Aztreonam for inhalation (Cayston): An inhaled antibiotic to improve lung symptoms in cystic fibrosis patients with pseudomonal infections

Aztreonam for inhalation is a monobactam antibacterial indicated to improve respiratory symptoms in cystic fibrosis (CF) patients with Pseudomonas aeruginosa. Aztreonam binds to penicillin-binding proteins of susceptible bacteria (gram-negative aerobic pathogens), which leads to inhibition of bacterial cell wall synthesis and death of the cell. Aztreonam's activity is not decreased in the presence of CF lung secretions.

Efficacy. The efficacy of inhaled aztreonam was evaluated over a period of 28 days of treatment in a randomized, double-blind, placebo-controlled, multicenter trial that enrolled patients with CF and P. aeruginosa. Patients >6 years of age with an FEV₁ between 25% and 75% predicted were randomly assigned to receive inhaled aztreonam (75 mg administered by inhalation 3 times a day) (n=80) or placebo (n=84) via the Altera Nebulizer System. All patients were required to take a dose of an inhaled beta-agonist prior to taking a dose of aztreonam or placebo and were required to have been off antibiotics for at least 28 days. Pulmonary function, as measured by percent change from baseline to day 28 in FEV₁ (in liters), improved to a greater extent in patients receiving inhaled aztreonam compared with those receiving placebo (10%, 95% CI, 6%–14%) and were similar in adult and pediatric patients. Two weeks after completion of drug treatment, the difference in FEV₁ between the inhaled aztreonam and placebo groups was 6% (95% CI, 2%–9%).

Safety. The safety of aztreonam for inhalation was evaluated in 344 patients from 2 placebo-controlled trials and 1 open-label follow-up trial. In controlled trials, 146 patients with CF received 75- mg inhaled aztreonam 3 times a day for 28 days. Adverse reactions reported in more than 10% of these patients included cough (54%), nasal congestion (16%), wheezing (16%), pharyngolaryngeal pain (12%), and pyrexia (13%). Bronchospasm and decrease in FEV₁ were seen in patients receiving inhaled aztreonam.