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 acceptable 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%.
