In vitro study of the post-antibiotic effect and the bactericidal activity of Cefditoren and ten other oral antimicrobial agents against upper and lower respiratory tract pathogens

In vivo Pharmacokinetics/Pharmacodynamics Profiles for Appropriate Doses of Cefditoren pivoxil against S. pneumoniae in Murine Lung-Infection Model

PURPOSE

Cefditoren, the active form of cefditoren pivoxil, is an oral cephalosporin antimicrobial drug. Although cefditoren exhibits high antimicrobial activity against Streptococcus pneumoniae, its pharmacokinetics/pharmacodynamics (PK/PD) characteristics remain unknown. This study aimed to determine its PK/PD parameter with target values for cefditoren against S. pneumoniae in S. pneumoniae lung-infected mice and to simulate MIC range of S. pneumoniae that can be expected to be treated at approved cefditoren doses in human using population pharmacokinetic (PPK) data from patients.

METHODS

Susceptibility testing and time-kill assays against S. pneumoniae ATCC® 49619 were performed for in vitro PD evaluation. Based on the results of a PK study in healthy mice and PD studies in S. pneumoniae lung-infected mice, optimal PK/PD parameters were determined using the correlation curve between the PK/PD parameters and lung bacterial count changes. The target value was calculated to achieve a 2 log10 reduction in the lung bacterial counts.

RESULTS

In vitro PD evaluation showed that cefditoren had a potent antimicrobial effect against S. pneumoniae in a time-dependent manner at concentrations above the MIC. In PK/PD analyses, both fAUC24/MIC and fCmax/MIC were well correlated with bactericidal efficacy, achieving 2 log10-kill with fAUC24/MIC ≥ 63 and fCmax/MIC ≥ 16.

CONCLUSIONS

Cefditoren pivoxil has good therapeutic efficacy against acute pneumonia caused by S. pneumoniae with a MIC ≤ 0.031-0.063 mg/L at approved doses in adults and children.

Cefditoren versus levofloxacin in patients with exacerbations of chronic bronchitis: serum inflammatory biomarkers, clinical efficacy, and microbiological eradication

Background

The aim of this open-label, randomized, parallel-group pilot study was to evaluate the efficacy of cefditoren pivoxil and levofloxacin in terms of speed of reduction in inflammatory parameters, clinical recovery, and microbiological eradication.

Methods

Forty eligible patients with acute exacerbation of chronic bronchitis (AECB) were randomized to receive cefditoren 200 mg twice a day for 5 days (n = 20) or levofloxacin 500 mg once daily for 7 days (n = 20).

Results

The inflammatory parameters which were significantly reduced at test-of-cure with respect to visit 1 were Krebs von den Lundgen-6 (KL-6) and interleukin-6. KL-6 decreased both in the overall study population (from 19 ± 11 UI/mL to 6 ± 8 UI/mL, P = 0.000) and in the cefditoren (from 19 ± 13 UI/mL to 8 ± 10 UI/mL, P = 0.006) and levofloxacin (from 19 ± 10 UI/mL to 5 ± 5 UI/mL, P = 0.000) arms. Similarly, interleukin-6 decreased both in the overall study population (from 13.35 ± 16.41 pg/mL to 3 ± 4.7 pg/mL, P = 0.000) and in the cefditoren (from 15.90 ± 19.54 pg/mL to 4.13 ± 6.42 pg/mL, P = 0.015) and levofloxacin (from 10.80 ± 12.55 pg/mL to 1.87 ± 1.16 pg/mL, P = 0.003) arms. At the end of treatment (test-of-cure, 6–9 days after drug initiation), the clinical success rate in the overall study population was 78%; the clinical cure rate was 80% in the cefditoren arm and 75% in the levofloxacin arm. Globally, bacteriological eradication at test-of-cure was obtained in 85% of the overall study population. Both treatments were well tolerated.

Conclusion

Cefditoren represents a valid option in the treatment of mild to moderately severe cases of AECB in the outpatient care setting. Moreover, the use of this cephalosporin is associated with a significant reduction of interleukin-6 and KL-6, two key mediators of lung inflammation and epithelial damage.

Clarithromycin Extended-Release Tablet

Clarithromycin is an orally active, advanced-generation macrolide that has been reformulated as an extended-release tablet (Biaxin) XL Filmtab allowing convenient once-daily administration. The reformulation is intended to improve patient compliance and the tolerability of the drug. Although maximum plasma clarithromycin concentrations are lower and reached later with the extended-release tablets than with the immediate-release tablets, the two formulations are bioequivalent with respect to the area under the plasma concentration-time curve. Bioequivalence is also achieved between the formulations for the microbiologically active metabolite, 14-hydroxy-clarithromycin. Two randomized trials in patients with acute exacerbations of chronic bronchitis (AECB) showed that a 7-day course of clarithromycin extended-release 1000 mg once daily produced clinical cure rates of 83% and 85% and bacteriologic cure rates of 86% and 92% at the test-of-cure study visit. Similar rates of cure were achieved with a 7-day course of twice-daily clarithromycin immediate-release and with a 10-day course of twice-daily amoxicillin/clavulanic acid.A 7-day course of clarithromycin extended-release 1000 mg once daily produced clinical and bacteriologic cure rates of 88% and 86%, respectively, in patients with community-acquired pneumonia (CAP). Similar cure rates were achieved in recipients of once-daily levofloxacin in the same trial. In patients with acute maxillary sinusitis, a 14-day course of either once-daily clarithromycin extended-release or twice-daily clarithromycin immediate-release produced statistically equivalent clinical cure rates of 85% and 79%, respectively. Both treatment groups achieved similar rates of radiographic success and resolution of sinusitis. Recent results indicate that clarithromycin extended-release 500 mg once daily for 5 days is also effective in the treatment of patients with streptococcal pharyngitis/tonsillitis and in the treatment of AECB. The most frequently reported drug-related events with clarithromycin extended-release were abnormal taste (7% incidence), diarrhea (6%) and nausea (3%). Most adverse drug reactions were of a mild and transient nature. In comparative clinical trials, clarithromycin extended-release had an improved gastrointestinal tolerability profile compared with the immediate-release formulation. In addition, clarithromycin extended-release was better tolerated than amoxicillin/clavulanic acid and as well tolerated as levofloxacin. Further studies are required to assess the cost-effectiveness ratio of clarithromycin relative to comparator antibacterial agents.

CONCLUSION

Clarithromycin extended-release is an effective treatment for AECB, CAP, acute maxillary sinusitis, and pharyngitis (although not approved for the latter in the US), and is administered in a convenient dosage regimen that has the potential to encourage good compliance. The reformulation modulates clarithromycin absorption kinetics thereby improving tolerability. Therefore, clarithromycin extended-release provides a useful option for the treatment of specific respiratory tract infections.

Cefditoren versus community-acquired respiratory pathogens: time-kill studies

The time-kill method was used to determine the bactericidal activity of cefditoren compared with oral cephalosporins, amoxicillin, amoxicillin/clavulanate and levofloxacin against a randomly selected group of strains isolated from community-acquired respiratory tract infections (CARTIs). Cefditoren was the only agent showing significant bactericidal activity (>or=3 log(10 )reduction of viable cells) within 4 h against all Streptococcus pneumoniae strains, both penicillin-susceptible (PEN S) or -resistant (PEN R), as well as against Streptococcus pyogenes, and Moraxella catarrhalis. Against beta-lactamase positive strains of Haemophilus influenzae, cefditoren was comparable to the quinolone and more active than other cephalosporins at 24 h. Cefditoren showed the best killing kinetic profiles and this observation may be important when choosing an oral third-generation cephalosporin as initial or sequential therapy.

In vitro activity of cefditoren: antimicrobial efficacy against major respiratory pathogens from Asian countries

In this study we evaluated the in vitro activities of cefditoren and 14 other comparator agents against 1025 isolates of major respiratory tract pathogens including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae and Staphylococcus aureus. Bacterial isolates were collected from 11 Asian countries. The majority of S. pneumoniae isolates (98.8%) were susceptible to cefditoren. The MIC(50) and MIC(90) values (minimum inhibitory concentrations for 50% and 90% of the organisms, respectively) of S. pneumoniae were <or=0.06 microg/mL and 1 microg/mL, respectively. These values were 2-32-fold lower than those of the other cephalosporins. Activity against S. pneumoniae was observed irrespective of penicillin or macrolide resistance. Cefditoren was also active against methicillin-susceptible S. aureus (100% susceptible; MIC(90)=1 microg/mL), H. influenzae (100% susceptible; MIC(90)<or=0.016 microg/mL) and M. catarrhalis (MIC(90)=0.016 microg/mL). However, the cefditoren MIC(90) of K. pneumoniae reached only 64 microg/mL (81.4% susceptible), which may be due to the high incidence of extended-spectrum beta-lactamases in Asian countries. Therefore, cefditoren should be considered as a therapeutic option for the treatment of respiratory tract infections in Asian countries.

Mechanisms by which antibiotics promote dissemination of resistant pneumococci in human populations

Mechanisms by which antimicrobials contribute to dissemination of pneumococcal resistance are incompletely characterized. A serial cross-sectional study of nasopharyngeal pneumococcal carriage in healthy, home-living children <or=6 years of age was conducted in four rural communities-two in Utah (1998-2003) and two in Idaho (2002-2003). Prevalence odds ratios for carriage of resistant pneumococci (OR(res)) and of susceptible pneumococci (OR(sus)) were estimated. Dynamic transmission models were developed to facilitate a mechanistic interpretation of OR(res) and OR(sus) and to compare the population impact of distinct antimicrobial classes. A total of 5,667 cultures were obtained; 25% of the cultures were positive, and 29% of isolates exhibited reduced susceptibility to penicillin. The adjusted OR(res) for recent individual and sibling cephalosporin use was 2.2 (95% confidence interval: 1.4, 3.4) and 1.8 (95% confidence interval: 1.0, 3.3), respectively. Neither individual nor sibling penicillin use was associated with increased OR(res). Rather, recent use of penicillins was associated with decreased carriage of susceptible pneumococci (OR(sus) = 0.2, 95% confidence interval: 0.1, 0.3). In simulations, both types of effects promoted dissemination of resistant pneumococci at the population level. Findings show that oral cephalosporins enhance the risk of acquiring resistant pneumococci. Penicillins accelerate clearance of susceptible strains. The effect of penicillins in increasing resistance is shared equally by treated and untreated members of the population.

Cefditoren pivoxil: a review of its use in the treatment of bacterial infections

Cefditoren pivoxil (Spectracef, Meiact) is a third-generation oral cephalosporin with a broad spectrum of activity against pathogens, including both Gram-positive and -negative bacteria, and is stable to hydrolysis by many common beta-lactamases. Cefditoren pivoxil is approved for use in the treatment of acute exacerbations of chronic bronchitis (AECB), mild-to-moderate community-acquired pneumonia (CAP), acute maxillary sinusitis, acute pharyngitis/tonsillitis and uncomplicated skin and skin structure infections (indications may differ between countries). In clinical trials in adults and adolescents, cefditoren pivoxil demonstrated good clinical and bacteriological efficacy in AECB, CAP, acute maxillary sinusitis, acute pharyngitis/tonsillitis and uncomplicated skin and skin structure infections and was generally well tolerated. Thus, cefditoren pivoxil is a good option for the treatment of adult and adolescent patients with specific respiratory tract or skin infections, particularly if there is concern about Streptococcus pneumoniae with decreased susceptibility to penicillin, or beta-lactamase-mediated resistance among the common community-acquired pathogens.

Cefditoren pivoxil versus cefpodoxime proxetil for community-acquired pneumonia: results of a multicenter, prospective, randomized, double-blind study

BACKGROUND

According to recently issued treatment guidelines, appropriate empiric choices for ambulatory patients with community-acquired pneumonia (CAP) are a macrolide, doxycycline (for patients aged > or = 8 years), or an oral beta-lactam agent with good activity against pneumococci.

OBJECTIVE

This study was designed to compare cefditoren pivoxil, a new beta-lactam, with cefpodoxime proxetil, a beta-lactam with an established role in the treatment of CAP.

METHODS

This was a multicenter, prospective, randomized, double-blind study conducted in the United States and South Africa. Ambulatory patients with a diagnosis of CAP were randomized to 14 days of treatment with cefditoren 200 or 400 mg BID or cefpodoxime 200 mg BID. Assessments of clinical cure and pathogen eradication were conducted at 2 visits during treatment, 1 posttreatment visit (s48 hours after completion of treatment), and 1 follow-up visit (7-14 days after completion of treatment). The development of resistant pathogens was assessed at the follow-up visit but not thereafter. The relative cost of treatment was not assessed.

RESULTS

The study enrolled 851 patients. Comparable clinical cure rates were observed among evaluable patients in the 3 treatment groups at both the posttreatment and followup visits: at the posttreatment visit, cure rates were 90.5% (162/179) for cefditoren 200 mg, 89.7% (148/165) for cefditoren 400 mg, and 92.2% (153/166) for cefpodoxime 200 mg; at the follow-up visit, they were a respective 88.4% (160/181), 87.2% (143/164), and 90.4% (151/167). Of the 171 strains of Streptococcus pneumoniae isolated before treatment, 22 (12.9%) had reduced susceptibility to penicillin, 5 (2.9%) of them penicillin resistant (minimum inhibitory concentration > or = 2 microg/mL). At the posttreatment visit, the overall eradication rates of pathogens isolated from microbiologically evaluable patients were 88.7% (134/151), 89.9% (134/149), and 95.7% (134/140) in the respective treatment groups (P = 0.031, cefditoren 200 mg vs cefpodoxime). Eradication rates of S pneumoniae were 93.8% (45/48), 95.7% (45/47), and 95.6% (43/ 45) in the respective treatment groups; those of Haemophilus influenzae were 90.2% (46/51), 97.7% (43/44), and 97.4% (37/38). The rates of resolution and/or improvement in clinical signs and symptoms were comparable between groups. The study drugs were well tolerated, with 1.7%, 2.5%, and 1.4% of patients in the respective groups discontinuing study drug prematurely due to a treatment-related adverse event, the majority of these associated with the digestive system.

CONCLUSION

The results of this study suggest that cefditoren may have a role in the treatment of CAP in ambulatory patients.

Cefditoren, a new aminothiazolyl cephalosporin

Cefditoren pivoxil, an oral third-generation cephalosporin, was approved by the Food and Drug Administration in September 2001. It has been used in Japan for several years. The greatest therapeutic potential of cefditoren appears to be its activity against gram-positive and gram-negative organisms causing respiratory tract infections and skin and skin-structure infections, such as Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis. Cefditoren is also effective against methicillin-susceptible strains of Staphylococcus aureus. Nevertheless, cefditoren has no activity against atypical pathogens, including Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella sp. Moreover, cefditoren does not inhibit Pseudomonas aeruginosa or Bacteroides fragilis. In virtually all studies, cefditoren has compared favorably against other orally administered antibiotics used against the most commonly isolated respiratory tract pathogens. Its side effect profile includes diarrhea, nausea, vomiting, headache, and dyspepsia. Cefditoren is indicated for treatment of mild-to-moderate acute exacerbations of chronic bronchitis, pharyngitis-tonsillitis, and uncomplicated skin and skin-structure infections caused by susceptible strains of organisms in adults and adolescents (> or = 12 yrs of age). Based on its reported antimicrobial activity, cefditoren has potential for empiric management of most commonly encountered respiratory tract infections. Additional studies will further define its role in clinical practice.

Randomized, double-blind, multicenter comparison of oral cefditoren 200 or 400 mg BID with either cefuroxime 250 mg BID or cefadroxil 500 mg BID for the treatment of uncomplicated skin and skin-structure infections

BACKGROUND

Uncomplicated skin and skin-structure infections are commonly observed in medical practice. Because these infections typically are confined to the superficial layers and seldom lead to the destruction of skin structures and resultant systemic dissemination, in general they can be treated with an oral antibiotic with potent microbiologic activity against gram-positive pathogens.

OBJECTIVE

This paper compares the efficacy and tolerability of 3 beta-lactam antibiotics in patients with uncomplicated skin and skin-structure infections.

METHODS

Two double-blind, multicenter, parallel-group studies were conducted, in which patients aged > or = 12 years with uncomplicated skin and skin-structure infections were randomized to receive cefditoren 200 or 400 mg, cefuroxime 250 mg, or cefadroxil 500 mg, each BID for 10 days. Study 1 compared cefditoren with cefuroxime; Study 2 compared cefditoren with cefadroxil. Clinical and microbiologic responses were assessed at a posttreatment visit (within 48 hours of treatment completion) and test-of-cure visit (7-14 days after treatment completion). Patients were monitored closely throughout the study with the use of physical examinations, clinical laboratory tests, and assessment of adverse events.

RESULTS

A total of 1,685 patients (855 males, 830 females; mean age, 41.1 years [range, 12-95 years]) were enrolled. Within both studies, the 3 treatment groups were similar at baseline based on demographic characteristics and types of infection. Cellulitis (26%), wound infection (25%), and simple abscess (15%) were the most common infections. Clinical cure rates at the test-of-cure visit were 85% (443/523) for cefditoren 200 mg, 83% (427/516) for cefditoren 400 mg, 88% (234/265) for cefuroxime, and 85% (211/248) for cefadroxil. At the test-of-cure visit, cefditoren 200 mg had eradicated significantly fewer of the causative pathogens isolated before treatment in microbiologically evaluable patients than did cefuroxime in Study 1 (P = 0.043) but significantly more of the pathogens than did cefadroxil in Study 2 (P = 0.018). Eradication rates for the most commonly isolated pathogens were generally similar in the 3 treatment groups in both studies, with the only significant difference favoring cefditoren 200 and 400 mg over cefadroxil for Peptostreptococcus species in Study 2 (P = 0.016 and P = 0.003, respectively). A minority of patients (< or = 5% in any treatment group) discontinued study-drug treatment prematurely due to a treatment-related adverse event, with statistically higher rates for cefditoren 400 mg than for cefditoren 200 mg and the comparator cephalosporins (each P < 0.05). All 3 cephalosporins were generally well tolerated. Most adverse events (>93%) were categorized as mild to moderate, with the most common being diarrhea, nausea, and headache.

CONCLUSION

In this population of patients with uncomplicated skin and skin-structure infections, including those due to Staphylococcus aureus or Streptococcus pyogenes, the clinical cure rate and tolerability of cefditoren were comparable to those of cefuroxime and cefadroxil.

Cefditoren pivoxil

Cefditoren pivoxil is an orally absorbed prodrug that is rapidly hydrolysed by intestinal esterases to the microbiologically active cephalosporin cefditoren. Cefditoren has a broad spectrum of activity against Gram-positive and Gram-negative bacteria, including common respiratory and skin pathogens. Cefditoren has shown excellent in vitro activity against the Gram-positive pathogens penicillin-susceptible and -intermediate Streptococcus pneumoniae, S. pyogenes and methicillin-susceptible Staphylococcus aureus. Cefditoren was inactive against methicillin-resistant S. aureus. Of the important Gram-negative pathogens, cefditoren had potent antibacterial effects against beta-lactamase-positive and -negative Haemophilus influenzae, H. parainfluenzae and beta-lactamase-positive and -negative Moraxella catarrhalis. Cefditoren does not have antibacterial activity against Pseudomonas aeruginosa or atypical respiratory pathogens and has only variable activity against anaerobes. In healthy volunteers, single doses of cefditoren pivoxil 200 and 400mg achieved maximal plasma concentrations of 2.6 to 3.1 mg/L and 3.8 to 4.6 mg/L, respectively. Cefditoren penetrates rapidly into bronchopulmonary and tonsillar tissue as well as inflammatory and noninflammatory blister fluid. In two, randomised, double-blind trials involving patients with acute exacerbations of chronic bronchitis (AECB), cefditoren 200 and 400mg twice daily for 10 days produced clinical cure rates of 88 to 89% within 48 hours of treatment completion. Clinical cure rates in patients with AECB were similar to those of either clarithromycin 500mg twice daily or cefuroxime axetil 250mg twice daily. In patients with streptococcal pharyngitis, a 10-day course of cefditoren pivoxil 200mg twice daily produced clinical cure rates of 94% at 4 to 7 days after treatment, which were similar to those observed for phenoxymethylpenicillin potassium 250 mg four times daily. In uncomplicated skin and skin structure infections, a 10-day course of cefditoren pivoxil 200 or 400mg twice daily produced the same clinical cure rate of 89% within 48 hours of treatment completion. These cefditoren pivoxil dosage regimens were as effective as a 10-day course of either cefadroxil 500 mg twice daily or cefuroxime axetil 250mg twice daily in treating uncomplicated skin and skin structure infections, including those caused by S. aureus and S. pyogenes. The most common adverse events associated with therapeutic doses of cefditoren pivoxil are diarrhoea, nausea, headache, abdominal pain and vaginal candidiasis.

Cefditoren Pivoxil

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Review of cefditoren, an advanced-generation, broad-spectrum oral cephalosporin

BACKGROUND

Cefditoren is an advanced-generation, broad-spectrum cephalosporin antibiotic approved for the treatment of acute bacterial exacerbation of chronic bronchitis (AECB), group A beta-hemolytic streptococcal pharyngotonsillitis, and uncomplicated skin/skin structure infections in adult and adolescent patients.

OBJECTIVE

This article briefly reviews the chemistry, antimicrobial activity, pharmacokinetics, efficacy, and safety of cefditoren.

METHODS

Literature was identified by a MEDLINE search (January 1985 to October 2001) of the medical literature, review of the English-language literature, reference lists within these articles, as well as data presented at the 40th Interscience Conference on Antimicrobial Agents and Chemotherapy.

RESULTS

Cefditoren has a broad spectrum of activity against many gram-negative and gram-positive aerobes, including Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis. Cefditoren is stable to hydrolysis by many common beta-lactamases. Cefditoren is rapidly absorbed (time to peak plasma concentration, approximately 2-3 hours) from the gastrointestinal tract and is almost completely eliminated via renal clearance of unchanged drug. The terminal disposition half-life of the compound is approximately 0.8 to 1.3 hours.

CONCLUSIONS

Cefditoren is effective in the management of AECB (in regimens of 400 mg twice daily for 10 days) and acute maxillary sinusitis, pharyngotonsillitis due to S pyogenes, and uncomplicated skin/skin structure infections (in regimens of 200 mg twice daily for 10 days). Cefditoren possesses broad activity against common pathogens of the respiratory tract and skin and is stable in the presence of numerous beta-lactamases. Its pharmacokinetic properties, in conjunction with in vitro susceptibility data, document the feasibility of twice-daily dosing.