Methods and apparatus for delivering aerosolized medication

• US 6,095,141 A
• Filed: 06/07/1999
• Issued: 08/01/2000
• Est. Priority Date: 10/17/1997
• Status: Expired due to Term

• Current Assignee: MAP Pharmaceuticals, Inc. (Abbvie Incorporated)
• Original Assignee: Sheffield Pharmaceuticals, Inc. (Theriva Biologics, Inc.)
• Inventors: Pavkov, Richard Matthew, Mohsen, Nahed Mohsen, Armer, Thomas Alex, Sudhalkar, Atul M., Evans, Bryce Burwick
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): MARTIN, TOOD M
• Application Number:
  US09/326,531
• Time in Patent Office: 421 Days
• Field of Search: 128/200.23, 128/203.15, 128/203.12, 128/200.14, 128/200.18, 128/200.21, 128/204.26, 128/204.25
• US Class Current: 128/204.26
• CPC Class Codes: A61M 15/0086 Inhalation chambers
• CPC Class Codes: A61M 15/0088 with variable volume
• CPC Class Codes: A61M 15/009 using medicine packages with incorporated spraying means, e.g. aerosol cans pocket atomiser of the injector type A61M11/08
• CPC Class Codes: A61M 15/0091 mechanically breath-triggered
• CPC Class Codes: A61M 15/0095 Preventing manual activation in absence of inhalation
• CPC Class Codes: A61M 2206/16 Rotating swirling helical flow, e.g. by tangential inflows

Abstract

A metered dose inhaler (10) for use with a pressurized aerosol canister (18) includes a housing (12) defining a conduit (16) with a mouthpiece (56), and an actuator (26) with a nozzle discharge orifice (30) arranged to discharge aerosol into the conduit. An air tube (34) is arranged within the conduit with an inlet (38) of the air tube formed in the conduit wall (74) and an outlet (36) of the air tube in opposing relationship with the nozzle orifice. Inhalation through the mouthpiece causes air to be drawn into the inlet and flow out of the outlet of the air tube to form an air jet which impinges on an oppositely moving aerosol plume from the orifice. Automatic actuation of the canister responsive to the patient'"'"'s inhalation is achieved by a canister trigger (154) connected to a movable piston assembly (132) forming a wall of a variable-volume chamber (162) in fluid communication with a venturi (184) in the air tube. Air drawn through the venturi by the user'"'"'s breath causes evacuation of air from the chamber, thereby moving the piston assembly and trigger to cause actuation of the canister.

Claims

1. An aerosol flow control apparatus providing automatic discharge of medication responsive to an inspiratory effort of a user, the apparatus comprising:

a pressurized canister of medication including a canister body and a hollow discharge stem which is movable with respect to the canister body between an inoperative position in which discharge of medication is prevented and an operative position in which medication is discharged through the discharge stem;

a housing adapted to support the canister and permit movement thereof between a first position in which the discharge stem is in the inoperative position to a second position in which the discharge stem is in the operative position, the housing further defining a primary air passage including an outlet through which a user can inhale and also defining a secondary air passage extending between the primary air passage and ambient air outside the primary air passage, the secondary air passage including a venturi having a throat;

a variable-volume device supported within the housing and including a wall which is movable with respect to the housing, the variable-volume device defining a variable-volume chamber therein in fluid communication with the venturi throat;

a canister restraint affixed to the movable wall of the variable-volume device, the canister restraint being movable with the movable wall from a rest position in which the canister is in the first position and relative movement between the canister body and discharge stem is prevented, to a discharge position in which the canister is free to move into the second position;

a resilient member which urges the canister into the second position upon movement of the canister restraint into its discharge position; and

the variable-volume chamber being in fluid communication with the primary air passage, whereby inhalation of a user through the outlet causes air to be drawn through the venturi throat thereby creating a low pressure in the throat which is communicated to the variable-volume chamber, the low pressure causing air to be evacuated from the chamber and thereby cause the movable wall to move the canister restraint into the discharge position.

2. The aerosol flow control apparatus of claim 1, wherein the venturi throat is connected to the chamber by a third air passage within the housing, and further comprising an adjustment device which may be selectively positioned to selectively vary the flow rate through the third air passage at a given flow rate through the primary air passage, thereby varying the timing of medication discharge in relation to the inhalation cycle of a user.

3. The aerosol flow control apparatus of claim 1, wherein the variable-volume device comprises a piston which is sealingly connected to a wall of the housing by a flexible diaphragm, and the canister restraint includes a member which is attached to the piston and which in the rest position intrudes into the path traveled by the canister between the first and second positions so as to prevent the canister from moving into the second position, evacuation of air from within the chamber of the variable-volume device causing the piston to move toward the housing wall and thereby withdraw the member into the discharge position permitting the canister to move into the second position.

4. The aerosol flow control apparatus of claim 1, wherein the housing comprises a main body portion which receives the canister, and an end cap which covers the end of the canister opposite from the end with the discharge stem and which engages the main body portion to prevent inadvertent removal therefrom, the resilient member comprising a compression spring between an inner surface of the end cap and the canister such that the spring bears against the canister when the end cap is engaged with the main body portion.

5. The aerosol flow control apparatus of claim 3, wherein the main body portion includes a generally cylindrical receptacle having a longitudinal axis and defining a generally cylindrical recess in which the canister resides, and further comprising a cocking device including:

an inner sleeve which surrounds the canister within the receptacle, the inner sleeve and canister being slidable together as a unit within the receptacle along the longitudinal axis, the inner sleeve further including at least one pin extending outwardly from an outer surface thereof through a slot in the receptacle; and

a cocking ring which surrounds the receptacle and has a surface which engages the at least one pin, the cocking ring being movable with respect to the receptacle so as to move the pin in the direction defined by the longitudinal axis toward the end cap so as to draw the inner sleeve and canister upward and thereby move the canister into a cocked position which permits the canister restraint to move into its rest position, thereby readying the apparatus for actuation in response to the inspiratory effort of a user.

6. The aerosol flow control apparatus of claim 1, wherein the variable-volume device comprises a resiliently compressible bellows, the bellows being disposed between a neck of the canister and a wall of the housing which faces the canister neck, the movable wall being an end wall of the bellows, the canister restraint being affixed to the end wall and contacting the canister neck, the bellows being compressible toward the housing wall in a direction substantially parallel to the direction in which the canister moves from the first position to the second position, the bellows being adapted to exert a spring force on the canister tending to urge the canister toward the first position, the spring force exceeding the force exerted on the canister by the resilient member by a predetermined amount which is selected such that when a user inhales through the outlet of the housing, the pressure force exerted on the end wall of the bellows by the difference between atmospheric pressure outside the bellows and the low pressure inside the bellows exceeds the predetermined amount, thereby causing the end wall to compress the bellows toward the housing wall and move the canister restraint into the discharge position such that the canister is moved into the second position by the resilient member.

7. In an aerosol delivery apparatus which houses a medication-containing canister having a canister body and a hollow outlet stem movable with respect to the canister body between an inoperative position in which discharge of medication is prevented and an operative position in which medication is discharged through the outlet stem, with the canister being movable within the apparatus between a first position in which the outlet stem is in the inoperative position and a second position in which the outlet stem is in the operative position, the apparatus including a housing defining a primary air passage having an outlet through which a user can inhale, a method of synchronizing discharge of medication from the canister with an inspiratory effort of a user through the outlet, the method comprising:

placing the canister in the first position;

preventing movement of the canister into the second position by a canister restraint which engages the canister to prevent said movement and which is movable in response to below-atmospheric air pressure within a variable-volume device arranged within the housing, the variable-volume device defining an air chamber therein, the canister restraint being movable to permit the canister to move into the second position upon a predetermined decrease in volume of the air chamber;

urging the canister toward the second position;

upon a user inhaling through the outlet, drawing air through a secondary air passage arranged within the housing, the secondary air passage extending from the primary air passage to ambient air outside the primary air passage; and

at least during the drawing step, providing fluid communication between the secondary air passage and the air chamber so as to communicate a below-atmospheric air pressure to the air chamber and thereby cause the chamber volume to decrease, whereby the canister restraint moves to permit said movement of the canister into the second position to discharge medication when the predetermined decrease in chamber volume is reached.

8. The method of claim 7, wherein the providing step comprises providing fluid communication between a throat portion of the secondary air passage and the variable-volume chamber to evacuate air therefrom, the throat portion having a reduced cross-sectional flow area relative to the remainder of the secondary air passage such that the air pressure in the throat portion is lower than the air pressure in the remainder of the secondary air passage when air is flowing therethrough.