Venous tone: are the phlebotonic properties predictive of a therapeutic benefit? A comprehensive view of our experience with Daflon 500 mg

Abstract

Venodilation has been shown to enhance clinical expression of venous insufficiency and, therefore, it has been suggested that increase of venous tone should improve clinical symptoms. Four controlled double-blind clinical trials versus placebo, or versus a new micronized flavonoid fraction, have shown the activity of Daflon 500 mg, which has been evaluated on venous tone using venous plethysmography. The first, randomized cross-over Phase II pharmacoclinical trial has shown that Daflon 500 mg is significantly 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); and 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 were observed 2 h after administration without any significant change in T50 outflow, cardiac index, capillary filtration index, blood pressure, cardiac or respiratory rates. The same acute effect of increasing venous tone has been demonstrated in another pharmaco-clinical trials, 1 and 2 h after ingestion by three groups, each composed of 10 women suffering from venous insufficiency: group I without varicose veins, group II during pregnancy, and group III with a post-thrombotic syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)