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PubMed1987

Postantibiotic effect of roxithromycin, erythromycin, and clindamycin against selected gram-positive bacteria and Haemophilus influenzae.

Recent experimental work has shown that a so-called PAE (postantibiotic effect, i.e. persistent suppression of regrowth after short exposure of bacteria to the study drug in vitro) is a feature of most current antibiotics. However, marked quantitative differences were found between different types of antibiotics and also between Gram-positive and Gram-negative organisms studied. A PAE has not yet been demonstrated for roxithromycin, a new macrolide antibiotic. Therefore, we compared the PAE of roxithromycin, erythromycin, and clindamycin against laboratory strains and clinical isolates of Staphylococcus aureus, Streptococcus pyogenes, Str. pneumoniae, and Haemophilus influenzae in vitro. Identical multiples of the MIC and identical exposure times resulted in similar PAEs for the three study drugs tested. Good correlations could be found between the area under the in-vitro concentration-vs-time curve (AUC) and PAEs. The longest PAE of 9.6 h was observed after exposure of Str. pneumoniae to 1.9 mg/l of roxithromycin for 6 h.

Clindamycin↗

PubMed1987

An in-vitro comparison of the intraphagocytic bioactivity of erythromycin and roxithromycin.

The binding to human polymorphonuclear leucocytes and the intracellular bioactivity of the macrolide antibiotics erythromycin and roxithromycin on Legionella micdadei, Listeria monocytogenes and Staphylococcus aureus were investigated in vitro by the combination of a fluorochrome microassay and a radioassay. Polymorphs with intact or absent membrane-associated oxidative metabolism were used to investigate the interactions which may occur between the intrinsic oxygen-dependent antimicrobial systems of human polymorphs and the test antibiotics, in the elimination of intracellular microbial pathogens. Elimination of O2-dependent antimicrobial systems with retention of phagocytic activity was achieved by using polymorphs from children with chronic granulomatous disease NaF-pulsed normal polymorphs. Both antimicrobial agents were actively concentrated by polymorphs. Erythromycin was concentrated ten-fold and roxithromycin approximately thirty-fold above extra cellular levels. Both agents possessed intracellular bacteriostatic activity for all three test microbial pathogens. Depletion of polymorph O2-dependent intrinsic antimicrobial systems interfered with the intracellular bioactivity of both antibiotics. This emphasizes the importance of interactions between cell-associated antibiotics and phagocyte antimicrobial systems in the elimination of intracellular microbial pathogens. Like erythromycin, roxithromycin is concentrated by human phagocytes and is bioactive intracellularly.

Bacteria↗

PubMed1986

In vitro activity of the new macrolide antibiotic roxithromycin (RU 28965) against clinical isolates of Haemophilus influenzae.

The in vitro activity of the new macrolide antibiotic roxithromycin (RU 28965) was compared with the activities of five other orally absorbable antimicrobial agents against 100 clinical isolates of Haemophilus influenzae. Roxithromycin MICs were generally twofold to fourfold higher than those of erythromycin; the MIC for 90% of the strains for roxithromycin was 8 micrograms/ml.

Anti-Bacterial Agents↗

PubMed1988

Activities of amikacin, roxithromycin, and azithromycin alone or in combination with tumor necrosis factor against Mycobacterium avium complex.

The effect of amikacin and two new macrolides (roxithromycin and azithromycin) used either alone or in combination with recombinant tumor necrosis factor (TNF) to inhibit or kill Mycobacterium avium complex in human macrophages was examined in vitro. Macrophage monolayers infected with M. avium complex (strain 101, serotype 1) were treated with antibiotics or TNF by using three different protocols: (i) antibiotics or TNF was added to the monolayers immediately after infection and washed out after 24 h, (ii) antibiotics or TNF was replenished daily for 4 dys, or (iii) infected macrophage monolayers were treated with antibiotics plus TNF for 4 consecutive days. The number of viable intracellular bacteria was determined after 2 and 4 days of treatment by lysing cultured macrophages. Treatment for 24 h resulted in an inhibition of growth, as determined by macrophage lysis at day 4, for all three antimicrobial drugs and killing of 22% of intracellular bacteria after treatment with TNF. After treating the monolayers with amikacin, roxithromycin, or azithromycin for 4 consecutive days and replenishing the drug concentration daily, we observed 18 +/- 6, 20 +/- 4, and 22 +/- 1% killing, respectively. TNF (100 U/ml) was added daily to the monolayers, which resulted in 54 +/- 5% killing after 4 days. Combinations of antibiotics with TNF were associated with 62 +/- 3% killing with TNF-azithromycin, 73 +/- 6% killing with TNF-roxithromycin, and 56 +/- 4% killing of intracellular M. avium complex with TNF-amikacin after 4 days. The mycobactericidal effect was enhanced (91 +/- 4% killing by roxithromycinamikacin). Combinations of antimicrobial agents with immunomodulators like TNF may be useful for treatment of M. avium complex infection.

Amikacin↗

PubMed1988

Roxithromycin disposition in tonsils after single and repeated administrations.

Levels of roxithromycin in serum and tissue were investigated in 29 subjects undergoing tonsillectomy. A total of 13 subjects received a single oral dose of 300 mg, and 16 received four oral doses 12 h apart as follows: a 300-mg loading dose followed by three 150-mg doses. Measurable levels of roxithromycin were present in tonsil samples of 11 of 13 subjects in the first group. The mean levels in tonsils and serum were 0.8 microgram/g and 6.7 micrograms/ml, resulting in a mean tissue/serum ratio of 0.16. In the multiple-dose group, roxithromycin was found in 14 of 16 subjects at mean levels in tonsils and serum of 1.6 micrograms/g and 8.7 micrograms/ml, and the tissue/serum ratio was 0.23.

Adolescent↗

PubMed1986

Disk diffusion susceptibility testing of two macrolide antimicrobial agents: revised interpretive criteria for erythromycin and preliminary guidelines for roxithromycin (RU 965).

The 15-micrograms erythromycin disk was twice evaluated for interpretive accuracy against 417 and then 266 strains of gram-positive cocci, Neisseria meningitidis, and Haemophilus influenzae by using the criteria suggested by the National Committee for Clinical Laboratory Standards. These studies suggest a revision of streptococcal and Staphylococcus sp. interpretive guidelines to criteria (greater than or equal to 23 mm = susceptible, less than or equal to 13 mm = resistant) that are more compatible with in vivo erythromycin concentrations. It is also recommended that zone diameters be modified for H. influenzae (greater than or equal to 23 mm = susceptible, less than 22 mm = resistant) and that meningococci not be tested. A wide moderately susceptible category (1.0 to 4.0 micrograms/ml) would primarily include enterococcus strains and those organisms that would then respond only to parenteral administration of erythromycin. Roxithromycin (RU 965 or RU 28965), a new oxime ether erythromycin derivative, was also evaluated by investigator-prepared 15-micrograms disks and later with 30- and 60-micrograms commercial disks. Although roxithromycin was comparable to erythromycin in activity and regression line statistics, changes in the susceptible disk criteria were necessary because of superior roxithromycin serum concentrations and a longer serum half-life. Preliminary susceptible breakpoint criteria were greater than 21 mm = susceptible, 10 to 20 mm = indeterminate, and less than or equal to 9 mm = resistant. By using the recommended interpretive criteria for both macrolides, less than 98% absolute agreement was obtained, therefore suggesting the application of a spectrum class concept.

Erythromycin↗

PubMed1989

Roxithromycin compared with erythromycin against genitourinary chlamydial infections.

The efficacy and safety of roxithromycin 300 mg once a day was compared with that of erythromycin 500 mg twice a day, both for seven days, in a double blind study of 281 patients (188 men, 93 women) with genitourinary chlamydial infections. At the end of the treatment 251 (89%) patients were evaluable, and at follow up two weeks later 227 (81%) were evaluable. The bacteriological cure rate was close to 100% at the end of both treatment regimens. At follow up 55/75 (73%) evaluable men and 38/39 (97%) evaluable women treated with roxithromycin were chlamydia negative compared with 50/71 (70%) evaluable men and 37/42 (88%) evaluable women treated with erythromycin. Of the 47 who were still chlamydia positive, reinfection could not be excluded in half the men and all the women. Side effects were mainly gastrointestinal and were found in about 15% of patients receiving each treatment, but did not necessitate discontinuing treatment in any case. Roxithromycin seems to be as safe and efficacious as erythromycin in treating chlamydial infections in men and women, and it has the advantage that treatment is by a single daily dose.

Chlamydia Infections↗

PubMed1989

[The effect of roxithromycin on the aerobic fecal flora in children].

To evaluate the effect of roxithromycin on aerobic flora in 14 children treated orally (5 mg/kg/day during 5 to 7 days) quantitative stool cultures were performed using selective media. Enterobacteriaceae (EB), streptococci D (STR D), Staphylococcus aureus, Candida were counted at days 0, 2 and 5 days, and 2 days after treatment. The MIC of each strain was determined for roxithromycin, erythromycin and spiramycin. Ten infants in a nursery had already received antibiotics. A moderate albeit significant (p less than 0.01) decrease was observed for EB, falling from 7.2 log 10 (range 5-9) to 4.9 (range 2-8) per gram of stools, rising to 5.8 after treatment. There was no significant effect for STR D. The MIC of roxithromycin for EB increased from 244 mg/l (range 0.03-512) to 340 (range 0.03-512). For STR. D, it increased from 138 (range 1-1024) to 427 (range 1-1024). The bacteria with low MIC (less than or equal to 64 mg/l for EB and less than or equal to 4 mg/l for STR. D) are Escherichia coli and Streptococcus faecium. The MIC increased for the three macrolides tested.

Adolescent↗

PubMed1989

Comparative effects of roxithromycin and erythromycin on cellular immune functions in vitro. 1. Uptake of 3H-macrolides by human macrophages.

The degree of penetration of roxithromycin in human macrophages was evaluated and compared with that of erythromycin. The results indicated that both macrolides at concentrations of 2, 10 and 20 micrograms/ml were concentrated by macrophages, even if roxithromycin was consistently and significantly more accumulated than erythromycin. Comparison of the degree of penetration of the two drugs into dead, resident and stimulated phagocytes indicated that the process of transfer through the macrophage wall was of an active nature, related to the metabolic state of the cells. Analysis of the binding of the two macrolides to intracellular proteins showed that more binding sites were available for erythromycin than for roxithromycin.

Analysis of Variance↗

PubMed1989

Comparative effects of roxithromycin and erythromycin on cellular immune functions in vitro. 2. Chemotaxis and phagocytosis of 3H-Staphylococcus aureus by human macrophages.

The in vitro effects of roxithromycin on human macrophage activity were compared with those of erythromycin. Half the MIC of roxithromycin significantly enhanced the phagocytosis of 3H-labelled Staphylococcus aureus by human macrophages. Bacterial phagocytosis was also increased after pre-incubation of staphylococci with roxithromycin. Erythromycin displayed a less stimulating effect. Pre-incubation of macrophages with the drugs caused a depression of staphylococcal uptake by phagocytes. Macrophage chemotaxis was unchanged in the presence of both macrolides.

Chemotaxis↗

PubMed1989

[Comparison of the in vitro post-antibiotic effect of C14 macrolides (erythromycin and roxithromycin) and C16 macrolides (josamycin and spiramycin) against Staphylococcus aureus].

In vitro post-antibiotic effect (PAE) induced by erythromycin, roxithromycin, josamycin and spiramycin has been compared on Staphylococcus aureus. Three MLSB sensitive and three MLSB inducible resistant S. aureus strains have been used. delta t was the time required for culture to increase by 1 log10 after drug removal in comparison with controls. For erythromycin and roxithromycin delta t ranged from 6 minutes at 1 x MIC to 48 minutes at 4 x MIC (average of the six strains at 4 x MIC: 33 minutes). For josamycin and spiramycin, delta t ranged from 36 at 1/2 x MIC to 138 minutes at 4 x MIC (average at 4 x MIC: 101 minutes). No difference was observed between MLSB sensitive and MLSB inducible resistant S. aureus strains. In our experimental conditions, PAEs observed with josamycin and spiramycin (16-membered-ring macrolides) were 2.5 to 3 times longer than those observed with erythromycin and roxithromycin (14-membered-ring macrolides). These results added to biological differences previously observed between 14-membered-ring and 16-membered-ring macrolides.

Erythromycin↗

PubMed1989

[Roxithromycin passage in the cervix mucus].

We studied the diffusion of roxithromycin in the cervix mucus of fifteen healthy normal women, aged 24 to 44 (median 37). They were consulting physician to have an IUD. After this intervention (between the 4 to 7 days of menstrual cycle) they received an antibiotic treatment with the standard dose of roxithromycin: 150 mg bd for a week. At the end of this treatment the cervix mucus was taken 1 to 12 hours after the last antibiotic dose. We dose the roxithromycin by a microbial assay (Bacillus subtilis ATCC 6633, antibiotic medium 1, pH 8) and the acid alpha-1-glycoprotein by an immunodiffusion assay. All women had drug measurable with levels from 0.45 to 2.07 mg/l (median: 0.80 mg/l). The acid alpha-1-glycoprotein levels were quite constant (median: 0.19 mg/l). The antibiotic concentrations observed are above the MIC of the major genital pathogens, mainly C. trachomatis, G. vaginalis, H. ducreyi and U. urealyticum, but lower than the MIC ov N. gonorrhoeae and M. hominis.

Administration, Oral↗

PubMed1988

[Multicenter study of the clinical efficacy and tolerance of roxithromycin compared to erythromycin ethylsuccinate in lower respiratory tract infections].

In a double blind, randomised investigation in 193 hospitalized patients, with low respiratory infections, roxithromycin (150 mg bd) and erythromycin ethylsuccinate (1 g bd) were compared. Assessment of safety was made in 183 patients and clinical response in 155 patients. The mean duration of treatment was 11 days in both groups. Clinical effectiveness was 82% (67/82) for roxithromycin and 77% (56/73) for erythromycin ethylsuccinate. Roxithromycin appears to have a good effectiveness and to be effective as erythromycin ethylsuccinate. The safety profile is satisfactory in both groups.

Adolescent↗

PubMed1988

Penetration of roxithromycin in bronchial secretions.

Roxithromycin sputum and serum concentrations after administration of therapeutic doses (150 mg in a single dose) were evaluated in six patients. Blood samples and pooled sputum samples were collected at corresponding time intervals up to 24 h after drug administration. Roxithromycin sputum levels were found to be almost always above serum concentrations, the highest sputum levels being 5.85 +/- 2.5 micrograms/ml in the interval ranging from 2 to 4 h after drug administration. Due to its antibacterial spectrum and favourable pharmacokinetic properties, roxithromycin, like other macrolide antibiotics, seems to be particularly indicated in the treatment of respiratory tract infections.

Age Factors↗

PubMed1990

Intraphagocytic activity of erythromycin, roxithromycin and azithromycin.

The intraphagocytic activity of erythromycin, roxithromycin and azithromycin against phagocytosed Staphylococcus aureus was compared. Erythromycin and roxithromycin both acted bacteriostatically at concentrations corresponding to 10 X MIC. Azithromycin, however, did not prevent intracellular proliferation of the staphylococci. On comparison of the pH dependency of the antibacterial activity of the three drugs, azithromycin was found to be inactivated earlier in an acidic milieu.

Azithromycin↗

PubMed1995

The overall safety of oral roxithromycin in paediatric clinical studies.

In two multicentre, non-comparative studies, a total of 477 children, aged 2 months to 15 years, suffering from respiratory tract infections or skin and soft tissue infections were treated with roxithromycin (50 mg sachets). The mean duration of treatment was 9 days and the mean daily dose was 6 mg/kg/day administered b.i.d. The overall safety of roxithromycin was assessed by analysing the adverse events reported by the patients or investigators, the discontinuation of treatment because of adverse events, and the laboratory data. Adverse events reported by 20 (4%) children were considered to be possibly drug related. These adverse events were mainly digestive in nature and mild or moderate in severity. Treatment was discontinued because of adverse events in six (1%) children. Analysis of laboratory data revealed a few variations without any clinical significance.

Administration, Oral↗

PubMed1995

Liquid chromatographic determination of the macrolide antibiotics roxithromycin and clarithromycin in plasma by automated solid-phase extraction and electrochemical detection.

A liquid chromatographic method for the determination of the macrolide antibiotics, roxithromycin and clarithromycin, in plasma is described. The method is fully automated, employing on-line solid-phase extraction for sample clean-up, using the Prospekt unit. Plasma samples, mixed with internal standard, were injected onto exchangeable CN cartridges. After washing, the compounds were eluted and transferred to a C18 analytical column for separation and electrochemical detection. Clarithromycin was used as internal standard when assaying roxithromycin and vice versa. The recovery of the solid-phase extraction method was 90% and higher, and the relative standard deviation was about 3%. The limit of quantitation was 0.5 mumol/l when 25 microliters of plasma was injected. Comparison with a liquid-liquid extraction method for sample clean-up showed good agreement.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

The effect of roxithromycin on the virulence of gram-positive cocci.

Antibiotics whose recognized mode of action comprises inhibition of bacterial protein biosynthesis are also recognized to modulate the expression of bacterial virulence factors when incorporated into culture media at sub-MIC levels. In this respect, one of the new macrolides, roxithromycin, has been examined for its effect on toxin/enzyme production by strains of Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae. Biosynthesis of staphylococcal coagulase and DNase could be potentiated, whereas that of staphylococcal alpha-hemolysin, streptolysins O and S, and pneumolysin were unaltered. Expression of one structural virulence factor, pneumococcal polysaccharide, was repressed in the drug's presence, resulting in potentiation of phagocytic ingestion of the drug-exposed bacteria. The drug failed to have any effect on ingestion of Staph. aureus or Strep. pyogenes. These studies provide evidence that roxithromycin may exhibit "added value" as an antibiotic in its ability to potentiate the susceptibility of Strep. pneumoniae to host defenses such as phagocytosis.

Bacterial Proteins↗