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Fetal outcome following roxithromycin exposure in early pregnancy.

OBJECTIVE: Because very little information exists on the fetal safety of roxithromycin, we aimed to extend the knowledge on fetal outcome in pregnant women who were exposed to roxithromycin in early pregnancy. METHODS: Twenty pregnant women inadvertently exposed to roxithromycin during early pregnancy were identified and prospectively followed-up. For comparison, 170 pregnant women matched by age and gravidity, not being exposed to any potential teratogenic agent during pregnancy, were recruited as controls. All gestations were confirmed by ultrasound examination, and participants were followed-up until delivery. Newborns were examined by a neonatologist. RESULTS: Of 20 pregnant women exposed to roxithromycin during early pregnancy, information was obtained from 17 cases. The median dose of roxithromycin to which pregnant women were exposed was 300 mg/day (range 300-450 mg/day) and exposure occurred at a mean of 4.0 (range 2.8-17.6) weeks. Mean gestational age at delivery was 39.2 weeks in the exposed group and 39.4 in the controls (p = 0.6). Birth weight of babies exposed in utero to roxithromycin was not different to controls. We did not observe any major malformation in the exposed group whereas three (1.8%) occurred in the control group. CONCLUSIONS: . Despite the limitations of the study due to the small sample size, roxithromycin appears not to be a major teratogen.

Adult↗

Comparative study of clarithromycin and roxithromycin in the treatment of community-acquired pneumonia.

The efficacy and tolerance of clarithromycin (250 mg twice daily) were compared with those of roxithromycin (150 mg twice daily) in an open, multicentre trial of 77 inpatients with community-acquired pneumonia. Sixty-five patients were clinically evaluable (34, clarithromycin; 31 roxithromycin). Efficacy was comparable between treatment groups: 26 of 34 patients (76%) treated with clarithromycin were clinically cured, including four with atypical pneumonia. In the roxithromycin group 25 of 31 patients (81%) were clinically cured and one was improved. Cough, appearance of sputum, and fever improved in most patients in both treatment groups. Chest X-rays after treatment showed resolution or improvement in 76% of patients who received clarithromycin and 87% of those who received roxithromycin. The clinical evaluation of the response generally agreed with the bacteriological response. Among patients who were bacteriologically evaluable for four target organisms (Streptococcus pneumoniae, Haemophilus influenzae, H. parainfluenzae, and Branhamella catarrhalis) the pathogen was eradicated in four of seven (57%) in the clarithromycin-treated group and in five of six (83%) in the roxithromycin-treated group. Adverse events were reported in more patients who received roxithromycin (21.6%) than in those who received clarithromycin (12.5%) although the incidences were not statistically significantly different. The majority of adverse events were transient increases in serum alanine aminotransferase, serum aspartate aminotransferase, and alkaline phosphatase. Clarithromycin was shown to be effective and well-tolerated; the clinical efficacy and safety of clarithromycin and roxithromycin were comparable.

Adult↗

Inhibitory effect of roxithromycin on adhesion of Klebsiella pneumoniae strains 3051, CF504 and LM21.

The effect of subinhibitory concentrations of roxithromycin on the adhesion of three strains of Klebsiella pneumoniae to Int-407 cells was studied. Adherence was markedly inhibited and the effect was increased when roxithromycin was added to the cell culture medium rather than to the bacterial growth medium. Several assays were performed in order to understand the mechanism by which roxithromycin exerted this inhibitory effect. The greatest effect was obtained when roxithromycin was concentrated in the extracellular compartment; when roxithromycin was concentrated in the intracellular compartment, the inhibitory effect was reduced. The analysis of adhesion factors of bacteria showed that exposure to roxithromycin did not alter their apparent structure or quantity. Roxithromycin appears to interfere in the interaction between bacteria and eukaryotic receptors.

Anti-Bacterial Agents↗

Impact of pharmaceutical dosage forms on the pharmacokinetics of roxithromycin in healthy human volunteers.

OBJECTIVES: The impact of two different pharmaceutical preparations on the pharmacokinetics of roxithromycin was investigated in healthy human volunteers. METHODS: The degradation kinetics and products of roxithromycin were investigated in simulated gastric fluid and simulated intestinal fluid. Two oral dosage forms of roxithromycin were employed: enteric-coated pellets and dispersible tablets. RESULTS: The degradation half-time of roxithromycin in simulated gastric fluid was 0.23 h, and three main degradation products were characterized. In contrast, roxithromycin was stable in simulated intestinal fluid and remained unchanged after a 1.00 h incubation. The roxithromycin enteric-coated pellets exhibited higher bioavailability and a more potent serum antibacterial activity than the dispersible tablets. CONCLUSIONS: The type of oral dosage forms of roxithromycin altered its pharmacokinetics. Whether or not this affects the in vivo antibacterial efficacy requires further study.

Adult↗

In vitro antimicrobial susceptibility of periodontopathic Actinobacillus actinomycetemcomitans to roxithromycin and erythromycin.

The in vitro minimal inhibitory concentrations (MIC) and minimal bactericidal concentration (MBC) of roxithromycin and erythromycin against Actinobacillus actinomycetemcomitans were evaluated. Sixty-seven different A. actinomycetemcomitans isolated from periodontal pockets of 101 subjects with different forms of early-onset and adult periodontitis and three reference strains of A. actinomycetemcomitans (ATCC 29522, ATCC 29523, and NCTC 9710) were included in this study. Erythromycin showed poor in vitro activity against A. actinomycetemcomitans; roxithromycin, on the contrary, exhibited good in vitro activity. Moreover, roxithromycin showed the best in vitro antimicrobial activity against 17 serotype a and 12 serotype c subpopulations of A. actinomycetemcomitans; against 38 serotype b subpopulation of A. actinomycetemcomitans, roxithromycin was consistently active. Roxithromycin exhibited MBC values usually equal to, or one-fold higher than MIC values. All the MBC values of erythromycin were three- to four-fold higher than the respective MIC result. Since roxithromycin is characterized by high concentrations in serum and good penetration and diffusion into gingival tissue, it could be expected to pass into the gingival crevicular fluid at levels sufficiently high to inhibit A. actinomycetemcomitans in vivo. These data indicate that roxithromycin might be a potential candidate for therapeutic trials in patients with A. actinomycetemcomitans-associated periodontitis.

Adolescent↗

Lack of in vitro and in vivo selection of bacterial resistance by roxithromycin.

The in vitro and in vivo selective pressure exerted by roxithromycin on Lancefield group A beta-haemolytic streptococci (GABHS) was investigated. In vitro antimicrobial activity on fifty GABHS strains was determined by the microdilution method and by boundary concentration (BC) determination. Insorgence of resistance was evaluated by redetermining MIC and BC after exposure to 16 x MIC roxithromycin concentration. In vivo insorgence of resistance was evaluated by MIC and BC determinations on the GABHS strain recovered from infected mice peritoneum, after treatment with 20 mg/kg roxithromycin. The roxithromycin serum kinetics was established in healthy and infected mice. Neither significant changes in GABHS MIC or BC after in vitro or in vivo exposure to roxithromycin nor a difference in roxithromycin serum levels between healthy and infected mice were detected, suggesting that the roxithromycin selection of resistance in GABHS is low.

Animals↗

Effect of roxithromycin on airway responsiveness in children with bronchiectasis: a double-blind, placebo-controlled study.

Increased airway responsiveness (AR) is frequently associated with bronchiectasis. Roxithromycin is a new semisynthetic macrolide antibiotic that also has anti-inflammatory activities. This study was designed to see whether roxithromycin could favourably alter the degree of AR in patients with bronchiectasis and increased AR. Twenty five children with bronchiectasis, who had an increased AR (defined as a provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) <25 mg x mL(-1) evaluated by the dosimeter method), were randomized, double-blind into two parallel groups. Thirteen of the children were treated with roxithromycin (4 mg x kg(-1) b.i.d.) for 12 weeks and 12 received placebo. FEV1, sputum purulence and leucocyte scores were assessed every 3 weeks. To estimate AR, high-dose methacholine challenge tests were performed before and after treatment. On the dose-response curve to methacholine, PD20 and maximal response (two indices of AR) were measured. Changes in FEV1 were not observed during the course of the study in both groups. A significant improvement in sputum features was noted after 6 weeks of treatment in the roxithromycin group. After 12 weeks of roxithromycin therapy, the geometric mean (range of 1 SD) of provocative cumulative dose producing a 20% fall in FEV1 (PD20) increased significantly (p<0.01) to 169.2 (83.2-344.2) breath units (BU) (1 BU denotes one inhalation of 1 mg x mL(-1) methacholine) and the mean+/-SD of maximal response decreased significantly (p<0.01) to 32.5+/-6.8%, as compared with the initial values (PD20 87.1 (47.3-160.4) BU; maximal response 40.9+/-7.4%). No significant changes in either parameter were observed in the placebo group. Our results indicate that roxithromycin may decrease the degree of airway responsiveness in patients with bronchiectasis and increased airway responsiveness. Further study is necessary to determine the mechanism by which roxithromycin reduces airway responsiveness in bronchiectasis and its clinical impact.

Adolescent↗

Three-day azithromycin compared with ten-day roxithromycin treatment of atypical pneumonia.

An open, randomized, multicentre study compared the efficacy and safety of 3-day azithromycin with 10-day roxithromycin for the treatment of atypical pneumonia. Azithromycin was administered 500 mg once daily to 90 and roxithromycin 150 mg bid to 60 patients. Causative pathogens were identified by serological methods. In the azithromycin treatment group, Mycoplasma pneumoniae was identified in 65, Chlamydia spp. in 9 and Coxiella burnetti in 1 patient. In the roxithromycin treatment group, M. pneumoniae was identified in 39, Chlamydia spp. in 9 and C. burnetti in 3 patients. 89 azithromycin and 53 roxithromycin patients were eligible for efficacy analysis. Clinical cure rate was 98.9% in the azithromycin and 94.3% in the roxithromycin treatment group. Adverse events were observed in 3 patients in each group. Azithromycin appears to be as effective as roxithromycin for the treatment of atypical pneumonia. The 3-day azithromycin regimen may offer an additional advantage over 10-day roxithromycin by virtue of its more convenient administration.

Adolescent↗

Economic analysis of treatment with roxithromycin in comparison with erythromycin in patients with lower respiratory tract infections.

A number of new antibiotics have lately become available for treatment of lower respiratory tract infections in out-patients. The new drugs are generally more expensive than the older ones, which might be justified by better effects, improved safety, or by other advantages. In this study, a retrospective economic analysis has been made using data from a previous trial comparing a new macrolide, roxithromycin, with an older 1, erythromycin stearate in the treatment of lower respiratory tract infections. The trial was multicentre, double blind, randomized and comparative. There were no significant differences in efficacy between treatments, although the cure rate was higher for roxithromycin, 85% vs 79% for erythromycin. 20/39 of the erythromycin-treated patients reported adverse events, vs 7/40 roxithromycin-treated subjects, a highly significant difference. More detailed information was obtained by reviewing the medical records of the participants, and from questionnaires distributed to the 3 centres that had included patients in the trial. Additional visits were found necessary for 4 patients treated with erythromycin and for 1 using roxithromycin. Using the healing rates in the present investigation, and including costs for initial drug treatments, second consultations, and failed therapy, average cost-effectiveness (SEK/patient cured) was 409 for roxithromycin-treated patients, and 488 for erythromycin-treated. Roxithromycin should then be cheaper than erythromycin stearate. With the same healing rate, roxithromycin would be less cost-effective, but indirect costs and effects on quality of life are not then taken into account.

Anti-Bacterial Agents↗

A comparative efficacy and safety study of clarithromycin, roxithromycin and erythromycin stearate in mild pneumonia.

The efficacy and safety of clarithromycin, roxithromycin and erythromycin stearate in mild pneumonia were compared in an open randomized trial. Eighty-six male patients, doing their obligatory military service, ranging between 19 and 24 years of age (mean 20), were randomly treated: 29 with clarithromycin 500 mg 12-hourly, 30 with roxithromycin 150 mg 12-hourly, and 27 with erythromycin stearate 500 mg 6-hourly, each course being administered for 10 days. Seventy-eight patients were able to be evaluated for efficacy, 28 receiving clarithromycin, 28 roxithromycin, and 22 erythromycin stearate. There were no significant differences among the groups in terms of clinical success rates (clinical cure or improvement: 89% for clarithromycin, 82% for roxithromycin, and 73% for erythromycin stearate, p = 0.32). However, we found that there were significant differences among the groups in terms of clinical cure rates (75% for clarithromycin, 64% for roxithromycin, and 41% for erythromycin stearate, p = 0.04). Adverse events, mostly gastrointestinal, caused discontinuation of treatment in 3.4% of the patients in the clarithromycin group, in 6.6% of the patients in the roxithromycin group, and in 18.5% of the patients in the erythromycin stearate group. The results indicate that there were no statistically significant differences among the three treatment groups in terms of clinical success rates, but that clarithromycin and roxithromycin were better tolerated.

Adult↗

[Comparison between colorimetry and HPLC on the stability test of roxithromycin].

AIM: To compare the stability of roxithromycin in solutions of different pH. METHODS: Roxithromycin solutions of different pH were prepared with water, simulate intestinal fluid (SIF) and simulate gastric fluid (SGF) shown to be the stability of these solutions were tested by colorimetry and HPLC. RESULTS: Roxithromycin was stable in water, SGF and SIF determined by colorimetry. However, it was found to be stable only in water and SIF but unstable in SGF as determined by HPLC. CONCLUSION: Roxithromycin is unstable in acidic medium like SGF. The metabolite of roxithromycin showed unfavorable interference on the assay of roxithromycin when colorimetry was used. Colorimetry can not be used for the determination and assay of roxithromycin in acidic solution like SGF.

Anti-Bacterial Agents↗

Roxithromycin, a new macrolide antibiotic, in the treatment of infections in the lower respiratory tract: an overview.

Roxithromycin is a new macrolide antibiotic with good absorption and a longer half-life than erythromycin. Worldwide clinical studies to evaluate its efficacy and safety in the treatment of infections of the lower respiratory tract have achieved a clinical success rate of 89% with few and mild side effects. Double-blind studies comparing roxithromycin with cephradine, erythromycin ethylsuccinate and doxycycline in pneumonia, acute exacerbations of bronchitis in patients with chronic obstructive airways disease, and acute bronchitis have been done. The clinical response to comparative regimens has been similar and ranges from 60% response with either regimen in patients with chronic airways disease to 90% response in patients with acute bronchitis or pneumonia. Roxithromycin appears to be as effective as erythromycin or doxycycline for the treatment of either Streptococcus pneumoniae or Haemophilus influenzae infections. A large double-blind trial comparing cephradine and roxithromycin in 90 cases of bacteriologically confirmed pneumococcal pneumonia in South African gold miners resulted in a 93% and 100% respective clinical response rate. The bacteriological results revealed interesting results in this same study, in that cultures from 17% of patients receiving roxithromycin and 23% of those receiving cephradine remained positive for S. pneumoniae after therapy was finished and an excellent clinical response had been obtained. Side effects in all studies have been transient and mild, with an elevated transaminase value being the most common in both roxithromycin and erythromycin or cephradine regimens. Roxithromycin appears to be a safe and effective oral antibiotic for the treatment of pneumococcal pneumonia and other infections of the lower respiratory tract, and is as effective as erythromycin, doxycycline or cephradine.

Humans↗

Comparative efficacy and toxicity of roxithromycin and erythromycin ethylsuccinate in the treatment of streptococcal pharyngitis in adults.

Roxithromycin is a novel oxime ether derivative of erythromycin. Previous studies have demonstrated similar in-vitro activity for roxithromycin and erythromycin. Roxithromycin has improved pharmacokinetic properties and may be a useful alternative agent for infections where erythromycin is indicated. We compared the efficacy and toxicity of roxithromycin and erythromycin ethylsuccinate in the treatment of streptococcal pharyngitis in adults. We also assessed compliance with treatment between the two agents. Roxithromycin and erythromycin ethylsuccinate were equally effective in resolving the symptoms and signs of pharyngitis. Erythromycin ethylsuccinate was superior to roxithromycin in achieving microbiological cure (90% vs. 33%, respectively). No differences were observed in toxicity or compliance with treatment between the two agents. Based on this prespective clinical trial, roxithromycin is not considered to be an acceptable alternative agent for acute streptococcal pharyngitis in adults.

Adolescent↗

No effect of roxithromycin on pharmacokinetic or pharmacodynamic properties of warfarin and its enantiomers.

The macrolide antibiotics are metabolized by cytochrome P-450 enzymes in the liver and interactions with similarly metabolized compounds have been described. Simultaneous treatment with erythromycin and warfarin is known to decrease warfarin clearance and prolong prothrombin time. Roxithromycin (RU 28965), a new erythromycin derivative with improved pharmacokinetic properties, might then, because of structure similarity, be expected to interact with warfarin. In 21 healthy volunteers, the effect of orally administered roxithromycin (150 mg b.i.d.) on warfarin steady-state kinetics, and the effects of warfarin on roxithromycin kinetics, were investigated in a double-blind, randomized study versus placebo. Since the warfarin enantiomers, R- and S-warfarin have both different potency and different metabolism, the ratio between the enantiomers with and without roxithromycin, was also determined. In this study, mean AUC for warfarin increased slightly from day 14 of warfarin treatment to day 28, but no difference was found between the roxithromycin group and the placebo group, and no change appeared in the ratio between the warfarin enantiomers. A moderate increase in dosage was needed to maintain hypocoagulability during warfarin medication, but there was no difference between the roxithromycin group and the placebo groups, respectively. In addition, roxithromycin kinetics appeared to be unaffected by warfarin treatment.

Adult↗

Roxithromycin (RU 965): effective therapy for experimental syphilis infection in rabbits.

Roxithromycin (RU 965), a new macrolide antibiotic, was shown to be effective for therapy of active syphilis in rabbits. Dark-field-positive lesions were produced in adult male rabbits by intradermal inoculation of approximately 10(6) Treponema pallidum organisms at each of 11 sites. Beginning 7 days after infection, six animals per group were treated with benzathine penicillin G (200,000 U, intramuscularly, weekly for 2 weeks) or roxithromycin (15 mg/kg of body weight, orally, twice daily for 15 days); six animals were not treated. Chancres in untreated animals were dark-field positive throughout the 16-day observation period; all benzathine penicillin-treated rabbits were dark-field negative 1 day after the initiation of therapy. Five of six animals treated with roxithromycin were dark-field negative on day 3 following the initiation of therapy; the sixth animal was dark-field negative by day 6. Lesions in untreated animals reached a mean (+/- standard deviation) maximum diameter of 14.7 +/- 1.91 mm compared with 8.4 +/- 3.6 mm for benzathine penicillin-treated (P less than 0.005) and 10.4 +/- 1.2 mm for roxithromycin-treated (P less than 0.001) animals. Ulceration occurred at 62 of 66 lesions in untreated animals compared with 0 of 66 lesions in each treated group. At 3, 6, and 12 weeks postinfection, Venereal Disease Research Laboratory antibody titers were significantly higher (P less than 0.05) in untreated than in treated animals. Titers in penicillin-treated versus roxithromycin-treated animals were significantly different at 6 weeks postinfection but not at 3 and 12 weeks postinfection. Transfer of tissue from treated rabbits to seronegative recipient animals did not reveal any evidence of persistent infection in the benzathine penicillin- or roxithromycin-treated animals. These findings indicate that benzathine penicillin and roxithromycin, at the doses indicated above, are effective in treating active syphilis in rabbit model.

Animals↗

Comparative Study of the Effects of Erythromycin and Roxithromycin on Action Potential Duration and Potassium Currents in Canine Purkinje Fibers and Rabbit Myocardium.

BACKGROUND: Erythromycin and roxithromycin are macrolide antibiotics in common clinical use. Erythromycin occasionally produces life-threatening arrhythmias (torsades de pointes) by blocking the outward potassium current responsible for repolarization of the cardiac action potential. METHODS AND RESULTS: We used standard cellular electrophysiological and whole-cell patch-clamping techniques to compare the relative efficacy of erythromycin and roxithromycin in prolonging cardiac action potential in canine Purkinje fibers and in blocking individual outward potassium currents in isolated rabbit ventricular myocytes. We demonstrated significant prolongation of action potential duration in canine Purkinje fibers by erythromycin but not roxithromycin at a concentration of 100 µM. The delayed rectifier, the outward potassium current thought to be most sensitive to modulation by drugs, was significantly depressed by both agents at concentrations of >/=30 µM in isolated rabbit ventricular myocytes. Both drugs had similar potencies (26% and 21% reduction by 30 µM erythromycin and roxithromycin, respectively, and 50% and 36% reduction by 100 µM erythromycin and roxithromycin). Neither agent significantly blocked other potassium currents (including the transient outward current). CONCLUSIONS: Taking into account normally observed peak blood concentrations of these agents in clinical use and the fact that roxithromycin is not normally administered intravenously, we conclude that the risk of proarrhythmia during normal clinical use of oral roxithromycin is extremely remote.

Journal Article↗

Antibacterial activity of roxithromycin: a laboratory evaluation.

Roxithromycin, formerly known as RU 28965 (9-[O [(2-methoxyethoxy)methyl]oxime]-erythromycin), is a novel 14 atom-membered semisynthetic macrolide with an antibacterial spectrum directed towards Gram-positive cocci and bacilli, Gram-negative cocci and some Parvobacteriaceae. The in vitro antibacterial activity of roxithromycin was compared with those of erythromycin and spiramycin against 275 clinical isolates by using 2-fold broth macro-dilution tests. The antibacterial spectrum of roxithromycin and erythromycin were qualitatively comparable (including the bacteriostatic type of activity and the profile of resistance), but minimal inhibitory concentrations of erythromycin were generally one half those of roxithromycin, except for Corynebacterium sp. and Bacteroides fragilis against which the new macrolide was more active. On the other hand, roxithromycin exhibited a superior in vivo antibacterial activity in laboratory animals, being up to six times more potent than erythromycin in curing experimentally infected mice. Roxithromycin showed high blood levels and long half-lives of elimination in rodents after oral administration, and its bioavailability amounted to 72% in mice and 85% in rats, compared to less than 10% for erythromycin. Roxithromycin was widely distributed throughout the body with a high degree of penetration into all tissues, particularly in the lungs.

Animals↗

[In vitro activity of roxithromycin, new semisynthetic macrolide against obligate anaerobes].

The "in vitro" susceptibility to roxithromycin and three other macrolides of 236 anaerobes isolated from clinical samples in 1984/1985 was determined by an agar-dilution method on Wilkins Chalgren medium. 90% of Gram positive cocci were susceptible to both roxithromycin and josamycin (MIC less than 1 mg/l, whereas 1 mg/l erythromycin and 2 mg/l spiramycin were able to inhibit respectively 46 and 86% of the same tested strains. No resistance to the four macrolides was observed among Eubacterium, propionibacterium and Bifidobacterium. Two C. perfringens strains and one C. difficile strain were resistant to all four macrolides, while 97% of Clostridium sp. strains were inhibited by 4 mg/l erythromycin, josamycin or roxithromycin. Against Gram positive anaerobes, roxithromycin was equal or superior to erythromycin and spiramycin. At a concentration of 4 mg/l, roxithromycin inhibited 82% of B. fragilis strains. Roxithromycin and josamycin were more active against Gram negative bacilli that erythromycin and spiramycin. Macrolides had no effect on Fusobacterium strains. In this study, 4 mg/l roxithromycin inhibited 217 of the 236 anaerobic strains investigated (92%).

Bacteria, Anaerobic↗