Generation of therapeutic microfoam

Abstract

A method for producing a microfoam suitable for use in scleropathy of blood vessels comprises introducing a physiologically acceptable blood-dispersible gas into a container ( 1 ) holding an aqueous sclerosant liquid and releasing the mixture of blood-dispersible gas and sclerosant liquid, whereby upon release of the mixture the components of the mixture interact to form a microfoam.

1 . A method for producing a microfoam suitable for use in scleropathy of blood vessels, characterised in that it comprises introducing a physiologically acceptable blood-dispersible gas into a container holding an aqueous sclerosant liquid and releasing the mixture of blood-dispersible gas and sclerosant liquid, whereby upon release of the mixture the components of the mixture interact to form a microfoam.  
     
     
         2 . A method as claimed in  claim 1 , characterised in that the mixture of blood-dispersible gas and sclerosant liquid is pressurised to a pre-determined level, in the range 800 mbar to 4.5 bar gauge.  
     
     
         3 . A method as claimed in  claim 2 , characterised in that the source of the blood-dispersible gas is removed before the mixture of blood-dispersible gas and sclerosant liquid is released, having pressurised the mixture to a pre-determined level.  
     
     
         4 . A method as claimed in any preceding claim, characterised in that the blood-dispersible gas is introduced through the same orifice or lumen as is used for the dispensing of the mixture of blood-dispersible gas and sclerosant liquid.  
     
     
         5 . A method as claimed in any preceding claim, characterised in that the physiologically acceptable blood-dispersible gas is introduced into the container holding the aqueous sclerosant liquid on the same day as the foam is to be used in scleropathy of blood vessels.  
     
     
         6 . A method as claimed in any preceding claim, characterised in that the sclerosant liquid is stored in the presence of an inert gas or mixture of inert gases.  
     
     
         7 . A method as claimed in any preceding claim, characterised in that the blood-dispersible gas is stored in a container provided with engaging means for the container holding the aqueous sclerosant liquid.  
     
     
         8 . A method as claimed in any  claim 7 , characterised in that the engaging means comprises an intermediate element.  
     
     
         9 . A method as claimed in  claim 8 , characterised in that part of the intermediate element is removed before the mixture of blood-dispersible gas and sclerosant liquid is released, having pressurised the mixture to a pre-determined level.  
     
     
         10 . A method as claimed in  claim 8  or  claim 9 , characterised in that the intermediate element includes a foaming element to allow the components of the mixture to interact to form a microfoam.  
     
     
         11 . A method as claimed in  claim 10 , characterised in that the foaming element comprises one or more passages of small cross-sectional dimension.  
     
     
         12 . A method as claimed in any preceding claim, characterised in that the mixture is passed through one or more passages having at least one cross-sectional dimension of from 0.1 to 30 μm, the ratio of gas to liquid being controlled such that a microfoam is produced having a density of between 0.07 g/ml to 0.19 g/ml and a half-life of at least 2 minutes.  
     
     
         13 . A device for producing a microfoam suitable for use in scleropathy of blood vessels, comprising a housing in which is situated a pressurisable chamber containing a solution of the sclerosing agent in a physiologically acceptable solvent; a pathway with one or more outlet orifices by which the solution may pass from the pressurisable chamber to the exterior of the device through said one or more outlet orifices and a mechanism by which the pathway from the chamber to the exterior can be opened or closed such that, when the container is pressurised and the pathway is open, fluid will be forced along the pathway and through the one or more outlet orifices; 
 said housing incorporating an inlet for the admission of a pressurised source of physiologically acceptable gas that is dispersible in blood; the gas being in contact with the solution on activation of the mechanism such as to produce a gas-solution mixture;    said pathway to the exterior of the housing including one or more foaming elements;    characterised in that the blood-dispersible gas is stored in a container provided with engaging means for the housing holding the aqueous sclerosant liquid.    
     
     
         14 . A device as claimed in  claim 13 , characterised in the foaming element(s) comprise one or more passages of cross sectional dimension 0.1 μm to 30 μm, through which the solution and gas mixture is passed to reach the exterior of the device, said passing of said mixture through the passages forming a microfoam of from 0.07 to 0.19 g/ml density and of half-life at least 2 minutes.  
     
     
         15 . A device as claimed in  claim 13  or  claim 14 , characterised in that the source of the blood-dispersible gas is removed before the mixture of blood-dispersible gas and sclerosant liquid is released, having pressurised the mixture to a pre-determined level.  
     
     
         16 . A device as claimed in  claim 15 , characterised in that the inlet for the admission of physiologically acceptable gas comprises the outlet used for dispensing of the mixture of blood-dispersible gas and sclerosant liquid.  
     
     
         17 . A device as claimed in any one of  claims 13  to  16 , characterised in that the engaging means comprises an intermediate element.  
     
     
         18 . A device as claimed in  claim 17 , characterised in that part of the intermediate element is removable before the mixture of blood-dispersible gas and sclerosant liquid is released, having pressurised the mixture to a pre-determined level.  
     
     
         19 . A device as claimed in  claim 17  or  claim 18 , characterised in that the intermediate element includes a foaming element to allow the components of the mixture to interact to form a microfoam.  
     
     
         20 . A device as claimed in any one of  claims 13  to  19 , characterised in that the engaging means comprises a connector which engages at one end with the container for the aqueous sclerosant liquid and at the other end with the container for the blood-dispersible gas.  
     
     
         21 . A device as claimed in  claim 20 , characterised in that the connector comprises a generally cylindrical element with open ends.  
     
     
         22 . A device as claimed in  claim 20  or  21 , characterised in that the connector includes a cam track, whereby rotation of the containers relative to each other moves them together in a controlled fashion.  
     
     
         23 . A device as claimed in  claim 22 , characterised in that the cam track is further provided with a release track, so that the containers may be separated again.  
     
     
         24 . A device as claimed in  claim 22  or  23 , characterised in that one or more detents is provided in the cam track, to enable the user to gauge the progress of the introduction of the blood-dispersible gas.  
     
     
         25 . A device as claimed in any one of  claims 13  to  24 , characterised in that a removable spacer is provided to prevent the containers from being pushed together until required.  
     
     
         26 . A device as claimed in  claim 25 , characterised in that the removable spacer takes the form of an annular collar positioned in between a connector in two parts.  
     
     
         27 . A device as claimed in any one of  claims 20  to  24 , characterised in that the connector includes an aerosol valve actuator mechanism, and the containers may be separated to leave the actuator mechanism attached to the container for the sclerosing agent.  
     
     
         28 . A device for producing a microfoam suitable for use in scleropathy of blood vessels, in the form of a kit comprising: 
 (a) a housing in which is situated a pressurisable chamber containing a solution of the sclerosing agent in a physiologically acceptable solvent; a pathway with one or more outlet orifices by which the solution may pass from the pressurisable chamber to the exterior of the device through said one or more outlet orifices and a mechanism by which the pathway from the chamber to the exterior can be opened or closed such that, when the container is pressurised and the pathway is open, fluid will be forced along the pathway and through the one or more outlet orifices; and    (b) a pressurised container containing a physiologically acceptable blood-dispersible gas; 
 said housing incorporating an inlet for the admission of blood-dispersible gas;  
   the gas being in contact with the solution on activation of the mechanism such as to produce a gas-solution mixture.    
     
     
         29 . A device as claimed in  claim 28 , characterised in that said pathway to the exterior of the housing includes one or more foaming elements.  
     
     
         30 . A device as claimed in any one of  claim 28  or  claim 29 , characterised in that the housing in which is situated the pressurisable chamber containing the solution of the sclerosing agent and the container containing the blood-dispersible gas are placed in a sealed package.  
     
     
         31 . A device as claimed in any one of  claims 13  to  30 , characterised in that the sclerosant liquid is stored in the presence of an inert gas or mixture of inert gases.  
     
     
         32 . A method of treating a patient in need of sclerotherapy of a blood vessel comprising administering a microfoam from a device as claimed in any one of  claims 13  to  31  to that blood vessel.