WO2007000611A1

WO2007000611A1 - Gas dispenser

Info

Publication number: WO2007000611A1
Application number: PCT/GB2006/050161
Authority: WO
Inventors: Michael Anthony Barrett
Original assignee: BOC Group Ltd
Current assignee: BOC Group Ltd
Priority date: 2005-06-29
Filing date: 2006-06-20
Publication date: 2007-01-04
Anticipated expiration: 2007-12-29
Also published as: TW200711676A; GB0513248D0; JP2009500568A; CN101212993A; CA2612289A1; EP1909869A1

Abstract

A gas dispenser (10) for releasing gas from a capsule (40) of the type having a body (42) and a frangible stem (44) to a delivery system is provided. The dispenser comprises a first housing portion (15) for receiving the body of a capsule and a second housing portion (20) for connecting the first housing portion to the delivery system. The first housing portion comprises a cavity (47) for receiving the stem of a capsule received by the second housing portion. At least one of the housing portions are movable relative to the other, this relative motion causes a shearing force to be applied to the capsule to cause rupture of the capsule such that a gas is released from the capsule.

Description

GAS DISPENSER

This invention relates to the field of gas dispensers, in particular those for releasing gas from a capsule of the type having a body and a frangible stem, where the gas is being dispensed to a delivery system.

Gas capsules of the type referred to above are known in the field of needle free drug delivery systems as described within EP0757202. The capsule of such a system is ruptured to release the gas contained therein. This gas then acts as a propellant for a dose of a particular drug that is to be transmitted to and driven through the skin of a patient.

Gas dispensers incorporated into known drug delivery systems typically comprise a volume within which the gas capsule is located. This volume may arise due to provision of a gas passage from the site of the rupture of the capsule to an outlet of the dispenser. Alternatively, or in addition to this gas passage, operation of the gas dispenser may involve movement of the gas capsule in relation to a unit which houses the capsule such that the outer envelope of motion of the capsule causes an additional volume to be provided to accommodate this movement.

For medical applications it is a requirement that the gas, for example helium, is of an exceptionally high level of purity. This requirement is imposed to ensure that the gas, which acts as a propellant for the drug to be delivered to the patient, is reflected at, rather than passing through, the skin of the patient.

In other applications, for example those in an industrial area, it is also desirable to avoid incorporation of ambient air into the propellant. In some circumstances, the capsule may contain a potentially flammable gas mixture. If the contents of the capsule are mixed with a volume of ambient air the oxidant level in the dispensed gas will be raised. It is possible that this could alter the concentration of the gas mixture to bring it within the flammable range for that mixture, such that if an ignition source were to be present, combustion could occur.

It is therefore an aim of the present invention, to seek to provide a gas dispenser with significantly reduced internal volumes to ensure that the dispensed gas more closely reflects the composition of the gas provided in the capsule.

According to the present invention there is provided a gas dispenser for releasing gas from a capsule of the type having a body and a frangible stem to a delivery system, the dispenser comprising: a first housing portion for receiving the body of a capsule; and a second housing portion comprising a cavity for receiving the stem of a capsule received by the first housing portion, at least one of the housing portions being movable relative to the other to cause a shearing force to be applied to the received capsule to rupture the capsule in order to release a gas therefrom.

By applying a shearing force to the capsule to cause rupture thereof, the body of the capsule itself need not be moved in relation to the housing portion retaining the body of the capsule. Consequently, the envelope provided to accommodate the capsule can be much closer to the external boundary of the capsule to enable internal volumes within the gas dispenser to be optimised.

The dispenser may comprise a connector for connecting the dispenser to a delivery system. The gas dispenser may comprise first and second housing detents for applying a force to each of the body and the stem of a received capsule respectively, upon relative movement between the housing portions. Each respective force may be applied in opposing directions to the respective portion of the received capsule such that the shearing force is applied to the capsule. The first housing detent may be provided by means for securing the body of a received capsule within the first housing portion, and the second housing detent may be provided by a wall defining the cavity. The dispenser may be configured so that the stem of the capsule is completely severed from the remainder of the capsule when the shearing force is applied. The severed stem of the capsule may be retained within the dispenser.

The second housing portion may be mounted on the first housing portion and is preferably rotatably mounted thereon. In the event that the gas capsule is configured such that a relative rotational motion may occur between the housing portions, the first housing portion may be configured to receive a capsule at a location spaced from an axis of relative rotation between the housing portions. As a result, the capsule orbits about this axis upon relative rotation between the housing portions.

A plenum may be provided for receiving gas released from the capsule. A valve may be provided between the plenum and an outlet of the gas dispenser for controlling delivery of gas to a delivery system.

The gas dispenser may be configured to release gas from a plurality of capsules, wherein the first housing portion is configured to receive the body portions of a plurality of capsules and the second housing portion comprises a plurality of cavities, each for receiving the stem of a respective capsule received by the first housing portion. The configuration of the cavities in the second housing portion may be such that the relative motion between the housing portions results in simultaneous rupturing of the capsules. Alternatively the configuration of the cavities in the second housing portion may be such that the relative motion between the housing portions results in sequential rupturing of the capsules. The gas dispenser may be configured to receive at least three capsules. The gas dispenser may be a hand held unit. The delivery system may comprise a regulator and/or a mask or a nozzle. The delivery system may be a drug delivery system. The gas dispenser may comprise a further first housing portion for receiving the body of at least one capsule. - A -

By providing a device that can accommodate a number of gas capsules the gas dispenser can be used to serve a range of non-standard applications by using a standard gas capsule. These different applications may require either a greater pressure charge than can be provided by a single gas capsule, or a multiple shot pressure charge. The multiple shot system can be used to deliver a number of different types of dose from the delivery system in a single application, even when such doses require different propellant gases. Alternatively, the same dose may be delivered on numerous, separate occasions by either connecting the same gas dispenser to a multiple shot delivery system or sequentially connecting the dispenser to a number of single shot delivery systems.

A combination of a gas dispenser and a gas capsule having a body portion and a frangible stem may be provided.

A drug delivery apparatus comprising a gas dispenser, as described above, together with a drug delivery system may be provided. An inlet to the drug delivery system may be configured to mate with an outlet of the gas dispenser such that a fluid tight seal is formed therebetween.

Preferred features of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of a gas dispenser;

Figure 2 is a longitudinal cross section through the gas dispenser shown in Figure 1 ;

Figure 3 is a plan cross section at line XX' of Figure 2;

Figure 4 is a plan cross section at line YY' of Figure 2;

Figure 5 is an alternative plan cross section at line YY' of Figure 2;

Figure 6 shows an isometric representation of a gas dispenser having a valve; Figure 7 shows a longitudinal cross section of the device in Figure 6 with the valve in a closed position;

Figure 8 shows a corresponding cross sectional representation to that shown in Figure 7 with the valve in an open position;

Figure 9a shows a dual ended gas dispenser;

Figure 9b shows a cross section at line ZZ¹ of Figure 9a;

Figures 10a to 10c show a gas dispenser with an integral collar;

Figure 11 shows a gas dispenser with an end cap; and

Figure 12 shows a schematic representation of a delivery apparatus comprising a gas dispenser.

The gas dispenser will be exemplified by reference to a drug delivery system. However it is envisaged that use of the gas dispenser herein described would be equally beneficial in industrial applications requiring high purity of the dispensed gas and adaptability to specific uses. The gas dispenser 10 shown in Figure 1 comprises a first housing portion 15 partially mounted within a second housing portion 20. The second housing portion is provided with a number of retaining members 25, more clearly depicted in Figure 2, which latch onto a ridge 35 formed on the first housing portion 15 to prevent the two components from being inadvertently separated, whilst permitting relative rotation between the housing portions about a common axis. The second housing portion 20 is configured such that it can be securely, but removably, connected to a delivery system (not shown). In Figure 1 this connection 30 is exemplified by a recess formed to cooperate with a bayonet type fitting formed on the mating component of a delivery system. Alternatively matable threads may be provided on the gas dispenser and the delivery system so that a screw type fitting is achieved. The first housing portion 15 is designed to accommodate one or more gas capsules 40. In this example, three such capsules are illustrated but a greater or smaller number of capsules 40 may be accommodated by the first housing portion 15. Each capsule 40 comprises a body portion 42, a collar portion 43 and a frangible stem 44. Such a capsule is known in the art for example as described in WO 04/063622. Pockets 45, as illustrated in Figure 3, are formed within the first housing portion 15 to each accommodate and locate the body portion 42 of a gas capsule 40. In this example, the pockets 45 are distributed evenly about the common axis. However, the design of the location of the pockets 45 need not be symmetrical but rather may be governed by restrictions on the overall design of the gas dispenser 10 or of the drug delivery system. A plate 48 is provided in the opening of the first housing portion 15 to secure the body portions 45 of the capsules 40 within the first housing portion 15. Plate 48 is provided with a number of recesses 47 corresponding to the number of pockets 45 and having the same spacing and distribution about the common axis as that of the pockets 45. Each recess 47 accommodates a collar portion 43 of one of the capsules 40. The combination of a close fitting pocket 45 about the body 42 of the capsule and the even closer fitting recess 47 about the collar 43 of the capsule ensures that the capsules 40 are securely retained by the first housing portion 15. Furthermore, the interface between the plate 48 and the first housing portion 15, and the interface between the plate 48 and the collars of respective capsules 40, are both provided with sealing means 75 (see Figure 7). In this example, the sealing means 75 is provided by o-rings.

The second housing portion 20 is provided with cavities 50. These cavities 50 are spaced about the common axis in a distribution corresponding to that of the pockets 45 within the first housing portion 15 (as illustrated in Figure 4). Consequently, when the first and second housing portions 15, 20 are assembled together into a single device 10, the stems 44 of the capsules 40 that are retained by the first housing portion 15 each protrude into a respective cavity 50. In this example, the cavities 50 are of similar size to one another and will, therefore, function in a control of alignment capacity during assembly of the first and second housing portions 15, 20.

Returning to Figure 2, the second housing portion 20 is provided with a vent hole 55, here formed along the common axis but it may be located in any region between the cavities 50 of the second housing portion 20. This vent hole 55 extends through the axial length of the second housing portion 20 from a region of the second housing portion 20 designed to mate with the first housing portion 15 to an outlet region of the second housing portion 20 designed to mate with a drug delivery system (not illustrated). In this example, a gas chamber 60 in fluid communication with the vent hole 55 is formed in the outlet region of the second housing portion 20. However, in the event that such a chamber 60 is required for the functioning of the drug delivery apparatus, the chamber 60 may be located within the drug delivery system itself. Alternatively, the geometric configuration of the delivery system may be such that it comprises a protrusion that mates with the chamber 60 to further reduce volumes within the assembled apparatus.

Once the first and second housing portions 15, 20 of the dispenser 10 have been assembled, a plenum 65 is formed between a surface of the plate 48 of the first housing portion 15 and a surface of the second housing portion 20. The plenum 65 provides a fluid path between the vent hole 55 and the (or each) capsule 40. The function of the plenum 65 will be described in greater detail below.

In operation of the gas dispenser 10, at least one of the housing portions 15, 20 is rotated about the common axis such that relative rotational movement is experienced therebetween. For example, the second housing portion 20 may remain stationary, together with the drug delivery system to which it is connected, with the first housing portion 15 rotated relative to the second housing portion 20. As the first housing portion 15 is rotated, the body portions 42 of respective capsules 40 are held fast within the first housing portion 15 by the plate 48, and so the capsules 40 are rotated about the common axis to each come into contact with a surface of a recess 47 of plate 48. This surface provides a first housing detent for applying force to the body of its respective received capsule 40 so that movement between the collar 43 of the capsule 40 and the first housing portion 15 is restricted. In practice, the fit between each recess 47 and the collar 43 of a capsule 40 received therein is very close so that substantially no movement occurs between the recess 47 and the collar 43 upon relative rotation of the housing portions 15, 20.

Furthermore, upon the relative rotation between the housing portions 15, 20, the stems 44 of the capsules 40 are each rapidly brought into contact with a surface of its respective cavity 50. This surface acts as a second housing detent for applying a reactive force to the stem 44 of its respective received capsule 40. This force is applied as relative movement between the stem 44 and the second housing portion 20 is checked by the interaction between the second housing detent and the stem 44. In other words, once the stems 44 each engage with the surface of a respective cavity 50, any additional movement of the first housing portion 15 in relation to the second housing portion 20 causes a shearing force to be applied to the capsule 40, in that, on the one hand a force is transmitted to the collar 43 of each of the capsules 40 via plate 48 from the rotation of the first housing portion 15 by the first housing detent whilst, on the other hand, a reaction force is applied to the stem 44 of each of the capsules 40 due to the contact between the stem 44 and the corresponding second housing detent of cavity 50. These opposing forces, collectively termed a shearing force, rupture the capsule, and may cause the stem 44 of each capsule 40 to be severed from the collar 43 of its respective capsule 40. The integrity of each capsule 40 is thus breached, and any compressed gas contained therein is allowed to escape into the plenum 65. The sealing means 75 inhibit ingress of high pressure fluid released from the capsule 40 into the pockets 45 of the first housing portion 15. The gas is conveyed along vent hole 55, into gas chamber 60, and from there into the drug delivery system. In the event that the stems 42 are severed from the remainder of the capsule 40, they may be retained within the cavities 50. As illustrated in Figure 4, in this example the cavities 50 are of similar size and so with relative rotation between the housing portions 15, 20 stems 44 simultaneously engage with a respective second housing detent. Consequently, the capsules 40 are ruptured simultaneously so that the gas dispenser 10 may provide a single shot delivery of a quantity of gas proportional to the number of gas capsules 40 contained within the device 10. Alternatively, the cavities in the second housing portion 20 may be configured as illustrated in Figure 5. As illustrated the cavities 51 , 52, 53 have different sizes and shapes, the cavities becoming progressively more elongated along the direction of relative rotation between the housing portions 15, 20. With the cavities configured in this manner, with relative rotation between the housing portions 15, 20, the stems 44 of the capsules 40 sequentially contact a respective second housing detent, resulting in sequential rupture of the capsules 40. A gas dispenser 10 having this configuration of cavities 51 , 52, 53 may provide a multiple shot delivery of gas, the number of shots being proportional to the number of gas capsules 40 contained within the device 10. In practice, as each capsule 40 is ruptured the passage of gas from the capsule 40 into the plenum 65 causes further rotational movement to be resisted until the pressure is reduced. This resistance reduces the sensitivity of the mechanism, and so delivery of a single shot at a time can be practicably effected. Consequently, a gas dispenser of this type may be used in combination with a number of different drug delivery systems or, alternatively, in combination with a multiple shot drug delivery system.

Figures 6 to 8 illustrate a gas dispenser of a similar type to that described above but incorporating a degree of control of the gas once it has been released from the capsules 40 by provision of a valve 70, for example a spool valve. In Figure 7 the apparatus is shown prior to rupture of the capsule 40 located within the first housing portion 15. The valve 70 is set to a closed position and the drug delivery system is connected to the gas dispenser 10 via connection 30 (not illustrated). The gas dispenser 10 may be provided with a mechanism that prevents attachment of the drug delivery system unless the valve 70 has been set to the closed position, thus ensuring that inadvertent actuation of the mechanism is prevented. Such actuation may lead to loss of the dose of drug to be delivered.

For single shot dispensing, the cavity configuration of Figure 4 is implemented so that the cavities 50 are of comparable size. With the valve 70 maintained in the closed position, the first housing portion 15 is rotated relative to the second housing portion 20 to cause rupture of the capsules 40 contained within the gas dispenser 10, as described above. Gas from these capsules passes into the plenum 65 and into vent hole 55 but is prevented from being conveyed to the gas chamber 60 by virtue of the position of the valve 70. Consequently, the gas pressure reaches equilibrium between the bodies 42 of the capsules, the plenum 65 and vent hole 55. The sealing means 75 provided between the housing portions 15, 20, between the first housing portion 15 and the plate 48 and also between the plate 48 and the collar 43 of the capsule serve to retain the elevated pressure gas within the plenum 65 and the vent hole 55. Further seals 80 are provided integral with the valve 70 to prevent the gas from passing to the gas chamber 60.

When it is desirable to discharge the gas dispenser 10 into the drug delivery system, the valve 70 is moved to an actuated position (as shown in Figure 8) in which a flow path is defined between the vent hole 55 and the gas chamber 60 to enable the pressurised gas to be delivered to the drug delivery system.

In the event that multiple shot dispensing is required, the cavity configuration illustrated in Figure 5 may be implemented in combination with the valve 70 of Figures 6 to 8. The capsules 40 are then ruptured in sequence as described above but the valve 70 is reset to the closed position between each relative rotation between the housing portions 15, 20. Use of the valve 70 thus provides a greater level of control to delivery of the high pressure gas. Consequently, the charge from each capsule 40 can be used to deliver separate doses of drugs to one or more patients using either a multiple shot drug delivery system or a number of separate drug delivery systems. In a further example, as illustrated in Figures 9a and 9b, a dual ended gas delivery dispenser 110 may be provided. A pair of first housing portions 115 is provided in combination with a modified second housing portion 120. Two sets of capsules 40 may be accommodated within the dispenser 110. Body portions 42 of each set of capsules 40 are received by a respective first housing portion 115 in a similar manner to that described above. The stems 44 of each of set of capsules are retained within cavities provided in opposing faces of the modified second housing portion 120 as illustrated. Plena 165 are provided into which gas from ruptured capsules 40 is temporarily stored upon actuation of the device. One or more valves 170 are provided to control delivery of gas from these plena 165 to a chamber 160 and subsequently to a delivery system connected to the second housing portion 120 via connection 130.

Actuation of the gas dispensing device 110 is effected by rotating one of the first housing portions 115 relative to the modified second housing portion 120. The stem 44 and the body 42 of each capsule 40 in a set of capsules consequently experience equal and opposite forces, collectively termed a shearing force as discussed above, leading to each capsule being ruptured so that the gas contained therein escapes to one of the plena 165.

Provision of the dual ended device further enhances the flexibility of the gas dispenser concept. The user may now dispense the gas from a single capsule or from any number of capsules up to, in this example, a maximum of six with each set comprising up to three capsules 40. In this way, the ability to vary the volume, pressure and composition of delivered gas can be significantly enhanced.

As indicated above, the number of capsules that may be accommodated in any of the first housing portions is flexible, and is only restricted in practice by the bulk of the dispenser. The bulk of the dispenser is, in turn, restricted by the portability requirements of the desired application. The example of up to three capsules 40 per set lends itself to a portable, hand-held device for use in precision applications, such as those to be found in the medical or analytical fields.

With further modifications to the second housing portion a dispenser having three, four or even five first housing portions may be readily achieved. Thus the capacity of the dispenser and therefore the flexibility of volume, pressure and composition of gas to be dispensed, can be further enhanced.

An alternative use for the gas dispenser is in the field of controlled inflation. For example, party balloons are generally filled with helium, and a gas dispenser as described herein would be suited to such an application. However, rapid delivery of the highly pressurised gas to the balloon would result in bursting of the balloon. Therefore, a valve having a variable flow rate control may be used to provide a graduated supply of gas therethrough. A gas dispenser having such a degree of control of released gas finds application in other fields, for example, as an inhalation device for dispensing oxygen or Heliox to a patient or to a recreational user through a mask designed to fit over the nose and/or mouth and which is attached to the gas dispenser via connection 30.

In order to achieve the same level of control, a gas dispenser having a valve as shown in Figures 7 and 8, or a gas dispenser with no valve, may be used in combination with a delivery system that comprises a regulator. A controlled inflation delivery system of this type would comprise a nozzle and a regulator, whereas an inhalation delivery system of this type would comprise a mask and a regulator.

The gas dispenser 10 may be provided with one or more additional gas flow paths between the capsule 40 and the delivery system for example by providing at least one further plenum 65 and associated vent hole 55.

The retaining members 25 may be splayed, for example using an annular release ring, in order to part the two housing components and thereby enable any ruptured capsules to be replaced. The release ring may be separate to the gas dispenser (not illustrated) and simply slipped over the first housing portion 15 when required, or it may be integral with the first housing portion 15 as shown in Figures 10a to 10c. As illustrated, such a release ring 85 may be provided on the first housing portion 15, and mounted thereon using a screw thread. Rotation of the ring 85 relative to the first housing portion 15 causes the ring 85 to be translated axially along the gas dispenser 10. Additional axial movement, as shown in Figure 10c, causes the ring 85 to be urged between the first housing portion 15 and retaining members 25 so that they are splayed radially outwards. Thus, retaining members 25 are forced to disengage ridge 35 and the housing portions 15, 20 are consequently released from one another.

Alternatively, as shown in Figure 11 , the first housing portion 15 of gas dispenser 10 may be provided with a removable end cap 90 to permit the removal of ruptured capsules 40 (together with any severed stems 44) and replacement thereof.

A gas dispenser 10 may be incorporated into an automated delivery unit, such as a hand held vaccination gun. In this alternative example, the relative rotation between the housing portions 15, 20 may be achieved using a mechanical or electromechanical device. Such a device may be manually controlled, for example through use of a trigger mechanism. Alternatively, the gas dispenser 10 may be incorporated into a larger, automated unit and mounted for example in the base of a wheelchair. It may be beneficial in such an embodiment for control of the dispensing to be automatically rather than manually controlled.

The examples shown implement a relative rotational movement between the first housing portion 15, 115 and the second housing portion 20, 120 to generate the shearing force experienced by the capsule 40. This configuration results in a compact device, the actuation of which does not result in any components of the device moving outside the original envelope of the apparatus. Alternatively, the shearing force can be generated by causing the first and second housing portions to undergo a relative translational movement with respect to one another. The stems 44 of the ruptured capsules 40 are retained within the apparatus, enhancing the safety and ease of use of the device.

Figure 12 illustrates, in schematic form, a delivery apparatus 200 having a gas dispenser 10 comprising first and second housing portions 15, 20 removably connected to a delivery system 190, for example a drug delivery system, an inhalation mask or a nozzle for attachment to a party balloon.

Claims

1. A gas dispenser for releasing gas from a capsule of the type having a body and a frangible stem to a delivery system, the dispenser comprising: a first housing portion for receiving the body of a capsule; and a second housing portion comprising a cavity for receiving the stem of a capsule received by the first housing portion, at least one of the housing portions being movable relative to the other to cause a shearing force to be applied to the received capsule to rupture the capsule in order to release a gas therefrom.

2. A gas dispenser according to Claim 1 , wherein the second housing portion comprises a connector for connecting the gas dispenser to a delivery system.

3. A gas dispenser according to Claim 1 or Claim 2, comprising: a first housing detent for applying a force in a first direction to the body of a received capsule upon relative movement between the housing portions; and a second housing detent for applying a force in a second direction opposing the first direction to the stem of the received capsule upon said relative movement thereby to apply the shearing force to the capsule.

4. A gas dispenser according to Claim 3, wherein the first housing detent is provided by means for securing the body of a received capsule within the first housing portion.

5. A gas dispenser according to Claim 3 or Claim 4, wherein the second housing detent is provided by a surface defining the cavity.

6. A gas dispenser according to any preceding claim, wherein the dispenser is configured to allow the extent of relative movement between the housing portions to be such that the shearing force causes the stem of a received capsule to be severed from the body of the capsule.

7. A gas dispenser according to Claim 6, wherein the second housing portion is configured to retain the severed stem of the capsule.

8. A gas dispenser according to any preceding claim, wherein the second housing portion is mounted on the first housing portion.

9. A gas dispenser according to Claim 8, wherein the second housing portion is rotatably mounted on the first housing portion.

10. A gas dispenser according to Claim 9, wherein the dispenser is configured to receive a capsule at a location spaced from an axis of relative rotation between the housing portions, such that the received capsule orbits about said axis upon relative rotation between the housing portions.

11. A gas dispenser according to any preceding claim, comprising a plenum for receiving gas released from a received capsule.

12. A gas dispenser according to Claim 11 , comprising a valve positioned between the plenum and an outlet of the gas dispenser for controlling delivery of gas to a del i very system .

13. A gas dispenser according to any preceding claim, configured to release gas from a plurality of capsules of the type having a body and a frangible stem to a delivery system, wherein the first housing portion is configured to receive the body portions of a plurality of capsules, and the second housing portion comprises a plurality of said cavities each for receiving the stem of a respective capsule received by the first housing portion.

14. A gas dispenser according to Claim 13, wherein the relative motion between the housing portions results in simultaneous rupturing of received capsules.

15. A gas dispenser according to Claim 13, wherein the cavities are of different size, such that the relative motion between the housing portions results in sequential rupturing of received capsules.

16. A gas dispenser according to any of Claims 13 to 15, configured to receive at least three capsules.

17. A gas dispenser according to any preceding claim, wherein the dispenser is a hand held unit.

18. A gas dispenser according to any preceding claim, comprising a further first housing portion for receiving the body of at least one capsule.

19. A combination of a gas dispenser according to any preceding claim and a gas capsule having a body portion and a frangible stem.

20. A delivery apparatus comprising: a gas dispenser according to any of Claims 1 to 17; and a delivery system, wherein an inlet to the delivery system is configured to mate with an outlet of the gas dispenser such that a fluid tight seal is formed therebetween.

21. Apparatus according to Claim 20, wherein the delivery system comprises a gas regulator.

22. Apparatus according to Claim 20 or Claim 21 , wherein the delivery system comprises a mask configured to fit over a mouth and/or nose of a user.

23. Apparatus according to Claim 20 or Claim 21 , wherein the delivery system comprises a nozzle for delivering gas to a receptacle.

24. Apparatus according to Claim 20, wherein the delivery system is a drug delivery system for needle free delivery of a drug through the skin of a patient.