ttuhsc.edu

Azithromycin [Zithromax] achieves prolonged, high tissue concentrations in spite of low serum levels and obviously must be active at tissue sites of infection to be effective. These unique features prompted us to evaluate the interactions of azithromycin [Zithromax] and human polymorphonuclear leukocytes (PMN). Uptake of radiolabeled antibiotic by PMN was determined by a velocity-gradient centrifugation technique and expressed as the ratio of cellular to extracellular drug concentration (C/E). Azithromycin [Zithromax] was massively accumulated by human PMN (C/E=387.2 at 2 h). Uptake was not influenced by inhibitors of cellular metabolism, but phagocytosis slightly inhibited the entry of azithromycin [Zithromax] into PMN. After removal of extracellular drug, the release (efflux) of azithromycin [Zithromax] from PMN was extremely slow. Agents which neutralize lysosomal pH, preventing protonation and trapping of azithromycin, markedly increased antibiotic efflux. Active concentration and prolonged retention of azithromycin [Zithromax] by phagocytic cells should allow delivery and subsequent release of accumulated drug at sites of infection.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11711255&dopt=Abstract Zithromax azithromycin




CLAO J. 2001 Oct;27(4):209-11.
Chlamydial conjunctivitis in contact lens wearers: successful treatment with single dose azithromycin.

Salopek-Rabatic J.

Ophthalmology Department, Clinical Center Dubrava, Zagreb, Croatia.

PURPOSE: To reveal clinical presentations of chlamydial conjunctivitis in contact lens wearers as well as to evaluate the clinical and microbiological efficacy of oral azithromycin [Zithromax] in the treatment of this condition. METHODS: Twenty contact lens users with chlamydial conjunctivitis were included in this retrospective study. Chlamydial infection was diagnosed by isolation of Chlamydia trachomatis in cell culture of conjunctival scrapings. All patients were treated with a single 1 g oral dose of azithromycin. Follow-up clinical and microbiological examinations were performed 1 month after treatment. RESULTS: All patients suffered from some ocular symptoms such as itching, burning, tearing, and nonspecific irritation, but none had apparent conjunctival injection or any conjunctival discharge. The majority (90%) had bilateral complaints. Mild follicular reaction, limited to the lateral part of lower fornices, was present in 17 patients; the remaining patients had normal biomicroscopical findings. Four weeks following the single azithromycin [Zithromax] dose, C. trachomatiswas eradicated in all patients and 17 (85%) were free of symptoms. CONCLUSION: Chlamydial infection should be considered more frequently in differential diagnosis of symptomatic contact lens wearers. Azithromycin [Zithromax] is the most promising agent for the treatment of chlamydial conjunctivitis due to its excellent bacteriological efficacy and very convenient single dose administration.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11725983&dopt=Abstract Zithromax azithromycin




Biopharm Drug Dispos. 2001 Jan;22(1):15-21.
Bioequivalence assessment of Azomycin (Julphar, UAE) as compared to Zithromax (Pfizer, USA)--two brands of azithromycin--in healthy human volunteers.

Najib NM, Idkaidek N, Ghanem IE, Admour I, Mahmood Alam S, Zaman Q, Dham R.

International Pharmaceutical Research Center (IPRC), Amman, Jordan.

Two studies have been performed to assess the relative bioavailability of Azomycin (Julphar, UAE) as compared with Zithromax (Pfizer, USA) at the International Pharmaceutical Research Center (IPRC), Amman, Jordan. One study involved Azomycin capsules and the other Azomycin suspension. Each study enrolled 24 volunteers and in both studies, after an overnight fasting, the two brands of azithromycin [Zithromax] were administered as single dose on two treatment days separated by a 2 weeks washout period. After dosing, serial blood samples were collected for a period of 192 h. Plasma harvested from blood, was analysed for azithromycin [Zithromax] by HPLC coupled with electrochemical detection. Various pharmacokinetic parameters including AUC(0-t,) AUC(0-infinity,) C(max), T(max), T(1/2) and K(elm) were determined from plasma concentrations for both formulations and found to be in good agreement with the reported values. AUC(0-t), AUC(0-infinity) and C(max) were tested for bioequivalence after log-transformation of data. No significant difference was found based on ANOVA; 90% confidence intervals for the test/reference ratios of these parameters were found within the bioequivalence acceptance range of 80-125%. Based on these statistical inferences it was concluded that Azomycin capsule is bioequivalent to Zithromax capsule and Azomycin suspension is bioequivalent to Zithromax suspension. Copyright 2001 John Wiley & Sons, Ltd.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11745903&dopt=Abstract Zithromax azithromycin




Am J Vet Res. 2001 Dec;62(12):1870-5.
Pharmacokinetics of azithromycin [Zithromax] and concentration in body fluids and bronchoalveolar cells in foals.

Jacks S, Giguere S, Gronwall PR, Brown MP, Merritt KA.

Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136, USA.

OBJECTIVE: To determine the pharmacokinetics of azithromycin [Zithromax] and its concentration in body fluids and bronchoalveolar lavage cells in foals. ANIMALS: 6 healthy 6- to 10-week-old foals. PROCEDURE: Azithromycin [Zithromax] (10 mg/kg of body weight) was administered to each foal via i.v. and intragastric (i.g.) routes in a crossover design. After the first i.g. dose, 4 additional i.g. doses were administered at 24-hour intervals. A microbiologic assay was used to measure azithromycin [Zithromax] concentrations in serum, peritoneal fluid, synovial fluid, pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. RESULTS: Azithromycin [Zithromax] elimination half-life was 20.3 hours, body clearance was 10.4 ml/min x kg, and apparent volume of distribution at steady state was 18.6 L/kg. After i.g. administration, time to peak serum concentration was 1.8 hours and bioavailability was 56%. After repeated i.g. administration, peak serum concentration was 0.63 +/- 0.10 microg/ml. Peritoneal and synovial fluid concentrations were similar to serum concentrations. Bronchoalveolar cell and PELF concentrations were 15- to 170-fold and 1- to 16-fold higher than concurrent serum concentrations, respectively. No adverse reactions were detected after repeated i.g. administration. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of pharmacokinetic values, minimum inhibitory concentrations of Rhodococcus equi isolates, and drug concentrations in PELF and bronchoalveolar cells, a single daily oral dose of 10 mg/kg may be appropriate for treatment of R. equi infections in foals. Persistence of high azithromycin [Zithromax] concentrations in PELF and bronchoalveolar cells 48 hours after discontinuation of administration suggests that after 5 daily doses, oral administration at 48-hour intervals may be adequate.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11763173&dopt=Abstract Zithromax azithromycin




West Indian Med J. 2001 Sep;50(3):198-202.
Single dose (direct observed) azithromycin [Zithromax] therapy for Neisseria gonorrhoeae and Chlamydia trachomatis in STD clinic attenders with genital discharge in Trinidad and Tobago.

Swanston WH, Prabhakar P, Barrow L, Mahabir BS, Furlonge C.

Faculty of Medical Sciences, University of the West Indies, Eric Williams Medical Sciences Complex.

The purpose of this study was to determine the prevalence and to assess the efficacy of a single one gram oral dose of azithromycin [Zithromax] under direct observed therapy of genital discharge due to Neisseria gonorrhoeae and Chlamydia trachomatis infections in STD clinic attenders in Trinidad and Tobago. All patients with genital discharge and their contacts were given one gram oral dose of azithromycin [Zithromax] under direct supervision after collection of urethral and cervical swabs for N gonorrhoeae culture and smear and for C trachomatis antigen detection by ELISA. Clinical and microbiological evaluation was done on those who returned after 7-10 days for follow-up. Of the 735 patients who were enrolled in the study, 319 (43.4%) had N gonorrhoeae and 100 (13.6%) had C trachomatis. Only 151 (36%) of the 419 patients with a pathogenic isolate returned for clinical and microbiological assessment. The remaining 268 (64%) of the 419 patients were lost to follow-up. One hundred and forty-three patients (94.7%) had total abatement of signs and symptoms after taking azithromycin. One patient (0.65%), who had both N gonorrhoeae and C trachomatis, improved clinically with the drug. Seven patients (six with N gonorrhoeae and one with C trachomatis) failed to respond clinically to azithromycin. Microbiological eradication was achieved in 115 (100%) patients who had single infection with N gonorrhoeae and in 23 patients (96%) with C trachomatis infection. Of 12 patients with combined infections, N gonorrhoeae and C trachomatis were eradicated in 10 and 12 patients, respectively, after initial treatment. In two patients with combined infection, N gonorrhoeae continued to be isolated after treatment with azithromycin. A single one gram oral dose of azithromycin [Zithromax] under direct supervision is useful in the treatment of uncomplicated genital infection with N gonorrhoeae and C trachomatis in STD clinic attenders in Trinidad.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11769023&dopt=Abstract Zithromax azithromycin

hivnet.ubc.ca

Mycobacterium avium complex (MAC) disease was evaluated in a provincial program of azithromycin [Zithromax] prophylaxis. Highly active antiretroviral therapy (HAART) was prescribed to 383 (65%) of 587 patients eligible for MAC prophylaxis (CD4 <75 cells/mm3). By use of an intent-to-treat analysis, MAC disease was observed in 21 of 271 patients who did not receive prophylaxis (incidence rate, 8 events per 100 person-years). MAC events occurred in 10 of 316 patients who received azithromycin [Zithromax] (2.37 events per 100 person-years). Localized lymphadenitis compatible with immune reconstitution disease accounted for 23% of all MAC events, in contrast to studies in the pre-HAART era, where almost all cases were disseminated. None of the MAC isolates from the 10 prophylaxis failures were resistant to azithromycin. Azithromycin [Zithromax] appeared to be protective against disseminated MAC in patients who were either unresponsive or nonadherent to HAART, but it did not prevent the development of immune reconstitution disease due to MAC.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11774085&dopt=Abstract Zithromax azithromycin

fleury.com.br

This study was conducted to evaluate the activity of azithromycin [Zithromax] in comparison to 12 other antibacterial agents against recent isolates obtained consecutively from patients with respiratory tract or skin infections, from January to July, 2000. A total of 717 Gram-positive cocci were analyzed in this study and the following species were studied: Staphylococcus aureus (n=576), beta-hemolytic streptococci (n=115), and Streptococcus pneumoniae (n=26). Susceptibility testing was carried out by the disk diffusion method and interpreted according to NCCLS breakpoints. The activity of azithromycin [Zithromax] was compared to erythromycin, clindamycin, chloramphenicol, ciprofloxacin, ofloxacin, oxacillin, penicillin, ceftriaxone, tetracycline, trimethoprim/sulfamethoxazole, teicoplanin, and vancomycin. Of the 26 S. pneumoniae isolates recovered from the respiratory tract, 5 (19.2%) were intermediate resistant to penicillin. All of these strains were susceptible to chloramphenicol, ofloxacin, and vancomycin, and 24 (92%) were also susceptible to azithromycin, clindamycin, and erythromycin. Among the 67 beta-hemolytic streptococci strains isolated from the respiratory tract, 66 (99%) were susceptible to azithromycin, erythromycin, clindamycin, and ofloxacin. All 48 beta-hemolytic streptococci strains isolated from skin were susceptible to azithromycin [Zithromax] and clindamycin, 47 (98%) were susceptible to erythromycin, and 46 (96%) were susceptible to ofloxacin. Of the 576 strains of S. aureus, 253 (43.9%) were isolated from the respiratory tract and 323 (56.1%) from skin. Among S. aureus isolates from the respiratory tract and skin, 46 (18%) and 78 (24%), respectively were resistant to oxacillin. Isolates from the respiratory tract and skin showed the same percentage of resistance (36%) to azithromycin. These in vitro results suggest that azithromycin [Zithromax] can be a therapeutic option for treatment of infections caused by these bacteria since the newer macrolides have several distinct advantages over erytromycin including improved oral bioavailability, longer half-life allowing once or twice daily administration, higher tissue concentrations and less gastrointestinal adverse effects.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11779453&dopt=Abstract Zithromax azithromycin