title: The PGI2-analogue iloprost and the TXA2-receptor antagonist sulotroban synergistically inhibit TXA2-dependent platelet activation.
abstract: The stable PGI2-analogue iloprost and the TXA2-receptor antagonist sulotroban (BM 13177) were investigated for possible synergistic effects on platelet aggregation in human platelet rich plasma in vitro. Iloprost and sulotroban synergistically inhibited U 46619, collagen, and the second wave of ADP-induced platelet aggregation. Iloprost and sulotroban at concentrations showing little or no inhibition alone resulted, in combination, in marked or complete inhibition of U 46619 or collagen induced aggregation. Combination of iloprost 10(-10) M, which had no effect on the concentration-response curve (CRC) to U 46619, with sulotroban 5 x 10(-6) M, which shifted the CRC to U 46619 by a factor of 3 to the right, resulted in a rightward shift of the U 46619 CRC by a factor of 4.5. To attain a 4.5-fold shift with either compound alone, a concentration of 5 x 10(-10) M iloprost or 10(-5) M sulotroban was required. A similar mutual enhancement of inhibitory effects was seen for combinations of the PGI2-analogue cicaprost (ZK 96.480) with sulotroban or the TXA2-receptor antagonist SQ 29548 with iloprost. When the TXA2-dependent part of collagen-induced aggregation was fully inhibited by sulotroban, the concentrations of iloprost necessary for 90% inhibition were reduced by a factor of 2.5 - 3. In the presence of acetylsalicylic acid, the synergistic action of sulotroban and iloprost was reduced and merely additive effects against U 46619-induced platelet aggregation were found, suggesting that the release of endogenous TXA2 plays an important role for the synergistic effect of the two compounds. The combination of a PGI2-analogue and a TXA2-antagonist may lead to a safer and more effective control of platelet activation than with either compound alone.
authors: Institute of Pharmacology, Research Laboratories of Schering AG, Berlin (West), FRG.
authors: S
authors: S
authors: Stürzebecher
authors: W
authors: W
authors: Witt
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000244:Adenosine Diphosphate / Q000037:antagonists & inhibitors; D001241:Aspirin / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003094:Collagen / Q000378:metabolism; D004357:Drug Synergism; D011464:Epoprostenol / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology; D016285:Iloprost; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic / Q000037:antagonists & inhibitors; D011465:Prostaglandins, Synthetic / Q000494:pharmacology*; D011982:Receptors, Prostaglandin / Q000187:drug effects*; D017482:Receptors, Thromboxane; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D010975:Platelet Aggregation Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic; D011465:Prostaglandins, Synthetic; D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; D013449:Sulfonamides; D000244:Adenosine Diphosphate; C040624:sulotroban; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C045749:SQ 29548; D003094:Collagen; D011464:Epoprostenol; D016285:Iloprost; D001241:Aspirin