A comparative study of the effects of some non-steroidal anti-inflammatory drugs on prostacyclin productionex vivo and on thromboxane B2 release by polymorphonuclearsin vitro

We have measured the formation of prostacyclin (PGI2) in the rat gastric mucosaex vivo following oral administration of indomethacin, protacine and sodium salicylate (SS). It has been found that protacine, like indomethacin but in contrast to SS, markedly reduces PGI2 synthesis as measured by inhibition of ADP-induced platelet aggregation. Parallel gastro-ulcerogenic studies demonstrate that protacine has very weak gastric irritancy when compared with indomethacin. In addition, the effect of these drugs has been evaluated on thromboxane B2 (TXB2) release by human polymorphonuclears (PMNs) stimulated with A23187 ionophorein vitro. It has been shown that protacine, like indomethacin, strongly inhibits cyclooxygenase activity as measured by radioimmunoassay of TXB2. SS partially prevents the inhibitory effect of either