Effects of pretreatment with anti-inflammatory drugs on ozone-induced lung damage in rats

The effects of pretreatment with acetylsalicylic acid (aspirin), hydrocortisone, indomethacin, and heparin administered ip against the pulmonary edema produced by O3-exposure (4 ppm for 4 hr) were studied in rats. These anti-inflammatory drugs were found to alter the injurious effect of O3 on lung differently. First, aspirin at the high dose (125 mg/kg) accentuated O3-induced lung injury, and had no effect at the low dose (10 mg/kg); second, hydrocortisone (50 mg/kg) failed to have any effect; third, indomethacin at a high dose (20 mg/kg) offered a significant degree of protection, but had no effect at the low dose (2.5 mg/kg); and fourth, heparin (1000 units/kg) also offered a significant degree of protection against the lung damage normally induced by O3-exposure. Several mechanisms for the favorable and unfavorable interactions of anti-inflammatory drugs with O3-exposure are discussed.