Intravenous infusion of a selective inhibitor of thromboxane A2 synthetase in man: influence on thromboxane B2 and 6-keto-prostaglandin F1 alpha levels and platelet aggregation.

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Abstract
The effect of the selective thromboxane A2 synthetase inhibitor OKY-1581, a pyridine derivative [sodium (E)-3-(4-(3-pyridylmethyl)phenyl)-2-methyl-2-propenoate], on thromboxane B2 and 6-keto-prostaglandin F1 alpha levels and platelet aggregation was studied in human volunteers. To clarify its effectiveness as an enzyme inhibitor, OKY-1581, at doses of 17, 83, 167, 417, 833, and 1667 micrograms/kg (n = 5 for each group), was injected intravenously, or was infused (10 micrograms/kg/min; n = 5) over 3 hr on 3 successive days. OKY-1580 (OKY-1581 free acid) was rapidly converted to its main beta-oxidized product, OKY-1565, and its reduced form, OKY-1558. During the study, plasma thromboxane B2 levels, inhibition of thromboxane B2 production in serum, and inhibition of rabbit platelet thromboxane A2 synthetase were monitored continuously. Twenty-five minutes after the injection of the above doses, plasma thromboxane B2 levels decreased by 4 +/- 7%, 40 +/- 14%, 57 +/- 7%, 68 +/- 6%, 93 +/- 5%, and 96 +/- 5% (mean +/- SD), respectively. Thromboxane B2 production in serum was decreased by 2 +/- 8%, 70 +/- 10%, 75 +/- 8%, 81 +/- 10%, and 96 +/- 8%, respectively, and rabbit platelet thromboxane A2 synthetase by 2 +/- 7%, 52 +/- 8%, 79 +/- 10%, 80 +/- 9%, 96 +/- 8%, and 95 +/- 7%. These parameters returned to the control levels 24 hr after the injection.(ABSTRACT TRUNCATED AT 250 WORDS)