Antithrombotic efficacy and its time course after application of naftidrofuryl in vivo.

The antithrombotic efficacy of naftidrofuryl (Naf) was assessed with the following method: an endothelial cell damage is induced in arteriolar vessels of the hamster cheek pouch by intravascular excitation of fluorescein-isothiocyanate-dextran. On these damaged cells, platelets adhere and a stable thrombus grows. This process progressively obstructs the vessel's aperture and hence reduces blood flow. Blood cell velocity may thus be used to quantitate thrombus growth. Thrombus growth is assessed before and repetitively after parenteral application of 1, 5 and 20 mg/kg Naf. Efficacy is compared with 10 and 100 mg/kg acetylsalicylic acid. Naf shows a significant antithrombotic property, beginning with a dosage of 1 mg/kg which further increases relative to the dosage, and the stability of thrombi decreased. The antithrombotic effectiveness of Naf increases continuously during 120 min after application. Vessel diameter and cell velocity were the same in compared groups thus excluding an influence of the vasodilatory property of Naf on thrombus growth. Sixty min after application, 5 mg/kg Naf was as effective as 10 mg/kg acetylsalicylic acid.