Permsin SathiropasGerman A. MarbetSomphong SahaphongFrançois DuckertCoagulation and Fibrinolysis LaboratoryMahidol University2018-06-142018-06-141988-07-01Thrombosis Research. Vol.51, No.1 (1988), 55-62004938482-s2.0-0023820738https://repository.li.mahidol.ac.th/handle/20.500.14594/15612Our investigations have demonstrated on 10 volunteers receiving either 500 mg or 100 mg acetylsalicylic acid (ASA) that a low collagen concentration (1 ug/ml) can best detect the aggregation defect caused by ASA. With the impedance aggregometry the mean inhibition reaches 82% and 52% with 500 mg and 100 mg ASA, respectively. Collagen at higher concentration (3 μg/ml) as well as ADP 10 and 25 μmol/1 are less sensitive, less than 25% inhibition was recorded. These results suggest that a1 μg/ml concentration of collagen is adequate for the control of the ASA effect up to 6 days after intake of 100 mg. Furthermore, the von Willebrand factor (vWF) dependent platelet aggregation induced by 0.6 and 1.0 mg/ml ristocetin was clearly diminished after ASA. Therefore, a ristocetin screening test in whole blood for vWF disorder is possibly distorted when the test is performed within 6 days from ASA administration. © 1988.Mahidol UniversityMedicineArticleSCOPUS10.1016/0049-3848(88)90282-4