Beneficial effects of UK 37248, a thromboxane synthetase inhibitor, in experimental endotoxic shock in the rat.

1 The effects of pretreatment with the thromboxane synthetase inhibitor UK 37248 (dazoxiben) administered 30 min before intravenous endotoxin (S. enteriditis) in the rat was investigated 2 Plasma prostaglandins and thromboxanes were determined via radioimmunoassay. Endotoxaemia was associated with significant elevations above control values (less than 200 pg/ml) in plasma thromboxane B2 (TXB2), prostaglandin E (PGE) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). Within 30 min after endotoxin administration plasma immunoreactive (i) iTXB2 was 875 +/- 90 pg/ml (n = 9), iPGE was 1670 +/- 271 (n = 9) and i6-keto-PGF1 alpha was 1191 +/- 209 pg/ml (n = 10). By 4 h plasma iTXB2 was 1743 +/- 328 pg/ml (n = 5), iPGE was 2589 +/- 494 pg/ml (n = 9) and i6-keto-PGF1 alpha was 4251 +/- 984 pg/ml (n = 10). UK 37248 pretreatment resulted in a significant (P less than 0.001) decrease in plasma iTXB2 at 30 min and 4 h to 193 +/- 28 pg/ml (n = 5) and 421 +/- 57 pg/ml (n = 5), respectively. Unexpectedly UK 37248 also significantly decreased plasma i6-keto PGF1 alpha at 30 min and 4 h to 360 +/- 75 pg/ml (n = 10) (P less than 0.005) and 1920 +/- 513 pg/ml (n = 10) (P less than 0.05), respectively, iPGE plasma levels were not significantly changed in the UK 37248-pretreated rats 30 min (2210 +/- 370 pg/ml (n = 9) or 4 h 3529 +/- 1093 pg/ml (n = 13) after endotoxin compared to the vehicle-treated rats. 3 UK 37248 significantly (P less than 0.05) reduced the endotoxin mortality rate at 24 h from 69% (n = 13) to 30% (n = 13), UK 37248 also reduced splanchnic infarction from 90% (n = 20) to 6% (n = 16). 4 UK 37248 significantly improved the endotoxin-induced thrombocytopaenia, disseminated intravascular coagulation, hypoglycaemia and lysosomal labilization. 5 We conclude that UK 37248 provides significant beneficial effects in experimental endotoxic shock in the rat.