Management of chronic bronchitis and acute exacerbations of chronic bronchitis

Utility of NT-proBNP for identifying LV failure in patients with acute exacerbation of chronic bronchitis

BACKGROUND

NT-proBNP has been widely regarded as a useful tool for diagnosis or exclusion of heart failure (HF) in many settings. However, in patients with acute exacerbation of chronic bronchitis (AECB), its roles have not been well described. The objective of this study was to evaluate the diagnostic performance of NT-proBNP for identifying left ventricular (LV) failure in such patients.

METHODS AND RESULTS

311 AECB patients and 102 stable chronic bronchitis patients with no history of HF were enrolled. Plasma NT-proBNP concentrations were measured using Roche Elecsys. The European Society of Cardiology (ESC) diagnostic principles were adopted to identify HF and the diagnostic performance of NT-proBNP was evaluated by ROC. Our results showed, the median NT-proBNP level in patients with LV failure [4828.4 (2044.4-9203.6) ng/L] was significantly higher than that in those without LV failure [519.2 (179.1-1409.8) ng/L, p<0.001] and stable controls [207.5 (186.5-318.2) ng/L, p<0.001]. LV failure, renal function, atrial fibrillation and systolic pulmonary artery pressure were independent predictors of NT-proBNP levels (all p<0.05). The area under ROC curve (AUC) of NT-proBNP for identifying LV failure was 0.884, significantly superior to clinical judgment alone (AUC 0.835, p = 0.0294). At the optimal cutoff value of 935.0 ng/L, NT-proBNP yielded sensitivity 94.4%, specificity 68.2%, accuracy 74.3% and negative predictive value 97.6%. Adding the results of NT-proBNP to those of clinical judgment improved the diagnostic accuracy for LV failure.

CONCLUSION

As a tool for diagnosis or exclusion of HF, NT-proBNP can help physicians identify LV failure in patients with AECB.

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.

Moxifloxacin: a review of its clinical potential in the management of community-acquired respiratory tract infections

Moxifloxacin is an extended-spectrum fluoroquinolone which has improved coverage against gram-positive cocci and atypical pathogens compared with older fluoroquinolone agents, while retaining good activity against gram-negative bacteria. The antibacterial spectrum of moxifloxacin includes all major upper and lower respiratory tract pathogens; it is one of the most active fluoroquinolones against pneumococci, including penicillin- and macrolide-resistant strains. In in vitro studies, emergence of bacterial resistance was less common with moxifloxacin than with some other fluoroquinolones, but this requires confirmation in large-scale clinical studies. As with other fluoroquinolones, moxifloxacin achieves good penetration into respiratory tissues and fluids. It shows a low potential for drug interactions and dosage adjustment is not required for patients of advanced age or those with renal or mild hepatic impairment. The efficacy of oral moxifloxacin has been demonstrated in large, well-designed clinical trials in patients with community-acquired pneumonia, acute exacerbations of chronic bronchitis or acute sinusitis. Moxifloxacin 400 mg once daily achieved bacteriological and clinical success rates of approximately 90% or higher. It was as effective as, or more effective than, comparators including clarithromycin, cefuroxime axetil and high dose amoxicillin in these trials. The most commonly reported adverse events in patients receiving moxifloxacin are gastrointestinal disturbances. Moxifloxacin is also associated with QTc prolongation in some patients; there are, as yet, no data concerning the possible clinical sequelae of this effect in high-risk patients. Moxifloxacin has a low propensity for causing phototoxic reactions relative to other fluoroquinolones, and animal data suggest that it has a low potential for causing excitatory CNS and hepatotoxic effects.

CONCLUSIONS

As an extended-spectrum fluoroquinolone, moxifloxacin offers the benefits of excellent activity against pneumococci, once daily administration and a low propensity for drug interactions. Although studies are needed regarding its tolerability in at-risk patients with QT interval prolongation, available data suggest that moxifloxacin is likely to become a first-line therapy option for the treatment of community-acquired lower respiratory tract infections, particularly in areas where drug-resistant S. pneumoniae or H. influenzae are common.