Are the phlebotonic properties shown in clinical pharmacology predictive of a therapeutic benefit in chronic venous insufficiency? Our experience with Daflon 500 mg.

In 3 controlled clinical trials, double blind versus placebo, the activity of Daflon 500 mg, a new micronised flavonoid fraction, has been evaluated on venous tone using venous plethysmography. A double-blind, randomized cross-over Phase II pharmaco-clinical trial has shown that Daflon 500 mg is statistically more effective than placebo on pathological legs, as well as normal legs. In this study, which included 20 patients suffering from post-thrombotic syndrome, Daflon 500 mg decreased: 1) venous capacity (p less than 0.001); 2) venous distensibility (p less than 0.001); 3) venous outflow time, measured by the two parameters total emptying venous time (p less than 0.001) and T2p (p less than 0.001). These modifications have been observed 2 hours after administration without any significant change in T50 outflow, cardiad index, capillary filtration index, blood pressure, cardiac or respiratory rate. The same acute effect of increasing venous tone has been demonstrated in another pharmacoclinical trial, 1 and 2 hours after ingestion in 3 groups of 10 women suffering from venous insufficiency: group I without varicose, group II during pregnancy and group III with a post-thrombotic syndrome. Finally, in a Phase III clinical trial, in 2 parallel groups of 20 patients each with functional chronic venous insufficiency, Daflon 500 mg has been compared to placebo. It was then demonstrated after 1 and 2 months treatment an improvement in the functional symptoms and edema accompanied by a statistically significant increase of the venous tone. (ABSTRACT TRUNCATED AT 250 WORDS)