IN-VITRO AND EX-VIVO EFFECTS OF ASPIRIN IN PATIENTS ON A LOW-DOSE ASPIRIN THERAPY

In 19 patients on a low-dose aspirin therapy with 100 mg/d, an insuffi cient effect of aspirin was observed in five patients (aggregations in duced by arachidonic acid and collagen, thromboxane B2-formation in se rum and after collagen). Aspirin added in vitro increased the inhibiti on to a degree comparable to that seen in the other 14 patients, i.e. the insufficient effect could be due to a lack of compliance or to a r educed availability of the drug. In another 20 patients there was a go od inhibitory effect of aspirin; additional aspirin did not increase t he inhibition of arachidonic acid-induced aggregation and serum-thromb oxane B2, but slightly increased collagen-induced aggregation and thro mboxane B2 formation. The effect was the same, whether the aspirin was given in vivo or added in vitro.