[Effects of anti-platelet aggregating agents on peplomycin induced pulmonary toxicity in mice].

In order to find a method to ameliorate pulmonary toxicity of peplomycin (PEP), microscopic changes of the lung following PEP administration and effect of anti-platelet aggregating agents on the toxicity was investigated in mice. When PEP was administered intravenously once a day for 7 days, microthrombi mainly composed of aggregated platelets and fibrin appeared in the capillaries of the lung in an early phase before severe pulmonary edematous lesions and fibrosis occurred. Combination therapy of anti-platelet aggregating agents such as phthalazinol, dipyridamole, ticlopidine and indomethacin suppressed these toxic changes. Especially, ticlopidine was the most effective and superior to prednisolone used clinically for amelioration of the toxicity. Microthrombi, preceding edematous lesions, were considered to be attributed to damages of endothelium by PEP, because PEP itself did not develop platelet aggregation in vitro and ex vivo. Therefore, the microthrombi are likely to produce congestion of pulmonary microcirculation leading to edematous lesions by increase of permeability, and to play significant roles in the development of pulmonary fibrosis in a late phase. Anti-platelet aggregating agents such as ticlopidine are concluded to ameliorate the lung toxicity by preventing microcirculation impairment with the microthrombus.