[Transport and localization of troxerutin in the venous wall]

The vein wall is nourished by diffusion of blood nutrients from the lumen and from the vasa vasorum. It is likely that drugs take the same ways to reach and diffuse through the vessel wall. Thus the uptake of a drug with affinity for the vein wall should give information on its transport to the tissue. This study aimed to explore troxerutin uptake by the long saphenous vein. Troxerutin is a naturally fluorescent flavonoid which has been known to improve subjective signs of patients with chronic venous insufficiency. Nine patients undergoing surgical treatment of varicosis were enrolled in the study. They received for the last 4 days before surgery either 3,500 mg of troxerutin (n = 4) or 1,000 mg twice daily (n = 2). Three patients as controls did not receive any drug. Two samples from thigh and calf long saphenous vein were harvested in each patients and investigated with a confocal laser scanning microscope developed by our institute measuring the fluorescence emitted by troxerutin after excitation by a 458 nm wavelength laser-beam. The intensity of the overall fluorescence was significantly higher in the treated groups (p < 0,001) and slightly higher in the patient who received 3,500 mg of troxerutin than with the lower dosage. The outer wall region provided the highest fluorescence in the treated group while a significant difference was observed in the fluorescence of the medial region between treated and control group. These results showed a marked affinity of troxerutin for the venous wall. The highest uptake in the outer wall region is likely to result from transport through vasa vasorum, owing to the rheologic properties of the drug. The significant medial fluorescence may account for the venous tone improvement with the drug.