Generation of therapeutic microfoam
AssigneeBTG International Limited
InventorsAnthony David Harman, Timothy David Boorman, Tariq Osman, Sheila Bronwen Flynn, David Dakin Iorwerth Wright
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Abstract
Improved therapeutic sclerosing microfoams and methods and devices for making them are provided that have advantage in producing a consistent profile injectable foam with minimal input by the physician yet using high volume percentages of blood dispersible gases, thus avoiding use of potentially hazardous amounts of nitrogen.
Claims60
A method for producing a microfoam suitable for use in sclerotherapy of blood vessels characterized in that it comprises passing a mixture of a physiologically acceptable blood dispersible gas and an aqueous sclerosant liquid 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 has a half-life of at least 2 minutes
A method as claimed in any one of the preceding claims characterized in that at least 50% by number of the gas bubbles of 25 μm diameter and above are of no more than 150 μm diameter and at least 95% of these gas bubbles are no more than 250 μm diameter.
A method as claimed in any one of the preceding claims characterized in that the mixture of gas and sclerosant liquid is in the form of an aerosol, dispersion of bubbles in liquid or macrofoam.
A method as claimed in any one of the preceding claims characterized in that the ratio of gas to liquid used in the mixture is 1 gram sclerosant liquid to from 6.25 to 14.3 volumes of gas at standard temperature and pressure.
A method as claimed in any one of the preceding claims characterized in that the physiologically acceptable blood dispersible gas comprises a major proportion of carbon dioxide and/or oxygen.
A method as claimed in any one of the preceding claims characterized in that the aqueous sclerosant liquid is a solution of polidocanol or sodium tetradecylsulfate (STS) in an aqueous carrier.
A method as claimed in any one of the preceding claims characterized in that the cross-sectional dimension is diameter and the one or more passages through which the gas and liquid mixture are passed to produce the microfoam have diameter of from 5 μm to 25 μm.
A method as claimed in any one of the preceding claims characterized in that the mixture of gas and liquid is passed through the same passage or passages a number of times.
A method as claimed in any one of the preceding claims characterized in that the gas is pressurized to 0.01 to 9 bar over atmospheric pressure.
A device for producing a microfoam suitable for use in sclerotherapy of blood vessels comprising a housing in which is situated a pressurisable chamber containing an aqueous sclerosant liquid;
- a pathway with one or more outlet orifices by which the liquid may pass from the pressurisable chamber to exterior of the device through 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 pressurized and the pathway is open, fluid in the chamber will be forced along the pathway and through the one or more outlet orifices
- said housing including one or more of (a) a pressurized source of physiologically acceptable gas that is dispersible in blood and (b) an inlet for admission of said gas;
- the gas being contacted with the liquid on activation of the mechanism such as to produce a gas liquid mixture
- said pathway to the exterior of the housing includes one or more elements defining one or more passages of cross-sectional dimension 0.1 μm to 30 μm, through which the gas liquid mixture is passed to reach the exterior of the device, said passing of the mixture through the passages forming a microfoam of from 0.07 to 0.19 g/mL density and having a half-life of at least 2 minutes.
A device for producing a microfoam suitable for use in sclerotherapy of blood vessels comprising a housing in which is situated a pressurisable chamber with one or more outlet orifices;
- a pathway by which contents of the chamber may be passed to exterior of the housing through the one or more outlet orifices and a mechanism by which the chamber can be pressurized such that its contents therein pass to the exterior along the pathway and through the one or more outlet orifices
- said pathway to the exterior of the housing or the chamber including one or more elements defining one or more passages of cross sectional dimension 0.1 μm to 30 μm, through which contents of the chamber are passed upon actuation of the mechanism.
A device as claimed in claim 34 wherein the chamber contains an aqueous sclerosant liquid and/or a physiologically acceptable blood dispersible gas
A device as claimed in claim 34 or 35 wherein actuation of the mechanism causes the mixture of solution and gas to pass through the passages and form a microfoam of from 0.07 to 0.19 g/mL and having a half-life of at least 2 minutes.
A microfoam comprising a physiologically acceptable gas that is dispersible in blood and an aqueous sclerosant liquid characterized in that the microfoam has a density of from 0.07 to 0.19 g/cm and is capable of being passed down a 21 gauge needle without reverting back to gas and liquid by more than 10%, based on liquid content reverting back to unfoamed liquid phase.
A microfoam comprising a physiologically acceptable gas that is dispersible in blood and an aqueous sclerosant liquid characterized in that the microfoam has a density of from 0.07 to 0.19 g/cm and is capable of being passed down a 21 gauge needle such that 50% or more by number of its gas bubbles of at least 25 μm remain at 150 μm diameter or less and at least 95% of these bubbles at 280 μm diameter or less.
Dependencies are inferred from the claim text.