Clarithromycin in 2003: sustained efficacy and safety in an era of rising antibiotic resistance

In VitroInduction of Resistance by Tissue Concentrations of Azithromycin, Clarithromycin, Cefixime and Amoxicillin/Clavulanate in Clinical Isolates ofStreptococcus pyogenes

This study evaluated the effects of exposure to serum, tonsils and breakpoint drug concentrations of clarithromycin, azithromycin, cefixime and amoxicillin/clavulanate on Streptococcus pyogenes susceptibility. Frequency of mutation and development of resistance after ten passages on antibiotic gradient plates, followed by ten passages without antibiotic, were determined. Phenotypes of macrolide-resistant strains grown at the end of multi-step selection were also determined. Azithromycin induced a surge of resistant strains more rapidly and frequently than clarithromycin, particularly at tonsils concentrations. With amoxicillin/clavulanate no strains showed minimum inhibitory concentrations (MICs) higher than the susceptibility breakpoint. Mutational frequencies were higher for azithromycin, at serum and breakpoint drug concentrations, than for the other drugs. Most of the macrolide resistant strains showed an MLS(B) phenotype. In conclusion, the ability to prevent the occurrence of resistance in clinical isolates of S. pyogenes was similar for amoxicillin/clavulanate and clarithromycin followed by cefixime > azithromycin when tonsil drug concentrations were considered, and greater for amoxicillin/clavulanate followed by clarithromycin > cefixime> azithromycin, at breakpoint and serum concentrations.

Generic versus non-generic formulation of extended-release clarithromycin in patients with community-acquired respiratory tract infections: a prospective, randomized, comparative, investigator-blind, multicentre study

BACKGROUND AND OBJECTIVE

There is a general concern about the use of multisource (generic) antibacterials in the clinical setting with registration based solely on bioequivalence data. In order to address this concern, two modified-release formulations of clarithromycin (i.e. the originator Klacid XL and the generic Klarithran MR) were compared in patients with acute community-acquired respiratory tract infections.

METHODS

Patients presenting with tonsillopharyngitis, sinusitis or pneumonia were randomized to receive either of the test drugs provided they clinically qualified for empirical clarithromycin treatment. The study endpoints were clinical and bacteriological cure rates, tolerability and safety. The study was designed to test for non-inferiority with regard to cure rates.

RESULTS

The main outcome of this study was that both agents had similar clinical (non-inferior) and bacteriological cure rates and demonstrated no difference in tolerability in patients. The study also demonstrated the clinical efficacy of clarithromycin when used as empirical treatment in patients with respiratory tract infections in community practice (i.e. 95% clinical cure rate).

CONCLUSION

The clarithromycin extended-release multisource product (Klarithran MR) does not differ significantly from the originator (Klacid XL) and the clinical cure rate of the generic formulation is non-inferior to that of the originator. The two formulations are tolerated similarly.

Cost-effectiveness of empirical prescribing of antimicrobials in community-acquired pneumonia in three countries in the presence of resistance

OBJECTIVES

To assess the cost-effectiveness of empirical outpatient treatment options for community-acquired pneumonia (CAP) in France, the USA and Germany, representing high, moderate and low antimicrobial resistance prevalence, respectively.

METHODS

A decision analytic model was developed for mild-to-moderate CAP outpatient treatment. Treatment algorithms incorporated follow-up after treatment failure due to resistance or other reasons. First-line treatment included moxifloxacin, beta-lactams, macrolides or doxycycline; second-line treatment used a different antimicrobial class. Country-specific resistance and co-resistance prevalences to first- and second-line therapy for the major CAP pathogens were derived from surveillance studies. Clinical failure rates due to antimicrobial-susceptible and -resistant pathogens were obtained from the literature or estimated. Total costs were estimated using standard sources and a third-party payer perspective. Outcome measures included first-line clinical failures avoided, second-line treatments avoided and hospitalizations avoided. Incremental cost-effectiveness ratios (ICERs) were calculated.

RESULTS

First-line moxifloxacin treatment followed by co-amoxiclav dominated all other treatments in France, the USA and in Germany for all outcome measures. Sensitivity analyses maintained moxifloxacin dominance in France and the USA but affected ICERs in some cases in Germany.

CONCLUSIONS

Antimicrobial resistance/spectrum have a significant impact on outcomes and costs in empirical outpatient CAP treatment. Despite low acquisition costs for generic antibiotics, first-line treatment effective against the major CAP pathogens, including strains resistant to other antimicrobials, resulted in better clinical outcomes in all countries and lower treatment costs for all.

Clinical implications of macrolide resistance in community-acquired respiratory tract infections

Laboratory surveillance data suggest that macrolide resistance among Streptococcus pneumoniae has increased dramatically over the past 15 years. This review examines the specifics of macrolide resistance and the clinical relevance of in vitro susceptibility testing in light of the pharmacokinetics and pharmacodynamics of azithromycin and clarithromycin. These drugs concentrate extensively within respiratory tissue and have other positive characteristics not reflected by in vitro susceptibility testing. In general, clarithromycin is the most potent macrolide and the one most likely to maintain clinical efficacy against the low-level resistance associated with most macrolide-resistant pneumococci in the USA. These findings suggest that susceptibility data may underestimate clinical utility and that clarithromycin still has a place in the empiric treatment of respiratory infections.

Role for 5-day, once-daily extended-release clarithromycin in acute bacterial exacerbation of chronic bronchitis

BACKGROUND

Clarithromycin is commonly dosed for 7 or more days in patients with acute bacterial exacerbation of chronic bronchitis (ABECB). Studies with other antibiotics have shown equivalent efficacy, reduced/similar frequency of adverse events, improved adherence and patient satisfaction, and lower treatment costs with a shorter treatment course.

PATIENTS AND METHODS

The study population was derived from two multicenter, randomized, double-blind (North America)/single-blind (France) comparative trials in which outpatients at least 35 years old with a presumptive diagnosis of obstructive ABECB were randomized to receive clarithromycin extended-release (ER) 1000 mg once daily for 5 days or a comparator agent--clarithromycin immediate-release (IR) 500 mg twice daily for 7 days (in North America) or telithromycin 800 mg once daily for 5 days (in France).

RESULTS

A total of 818 patients were randomized (411 to clarithromycin ER and 407 to a comparator agent). The clinical cure rate in clinically evaluable patients at the follow-up visit was 90% each for the clarithromycin ER group (318/353) and the comparator group (318/355). The patient bacteriological cure rate and the overall target pathogen eradication rate in clinically and bacteriologically evaluable patients were each 92% for the clarithromycin ER group (155/168 and 189/205, respectively) and 93% for the comparator group (147/158 and 183/197, respectively) at the follow-up visit. The study drugs were generally well tolerated, with < 2% of patients discontinuing their treatment prematurely due to a drug-related adverse event. The incidence of drug-related adverse events was 18% (73/411) in the clarithromycin ER group and 24% (97/407) in the comparator group. Clarithromycin ER-treated patients reported statistically significantly fewer episodes of abdominal pain than did patients treated with a comparator agent (0.2% vs. 1.7%, respectively; p = 0.037). This combined analysis is limited by differing blinding methods, comparator agents, and their duration of administration. Furthermore, many patients were excluded from the clinically and bacteriologically evaluable group due to lack of a pretreatment target pathogen.

CONCLUSION

A once daily, 5-day clarithromycin ER regimen appears to be a suitable choice for treating patients with ABECB.

Optimizing the management of community-acquired respiratory tract infections in the age of antimicrobial resistance

Community-acquired respiratory tract infections (CARTIs) are the most common reason for prescribing antibiotics in the primary care setting. However, over the last decade, the management of CARTIs has become increasingly complicated by the steady increase in prevalence of drug-resistant pathogens responsible for these infections. As a result, significant attention has been directed at understanding the mechanisms of pathogen acquisition of resistance, drivers of resistance and methods for preventing the development of resistance. Data from recent surveillance studies suggest a slowing or decline in resistance rates to agents, such as beta-lactams, macrolides, tetracyclines and folic acid metabolism inhibitors. However, resistance to one antimicrobial family--the fluoroquinolones--while still low, appears to be on the increase. This is of significant concern given the rapid increase in resistance noted with older antibiotics in recent history. While the clinical implications of antibacterial resistance are poorly understood, the overall rates of antimicrobial resistance, as reported in recent surveillance studies, do not correspond to current rates of failure in patients with CARTIs. This disconnection between laboratory-determined resistance and clinical outcome has been termed the in vitro-in vivo paradox and several explanations have been offered to explain this phenomenon. Solving the problem of antimicrobial resistance will be multifactorial. Important factors in this effort include the education of healthcare providers, patients and the general healthcare community regarding the hazards of inappropriate antibiotic use, prevention of infections through vaccination, development of accurate, inexpensive and timely point-of-care diagnostic tests to aid in patient assessment, institution of objective treatment guidelines and use of more potent agents, especially those with a focused spectrum of activity, earlier in the treatment of CARTIs as opposed to reserving them as second-line treatment options. Ultimately, the single-most important factor will be the judicious use of antibiotics, as fewer antibiotic prescriptions lead to fewer antimicrobial-resistant bacteria.

Comparison of clarithromycin and ciprofloxacin therapy for Bacillus anthracis Sterne infection in mice with or without 60Co gamma-photon irradiation

Biological agents and ionizing radiation lead to more severe clinical outcomes than either insult alone. This study investigated the survival of non-irradiated and (60)Co-gamma-irradiated mice given therapy for inhalation anthrax with ciprofloxacin (CIP) or a clinically relevant mixture of clarithromycin (CLR) and its major human microbiologically important metabolite 14-hydroxy clarithromycin (14-OH CLR). All B6D2F1/J 10-week-old female mice were inoculated intratracheally with 3 x 10(8) c.f.u. of Bacillus anthracis Sterne spores 4 days after the non-lethal 7 Gy dose of (60)Co gamma radiation. Twenty-one days of treatment with CLR/14-OH CLR, 150 mg kg(-1) twice daily, or CIP, 16.5 mg kg(-1) twice daily, began 24 h after inoculation. Pharmacokinetics indicate that the area under the curve (AUC) for 14-OH CLR on the concentration-versus-time graph was slightly higher in gamma-irradiated than non-irradiated animals. Neither drug was able to increase survival in gamma-irradiated animals. CIP and CLR/14-OH CLR therapies in non-irradiated animals increased survival from 49 % (17/35 mice) in buffer-treated animals to 94 % (33/35) and 100 %, respectively (P < 0.001). B. anthracis Sterne only was isolated from 25-50 % of treated mice with or without irradiation. Mixed infections with B. anthracis Sterne were present in 50-71 % of gamma-irradiated mice but only in 5-10 % of mice without irradiation.

Efficacité et tolérance de la clarithromycine, forme à libération modifiée en traitement court de cinq jours dans les exacerbations aiguës de bronchite chronique, comparativement à la télithromycine

BACKGROUND

The extended-release formulation of clarithromycin (CLA-ER) allows using this macrolide as a single daily dose. The purpose of this study was to evaluate the efficacy and safety of the CLA-ER formulation (500 mgx2) vs telithromycin (TELI) (400 mgx2) as a short course 5-day treatment, once a day, in patients with AECB.

METHOD

This randomized double-blind study was conducted in patients with AECB without severe airflow limitation (FEV1>35%), with sputum purulence (mandatory criterion), and with either increased sputum volume or increased dyspnea, or both (Anthonisen criteria I or II).

RESULTS

Three hundred sixty-two patients were assessed (62.6 years of age+/-12.9, men: 58.8%) positive culture on inclusion for 53.8%, with Haemophilus influenzae (N=57), Moraxella catarrhalis (N=42), and Streptococcus pneumoniae (N=41). In the per protocol population, the clinical success rate at day 8 was 97% (161/166) vs 97% (146/151), 97.5% CI=[-4.12 -4.71], the clinical cure rate at day 30 was 78% (129/166) versus 77% (116/151), P=0.85, and mean time without recurrence was 62 days versus 61 days (P=0.51), in CLA-ER and TELI groups, respectively. Fourteen patients in the CLA-ER group (8.2%) and 20 patients in the TELI group (12.4%) experienced at least one treatment-related adverse event (P=0.21), upon which gastrointestinal events were the most commonly reported treatment-related ones.

CONCLUSION

CLA-ER (1000 mg once a day) for 5 days is at least as effective as telithromycin in the treatment of AECB without severe airflow limitation and is well tolerated.

Comparative efficacy of once daily, 5-day short-course therapy with clarithromycin extended-release versus twice daily, 7-day therapy with clarithromycin immediate-release in acute bacterial exacerbation of chronic bronchitis

OBJECTIVE

The objective of this study was to compare the efficacy, tolerability, and safety of two clarithromycin regimens, extended-release (ER) 1000 mg once daily for 5 days and immediate-release (IR) 500 mg twice daily for 7 days, in the treatment of acute bacterial exacerbation of chronic bronchitis (ABECB).

PATIENTS AND METHODS

This was a double-blind, randomized, parallel-group, multicenter study of ambulatory patients at least 40 years old with a presumptive diagnosis of ABECB, purulent sputum, and documented evidence of chronic obstructive pulmonary disease (COPD), including forced expiratory volume in one second (FEV(1)) < 70% of predicted value. Clinical cure, bacteriological cure, and target pathogen eradication rates were determined at a test-of-cure visit (study days 14-40). Safety was assessed based on the incidence of study drug-related adverse events.

RESULTS

A total of 485 patients were randomized (240 to ER and 245 to IR). Clinical cure rates were similar for evaluable patients treated with ER (84%, 157/187) and those treated with IR (84%, 172/204) (95% CI -7.9, 7.2). The bacteriological cure rates were 87% (82/94) and 89% (91/102), and the overall target pathogen eradication rates were 88% (107/122) and 89% (117/131) for the respective treatment groups. The incidence of adverse events was 13% (31/240) in the ER group and 18% (45/245) in the IR group. The rate of gastrointestinal adverse events was lower with ER (8%, 19/240) compared to IR (11%, 26/245). Clarithromycin ER-treated patients reported statistically significantly fewer adverse events due to abnormal taste than did clarithromycin IR-treated patients (3% and 8%, respectively, p = 0.012).

CONCLUSION

Both once-daily, 5-day, short-course therapy with clarithromycin ER and 7-day, twice-daily therapy with clarithromycin IR were effective in resolving clinical signs/symptoms of ABECB and eradicating the causative pathogens, with no statistically significant difference in clinical cure rate between the treatment groups. Clarithromycin ER was better tolerated, causing fewer gastrointestinal adverse events and statistically significantly fewer reports of abnormal taste as compared with clarithromycin IR.