Guanidine derivatives as combined thromboxane A2 receptor antagonists and synthase inhibitors.

A new series of omega-disubstituted alkenoic acid derivatives derived from samixogrel 5 were designed and synthesized as combined thromboxane A2 receptor antagonists/thromboxane A2 synthase inhibitors with improved solubility and reduced protein binding compared to 5. Hexenoic acid derivatives with a 3-pyridyl group and 3-(2-cyano-3-alkyl-guanidino)phenyl substituent were found to be optimal with regard to this dual mode of action. The most potent compound, E-6-(3-(2-cyano-3-tert-butyl-guanidino)phenyl)-6-(3-pyridyl)hex-5-eno ic acid, "terbogrel" 32 inhibits the thromboxane A2 synthase in human gel-filtered platelets with an IC50 value of 4.

PK/PD simulations as a tool for rational design of clinical dosage regimens: an example with Fradafiban.

In clinical studies, pharmacodynamic effects should be achieved, e.g. maintenance of certain effects with reversibly acting drugs.

Profound and sustained inhibition of platelet aggregation by Fradafiban, a nonpeptide platelet glycoprotein IIb/IIIa antagonist, and its orally active prodrug, Lefradafiban, in men.

Background: Clinical trials have demonstrated that platelet glycoprotein (GP) IIb/IIIa antagonists effectively prevent acute thrombotic events. Orally active GP IIb/IIIa antagonists are essential to evaluate the clinical benefit of long-term treatment. We therefore investigated platelet inhibition by the GP IIb/IIIa antagonist Fradafiban (BIBU 52; Fradafiban is the recommended INN of BIBU 52) and its orally administered prodrug, Lefradafiban (BIBU 104; Lefradafiban is the recommended INN of BIBU 104) in healthy subjects.

Antagonism of the GPIIb/IIIa receptor with the nonpeptidic molecule BIBU52: inhibition of platelet aggregation in vitro and antithrombotic efficacy in vivo.

The glycoprotein (GP) IIb/IIIa (the alphallb beta3 integrin) found on platelets binds fibrinogen or von Willebrand factor when the platelet is activated, thereby mediating the aggregation of platelets. Blockade of the GPIIb/IIIa should prevent platelet aggregation independent of the substance or substances responsible for activating the platelets. This comprehensive inhibition of platelet aggregation is thought to be an effective therapeutic approach to various clinical thromboembolic syndromes.

Inhibition of platelet aggregation as a surrogate marker.

Using acetylsalicylic acid-dipyridamole, a combined thromboxane receptor antagonist-thromboxane synthase inhibitor, and a fibrinogen receptor antagonist as examples, this article discusses the predictive value of several methods that may be employed in the evaluation of antiaggregatory effects and their suitability as surrogate markers for the planning of patient studies. Platelet aggregation in various ex vivo tests and the effects of drugs on these tests were investigated using platelet aggregation in platelet-rich plasma and in whole blood, and in thrombus formation on a thrombogenic surface. Drug-induced inhibition of platelet aggregation is based on the modulation of metabolic processes or interactions at the membrane-receptor level.