Clinical evaluation of a venotropic drug in man. Example of Daflon 500 mg

Chronic venous insufficiency (CVI) of the lower limbs is a complex and fluctuating disease by its pathogenic mechanisms and its clinical symptoms. Although symptoms are subjective, they affect the quality of life and socio-professional activity of many patients. This is why convincing demonstration of therapeutic activity of a venotropic drug should be carried out according to strict methodology. Only randomized double-blind controlled trials versus placebo (no reference drugs being available) could demonstrate the activity on condition that they are set up in a protocol, the statistical design of which, is adapted and defined "a priori". Inclusion, non inclusion and judgement criteria must be rigorous, taking into account many exogenous and endogenous factors which could have influence on the severity or the change in CVI and on the comparability of groups at the beginning and at the end of the study. Thus, the main risk factors of CVI (heredity, obesity, obstetrical and gynecological history, estroprogestogen treatment, profession, environment, etc.) and the season when the patient is recruited should be taken into account. With respect to all these restraints on methodology, the venotrotopic activity of a flavonoid Daflon 500 mg (2 tablets daily) was demonstrated in 200 patients (174 women, 26 men) with organic CVI (n = 83) or functional CVI (n = 117) treated for two months in two double-blind randomized trials versus placebo. The venotropic activity of Daflon 500 mg, was shown by a significant reduction of CVI signs and symptoms, whether organic or functional, and a significant improvement in venous hemodynamics according to plethysmographic parameters. Good acceptability was observed after medium and long term trials.