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

Abstract

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.

Pharmacokinetic and Pharmacodynamic Properties of a New Thromboxane Receptor Antagonist (Z‐335) after Single and Multiple Oral Administrations to Healthy Volunteers

“…The duration of inhibitory action of Z-335 on the platelet TXA 2 receptor was much longer than those of the other TXA 2 receptor antagonists such as BM13.177, 12,13 SQ28,688, 14 and FK070 3 and was almost the same as that of vapiprost. 2 In the case of vapiprost, the progressive and sustained inhibition of the TXA 2 receptor was possibly achieved through a slow dissociation from the receptive sites.…”