Desethyl KBT-3022

A highly sensitive, accurate and reproducible gas chromatographic method for the determination of a main metabolite, 2-[4,5-bis(4-methoxy-phenyl)thiazol-2-yl] pyrrol-ylacetic acid (desethyl KBT-3022) of a new antiplatelet agent, ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-ylacetate (KBT-3022), in the human or dog plasma has been developed. Desethyl KBT-3022 in the plasma was extracted with a mixture of n-hexane and dichloromethane (1:1), and was derivatized using pentafluorobenzyl bromide. The obtained pentafluorobenzyl derivative of desethyl KBT-3022 in the plasma was separated by high-performance liquid chromatography. After the separation, the pentafluorobenzyl derivative of desethyl KBT-3022 was detected by gas chromatography. Gas chromatography was performed with a Ultra 1 column (12 m x 0.22 mm i.d., film thickness 0.33 microns), using an electron capture detector. 2-[2-(4,5-Bis(4-methoxyphenyl)thiazol-2-yl)pyrrol-l-yl]propionic acid was used as an internal standard. The detection limit of desethyl KBT-3022 in the plasma was 0.2 ng/ml. The coefficients of variation were below 5.3%. This method was applied to the determination of the plasma concentration of desethyl KBT-3022 after oral administration of KBT-3022 to dogs.

The effect of KBT-3022 (ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-ylacetate), a new cyclooxygenase inhibitor, on experimental brain edema was studied. In vitro, KBT-3022 (100 microM) and its metabolite desethyl KBT-3022 (10 and 100 microM), but neither acetylsalicylic acid nor indomethacin, inhibited arachidonic acid-induced swelling of guinea pig cortical slices. KBT-3022 (3-100 microM) and desethyl KBT-3022 (3-30 microM), but neither acetylsalicylic acid nor indomethacin, inhibited lipid peroxidation in guinea pig brain homogenate. In vivo, oral administration of KBT-3022 (1, 3 and 10 mg/kg) and indomethacin (10 and 30 mg/kg), but not acetylsalicylic acid, prevented brain edema induced by bilateral carotid occlusion and recirculation in gerbils. Indomethacin then prevented postischemic hyperthermia, but not KBT-3022. KBT-3022 (10 mg/kg) and indomethacin (30 mg/kg) inhibited lactate accumulation in gerbil brain after ischemia and recirculation. These results suggest that KBT-3022 prevents development of both cytotoxic edema in vitro and vasogenic edema in vivo.

1. The mechanism of action of a new antiplatelet agent, KBT-3022 (ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-ylacetate) and its active main metabolite, desethyl KBT-3022, was investigated. 2. KBT-3022 and desethyl KBT-3022 inhibited cyclooxygenase from ovine seminal gland with IC50 values of 0.69 and 0.43 microM, respectively. 3. At concentrations higher than those required for cyclooxygenase inhibition, desethyl KBT-3022 inhibited cAMP-phosphodiesterase, specific binding of U46619, and release of phosphatidic acid from thrombin-stimulated platelets. 4. Oral administration of KBT-3022 inhibited the production of thromboxane B2 during blood coagulation more potently than the production of 6-keto-prostaglandin F1 alpha from aortic strips in guinea pigs. 5. These findings suggest that KBT-3022 may inhibit platelet activation principally via the inhibition of cyclooxygenase by desethyl KBT-3022.