It is known to provide a pump assembly for the dispensation of fluids in predetermined measured amounts and in which the measured amount may be varied. It is further known to provide sealing arrangements for the discharge port of such assemblies. A problem with current assemblies is that the valve means provided are often unsuitable for the dispensation of pasty, viscous fluids such as certain medications, without the clogging of components that renders the pump assembly inoperable. Another problem is that current assemblies are unsuitable for the administration of fluids directly into the mouth as may be desired in the case of dispensing a viscous medication to a child to avoid the spillage and wastage of medication. A further problem is the accurate dispensation of pasty, viscous fluids in terms of volume dispensed and active ingredient dispensed.

According to the present invention there is provided a pump assembly comprising:- a discharge spout; a pump chamber; a housing; means for varying the pump chamber volume; resilient means for biasing the pump chamber into a position corresponding to the maximum

volume of the pump chamber; a fluid flow passage for transport of fluid from a position external of the pump chamber, to a position internal of the pump chamber; inlet valve means for sealing the fluid flow means; means for attachment of the pump assembly to a container; discharge valve means for sealing the discharge spout are disposed adjacent an end of the discharge spout remote from the pump chamber, wherein the fluid dispensed via the discharge valve means is directed laterally and the valve means are suitable for use with pasty, viscous fluids.

An advantage of such an assembly is that the reliable dispensation of pasty, viscous fluids is facilitated. Also the discharge of fluid directly into a patient's mouth is safely and hygienically achieved.

Preferably the pump assembly comprises: a discharge spout; a pump chamber; a housing; means for varying the pump chamber volume; resilient means for biasing the pump chamber into a position corresponding to the maximum volume of the pump chamber; a fluid flow passage for transport of fluid from a position external of the pump chamber, to a position internal of the pump

chamber; inlet valve means for sealing the fluid flow means; means for attachment of the pump assembly to a container; wherein: - the means for varying the pump chamber volume comprises: an actuator button assembly; stop means for limiting the vertical travel of the actuator button assembly; the stop means comprising: means for pre-setting the dosage for dispensation; and calibration means for accurate control of dosage to be dispensed.

Pre-setting of the dosage for dispensation, for instance by a pharmacist provides a reliable way of ensuring that the correct dosage is given. This is particularly useful for prescribed medications where the dosage to be dispensed will generally not vary.

Calibration means ensures that the correct amount of active medication is delivered to the patient. This is very important and overcomes the problems of traditional methods such as a bottle and spoon where the accurate assessment of dosages is difficult.

Preferably the means for pre-setting the dosage for dispensation comprises a raised pip selectable in one of a plurality of guide channels.

The use of a number of guide channels in one

device allows the pump assembly to be used for a range of dosage levels. This reduces the number of different pump assemblies a pharmacist for instance would have to stock.

Preferably the raised pip comprises a bevel on its lower surface to allow the raised pip to pass under a portion of the housing of the pump chamber to move the raised pip from a slot to one of the guide channels.

The bevel enables the raised pip to be moved from the horizontal slot into one of the guide channels.

The absence of a bevel on any of the other edges of the raised pip prevents the raised pip from moving out of the guide channel initially selected. This has the advantage that the dose once set can not easily be changed whether accidentally or deliberately.

Preferably the guide channels comprise an enlarged portion at the uppermost end of each guide channel for receiving the raised pip upon rotation of the actuator button assembly about the vertical axis of the pump chamber for prevention of accidental axial movement of the actuator button assembly.

The enlarged portion provides a position in which the raised pip may be moved to, to 'lock' the pump assembly and prevent the axial movement of the actuator button assembly either up or down. This provides a child-resistant means of securing the assembly. This is particularly advantageous when the medication is potentially poisonous. The design of the enlarged portion and the guide channels means that this child resistant measure is not required to be

used. This is advantageous for those without children or for the elderly where the operation of child- proofing devices is often difficult or impossible.

Preferably the inlet valve means comprises a positive valve means for sealing with the pump assembly in any orientation.

This allows the assembly to be used in the inverted position or tilted which allows the assembly to be used with a patient who is lying in a bed.

Preferably the discharge valve means comprises a tip seal formed at the tip of the discharge spout.

The discharge valve being at the tip of the discharge spout allows for the valve to be easily cleaned and inspected. Also the valve being at the tip of the discharge spout prevents air entering the discharge spout when the assembly is between operations. This helps to prevent contamination of any residue in the spout.

Preferably the surface of the tip seal lies flush with the exterior surface of the discharge spout.

This provides a smooth surface to be placed in the mouth of the patient and prevents the risk of cuts to the mouth.

Preferably the fluid dispensed is dispensed substantially perpendicularly to the axis of the discharge spout.

Dispensation of the fluid perpendicularly to the

axis of the discharge spout advantageously prevents the dispensed fluid from contacting the back of the user's throat with significant speed or force. This reduces the risk of damage to the throat or risk of choking on the fluid dispensed.

Preferably a sealing ring is positioned between the housing and the actuator button assembly for improved sealing.

The sealing ring acts to improve the nature of the seal between the actuator button assembly and the housing. This prevents the unwanted leakage of fluid from the pump chamber via the housing actuator button assembly interface.

Particular embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a first embodiment of a pump dispenser of the invention shown assembled on a container, Figure 2 is another perspective view of the device of Figure 1, Figure 3 is an external view of a part of the first embodiment of the invention, Figure 4 is a sectional view of the first embodiment of the invention, Figure 5 is a perspective view of an inlet valve of the invention, Figure 6A is a sectional view of an inlet valve of the invention in the closed state, Figure 6B is an sectional view of an inlet valve of the invention in the open state, Figure 7 is a perspective view of an alternative inlet valve of the invention, Figure 8A is a sectional view of an alternative inlet valve of the invention in the closed state, Figure 8B is a sectional view of an alternative inlet valve of the invention in the open state, Figure 9A is a sectional view of a further alternative inlet valve of the pump dispenser of the invention in the closed state, Figure 9B is a sectional view of a further alternative inlet valve of the pump dispenser of the invention in the open state, Figure lOA is a sectional view of a further alternative inlet valve of the pump dispenser of the invention in the closed state, Figure lOB is a sectional view of a further alternative inlet valve of the pump dispenser of the invention in the open state, Figure lOC is a perspective view of a plug seal of a further alternative inlet valve of the pump dispenser of the invention, Figure 11 is a perspective view of a part of the discharge spout of the invention, Figure 12 is a perspective view of an outlet valve of the invention, Figure 13A is a sectional view of an alternative outlet valve of the invention in the closed state, Figure 13B is a sectional view of an alternative outlet valve of the invention in the open state, Figure 13C is a sectional view taken along section A-A of Figure 13A, Figure 14A is a sectional view of an alternative outlet valve of the invention in the closed state, Figure 14B is a sectional view of an alternative outlet valve of the invention in the closed state, Figure 14C is a sectional view of an alternative

outlet valve of the invention in a closed state, Figure 15 is a perspective view of a second embodiment of the pump dispenser of the invention shown assembled on a container Figure 16 is an external view of a part of the second embodiment of the pump dispenser of the invention, Figure 17 is a perspective view of a second embodiment of the invention, Figure 18 is a sectional view of a second embodiment of the pump assembly of the invention.

A first embodiment of the pump dispenser of the invention will now be described. Fig. 4 shows a pump assembly 10 comprising a pump housing 11 connected to a container 1 (as shown in Fig. 2) by means of a male/female threaded connection 14.

With the dispenser in the orientation shown in Figures 1 to 4 the housing 11 comprises a generally cylindrical portion 41 disposed substantially vertically above the container 1 and a discharge spout 40 disposed in a generally perpendicular direction with respect to the cylindrical portion 41 and the container 1. Preferably, the discharge spout 40 is disposed at a slight upward angle from the horizontal as shown in Fig. 4 for ease of insertion in the mouth.

Advantageously the discharge spout 40 may be disposed perpendicularly to the cylindrical portion 41 of the housing 11 to reduce production costs and simplify manufacture. A raised collar 12 is formed on the external surface of the housing 11 as a means for gripping of the pump assembly 10. The collar 12 has a multitude of narrow ribs 18, as shown in Fig. 3, for improved grip to aid attachment of the housing 11 to

the container 1, and for ease of handling in use. The collar 12 is disposed near the base of the housing 11 nearest the container 1. Alternatively the collar may be positioned at other positions on the housing for instance near the top of the housing 11 to enable the apparatus to be operated single-handed by allowing the apparatus to be gripped around the collar 12 with thumb and finger and operated by another finger of the same hand.

The means for gripping the apparatus is not restricted to the form of a collar 12 but may alternatively be in the shape of two outwardly extending flanges joined to the housing 11 whereby the flanges provide a comfortable grip for the user's fingers and aid the fixing and unfixing of the housing 11 from the container. Also the flanges aid operation of the apparatus by providing a seating point for two fingers, which can be hooked under the flanges, while a third finger operates the apparatus.

An actuator button assembly 20 reciprocally axially slidable within the housing 11 comprises a generally cylindrical portion 60 blanked at one end and having a flared skirt 24 at the other end and a spring 13 disposed vertically between an inner surface 25 of the top of the actuator button assembly 20 and the base 17 of the housing 11 to bias the actuator button assembly 20 into the extended position. The top surface of the actuator button assembly 20 may have concentric ribs 65 (shown in Fig. 2) for improved grip for a finger whilst operating the pump assembly 10.

The actuator button assembly 20 is connected to the cylindrical portion 41 of the housing 11 by means

of a slidable contact between the flared skirt 24 formed at the lowermost end of the actuator button assembly 20 and the inside surface 42 of the cylindrical portion 41. Upon insertion of the actuator button assembly 20 in the cylindrical portion 41 of the housing 11 the sides 43 of the actuator button assembly 20 are flexed inwards due to the increased diameter of the actuator button skirt 24 relative to the cylindrical portion 41. The residual outward force exerted by the sides 43 of the actuator button assembly 20 on the inside surface 42 of the cylindrical portion 41 through the flared skirt 24 provides an air tight seal. Alternatively a sealing ring (not shown) may be positioned between the inside surface 42 of the cylindrical portion 41 and the actuator button assembly 20 near the flanged skirt 24.

The sealing ring would remain fixed relative to the actuator button assembly and slide relative to the inside surface 42 upon depression of the actuator button assembly 20 to provide an improved seal.

A stop means 21 is provided to limit the vertical travel of the actuator button assembly 20 within the cylindrical portion 41 of the housing 11. The stop means 21 comprises a raised pip 22 formed at a position on the side 43 of the actuator button assembly 20 for sliding engagement in one of a number of guide channels 23 formed in the generally cylindrical portion 41 of the housing 11 as shown in Fig. 3. Preferably the raised pip 22 is formed near the mid-point of the side 43 of the actuator button assembly 20 to allow an adequate length of stroke of the actuator button. Each guide channel 23 is aligned with the vertical axis of the cylindrical portion 41 and acts to limit the travel of the actuator button

assembly 20 by blocking the movement of the raised pip 22 at the uppermost and lowermost ends of the guide channel 23.

A number of guide channels 23 may be provided of differing lengths providing different degrees of movement of the actuator button assembly 20 upon selection of the appropriate guide channel 23. It is envisaged that the apparatus will be pre-set at the point of sale by, for instance, a pharmacist and the raised pip 22 will not thereafter be moved between guide channels 23. The apparatus is intended to be supplied to the pharmacist pre-assembled with the raised pip 22 positioned in a horizontal slot 62 near the top of the actuator button assembly 20 which prevents the actuator button assembly from sliding outwards out of the housing 11 and prevents the actuator button assembly 20 sliding inwards until the proper time. The pharmacist selects the correct dosage to be administered by rotating the actuator button assembly 20 in the housing 11 until the raised pip 22 is aligned with the guide channel 23 corresponding to that dosage. The pharmacist then pushes down on the actuator button with a relatively high force causing the raised pip 22 to pass from the horizontal slot 62 to the guide channel 23, as shown in Fig. 3. This movement is accommodated by the side 43 of the actuator button assembly 20 flexing inwards slightly.

Preferably the process of selecting the guide channel 23 is facilitated by the raised pip 22 comprising a bevelled bottom edge 61 to urge the raised pip 22 under the housing 11 when pushed with a relatively high force. The other surfaces of the raised pip 22 are not bevelled and therefore movement

of the raised pip 22 from the guide channel 23 initially selected is prevented. In this way there is provided a calibrated scale that can be pre-set at the point of sale and is subsequently tamper-proof.

Alternatively the apparatus can be supplied for sale to the end-user with the raised pip 22 positioned in the horizontal slot 62 allowing the user to select their own dosage. This would be preferable where the medication is non-prescription and the apparatus would be directly available to the public. Embossed lines 63 may be provided on the exterior surface of the actuator button assembly 20 to act as a visual aid to the pharmacist in lining up the raised pip 22 before selecting the guide channel 23.

Also preferably there are provided shallow vertical recesses 64 on the inside surface 42 of the housing 11 between the horizontal slot 62 and the guide channels 23 to prevent the raised pip 22 moving accidentally sideways into the wrong guide channel 23 as the raised pip 22 is pushed down. Calibration marks 66 are provided on the exterior of the actuator button assembly 20 for describing the dosage amount corresponding to each guide channel 23. The nature of the pre-set calibrated scale and calibration marks 66 make the apparatus 10 particularly suitable for use by the visually impaired. Preferably dosage amounts may vary from 2.5 to 5 ml. In addition at the uppermost end of each guide channel 23 there is formed an enlarged portion 38. The width of the guide channel 23 in the enlarged portion 38 is greater than the width of the raised pip 22. At the point of the actuator button assembly 20 stroke at which the raised pip is aligned with the enlarged portion 38 of the selected guide channel 23 the actuator button assembly 20 may

be manually rotated clockwise about the vertical axis of the cylindrical portion 41 of the housing 11 to lockingly engage the raised pip 22 in the enlarged portion 38 of the guide channel 23 so that axial movement of the actuator button assembly 20 is prevented. In this way the pump assembly 10 can be locked in a position where accidental dispensing can be avoided.

The pump assembly 10 may be unlocked by manually rotating counter-clockwise the actuator button assembly 20 to disengage the raised pip 22 from the enlarged portion 38 of the guide channel 23.

This method of selection provides a child- resistant and non-adjustable means of selecting the correct dosage for dispensation. Accuracy of the dose dispensed is ensured by the guide channels 23 which are pre-set, preferably by a qualified pharmacist, thereby inaccuracy associated with traditional apparatus that requires accurate setting of the apparatus or good judgement of quantities by the user is avoided.

Hence, a variable volume pump chamber 16 is formed, comprising the actuator button assembly 20 and the housing 11 such that the volume of the pump chamber 16 can be preset to one of a number of known, set amounts using the stop means 21.

The spring 13 biases the actuator button assembly 20 into the extended position wherein the raised pip 22 of the stop means 21 is in contact with the uppermost end of the guide channel 23 selected.

A tubular extension 35 is formed integrally with the base 17 such that a vertical conduit 36 is formed passing from the container 1 to the variable volume pump chamber 16. A dip tube 32 is push-fitted into the tubular extension 35. The diameter of the conduit 36 being slightly less than the diameter of the dip tube 32, the dip tube 32 is held by means of friction.

The lowermost end of the dip tube 32 extends downwards substantially to the lowermost point of the container 1.

An inlet valve 30 is provided for closing off the uppermost end of the tubular extension 35. A first version of the inlet valve 30 as shown in Figs. 5, 6A and 6B comprises a flexible member comprising a base 90, a first frusto-conical portion 91, a second frusto-conical portion 94, a sealing portion 92 and a rim 93. The inlet valve 30 is positioned over the tubular extension 35 with the base 90 of the inlet valve 30 in contact with the base 17 of the housing 11 and held in place by the action of the spring 13 which contacts the base 90. The first frusto-conical portion 91 extends upwardly from the base 90 into contact with the rim 93. The second frusto-conical portion 94 extends downwardly from the rim 93 to the sealing portion 92. Two incisions 95 are formed in the rim 93 of the inlet valve 30. At rest, as shown in Fig. 6A, with the actuator button assembly 20 stationary the sealing portion 92 is held in sealing contact with the top of the tubular extension 35 preventing liquid in the pump chamber 16 from draining back into the container 1 and preventing liquid in the container 1 entering the pump chamber 16. Preferably the inlet valve 30 is manufactured from low-density polyethylene or other suitable flexible material.

Alternatively a second version of the inlet valve 30 as shown in Figs. 7, 8A and 8B comprises a base 100, an upwardly extending sleeve 101 surrounding the tubular extension 35 and a sealing plug 103 contactable with the opening of the tubular portion 35 and held in position by four spring arms 102. In the rest position as shown in Fig. 8A with the actuator button assembly stationary the sealing plug 103 is in sealing contact with the tubular extension 35 and acts to prevent liquid transfer across the inlet valve in either direction. During operation of the pump assembly, as shown in Fig. 8B, the sealing plug is unsealed from the tubular extension 35 due to the reduced pressure in the pump chamber 16 as the actuator button assembly 20 is raised. The movement of the sealing plug 103 is accommodated by the flexing of the spring arms 102.

A third version of the inlet valve 30 as shown in Figures 9A and 9B, comprises a plug seal 500 which slides up and down in the tubular extension 35 guided by three ribs 501. The upper end 502 of the tubular extension 35 has a conical shape and the mating part 503 of the plug seal 500 consists of a raised flexible rib, facilitating more effective sealing. In the rest position with the actuator button assembly stationary, the plug seal 500 is maintained in the sealed position by gravity with the mating portion 503 in sealing contact with the upper end 502 of the tubular extension 35. During operation of the pump assembly, as the button is raised, the plug seal 500 rises in the tubular extension 35 guided by the surrounding spring 13 allowing product to be dispensed in the direction shown by the arrows in Figure llB.

Figures 9A and 9B also show the presence of a skirt seal 530 manufactured from a material such as an elastomer or plastic or mixture thereof and comprising outwardly extending lower flanges 531 in sealing contact with the cylindrical portion 41 of the housing 11, upwardly extending button flanges 532 in sealing contact with the inner surface of the cylindrical portion 60 of the button assembly 20, and a downwardly extending cylindrical portion 533 positioned internally of the spring 13. The skirt seal 530 acts to prevent fluid from transferring from the variable volume pump chamber 16 to the upper portion 540 of the actuator button assembly 20 or between the cylindrical portion 41 of the housing 11 and the cylindrical portion 60 of the actuator button assembly 20 as well as to support and keep in alignment the spring 13.

The dimensions of the skirt seal 530 relative to the internal diameter of the variable volume pump chamber 16 result in a sealing force being exerted by the sealing skirt 530 against the internal walls of the pump chamber 16. The upper end of the spring 13 acts against the skirt seal 530. During operation of the pump assembly, the skirt seal 530 moves axially as one with the actuator button assembly 20.

A fourth version of the inlet seal 30 as shown in Figs. lOC, lOB and 10C comprises a plug seal 600 which slides up and down in the tubular extension 35 guided by three ribs 601. The lower end 603 of the plug seal 600 is pointed to increase the reliable movement of the plug seal 600 axially within the conduit 36. The upper end of the tubular extension 35 and the mating part 607 of the plug seal are configured in the same manner as the third version of the inlet seal 30.

The fourth version differs from the third version in that the mating part 607 is surrounded by a concentric annulus 602 spaced apart from the mating part 607 and joined to it by a number of spring arms 605. Preferably there are at least three spring arms 605, but there may be four, five or more spring arms 605. The plug seal rests in the conduit 36 as with the fifth version of the inlet seal 30 with the mating part 607 contactable with the conical portion of the tubular extension 35. The annulus 602 rests on the flattened portion 608 of the upper end of the tubular extension 35. The spring 13 extends from the top surface of the annulus 602 upwardly to the skirt seal 530, thus holding the annulus 602 in position. The inherent springiness of the plug seal 600, which may be manufactured from low density polyethylene or similar material, allows the mating part 607 of the plug seal 600 to disengage from the tubular extension 35 without the annulus 602 being displaced.

Thus the fourth version of the inlet valve 30 provides a means of sealing the inlet with the apparatus in any orientation and the nature of the spring arms 605 allows the valve to close even when the fluid passing through the valve is pasty or viscous.

The first, second and fourth versions of the inlet seal 30 are "positive" valves being capable of sealing with the apparatus 10 in any orientation, and not requiring the force of gravity to enable sealing.

The third version of the inlet valve 30 as shown is a "gravity" valve being held in the sealed position by gravity and remaining in that position while the actuator button assembly 20 is at rest. However, the

third version of the inlet valve 30 may be easily modified to make it a "positive" valve capable of sealing in any orientation by the addition of a low- load spring biasing the inlet valve 30 into contact with the tubular extension 35 whilst the actuator button assembly 20 is stationary, as shown in the fourth version of the inlet valve 30.

The discharge spout 40 adjoins, and is in communication with the cylindrical portion 41 of the housing 11 substantially towards the base 17 of the housing 11. Preferably, the discharge spout 40 is opposite the raised pip 22 of the stop means 21 to allow the user to view the dosage being dispensed to the patient. This is an advantage when an adult is administrating medication to a child.

A discharge valve 50 is disposed at the end of the discharge spout 40 remote from the cylindrical portion 41 of the housing 11 as shown in Fig. 11. At the end of the discharge spout 40 remote from the cylindrical portion 41 are formed two opposing slits 110 in the wall of the discharge spout 40 that extend from the tip 111 of the discharge spout 41 towards the cylindrical portion 41 of the housing 11 so forming two prongs 112 extending along the major axis of the discharge spout 40 separated by the slits 110. The slits 110 continuous from one side of the discharge spout 40 to the other side via the tip 111 define a slot 113. Preferably the edges of the slot 110 are straight-sided.

A first version of the discharge valve 50, as shown in Fig. 12, comprises a tip seal 120 inserted into the slot 113 formed in the discharge spout 40.

The tip seal 120 comprises a tongue 121, side walls 122, a cross-piece 123 extending between the two side walls 122 and a tip 124. The tip seal is inserted into the slot 113 with the tongue 121 foremost, the tongue 121 being dimensioned so that it is able to slide internal of the discharge spout 40. The side walls 122 are dimensioned to fit sealingly into the slot 113 with the edges 125 of the side walls 122 sealing against the inside surface 114 of the prongs 112 and the internal surface 126 of the side walls 122 sealing against ledges 115 formed on the inside surface 114 of the prongs 112.

Notches 116 are formed on the inside surface 114 of the prongs 112 aligned with the ledges 115 and spaced from them by a distance equivalent to the width of the cross-piece 123 of the tip seal 120. When the tip seal 120 is inserted in the discharge spout 40 the cross-piece 123 passes over the notches 116 aided by the notches 116 presenting ramped surfaces 117 to the cross-piece 123 and is firmly secured in the gap between the notches 116 and the ledges 115. In the rest position with the actuator button assembly 20 stationary the exterior surface of the tip seal 120 lies flush with the exterior surface of the discharge spout 40 and all exterior edges of the tip seal 120 are sealed preventing liquid or air crossing the seal in either direction. This has the advantage that biological contamination of the contents of the pump chamber 16 is prevented when the apparatus is between actuations. Similarly to the inlet valve 30 the discharge valve 50 is a 'positive' valve capable of sealing in any orientation.

A second version of the discharge valve 50 is

shown in Figures 13A, 13B and 13C. The tongue 121 is elongated and comprises at the end furthermost from the tip 124 a discharge plug 250. The end of the tongue 121 nearest the tip 124 is joined to the cross- piece 123. The discharge plug 250 comprises a conical section 251 for engaging sealingly with a raised step 252 of the discharge spout 40 and three longitudinal ribs 253 which act to guide the discharge plug 250 axially within the discharge spout 40. Preferably, the tongue 121 has a circular cross-section.

The length of the tongue 121 is such that when the discharge valve 50 is inserted in the end of the discharge spout 40, the tongue 121 forms a serpentine shape which, due to its elastic material properties, acts to bias the sealing plug 250 into contact with the raised step 252. During operation of the pump assembly increased fluid pressure in the variable volume pump chamber 16 and lower portion of the discharge spout 40 forces the sealing plug 250 out of contact with the raised step 252 allowing fluid to pass around the sealing plug and out of the tip seal 120.The modified tip seal 120 shown in Figs. 13A and 13B comprises a side wall 122 on only one half of the discharge spout 140. Sealing contact between the side wall 122 and the spout 40 at the base of the tip seal 120 is enhanced by a wall tongue 258 and groove 259 arrangement which also acts to keep the side wall 122 in alignment as it flexes during operation of the pump assembly 10. The path of the discharging fluid is shown by arrows in Figure 13B. The cross-section of the sealing plug 250 taken at section A-A of Figure 13A is shown in Figure 13C. The sealing plug 250 may comprise more than 3 longitudinal ribs 253.

A third version of the discharge valve 50 is shown in Figures 14A and 14B. This version of the discharge valve 50 works in a similar manner to the second version described above. The sealing plug 250 now comprises a flattened sealing portion 255 at the end of the tongue 121 furthest from the tip 124. An advantage of this version is improved sealing contact between the flattened portion 255 and the raised step 252 in use with some fluids.

The flattened portion 255 may be modified as shown in Figure 14B, to comprise a raised flexible rib 256 on the discharge plug 250. In addition, the raised step 252 may be replaced by a frusto-conical portion 257. An advantage of this version is that improved sealing contact between the discharge plug 250 and the frusto-conical portion 257 is achieved in use with some fluids.

Each of the above versions of discharge valve 50 is designed to be manufactured as a single-moulded component. This has the advantage of reduced manufacturing and assembly costs.

A fourth version of the discharge valve 50 is shown in Figure 14C. This version of the discharge valve 50 works in a similar manner to the second and third versions described above.

In this version, the discharge spout 40 is again open at its remote end and includes a slit 110 in the wall of the discharge spout 40. A discharge valve 300 includes a rounded end portion 301 which fits within the open end of discharge spout 40, a rib 302 connecting the end portion 301 to a body portion 303

and a serpentine tongue 304 connecting the body portion 303 to the discharge plug 250. The discharge plug 250 is formed with three ribs 253 to assist the discharge plug in sliding in the discharge spout 40 and includes at its end remote from the serpentine tongue 304 a raised flexible rib 256 which seats in a frusto-conical portion 257 within the discharge spout 40 in a similar manner to the arrangement shown in Figure 14B. The body portion 303 also includes a flexible rib 306 extending from the body portion 303 approximately parallel and opposite to rib 302 and including at its end remote from body portion 303, a stepped end portion 307, which fits within a recess 308 of the rounded end portion 301 and allows flexing of the rib 306 in use. The rib 306 fits within slit 110 of the discharge valve 40 to close off that slit in its rest position. A vane member 310 of greater width than the ribs 302, 306 extends diagonally within the discharge valve member from a lower part of the body portion 303 to a part adjacent the remote end of rib 306.

The fourth version of discharge valve 50 described above operates in a similar manner to the second and third versions described above, but is designed to facilitate manufacture and assembly.

The operation of the pump assembly 10 will now be described, assuming an initial position where the pump chamber 16 is primed with fluid and the actuator button assembly 20 is extended in the rest position.

The first stage of the dispensing cycle comprises the finger-operated depression of the actuator button assembly 20 and spring 13. This reduces the volume of

the variable volume pump chamber 16 and increases the pressure of the fluid contained therein. This increased pressure acts on the inlet valve 30 to firmly seal the plug 103, 500, 600 or sealing portion 92 against the tubular extension 35 thereby preventing discharge of the fluid in the pump chamber 16 into the dip tube 32. At the same time, the increased fluid pressure acts on the inner surfaces 126 of the side walls 122 of the tip seal 120 causing them to bow outwards and the edges 125 to unseal from the inside surface 114 of the prongs 112 of the discharge spout 40.

The tip seal is held in place in the discharge spout 40 and is not ejected by the action of the notches 116 restraining the movement of the cross- piece 123. Therefore the tip 124 of the tip seal 120 remains stationary throughout the operation of the apparatus. The bowing outwards of the side walls 122 is accommodated in the first version of the tip seal 120 by the tongue 121 of the tip seal 120 moving along the discharge spout 40 towards the tip 124 of the tip seal 120. Movement of the side wall 122 in the second and third versions of the tip seal 120 is accommodated by the movement of the groove 259 over the wall tongue 258. Therefore fluid from the pump chamber 16 is discharged through the gaps so formed between the edges of the slot 113 and the edges 125 of the tip seal 120.

Preferably the tip of the discharge spout 40 is placed in the patient's mouth during operation of the apparatus and the fluid is dispensed directly into the mouth. This is advantageous since the apparatus leaves no messy residue as happens when using a spoon to

dispense medication. Also there is no danger of spillage and the apparatus 10 comprising positive inlet 30 and discharge 50 valves can be used in any orientation allowing for instance the medication to be dispensed to a child lying in a bed. Also advantageously the positioning of the gaps between the edges of the slots 113 and the edges 125 of the tip seal 120 being on the sides of the discharge spout 40 medication is dispensed laterally into the mouth as shown by the arrows in Fig. 2. This eases dispensation, avoiding the danger of damage to the rear of the user's throat and reducing the forward velocity of delivery of the medication. Both of these effects reduce the chance of choking of the user or causing the user discomfort.

At this point, the specified dose of fluid has been discharged. Upon release of the actuator button assembly 20, the spring 13 acts on the inner surface 25 of the top of the actuator button assembly 20 to axially move the actuator button assembly 20 back into the extended position. This movement produces a drop in the pressure of the pump chamber 16 due to the airtight nature of the seal between the housing 11 and the skirt 24 and/or skirt seal 530 of the actuator button assembly 20. This drop in pressure acts on the tip seal 120 causing the side walls 122 to move back into the rest position sealing the discharge valve 50.

At the same time, the drop in pressure acts to unseat the sealing plug 103, 500, 600 or sealing portion 92 of the inlet valve 30 from the tubular extension 35; the movement accommodated in the first version of the inlet valve 30 by the upward rolling of the rim 93 as shown in Figure 6B leading to the extension of the first frusto-conical portion 91 and the reduction in

length of the second frusto-conical portion 94 leading to the sealing portion 92 being lifted from the tubular extension 35. The movement is accommodated in the second version of the inlet valve 30 by the movement of the spring arms 102 as shown in Figure 8B.

Fluid from the container 1 is drawn up the dip tube 32 into the pump chamber 16 via the incisions 95 in the first embodiment of inlet valve 30 or the gaps between the spring arms 102 in the second embodiment of the inlet valve 30 or the gap between the plug 500 and the tubular extension 35 in the third version due to the pressure differential between the pump chamber 16 and the container 1. The movement is accommodated in the fourth version of the inlet valve 30 by the movement of the spring arms 605 as shown in Fig. 10B.

The spring 13 axially extends the actuator button assembly 20 until the raised pip 22 of the stop means 21 contacts the uppermost end of the selected guide channel 23. Once the actuator button assembly 20 has stopped extending, the inlet valve 30 re-seals.

At this point, one dispensing cycle has been performed. Advantageously the dispenser can be operated single-handed.

A second embodiment of the invention is shown in Figs. 15 to 18.

In this embodiment, the variable volume pump chamber 816 is disposed substantially horizontally with the container 801 substantially perpendicular to the pump chamber 816.

The housing 811 comprises a generally cylindrical

portion 841 and a discharge spout 840 in axial alignment with the cylindrical portion 841.

An actuator button assembly 820 is disposed for reciprocable axial movement within the cylindrical portion 841 of the housing 811. The actuator button assembly 820 comprises a cylindrical outer sleeve 825 with one end blanked to form a finger-operated button 826 and the other end open. A stop means 821 is provided to limit the horizontal travel of the outer sleeve 825 within the housing 811. The stop means 821 comprises a raised pip 822 formed near a mid-point on the side 843 of the outer sleeve 825 slidably engaged in one of a number of guide channels 823 in the cylindrical portion 841 of the housing 811. The stop means 821 operates in an identical manner to the stop means 21 of the first embodiment.

Alternatively in a modified version of the stop means 821 there is no horizontal slot 62. Instead the apparatus is supplied with the actuator button assembly 820 inserted in the cylindrical portion 841 of the housing 811 with the raised pip 822 butted against the top rim 830 of the housing and held in position by the action of a button retention snap 831 as shown in Fig. 17. Before the first use of the apparatus the actuator button is rotated to align the raised pip 822 with the correct guide channel 823 and the actuator button is then depressed with a relatively high force causing the button retention snap 831 to break and the raised pip 822 to move under the housing 811 into the guide channel 823 in the same way as the raised pip moves from the horizontal slot 62 to the guide channel 23 in the first embodiment of the invention.

The actuator button assembly 820 also comprises a cylindrical inner sleeve 827 dimensioned so that the external diameter of the inner sleeve 827 is less than the internal diameter of the cylindrical portion 841 of the housing 811. Also the inner sleeve 827 is dimensioned so that the external diameter of the inner sleeve 827 is less than the external diameter of the outer sleeve 825 and greater than the internal diameter of the outer sleeve 825. The rim 828 of the outer sleeve 825 has a circumferential shoulder 829 formed on the internal surface for mating connection with the inner sleeve 827. The inner sleeve 827 is positioned internally of the cylindrical portion 841 of the housing 811 adjacent to, and restrained by, the outer sleeve 825 and the action of the spring 813 on the base 817 of the inner sleeve 825.

Hence, an annular space 870 is formed between the external surface 871 of the inner sleeve 827 and the internal surface 872 of the cylindrical portion 841 of the housing 811. This space 870 is sealed at the end nearest the outer sleeve 825 by an hydraulic seal 873 and the end nearest the discharge spout 840 by a flexible membrane 874. The hydraulic seal 873, which may comprise an 0-ring sealing ring, is disposed in fixed contact with the external surface 871 of the inner sleeve 827 and in slidable contact with the internal surface 872 of the cylindrical portion 841 of the housing 811. Hence the hydraulic seal 873 forms a fluid-tight, movable seal within the annular space 870. The membrane 874 is annular in shape comprising a central hole 875 aligned substantially with the long axis of the housing 811. The membrane 874 has a convoluted cross-section. The rim 876 of the membrane 874 is held in place abutted between the inner sleeve

827 and one end of a restoring spring 813. The other end of the spring 813 is abutted against a shoulder 880 formed on the internal surface the housing 811 at the junction between the cylindrical portion 841 and the discharge spout 840.

A variable volume pump chamber 816 is defined between the base 817 and the discharge spout 840.

Fluid communication between the annular space 870 and the pump chamber 816 is affected by a pump chamber intake port 877 formed in the base 817 of the inner sleeve 827.

A dip tube 832 communicates with the annular space 870 through a tubular extension 835 of the housing 811. The dip tube 832 is push-fitted into the extension 835 and held in place by friction as in the first embodiment of the invention. Preferably, the tubular extension 835 is disposed in opposition to the stop means 821 and calibrated scale 866 to allow the user whilst holding the apparatus by the container 81 to easily read the calibrated scale 866. The tubular extension 835 is surrounded by a collar 812 for attachment/removal of the pump assembly 810 to a container 81 by means of a screw threaded arrangement or other suitable fluid tight removable coupling mechanism. The collar 812 may be ribbed as in the first embodiment of the invention. The dip tube 832 extends substantially to the bottom of the container 801.

The operation of the pump assembly 810 will now be described assuming an initial position where the pump chamber 816 is primed with fluid and the actuator button assembly 820 is extended in the rest position.

The first stage of this dispensing cycle comprises the finger-operated depression of the outer sleeve 825 of the actuator button assembly 820. The outer sleeve 825 in conjunction with the inner sleeve 827, hydraulic seal 873 and the base 817, move axially within the housing 811 compressing the spring 813, decreasing the volume of the pump chamber 816 and increasing the pressure of the fluid contained therein. At the same time, the flexible membrane 874 is forced into sealing contact with the base 817 by the increased fluid pressure in the pump chamber 816 and the fluid is discharged via the discharge valve 850 in the same manner as in the versions of the first embodiment. As with the first embodiment, the inward movement of the actuator button assembly 820 is constrained by the stop means 821.

When the actuator button assembly 820 is released, the spring 813 acts to extend the actuator button assembly 820 back to its rest position. At the same time, the pressure differential causes the discharge valve 850 to sealingly close and the flexible membrane 874 to unseal from the base 817 opening up fluid communication between the container 801 and the pump chamber 816 via the dip tube 832 and the pump chamber intake port 877. During the return stroke of the actuator button assembly 820 the dip tube 832 is in constant communication with a portion of the annular space 870 and via the pump chamber intake port 877 with the pump chamber 816. Hence the fluid in the container 801 is drawn into the pump chamber 816 by the negative pressure of the pump chamber relative to the fluid in the container 801.

At this point one dispensing cycle has been performed. Advantageously the dispensing cycle can be operated single-handed.

The invention is not limited to the embodiments described above and various modifications to the invention may be made within the scope of the appended claims.