Tissue reaction follwing intratracheal application of roentgen contrast media in rats.

Contrast media (CM) given orally for roentgen examination of the upper gastrointestinal tract may inadvertently enter the lungs. The present paper describes the local effects on the lungs of rats after a single intratracheal instillation of the nonionic, iso-osmolar, dimer CM iodixanol and iotrolan, and the ionic hyperosmolar, monomeric CM diatrizoate. Hydrochloric acid (HCl) and saline were included as positive and negative controls, respectively. The test compounds were given by intratracheal instillation to anesthetized rats at low dose volumes of 0.5 ml/kg b.w. The animals were killed 6 hours, 24 hours or 7 days after dosing, and the trachea and lungs subjected to histopathological examination. Acute signs of dyspnea were observed in 7 out of 15 animals that received HCl. No clinical signs could be related to treatment with any of the CM. Histomorphological assessment of the respiratory tract did not reveal any CM-related adverse effects, whereas animals treated with HCl showed marked histopathological changes. The results indicate that accidental exposure of the respiratory system to iodixanol, iotrolan or diatrizoate is unlikely to cause any significant tissue damage or lead to respiratory complications.