Antiplatelet effects of the novel thromboxane A2 receptor antagonist sodium (E)-11-[2-(5,6-dimethyl-1-benzimidazolyl)-ethylidene]-6,11- dihydrodibenz[b,e] oxepine-2-carboxylate monohydrate.
The effects of KW-3635 (sodium (E)-11-[2-(5,6-dimethyl-1-benzimidazolyl)- ethylidene]-6,11-dihydrodibenz[b,e] oxepine-2-carboxylate monohydrate, CAS 127166-41-0) on platelet aggregation were examined. In human washed platelets, KW-3635 shifted the concentration-aggregation curves for U-46619, a thromboxane A2 (TxA2) mimetic, to the right. The pA2 value for KW-3635 was 8.8 +/- 0.10, while those for sulotroban and daltroban were 6.31 +/- 0.18 and 7.75 +/- 0.07, respectively. In human platelet rich plasma (PRP), KW-3635 at 10(-8) mol/l to 10(-6) mol/l inhibited the aggregations induced by U-46619 (1 mumol/l) or collagen (1.5 micrograms/ml). However, KW-3635 at up to 10(-5) mol/l did not affect the primary phase of platelet aggregation induced by adenosine diphosphate or epinephrine. KW-3635 at 10(-5) mol/l did not affect the antiaggregatory effects of the prostaglandins PGI2, PGE1 and PGD2. These results indicate that KW-3635 is a potent and selective TxA2 receptor antagonist. The TxA2 antagonistic effects of KW-3635 were compared with that of daltroban in PRP from various animals species. The effects of KW-3635 on platelet aggregation were species-dependent and KW-3635 exhibited the most prominent activity in human platelets. The activities of KW-3635 in mouse and rabbit PRP were much less potent. In PRP from guinea-pigs, dogs, cats and rats, KW-3635 exhibited moderate anti-aggregatory effects. In the guinea-pig PRP, KW-3635 at 10(-7) mol/l to 3 x 10(-6) mol/l inhibited both the platelet aggregation and the concomitant adenosine triphosphate secretion in a concentration-dependent manner, the effect being more potent than those of sulotroban and daltroban. In the experiments on the platelet aggregation ex vivo in guinea-pigs, KW-3635 at oral doses of 3 and 10 mg/kg inhibited the aggregations induced by U-46619 (1, 3 mumol/l), collagen (3, 6, 9 micrograms/ml) and arachidonate (50, 100 mumol/l). The effects lasted for longer than 7 h following oral administration. These results indicate that KW-3635 is a specific and orally active TxA2 receptor antagonist. KW-3635 is expected to be a drug useful for the treatment of patients with thrombotic disorders.
Karasawa
A
A
Department of Pharmacology, Kyowa Hakko Kogyo Co., Ltd., Shizuoka, Japan.
Kawakage
M
M
Shirakura
S
S
Higo
K
K
Kubo
K
K
Ohshima
E
E
Obase
H
H
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000255:Adenosine Triphosphate / Q000097:blood; D000328:Adult; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology*; D001584:Benzoxepins / Q000494:pharmacology*; D002415:Cats; D004285:Dogs; D004347:Drug Interactions; D004837:Epinephrine / Q000037:antagonists & inhibitors; D006168:Guinea Pigs; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008875:Middle Aged; D010648:Phenylacetates / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000037:antagonists & inhibitors; D011453:Prostaglandins / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D011982:Receptors, Prostaglandin / Q000037:antagonists & inhibitors; D017482:Receptors, Thromboxane; D013449:Sulfonamides / Q000494:pharmacology; D013928:Thromboxane A2 / Q000037:antagonists & inhibitors*
D001562:Benzimidazoles; D001584:Benzoxepins; D010648:Phenylacetates; D010975:Platelet Aggregation Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic; D011453:Prostaglandins; D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; D013449:Sulfonamides; D013928:Thromboxane A2; C040624:sulotroban; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000255:Adenosine Triphosphate; C051762:daltroban; C065729:KW 3635; D004837:Epinephrine