Device and method for creating aerosols for drug delivery
A drug delivery device and method is disclosed which produces aerosolized particles of pharmaceutically active drug for delivery to a patient by inhalation. The device is comprised of a liquid feeding source such as a channel to which formulation is added at one end and expelled through an exit opening. The feeding channel is surrounded by a pressurized chamber into which gas is fed and out of which gas is expelled from an opening. The opening from which the gas is expelled is positioned directly in front of the flow path of liquid expelled from the feeding channel. Various parameters are adjusted so that pressurized gas surrounds liquid flowing out of the feeding channel in a manner so as to maintain a stable capillary microjet of liquid until the liquid exits the pressure chamber opening and is aerosolized. The aerosolized particles having a uniform diameter in the range of about 1 to 5 microns are inhaled into a patient's lungs and thereafter reach the patient's circulatory system.
1. The method of delivering an aerosol to the patient, comprising:
feeding a pharmaceutically active drug through a cylindrical channel of a feeding source in a manner which causes the liquid to be expelled from an exit opening as a liquid stream wherein the exit opening has a diameter in a range of from about 0.002 mm to about 2 mm;
forcing a gas through a pressure chamber in a manner which causes the gas to exit the pressure chamber from an exit orifice having a diameter in a range of about 0.002 mm to about 2 mm, the gas exiting downstream of a flow path of the liquid stream expelled from the exit opening of the feeding source;
wherein the exit opening of the feeding source is separated by a distance of from about 0.002 mm to about 2 mm from the exit opening of the feeding source;
wherein the liquid stream is accelerated by tangential viscous stress exerted by the gas on the stream and the liquid is focused on the exit orifice of the pressure chamber by the gas.
2. The method of claim 1 , wherein the liquid has a viscosity in a range of from about 10 −4 to about 1 kg/m/sec.
3. The method of claim 1 , wherein the gas is air.
4. The method of claim 1 , wherein the gas is a non-toxic gas.
5. The method of claim 4 , wherein the non-toxic gas is CO 2 .
6. The method of claim 1 , wherein the liquid is forced through the channel at a rate in a range of about 0.01 nl/sec to about 100 microliters/sec.
7. The method of claim 6 , wherein the gas is forced through the opening of the pressure chamber at a rate in the range of from about 50 m/sec to about 2000 m/sec.
8. The method of claim 1 , wherein the liquid is fed through the channel at a rate in a range of about 1 nanoliter/sec to about 100 microliters/sec and further wherein the gas is forced through the opening of the pressure chamber at a rate in the range of from about 100 to 500 m/sec.
9. The method of claim 1 , wherein the exit opening has a diameter in the range of from about 0.01 mm to about 0.4 mm, and
wherein the exit opening of the feeding source is separated by a distance of from about 0.01 to about 2 mm from the exit orifice in the pressure chamber.
10. The method of claim 1 , wherein the liquid formulation fed through the channel has a volume in the range of 5 microliters to 10,000 microliters.
11. A method of delivering aerosolized particles of a pharmaceutically active drug to a patient, comprising:
feeding liquid formulation comprised of a pharmaceutically active drug through a channel of a liquid feeding source to an outlet having a diameter in a range of from about 0.002 mm to about 2 mm;
feeding gas through an orifice having a diameter in a range of from about 0.002 mm to about 2 mm, the orifice being positioned downstream of the outlet in a direction aligned with a direction of flow out of the outlet as a liquid stream;
wherein the feeding source outlet is separated by a distance of from about 0.002 mm to about 2 mm from the orifice; and
wherein the liquid stream is accelerated by tangential viscous stress exerted by the gas on the liquid stream and the liquid and gas are each fed at a rate relative to each other so as to form aerosolized particles having a size in the range of about 0.1 micron to about 10 microns.
12. The method of claim 11 , wherein gas is forced into an area around the feeding source outlet at a pressure in the range of 10 mBar above atmospheric pressure and further wherein the liquid has a viscosity in the range of from 10 −4 to 1 kg/m/sec.
13. The method of claim 12 , wherein gas is forced into an area around the feeding source outlet at a pressure below 50,000 mBar above atmospheric pressure.
14. The method of claim 12 , wherein gas from the pressure chamber surrounds liquid exiting the feeding source outlet which liquid is drawn into the orifice concentrically being focused by the gas flowing out of the outlet, and further wherein the aerosolized particles formed are uniform in size to the extent of having a relative size standard deviation of 3 to 30%.
15. The method of claim 11 , wherein the liquid formulation fed through the channel has a volume in the range of 5 microliters to 10,000 microliters.