapidly progressive lung disease in a patient with cystic fibrosis on long-term azithromycin: possible role of mycoplasma infection.

Macrolides is effective therapy in patients with cystic fibrosis (CF). We describe a girl with CF given long-term azithromycin who died of rapidly progressive lung disease. She was found to have rising titers of mycoplasma serology, suggesting a possible causative role of a resistant mycoplasma infection. Mycoplasma infection should be considered in CF patients who are deteriorating, even if they are being treated with macrolides, to which these organisms are usually susceptible.

Adolescent↗