Dry Powder Inhaler

Abstract

The present invention relates to a dry powder inhaler for administering a medicament via oral inhalation route to a subject. Particularly, the dry powder inhaler according to present invention is suitable for delivering accurate doses of a medicament in different ranges of inspiratory capacity of the subject.

We claim: 
     
         1 - 16 . (canceled) 
     
     
         17 . A method of indicating the inhalation dosage dispensed from a dry powder inhaler through emission of an audible signal, the method comprising:
 (a) opening of a lever or a mouthpiece cap of said inhaler to prime a breath activated mechanism (BAM) by rotation of the lever or the mouthpiece cover from a substantially closed to a substantially open position;   (b) successively moving a BAM flap from a substantially closed position to a substantially open position, wherein a bistable biasing spring holds the BAM flap in the substantially closed position until the bistable biasing spring is overcome by a breath induced low pressure to allow opening of the BAM flap; and   (c) wherein an audible signal is emitted upon movement of the BAM flap to said open position and wherein the audible signal is directly emitted by the movement of the bistable biasing spring, directly emitted by the movement of the BAM flap from a substantially closed position to a substantially open position or is directly emitted by a combination of the movement of the BAM flap and the bistable biasing spring.   
     
     
         18 - 19 . (canceled) 
     
     
         20 . The method of  claim 17 , wherein the dry powder inhaler comprises:
 (a) a body;   (b) a dose-ring subassembly comprising a dose ring and an airway including a swirl chamber and a mouthpiece, wherein the airway has airway inlets and an airway outlet, said airway forming a conduit for bypass air and drug laden air to mix and enter the swirl chamber, and wherein the dose ring is fully enclosed in the body of the dry powder inhaler during use and is capable of rotating through a segment of the airway, said dose ring comprising a plurality of sealed longitudinal foil packets, with each packet containing dry powder comprising a dose of a drug,   (c) the BAM comprising a BAM flap movable from a substantially closed position to a substantially open position and the bistable biasing spring holding the BAM flap in the substantially closed position, the BAM being primed by rotation of a mouthpiece cover from a substantially closed to a substantially open position such that breath induced low pressure overcomes the bistable biasing spring to allow opening of the BAM flap wherein the bistable spring acts to move the BAM flap to the open position, and   (d) a piercer blade;   wherein during the BAM flap travel from the closed to the open position, the movement of the BAM flap forces a latch retaining an energized dose opening mechanism to be disengaged, thereby triggering dose opening by the piercer blade, wherein the dose opening mechanism is energized by the opening of the mouthpiece cover and is held in a latched position until disengaged by movement of the BAM flap and further wherein the piercer blade is a blade with tangs which cut a slit in the sealed foil packet of a dose pocket located on a dose ring such that the piercer blade moves through a lower foil, the dose pocket and an upper foil, and wherein the tangs fold the foils of the foil packet into flaps which are pushed upwards and towards a long side of the dose pocket as the piercer moves upwards.   
     
     
         21 . The breath-actuated dry powder inhaler of  claim 17 , wherein the dose opening mechanism comprises a shuttle that rotates around an axis of the dry powder inhaler and furthermore incorporates a track that guides the piercing element into and out of the sealed foil packet. 
     
     
         22 . The breath-actuated dry powder inhaler of  claim 17 , wherein inhaler incorporates a track that guides the piercing element into and out of the sealed foil packet, the track comprising at least three sections: a horizontal track, a pierce track and a retract track with flexible gates at interfaces that force the piercing element to follow a single route around the track. 
     
     
         23 . The breath-actuated dry powder inhaler of  claim 17 , which is reset by closing of the mouthpiece cover by a patient, wherein a priming component acting in a reverse direction to a priming action engages with a trigger to close the BAM flap and moreover remains engaged with the trigger to prevent the BAM flap from moving. 
     
     
         24 . The breath-actuated dry powder inhaler of  claim 17 , wherein during the resetting action, the priming component also acts on an indexing component which drives the dose ring to rotate and positions a next unopened dose pocket in line with the airway and the piercer ready for the next inhalation. 
     
     
         25 . The breath actuated dry powder inhaler of  claim 17 , wherein the swirl chamber comprises of tangential inlets, a convergent section, an internal post and an attenuator. 
     
     
         26 . The breath actuated dry powder inhaler of  claim 17 , wherein said inhaler is reusable. 
     
     
         27 . The breath-actuated dry powder inhaler of  claim 17 , wherein the dose ring has dose units ranging from about 15 units to about 120 units. 
     
     
         28 . The breath-actuated dry powder inhaler of  claim 17 , wherein the movement of the BAM flap to the open position results in a push of air to sweep through the dose pocket. 
     
     
         29 . The breath-actuated dry powder inhaler of  claim 17 , wherein, the said dose pocket is slit open prior to the sweep of air through the dose pocket. 
     
     
         30 . The breath-actuated dry powder inhaler of  claim 17 , wherein the swirl chamber has a convergent section cone angle of about 50° to 70°. 
     
     
         31 . The breath-actuated dry powder inhaler of  claim 17 , wherein the swirl chamber has an attenuator design selected from the group consisting of a reverse angled mesh design and a crosshair mesh design. 
     
     
         32 . The breath-actuated dry powder inhaler of  claim 17 , further comprising a magnifying lens on an upper clamshell of the body to display a number of doses remaining in the device. 
     
     
         33 . The breath-actuated dry powder inhaler of  claim 17 , wherein the piercer blade is of a planer shape, a spiral shape or a triangular shape. 
     
     
         34 . The breath-actuated dry powder inhaler of  claim 17 , wherein the piercer blade has at least one tang.