Indobufen is a potent inhibitor of whole blood aggregation in patients with a high atherosclerotic risk.

The newly developed method, based on the quantitation of changes in electrical impedance, to determine platelet aggregation in whole blood was applied to the evaluation of the effects of Indobufen, a well known inhibitor of platelet rich plasma aggregation. The platelet antiaggregatory activity of the drug after single (200 or 400 mg) and repeated doses (200 mg or 200 mg b.i.d. for 1 week) was determined on whole blood aggregation and thromboxane B2 formation by platelet rich plasma of 16 patients with high risk of atherosclerosis. At 2 hr after the single dose treatments, Indobufen significantly reduced the whole blood aggregation induced by 0.5-2 micrograms/ml collagen. At 24 hr from the intake of the drug the aggregation was significantly inhibited in patients who ingested the 400 mg dose only. As far as the repeated administrations are concerned, it appears that the inhibition of whole blood aggregation and thromboxane B2 formation by platelets reached 12 hr after the last drug administration was comparable to the degree of inhibition achieved 2 hr after Indobufen intake. It is concluded that Indobufen orally administered to patients with high risk of atherosclerosis is a potent inhibitor of whole blood aggregation.