MATERIAL DISPENSERS, E.G. FOR USE AS RUMEN BOLUSES

Abstract: A dispenser for use, for instance, as a rumen bolus is a generally cylindrical container (1) for material to be dispersed into the digestive tracts, etc. of a ruminant. The container has a closure (3) held in place by a controlled release glass (CRG) member (5). When this member is dissolved, the closure (3) comes out and the contents are released. The cylindrical container can be formed by a hole in a larger member which has several such holes so that different materials can be released, or materials released at different times. Variants include stacked arrangements in which several dispenser compartments are coupled so that as one is emptied a CRG member is dissolved to release material in the next compartment. In some cases the CRG member acts both as the release device, and as the closure for its compartment, and in others it also acts as a means of linking a number of detachable sections.

Description: Background of the Invention The invention relates to dispensers, and especially to the intra-ruminal delivery of veterinary materials to ruminant animals, and to rumen boluses for effecting such delivery. One form of intermittent release device is described in specification No. WO-A-8600 519. That arrangement is an orally administrable multi-compartment container in which adjacent compartments are separated by a barrier. Mechanical means are provided in each compartment for rupturing the barrier to release the compartment contents. An object of this invention is to provide improved forms of dispensers suitable for use, inter alia, as rumen boluses. Summary of the Invention According to the invention, there is provided a dispenser for dispensing material into a fluid medium, which dispenser when in use is located in the fluid medium into which the material is to be dispensed, the dispenser including a container for the material to be dispensed, a closure for the container, characterised by a retainer which holds the closure in place, the retainer being made of a controlled release glass (CRG) material, wherein in use the dispenser is immersed in the fluid medium so that the CRG retainer is subjected to the dissolving action of the fluid, so that the CRG dissolves in the fluid medium, whereby the retainer is rendered ineffective after a period which depends on the characteristics of the CRG container, so that the closure is released to cause the material to be dispensed to be released to the fluid medium. Brief Description of the Drawings Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a multi-dispenser pack. Fig. 2 is a section along the line II-II of one of the dispensers of the pack of Fig. 1. Fig. 3 is a plan view of another multi-dispenser pack. Fig. 4 is a section along the line IV-IV of three of the dispensers of the pack of Fig. 2. Fig. 5 is a section of an assembly of two dispensers so arranged that they can be released sequentially. Figs. 6 to 11 are partial sections showing different ways to secure dispensers such as shown in Fig. 2 for sequential release. Description of Preferred Embodiments of the Invention Figs. 1 and 2 show a first form of multi-dispenser pack in which for each individual dispenser of capsule there is a separate closure member and release member. This arrangement is a cylindrical member 1 of a plastics material such as an acrylic material with five holes such as 2 in it, each such hole accommodating a material to be released. In the case of a pack for insertion into the rumen of a cow this material could be a nutrient or a material of medicinal value. Each hole is closed by a rubber or plastics ball 3 resting on a bevelled region 4 of a wall of its hole. This ball is retained in place by a rod or tube 5 of a controlled release glass (CRG). To give scale, the CRG rod in one example was 13 mm long. When the bolus formed by the pack shown in Figs. 1 and 2 is in the rumen, the fluids therein dissolve the CRG rods, and when such a rod is dissolved sufficiently, its ball is released and the material in the appropriate hole is released into the animal's rumen. The CRG rods can have different release times and the various holes or capsules can contain different materials. The CRG materials used for the rods or tubes are made from materials listed in Table 1, which appears at the end of the specification. This table shows starting points for five different CRG materials. For each example the materials after being mixed are melted in an electrical resistance furnace in air, at a temperature of about 1100°C for 30 mins. The resulting material is then cast and annealed. Table 2, also near the end of the specification, indicates the compositions of the resulting materials, with the release characteristics. The numbered compositions in Table 2 correspond to the batches in Table 1. The arrangement of Figs. 3 and 4 is similar in essence to that of Figs. 1 and 2, but has seven capsules, listed as C1 to C7. These are of similar dimensions to the holes in Figs. 1 and 2. In this case the balls such as 9 are held in place by discs such as 10, 11, 12 of CRG. Each of these discs is received by shoulders on the inner surfaces of the holes, and the discs are held in place by a polythene cap 13, which is a snap-on fit over the body 14 of acrylic material. Naturally where the arrangement is used in a living creature such as a cow, the materials used are harmless and non-toxic. We now come to a number of arrangement which follow the principles of the above-described arrangements, but with slightly different release mechanisms. In addition, these arrangements include a number of capsules with successive release, i.e. a pulse release arrangement. In Fig. 5 we see an assembly of two similar capsules, each of which includes a cap portion 20 of an acrylic plastics and a base portion 21 of polythene. The two fit together by spring rings 22, 23 on the base 21, into which the rim of the cap fits. On the outer surface of the cap there is a centrally located lug 24 with a hole in it, surrounded by holes 25, four in number in this case. Such capsules have outside diameters of about 35 mm. The lug 26 on the lower cap projects through a hole 27 in the bottom of the base portion, and is held there by a rod 28 of CRG, under which is an O ring 29. When the material in the upper capsule 6 has been used up, the fluid in which the assembly is located gets to the rod 28, which is dissolved. When this action has gone far enough, the two capsules separate, and the contents of the lower capsule can escape. Such an arrangement can consist of a number of similar capsules stacked together, i.e. with another capsule (not shown) below the lower capsule of Fig. 5. With the assembly as shown, as soon as the device is installed, in the rumen of a cow or sheep in the present case, the contents of the upper capsule commence to escape by solution in the "ambient" fluid. However, if it is desired to have a delay before the contents of the first capsule are used, then the holes 25 could initially each be filled with a disc of CRG. Figs. 6-11 show alternative ways of securing two capsules, each otherwise similar to the capsules of Fig. 5, together. Here also a larger number can be stacked together. In Fig. 6 the lower portion of one capsule and the upper portion of the other are separated by a sealing ring 30, and are fastened together by two washers 31, 32, with a dumb-bell shaped rubber or the like rod extending through the washers. The upper end of this rod has a CRG rod or tube 34 forced through it. When this CRG rod or tube is exposed to fluid, it is dissolved away, so that the distorted end of the rod 34 returns to its normal size, and the washer 31 comes off the rod, so that the capsules separate and the lower one commences to release its contents. In Fig. 7 one washer 35, in this case the lower one, has a shank which fits through a hole in the other washer 36, the two washers being held together as shown by a CRG rod or tube 37. When the rod or tube 37 is dissolved, the washer 35, which is under tension against the capsule base, is released and comes off. Hence the upper capsule also comes off, and releases the material in the lower capsule. Here, as in all the other arrangements described herein, the pieces of capsule, etc., which come off leave the animal in the usual way, i.e. by regurgitation or in the faeces. Fig. 8 shows two capsules held together by a grommet 38 with a CRG ball 39 in the middle. This ball is held in place by a recess on one side of the central shaftof the grommet, and a spike on the other side. When the CRG rod has dissolved sufficiently, the grommet collapses inwardly and releases the capsules from each other. In the arrangement of Fig. 9 the capsules are held together by a stud 40 of a suitable plastics material, with a portion of reduced cross section at one end forced through a hole in a CRG disc 41. Hence when the CRG has dissolved sufficiently, the stud no longer effectively holds the capsules together so they separate to release the material in the lower capsule. In Fig. 10 we see a stud 42 of plastics material which co-operates with a ferrule 43 of CRG. When the CRG has dissolved sufficiently, the capsules separate since the upper end of the stud is smaller in diameter than the holes in the capsule. In Fig. 11 we see a stud 44 whose upper end is "splayed" over the surface of the upper capsule's base portion, and a frusto-conical member 45. When the CRG has dissolved sufficiently, the stud 44 collapses to release the upper capsule so that the capsules separate, thus releasing the material in the lower capsule. In all of the above arrangements the preferred materials for most of the components - except the CRG portions - are a suitable non-toxic plastics material. However, in some cases metallic components may be used, especially when the dispensing arrangement is used other than inside a living creature. Although we have described the dispensers as used for rumen boluses in ruminants, they have a wide range of other applications where material has to be dispensed accurately at known intervals. In some arrangements described above we have shown circular containers; the ones actually shown are right circular cylindrical containers. However, these cylindrical containers could have a variety of different cross-sections other than circular. Thus, for example, square or hexangular cross-sections could also be used. The above dispensers are made in the main from relatively cheap non-toxic plastics material, for instance using injection moulding. The CRG members used to control the time of release are small compared with the whole dispenser, so that although they are precision components made to close tolerances they are relatively cheap. To give an indication of relative sizes, the overall diameter of the multiple dispenser shown in Fig. 1 is 30 mm, and its CRG rod is about 13 mm long and 1.5 mm thick. The dimensions of the other dispensers are comparable to those of the single dispenser portions of the Figs. 1-2 arrangement.

Claims: 1. A dispenser for dispensing material into a fluid medium, which dispenser when is use is located in the fluid medium into which the material is to be dispensed, the dispenser including a container for the material to be dispensed, a closure (3; 9; 21; 31, 32; 35, 36; 38; 40; 42; 44) for the container, characterised by a retainer (5; 11; 28; 34; 37; 39; 41; 43; 45) which holds the closure in place, the retainer being made of a controlled release glass (CRG) material, wherein in use the dispenser is immersed in the fluid medium so that the CRG retainer is subjected to the dissolving action of the fluid, so that the CRG dissolves in the fluid medium, whereby the retainer is rendered ineffective after a period which depends on the characteristics of the CRG retainer, so that the closure is released to cause the material to be dispensed to be released to the fluid medium. 2. A dispenser as claimed in claim 1, wherein the container is of generally cylindrical shape and the closure is ball of a rubber or plastics material, and wherein the ball is held in place by a rod or tube of CRG which froms the retainer and extends transversely across the container on the outside of the ball. 3. A dispenser as claimed in claim 1, wherein the container is of generally cylindrical shape and the closure is a ball of a rubber or plastic material, and wherein the ball is held in place by a disc of CRG received in recesses in the inner wall of the container. 4. A dispenser as claimed in claim 2, wherein the CRG retainer is a disc on the outside of the ball and secured in the sides of the container. 5. A multi-dispenser assembly, which includes a cylindrical member with a number of holes each of which froms the container for a single dispenser as claimed in claim 1. 6. a dispenser as claimed in claim 1, wherein the functions of the closure and of the retainer are combined in a single member of CRG.

Inventors: ARCH, ALFRED JOHN, DRAKE, CYRIL FRANCIS
Applicants: STC PLC
Application year: 1987
Main classification: A61D7
IPC codes: A61M31, A61D7, A61K9