SAN DIEGO, CA—Oral delafloxacin 200mg and 400mg doses are effective for the treatment of acute bacterial exacerbation of chronic bronchitis (ABECB) and for community-acquired pneumonia (CAP), according to results of two double-blind randomized phase 2 trials presented at IDWeek2012.

Delafloxacin is an investigational fluoroquinolone antibiotic effective against gram-positive and gram-negative bacteria, including methicillin-resistant and quinolone-resistant strains of Staphylococcus aureus, noted Jarrod Longcor, MBA, of Rib-X Pharmaceuticals, New Haven, CT.

The safety and efficacy of delafloxacin was compared to levofloxacin for the treatment of ABECB in 280 outpatients. Patients were given 100mg (n=70), 200mg (n=68), or 400mg (n=69) delafloxacin capsules once daily for 5 days, or levofloxacin 500mg tablets (n=73) for 7 days (1:1:1:1 ratio). Patients were ≥40 years of age and had clinical signs/symptoms, purulent sputum (gram strain qualified), and clinical documentation of ABECB.

“Clinical response was similar across treatment groups and no statistically significant dose-response trends were noted,” he said. All S. pneumoniae (22 patients) and H. influenzae (39 patients) pathogens were eradicated. For delafloxacin 100mg, 200mg, and 400mg and levofloxacin 500mg, respectively, pathogen eradication rates, defined as microbiological efficacy, were as follows: 67%, 80%, 100%, and 100% for M. catarrhalis (31 patients); 90%, 100%, 90%, and 83% for H. parainfluenzae (38 patients); 100%, 100%, 0%, and 50% for K. pneumoniae (5 patients); 67%, 100%, 100%, 100%, and 100% for S. aureus (9 patients); and 0%, 100%, 100%, 100% for P. aeruginosa (9 patients).


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The study of 309 outpatients sought to establish the optimal dose of delafloxacin for the treatment of CAP. Patients were given delafloxacin capsules 100mg, 200mg, or 400mg once daily (1:1:1 ratio) for 7 days. Patients were ≥18 years old and had ≥2 clinical signs/symptoms, purulent sputum (gram strain qualified), and a positive chest x-ray.

Clinical and bacteriological cure rates were similar in the delafloxacin 200mg and 400mg groups, and slightly lower in the 100mg group. For 100mg, 200mg, and 400mg doses, respectively, pathogen eradication rates were as follows: 88%, 86%, and 100% for S. pneumoniae (46 patients); 91%, 96%, and 97% for H. influenzae and H. parainfluenzae (94 patients); and 83%, 100%, and 91% for atypicals (33 patients). For S. aureus (17 patients), eradication was 100% across all groups.

“All three doses of delafloxacin were safe and well tolerated and were effective in resolving or improving clinical signs and symptoms of CAP, eradicating the target pathogens, and resolving or improving radiographic evidence of pneumonia,” he noted.

A dose-dependent increase in the incidence of gastrointestinal adverse events was observed in both trials, with mild diarrhea being the most common. The researchers noted no clinically meaningful changes in laboratory values, ECGs, or vital signs and there were no patient deaths.