The invention relates in particular to an injectable sclerosant drug foam comprising: (i) a matrix (ii) at least one fluid (iii) at least one sclerosant drug (iv) a medical gas or medical gas mixture accepta ble for intravenous use, (v) wherein said matrix has physical properties, which are comparable to denatured blood, wherein the denatured blood is obtainable from a fresh human venous whole blood sample of 1 ml volume, which is heated in a cylindrical polyethylene container with 3 mm inner diameter and 3,4 mm outer diameter for about 0,5 min. to about 10 min. at a temperature of about between 70°C and 100°C and/or (vii) said level of denaturation is defined by the change of red-colored hemoglobin to brown as an indicator, wherein Fe2+ is reduced to Fe3+ in the hemoglobin complex to a degree of at least 80%, preferably 90% and even more preferably 95%.
