Solithromycin, a novel macrolide antibiotic, shows promise in pneumonia treatment
Solithromycin, a new fourth-generation macrolide antibiotic, is noninferior to moxifloxacin for treating patients with community-acquired bacterial pneumonia (CABP), according to the SOLITAIRE-ORAL* study.
Study primary outcome assessed early clinical response, which was an improvement in at least two out of four symptoms: chest pain, dyspnoea, cough, and sputum production, without worsening of any symptom at 72 hours. [Lancet Infect Dis 2016;doi:10.1016/S1473-3099(16)00017-7]
Solithromycin was noninferior to moxifloxacin in achieving early clinical response, with 78.2 percent of patients in solithromycin group achieving the primary outcome, compared with 77.9 percent of patients in moxifloxacin group (difference 0.29 percent, 95 percent confidence interval [CI], -5.5-6.1).
Patients with CABP of pneumonia outcomes research team (PORT) class III or IV severity achieved early clinical response at a slightly better rate when given solithromycin compared with those given moxifloxacin, while the reverse was true for PORT risk class II patients, although the difference was not statistically significant in both cases.
Similarly, solithromycin demonstrated noninferiority to moxifloxacin in both clinically evaluable population (80.9 versus 81.1 percent, difference -0.19 percent, 95 percent CI, -5.8-5.5) as well as microbiological intention-to-treat population (74.9 vs 78.8 percent, difference -3.87 percent, 95 percent CI, -12.0-4.3).
Safety profile of both drugs was similar, with the most common adverse events being diarrhoea, nausea, and headache. Both groups have similar number of serious adverse events, with a mortality rate of 1.4 percent, but these were unrelated to study drugs according to the researchers.
The randomized double-blind SOLITAIRE-ORAL phase III trial compared 860 pneumonia patients with PORT risk class II, III, or IV, randomly assigned to oral solithromycin once daily (800 mg on day 1, 400 mg on days 2-5, placebo on days 6-7) or oral moxifloxacin 400 mg once daily for 7 days.
Existing recommendations for CABP treatment are variable, and generally fall into three broad categories: respiratory fluoroquinolone alone, β-lactam antibiotic alone, or β-lactam antibiotic combined with a macrolide.
Fluoroquinolones can disrupt normal gut flora, increasing risk for Clostridium difficile colitis, while β-lactam antibiotic monotherapy leaves possible atypical pathogens such as Legionella spp untreated, posing concerns over existing therapies.
“The prevalence of pneumococcal macrolide resistance in developed countries is approaching 50 percent,” said the authors.
Solithromycin can offer a fourth treatment option for CABP, the researchers said, noting that it might be particularly useful for treating CABP cases caused by macrolide-resistant pathogens and atypical Legionella spp, while also providing anti-inflammatory effects, which could benefit CABP patients.