Generation of therapeutic microfoam

#The present invention relates to a method and apparatus for the generation of microfoam comprising a sclerosing material, particularly a sclerosing liquid, which is suitable for use in the treatment of various medical conditions involving blood vessels, particularly varicose veins and other disorders involving venous malformation.

#Sclerosis of varicose veins is based on the injection into the veins of liquid sclerosant substances which, by inter alia causing a localised inflammatory reaction, favour the elimination of these abnormal veins. When a sclerosing substance is injected in liquid form, it is mixed with the blood contained in the vein and is diluted in an unknown proportion. The results are uncertain, owing to over-dosage or under-dosage, and are limited to short varicose segments. As the size of the varicose veins to be injected decreases, this dilution is less and the results obtained are more predictable.

#Until recently, sclerosis was a technique selected in cases of small and medium varicose veins, those with diameters equal to or greater than 7 mm being treated by surgery. Sclerosis and surgery complemented one another but sclerosis treatment continued not to be applicable to large varicose veins. In these large varicose veins, if a sclerosing substance was injected, its concentration in the vein, its homogeneous distribution in the blood, and the time for which it is in contact with the internal walls of the vessel treated were not known.

#FIG. 1 shows a cross-sectional view of a device of the second aspect of the invention incorporating a cam track mechanism, as further described in Example 1 below.

#FIG. 2 shows an exploded view of a canister device of the second aspect incorporating a variant of the cam track mechanism of FIG. 1, as further described in Example 2 below, in which FIG. 2a shows the connector, FIG. 2b shows the complete assembly, FIG. 2c shows a cut-away portion of the connector, and FIG. 2d and FIG. 2e show cross-sections of the cam mechanism.

#FIG. 3 shows an exploded view of a canister device of the second aspect incorporating a screw thread mechanism, as further described in Example 3 below, in which FIG. 3a shows the complete assembly FIG. 3b shows a cross-section of the assembled device.

#FIG. 1 illustrates a device of the second aspect of the invention incorporating a cam track mechanism. The device comprises a container (1) for an aqueous sclerosant liquid, a container (2) for a physiologically acceptable blood-dispersible gas and an engaging means comprising a connector (3).

#The device is designed to be used with the container (1) for the aqueous sclerosant liquid charged with 18 ml of a polidocanol formulation, comprising 1% polidocanol in a pH 7.3 phosphate-buffered aqueous solution including a small proportion of ethanol to solubilise the polidocanol, and a mixture of 75% CO2/25% N2 gas at 0.5 bar absolute pressure. The aerosol valve on the can continuously meters a specified mix ratio of liquid to gas to create a foam of specified density.

#The container (2) for a physiologically acceptable blood-dispersible gas is charged with pure oxygen gas at 5.8 bar absolute pressure. It is used to pressurise the container (1) for the aqueous sclerosant liquid just before the microfoam is required, and is then discarded. The reason for adding the oxygen at the last moment before use is that polidocanol appears incompatible with long term exposure to pressurised oxygen.