<p>Rat groupings.</p>

Excessive mechanical stress triggers an inflammatory cascade, leading to lung damage, pulmonary oedema, and systemic complications. While macrolide antibiotics such as azithromycin (AZM) have demonstrated anti-inflammatory and epithelial barrier strengthening effects, their use is limited by concerns regarding antibiotic resistance.

EP317, an azithromycin-derived compound with negligible antibacterial activity, was designed to retain the immunomodulatory and epithelial barrier enhancing effects of AZM while mitigating the risk of bacterial resistance. This study investigated the effects of AZM and EP317 in a rat model of VILI. Forty-eight rats were divided into six groups (N = 8 per group), receiving either placebo, AZM, or EP317 (5 mg/kg daily for seven days), with half of the animals subjected to mechanical ventilation with peak airway pressure at 35 cmH₂O. Both compounds attenuated ventilation-induced pulmonary oedema, reflected in a smaller increase in lung wet/dry ratio, whereas ventilation-induced increases in total protein in bronchoalveolar lavage fluid (BALF) were not significantly reduced by either treatment.