Pharmacokinetic and pharmacodynamic profiles of CS-518, a selective, long-lasting thromboxane synthase inhibitor, after single and multiple oral administration to healthy volunteers

Whole blood production of thromboxane, prostacyclin and leukotriene B4 after dietary fish oil supplementation in man: effect of vitamin E

12 subjects were given 30 ml/day of a fish oil already stabilized with vitamin E (1.5 IU/g) and other natural antioxidants (fish oil, FO), and the same fish oil supplemented with extra vitamin E (to total 4.5 IU/g) (FO+E), in a randomized double-blind cross-over study. The whole blood production of thromboxane B2, measured in serum, was reduced after 4 weeks of ingestion of both FO+E (by 47%, P < 0.01) and of FO (by 40%, P < 0.05) whereas 6-keto-PGF1 alpha increased slightly in both cases, by 4% and 5% respectively, both NS. Leukotriene B4 production decreased on both FO+E (by 20%, NS) and FO (by 17%, P < 0.05). This study thus showed that a stabilized fish oil had marked effects on eicosanoid production, which may be important for its cardiovascular effect. Further supplementation with vitamin E had no additional effect, indicating that the vitamin E content (1.5 IU/g) in this stabilized fish oil might have been optimal.

Pharmacokinetic and pharmacodynamic properties of FK070 (KDI-792), a novel thromboxane receptor antagonist/thromboxane synthetase inhibitor, after single and multiple oral administrations to healthy volunteers

FK070, a thromboxane A2 (TXA2) receptor antagonist/TXA2 synthetase inhibitor, was given orally to healthy male volunteers in a single- and multiple-dose study. In the single-dose study (200, 300, 400 mg), the area under the plasma concentration-time curve (AUC) and the maximum plasma concentration (Cmax) increased non-linearly with dose, while the mean elimination half-life (V0) was essentially unchanged (3.9-7.3h). Recovery of the unchanged drug in the urine was 12-25%. Cmax and AUC as determined with 200 mg of drug after a meal decreased by about 60 and 30%, respectively. Ex-vivo platelet aggregation in the plasma by a TXA2 analogue, U46619, was almost completely inhibited within 1 h, after all doses of drug, with a significant dose-dependent inhibition maintained for 8 h or more, which was much longer than was expected from drug plasma concentration. The aggregation by adenosine diphosphate (ADP) was inhibited to a lesser extent. FK070 also inhibited TXA2 synthetase as evidenced by decreased production of TXB2 and reciprocally increased production of 6-keto-prostaglandin F1 alpha in the serum during ex-vivo whole blood coagulation. These effects peaked 1 h after drug and lasted until 4 h with the higher doses. In the multiple-dose study (300 mg, twice a day, after meals for 6.5 days), drug concentrations in the plasma were well fitted to a three-compartment open model with first-order absorption. FK070 afforded extensive inhibition of platelet aggregation by U46619 throughout the administration period, with a significant inhibition lasting as long as 48 h after conclusion of administration. No clearly drug-related changes were found in routine laboratory tests, subjective and objective findings, or vital signs. FK070 was concluded to be well tolerated and to provide long-lasting blockade of TXA2 receptors, and plasma concentration-dependent inhibition of TXA2 synthetase in the platelets.

Changes in plasma and urinary 11-dehydrothromboxane B2 in healthy subjects produced by oral CS-518, a novel thromboxane synthase inhibitor

When 50 mg CS-518, a novel thromboxane (TX) A2 synthase inhibitor, was orally administered to healthy male volunteers, the plasma concentration of CS-518 peaked after 0.5 h and then decreased with a half-life of 0.44 h. There was no significant change in the plasma concentration of circulating TXB2, whereas that of circulating 11-dehydrothromboxane B2 (11-dhTXB2), an enzymatic metabolite of TXB2, was significantly decreased from 0.5 h to 24 h after administration; the maximal decrease to about 25% of the pre-dose value was found at 6 h. After CS-518 100 mg b.d. for 4.5 days, plasma 11-dhTXB2 was suppressed to the same extent as after the single dose of 50 mg from 6 h after the initial dose throughout the administration period. The urinary excretion of 11-dhTXB2 corrected for the creatinine level was significantly decreased by 70-84% throughout the treatment. These results suggest that CS-518 causes long-lasting inhibition of TXA2 synthase despite its rapid elimination from plasma, and that circulating 11-dhTXB2 in plasma and its urinary excretion can serve as a quantitative index of TXA2 synthase inhibition in vivo by CS-518.