Inhaled levofloxacin (brand name Quinsair) is an antibiotic used for long-term lung infection treatment caused by Pseudomonas aeruginosa in adults with cystic fibrosis (CF). Levofloxacin is a well-known antibiotic, and tablets and solutions for infusion have been approved and prescribed for treating infections since the 1990s.

Inhaled levofloxacin has been approved in the European Union and Canada for people with CF. It has not yet been approved by the FDA for this indication in the United States. A Phase 3 clinical trial (NCT01270347) has been completed.

How inhaled levofloxacin works

People with CF have an accumulation of thick mucus in the lungs, creating an optimal environment for bacteria to easily grow, leading to infections.

Levofloxacin belongs to a group of antibiotics known as fluoroquinolones. They work by blocking enzymes that P. aeruginosa bacteria use to make copies of their DNA during cell multiplication. By blocking these enzymes, it stops the growth of bacteria that are causing the infection.

Studies on inhaled levofloxacin

Inhaled levofloxacin (Quinsair) was studied in people with CF and P. aeruginosa lung infection. The first study compared Quinsair to a placebo (NCT00503490), with Quinsair showing better results than the placebo because it improved the FEV1 after 28 days of treatment. FEV1 is the most air a person can breathe out in one second and is a measure of lung function.

The second trial compared it with another inhaled antibiotic (tobramycin) in 282 participants (NCT01270347) and showed that Quinsair was at least as good as tobramycin at improving FEV1 after one to three treatment cycles.

The results of a meta-analysis comparing the effectiveness of inhaled antibiotics for people with CF and Pseudomonas aeruginosa lung infection were presented at the 2016 International Congress of the European Respiratory Society (ERS) and showed that Quinsair was comparable to three other inhalable antibiotics approved in Europe (aztreonam, tobramycin and colistimethate sodium).

Aztreonam 75 mg three times daily led to the greatest increase in FEV1 at four weeks of treatment, but Quinsair was found to be superior to colistimethate sodium, tobramycin inhaled powder, and tobramycin inhaled solution. Still, the results showed there was no evidence indicating the other solutions were more effective than Quinsair.

A 24-week analysis showed that Quinsair was linked to the lowest hospitalization risk, with a 96.5 percent probability of being the most appropriate treatment option. Other analyses, such as sputum density scores, the need for additional antibiotics against P. aeruginosa, and the study of abandonment rates were similar in all inhaled antibiotics in all instances.

The most common side effects of Quinsair are cough, taste disturbances, and tiredness or weakness. Quinsair must not be used in people with epilepsy and those with a history of tendon disorders related to the use of fluoroquinolone antibiotics. Also, pregnant or breastfeeding women must not use it.

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