the present invention now will be described more fully hereinafter with reference to the accompanying drawings , in which preferred embodiments of the invention are shown . this invention may , however , be embodied in many different forms and should not be construed as limited to the embodiments set forth herein ; rather , these embodiments are provided so that this disclosure will be thorough and complete , and will fully convey the scope of the invention to those skilled in the art . like numbers refer to like elements throughout . in the figures , certain components and the thicknesses of some layers may be exaggerated for clarity . with reference to fig1 – 4 , a medicament inhalation delivery device 101 according to embodiments of the present invention is shown therein . the delivery device 101 includes a dispenser 100 and a delivery tube 180 ( see fig1 ). the dispenser 100 includes a pressurizing mechanism 110 , a storage volume 116 and a diffuser tube 120 . the dispenser 100 contains a quantity of a desired medicament 5 ( see fig3 ) in the storage volume 116 . preferably , the quantity of medicament corresponds to a single therapeutic dose . the medicament 5 may be a sterile , dry powder medicament . generally , and as discussed in greater detail below , the medicament 5 may be delivered to the airway of the user , typically to the mouth or nose of the user by locating the free end of the delivery tube 180 adjacent the user &# 39 ; s mouth or nose and actuating the pressurizing mechanism 110 . in this manner , a carrier gas 111 is forced through the storage volume 116 , the diffuser tube 120 and the delivery tube 180 . as the carrier gas 111 flows through the storage volume 116 , the medicament 5 becomes entrained in the gas 111 and is transported and expelled from the delivery tube with the gas to the user . optionally , the delivery tube 180 may be omitted , in which case the open end of the diffuser tube 120 may be directly located adjacent the mouth or nose of the user . as best seen in fig2 and 3 , the dispenser 100 includes an upper sheet 140 , a lower sheet 160 and an intermediate sheet 150 . the relative thickness of the intermediate sheet 150 is exaggerated in fig3 and 4 for clarity . the upper sheet has a blister 142 and a cone - shaped channel 144 formed therein . the blister 142 and the channel 144 are surrounded by marginal portions 146 a , 146 b and 146 c ( fig3 ). the lower sheet 160 has a reservoir 166 formed therein and marginal portions 162 , 164 surrounding the reservoir 166 . the sheets 140 , 150 , 160 are relatively configured and disposed such that the upper sheet 140 is joined to the intermediate sheet 150 , and thereby to the lower sheet 160 , by the marginal portions 146 a and 146 c ( see fig2 ). while the intermediate sheet 150 is shown as extending the full length of the dispenser 100 , the intermediate sheet 150 may be abbreviated and may comprise multiple , discrete sheets . for example , one such sheet may include the membrane 152 as described below and another , separate such sheet may include the membrane 154 as described below . a central portion 146 b of the upper sheet 140 is laminated to the intermediate sheet 150 and overlies the reservoir 166 . the length d of the reservoir 166 is greater than the length c of the central portion 146 b so that an entrance opening or port 114 and an exit opening or port 118 are defined on either side of the central portion 146 b . the ports 114 and 118 have lengths a and b , respectively . the intermediate sheet 150 includes a first or entrance membrane 152 ( indicated by dashed lines in fig2 ) which extends fully across the port 114 . the intermediate sheet 150 also includes an exit membrane 154 ( indicated by dashed lines in fig2 ) which extends fully across the port 118 . in this manner , the reservoir 166 , the entrance membrane 152 , the exit membrane 154 and the central portion 146 b define the reservoir 166 within which the medicament 5 is fully encapsulated in the storage volume 116 . the blister 142 and the marginal portion 162 form the pressurizing mechanism 110 and define a gas chamber 112 . the gas chamber 112 is disposed immediately adjacent the port 114 and is fully sealed from the storage volume 116 by the entrance membrane 152 . similarly , the channel 144 and the marginal portion 164 form the diffuser tube 120 and define a passage 122 and a delivery opening 124 . the passage 122 is disposed immediately adjacent the port 118 and is fully sealed from the storage volume 116 by the exit membrane 154 . the upper and lower sheets 140 , 160 are preferably thermoformed from a suitable polymeric or elastomeric material . more preferably , the upper and lower sheets 140 , 160 are formed of a co - laminated or co - extruded film including a layer of thermoformable polyethylene terephthalate ( pet ) on the exterior thereof and a layer of heat - sealable polyethylene on the interior thereof . the intermediate layer 150 is preferably formed of a layer of polyethylene . preferably , the intermediate layer 150 has a thickness of between about ½ and 4 mil . preferably , the intermediate layer 150 has a burst pressure of between about 4 . 4 and 89 . 0 newtons . preferably , the intermediate layer 150 has a tensile strength of between about 10 and 50 mpascals . the gas chamber 112 preferably has a volume of between about 0 . 2 and 10 milliliters . the gas in the gas chamber 112 and the gas in the storage volume 116 can be the same or different gases . these gases may be air or other suitable gases . for example , noble gases , n 2 , ar or he may be used . the medicament 5 may be any substance which produces a clinically useful result . by “ clinically useful result ” is meant clinically adequate prevention or treatment of a disease or condition by administration of a substance . examples include , but are not limited to , clinically adequate control of blood sugar levels ( insulin ), clinically adequate management of hormone deficiency ( pth , growth hormone , etc . ), expression of protective immunity ( vaccines ), prevention of thrombosis ( heparin or derivatives ), alleviation or prevention of pain ( antimigraines , opiods , etc . ), infection control ( antibiotics ), allergy control , or clinically adequate treatment of toxicity ( antitoxins ). more preferably , the medicament 5 is a dry powder consisting of a substance producing a clinically useful result . such substances may be incorporated as components of mixtures with other excipients by processes which are known in the art . such processes may include , but are not limited to , freeze drying of mixtures followed by dry blending , spray drying and supercritical processing methods . the dispenser 100 ( or a series of dispensers 100 ) may be formed on a web in a manner similar to that commonly employed to form blister packs . the blister 142 and the channel 144 are thermoformed in a web corresponding to the upper sheet 140 , and the reservoir 166 is thermoformed in a web corresponding to the lower sheet 160 . a web corresponding to the intermediate sheet 150 is inserted between the webs corresponding to the sheets 140 and 160 . the webs corresponding to the sheets 140 , 150 and 160 are then heat sealed in the layered configuration as shown in fig3 with the medicament 5 disposed in the reservoir 160 . preferably , the medicament 5 is first placed in the reservoir 166 , the web corresponding to the sheet 150 is thereafter heat sealed to the web corresponding to the sheet 160 to package the medicament 5 , and the web corresponding to the sheet 140 is thereafter heat sealed to the opposite side of the web corresponding to the sheet 150 to form a unitary dispenser 100 . the dispenser 100 is then die cut or otherwise severed from the remainder of the webs . for inhalation through the nose , the dispenser 100 is preferably used without the delivery tube 180 . for inhalation through the mouth , the dispenser 100 may be mounted in the opening 182 b of the delivery tube 180 by means of slots 184 ( fig1 ). the delivery opening 182 a of the delivery tube 180 is placed adjacent the user &# 39 ; s mouth or , alternatively , the delivery opening 124 of the diffuser tube 120 is placed adjacent the user &# 39 ; s nose . preferably , in operation , the dispenser 100 is oriented such that the blister 142 is on top and the reservoir 166 is on bottom . the user then begins inhaling through the delivery tube 180 or the diffuser tube 120 . as the user is inhaling , the user applies a compressive load to the blister 142 as indicated by the direction arrows l in fig4 . this may be conveniently and effectively accomplished by squeezing or depressing the blister 142 and the marginal portion 162 between the user &# 39 ; s thumb and one or more fingers . as the user compresses the blister 142 , the pressure within the gas chamber 112 is increased , thereby applying an increasing load to the entrance membrane 152 . when a prescribed pressure is created in the gas chamber 112 , the entrance membrane 152 will burst , placing the gas chamber 112 in fluid communication with the storage volume 116 . the exit membrane 154 is substantially immediately thereafter loaded by the same pressure and bursts as well , placing the storage volume 116 in fluid communication with the passage 122 . as a result , a continuous flow path is provided from the gas chamber 112 to the delivery opening 124 . the gas 111 originally in the gas chamber 112 is displaced at high velocity through the ports 114 , 118 and the storage volume 116 such that the gas 111 aerosolizes the medicament 5 and a plume 5 a including the medicament 5 is forced out of or expelled from the dispenser 100 as shown in fig4 . the diffuser tube 120 and / or the delivery tube 180 enable expansion and mixing of the plume and also allow the plume 5 a to slow before ultimate delivery to the user . it will be appreciated that the carrier gas 111 which aerosolizes the medicament may include some or all of the gas stored in the storage volume 116 . moreover , dispensers according to the present invention may be configured such that the gas originally stored in the gas chamber 112 does not ultimately form a part of the plume 5 a , but rather this gas displaces a downstream quantity of gas which aerosolizes the medicament 5 . means other than the thermoformed reservoir 166 may be employed to hold the medicament 5 in the flow path of the gas . for example , the reservoir may be separately formed from the pressurizing mechanism 110 or the diffuser tube 120 , for example . the delivery device 101 and the dispenser 100 provide a number of advantages . the dispenser 100 is cost effective to manufacture and may correspond to the cost of simply packaging single doses of the medicament 5 itself . the delivery device 101 and the dispenser 100 are easy to use . the dispenser 100 can provide a single , accurately measured dose . because of the provision of the pressurizing mechanism 110 , the dispenser 100 does not require a high degree of inspiratory effort on the part of the user to deliver the full , prescribed dose . the dispenser 100 may be disposable , so that no cleaning or reloading is required . the preferred properties of the membranes 152 , 154 and the configurations and dimensions of the blister 142 and the reservoir 166 will depend on the amount and characteristics of the medicament 5 , as well as the operational characteristics desired . the prescribed pressure should be high enough to create a sufficient carrier gas velocity to dispense and deaggregate the medicament 5 to thereby create a cloud of the medicament 5 which is suitable for inhalation and which can propel substantially all of the medicament 5 . a residue of the medicament 5 may remain in the reservoir 166 after application . preferably , the amount of residue is no more than 10 % of the original amount of medicament 5 . however , the prescribed pressure is preferably sufficiently low as to not require undue effort from the user to generate the prescribed pressure in the gas chamber 112 . the prescribed pressure of the dispenser 100 necessary to deliver the medicament 5 will depend on the effective burst pressure and tensile strength of one or both of the membranes 152 and 154 . the performance of the dispenser 100 may be varied by appropriately selecting and configuring the materials of the membranes to provide the effective burst pressures and tensile strengths of the membranes 152 and 154 . for some applications , it may be desirable to provide both of the membranes 152 and 154 with substantially the same effective burst pressures and / or tensile strengths . this may be accomplished by forming the membranes 152 and 154 of the same material and with the same dimensions . for some applications , it may be desirable to provide one of the membranes 152 , 154 with a higher effective burst pressure and / or tensile strength than the other membrane 152 , 154 . it has been found that a more complete emitted dose ( i . e ., less residual medicament remaining in the reservoir 166 following activation ) may be achieved when one of the membranes 152 , 154 ruptures at a pressure significantly below the prescribed pressure . in particular , it has been found that for some embodiments the residual dose is substantially reduced or effectively eliminated when the entrance membrane 152 is adapted to burst at a pressure less than the pressure required to burst the exit membrane 154 . preferably , the entrance membrane 152 is adapted to burst at between about 20 and 80 % of the pressure at which the exit membrane 154 bursts . the membranes 152 , 154 may be adapted to burst at different pressures by appropriate selection of the relative materials , thicknesses and / or different sizes of ports 114 , 118 . alternatively or additionally , the following features may be used to provide differential bursting pressures . these features may be used individually or in combination . with reference to fig5 , an intermediate sheet 250 as shown therein may be substituted for the intermediate sheet 150 of the dispenser 100 . the intermediate sheet 250 includes an entrance membrane 252 and an exit membrane 254 ( each indicated by dashed lines ) corresponding to the membranes 152 and 154 , respectively . the intermediate sheet 250 may be formed in the same manner as the intermediate sheet 150 except that the sheet 250 is further provided with embossments 252 a and 254 a on the membranes 252 and 254 to control the break pattern of the film . the embossments can be depressions , deformations , scored regions or reduced thickness regions in the film of the sheet 250 and serve to provide preferential release portions or weakened locations . the embossments 252 a and 254 a may have different patterns ( as shown ) or the same pattern . one of the embossments 252 a , 254 a may be omitted . in particular , the embossment 254 a may be omitted in order to provide the membrane 252 with a lower effective burst pressure than the membrane 254 . an alternative embossment pattern includes multiple small points which , upon application of a relatively low pressure , will break to convert the selected membrane ( s ) into a mesh . the embossments 252 a , 254 a may be formed by any suitable means , for example , by mechanical and / or heat stamping . with reference to fig6 , a dispenser 300 according to a further embodiment is shown therein . the dispenser 300 includes upper and lower sheets 340 and 360 corresponding to the upper and lower sheets 140 and 160 , respectively , and can be constructed in the same manner as the dispenser 100 except that the intermediate sheet 150 is replaced with intermediate sheets 350 a and 350 b . the sheet 350 a includes the entrance membrane 352 ( indicated by dashed lines ) and the sheet 350 b includes the exit membrane 354 ( indicated by dashed lines ). the sheets 350 a , 350 b are formed of oriented films . as used herein , “ oriented film ” means a film which is drawn in the direction of flow during or after extrusion . preferably , the sheets 350 a , 350 b are formed of uniaxially oriented films . preferably , the films of the sheets 350 a , 350 b are oriented at different angles and , more preferably , at an angle of about 90 degrees with respect to one another . most preferably , the film of the sheet 350 a ( and , thus , the film of the entrance membrane 352 ) is oriented to tear along an axis p substantially parallel to the flow path and the film of the sheet 350 b ( and , thus , the film of the exit membrane 354 ) is oriented to tear along an axis r substantially perpendicular to the flow path . with reference to fig7 and 8 , a dispenser 400 according to a further embodiment of the present invention is shown therein . the dispenser 400 corresponds to the dispenser 100 except that the dispenser 400 is further provided with an end cap assembly 490 . the end cap assembly 490 includes a cap 492 that is removably mounted on the diffuser tube 420 as shown in fig7 . a connector string 494 is secured to the cap 492 , extends through the passage 422 , and is secured to the exit membrane 454 . in use , the user first pulls the cap 492 away from the diffuser tube 420 , thereby tearing and / or pulling a portion or all of the exit membrane 454 away as shown in fig8 . in this manner , the port 418 is partially or fully opened at a desired dispensing time . the user may then actuate the dispenser 400 in the manner described above with regard to the dispenser 100 . with reference to fig9 , a dispenser 500 according to further embodiments of the present invention is shown therein . the dispenser 500 corresponds to the dispenser 100 except as follows . a piercing member 553 can be molded into or otherwise secured to the lower sheet 560 ( e . g ., prior to heat sealing the upper , lower and intermediate sheets ). the piercing member 553 extends into the storage volume 116 below the entrance membrane 552 . when the blister 542 is depressed , the pressure therein causes the entrance membrane 552 to deform or bulge downwardly into contact with the piercing member 553 . in this manner , the membrane 552 may be pre - pierced or burst at a pressure lower than the pressure required to burst the exit membrane 554 . with reference to fig1 , a dispenser 600 according to further embodiments of the present invention is shown therein in a partially actuated position . the dispenser 600 corresponds to the dispenser 100 except as follows . a piercing member 653 is molded into or otherwise secured to the upper sheet 640 and , more particularly , into the blister 642 . prior to actuation of the pressurizing mechanism 610 , the piercing member 653 extends downwardly into the gas chamber 612 and is positioned suspended above the entrance membrane 652 . when the blister 642 is depressed , the piercing member 653 is displaced and moves to contact the entrance membrane 652 . in this manner , the membrane 652 may be pre - pierced or burst at a pressure lower than the pressure required to burst the exit membrane 654 . with reference to fig1 , a dispenser 700 according to further embodiments is shown therein in a partially actuated position . the dispenser 700 corresponds to the dispenser 100 except as follows . the stiffness , elasticity and other appropriate characteristics of the upper sheet 740 , the lower sheet 760 and the intermediate sheet 750 are selected such that , as the blister 742 is depressed in a direction m , the portions of the several sheets 740 , 750 , 760 upstream of the entrance port 714 ( collectively , the dispenser portion 703 ) stretch laterally in the direction n relative to the portions of the sheets 740 , 750 , 760 downstream of the entrance port 714 ( collectively , the dispenser portion 705 ). this stretching increases the length e of the port along the direction n ( i . e ., substantially along the length of the flow path ) and thereby distorts the entrance membrane 752 . such distortion creates non - uniformity in the entrance membrane 752 and resultant stress concentrations . in this manner , the entrance membrane 752 may be burst at a pressure lower than the pressure required to burst the exit membrane 754 . with reference to fig1 and 13 , a dispenser 800 according to further embodiments of the present invention is shown therein . the dispenser 800 has an upper sheet 840 , an intermediate sheet 850 and a lower sheet 860 corresponding to the sheets 140 , 150 and 160 , respectively , except as follows . the upper sheet 840 and the lower sheet 860 are integrally formed as a clam shell member 810 and are pivotably joined by hinge portions 812 . cone shaped diffuser channels 844 a and 844 b are formed in the sheets 840 and 860 , respectively . to assemble the dispenser 800 , the sheets 840 , 860 are folded or pivoted about the hinges 812 with the sheet 850 positioned therebetween . the channels 844 a , 844 b combine to form an enlarged conical diffuser tube 820 . optionally , the channel 844 b may be replaced with a planar portion as is the dispenser 100 . the dispenser 800 has a generally accordion or bellows shaped blister 842 . the blister 842 has generally vertically extending ring shaped walls 842 a and ring shaped , rounded connecting walls 842 b . the walls 842 a are preferably substantially concentric with each other and with the walls 842 b . the blister 842 is tapered such that the diameters of the walls 842 a , 842 b decrease incrementally toward the upper end of the blister 842 . when the blister 842 is depressed , the walls 842 tend to guide the blister 842 in a vertical direction v which is preferably collinear with the common central axis of the walls 842 a , 842 b . the rounded walls 842 b allow the blister 842 to collapse easily against the underlying segments . the telescoping shape of the blister 842 helps to prevent roll - over of the blister as it is being depressed . with reference to fig1 and 15 , a delivery device 901 according to further embodiments of the present invention is shown therein . the delivery device 901 includes a delivery tube 980 and a dispenser 900 corresponding to the dispenser 100 . the delivery tube 980 is configured and formed of a suitable material such that the delivery tube 980 is foldable . suitable materials may include polystyrene , polyvinyl chloride ( pvc ), polypropylene , polyethylene , polyester or abs . the delivery tube 980 may be maintained in a folded position , as shown in fig1 , such that portions 986 a and 986 b of the delivery tube 980 are joined along a fold 981 . this position may be particularly advantageous for storing the delivery device 901 . when the user wishes to administer a dose from the dispenser 900 , the user may unfold the portion 986 b about the fold 981 to extend the delivery tube 980 in the delivery position as shown in fig1 . with reference to fig1 and 17 , a delivery device 1001 according to further embodiments of the present invention is shown therein . the delivery device 1001 includes a dispenser 1000 corresponding to the dispenser 100 . the delivery device 1001 further includes a delivery tube 1080 . the delivery tube 1080 includes a plurality of telescoping segments 1086 a , 1086 b , 1086 c . for storage , the delivery tube 1080 may be slidably nested or compressed as shown in fig1 . the delivery tube 1080 may thereafter be re - extended as shown in fig1 for use . with reference to fig1 , a delivery device 1101 according to further embodiments of the present invention is shown therein . the delivery device 1101 includes a dispenser 1100 corresponding to the dispenser 100 . the delivery device 1101 further includes a delivery tube 1180 . the delivery tube 1180 corresponds to the delivery tube 180 except that a plurality of baffles 1188 a and 1188 b are secured to the interior surface 1181 of the delivery tube 1180 and extend radially inwardly therefrom . the baffles 1188 a , 1188 b are preferably integrally molded into the delivery tube 1180 . the baffles 1188 a and the baffles 1188 b extend from opposing sides of the delivery tube 1180 and are arranged in a sequentially alternating fashion . the baffles 1188 a , 1188 b may serve to slow the plume of medicament from the dispenser 1100 . the baffles 1188 a , 1188 b may also serve to deaggregate the medicament and also to induce additional turbulence in the carrier gas stream to aid in mixing of the medicament with the carrier gas stream . with reference to fig1 , a delivery device 1201 according to further embodiments of the present invention is shown therein . the delivery device 1201 includes a dispenser 1200 corresponding to the dispenser 100 . the delivery device 1201 further includes a delivery tube 1280 . a helical rib 1287 is secured to and extends radially inwardly from the interior surface 1281 of the delivery tube 1280 . the rib can be integrally molded with the delivery tube 1280 . the helical rib 1287 extends down at least a portion of the length of the interior wall of the delivery tube 1280 . preferably , the rib 1287 has a radially extending height of between about ⅕ and ⅘ of the exit tube diameter . the helical rib 1287 may serve the functions discussed above with regard to the baffles 1188 a , 1188 b . with reference to fig2 , a delivery device 1301 according to further embodiments of the present invention is shown therein . the delivery device 1301 includes a dispenser 1300 corresponding to the dispenser 100 , for example . the delivery device 1301 further includes a delivery tube 1380 corresponding to the delivery tube 180 except as follows . a mesh or screen 1389 is positioned in and secured to the interior surface 1381 of the delivery tube 1380 . preferably , the screen 1389 extends fully across the width of the delivery tube 1380 . the preferred mesh size of the screen 1389 will depend on the optimum particle size of the powder to be delivered . the screen 1389 is preferably formed of a plastic material . the screen 1389 may serve the functions discussed above with regard to the baffles 1188 a , 1188 b . as a further alternative , baffles corresponding to the baffles 1188 a , 1188 b may be secured to and extend radially inwardly from the interior wall or the delivery opening 124 of the diffuser tube 120 , for example . similarly , a helical rib corresponding to the helical rib 1287 may be provided in the diffuser tube 120 , for example . also , as a further alternative , a screen corresponding to the screen 1389 may be mounted in the diffuser tube 120 or the port 124 . the foregoing is illustrative of the present invention and is not to be construed as limiting thereof . although a few exemplary embodiments of this invention have been described , those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention . accordingly , all such modifications are intended to be included within the scope of this invention as defined in the claims . therefore , it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed , and that modifications to the disclosed embodiments , as well as other embodiments , are intended to be included within the scope of the appended claims . the invention is defined by the following claims , with equivalents of the claims to be included therein .
a medicament delivery device for administering a medicament to a user includes a medicament reservoir and an entrance port and an exit port each disposed adjacent the reservoir . a gas chamber disposed adjacent the entrance port . the device includes a pressurizing mechanism operable to pressurize said gas chamber to at least a prescribed pressure . a first frangible membrane extends across the entrance port and separates the reservoir from the gas chamber . a second frangible membrane extends across the exit port . when the pressurizing mechanism is attached , at least one of the first and second membranes is responsive to the prescribed pressure in the gas chamber to burst to allow gas to flow through the entrance port and the reservoir and to carry the medicament through the exit port .