Sustained release capsules
The invention relates to an intraruminal sustained release capsule which is capable of delivering a sustained release dose of a first medicament to an animal, as well as either or both of a dump dose of a second medicament or mineral, and an exit dose of a third medicament or mineral. The capsule can have a dissolvable overcap molded from plasticized starch enabling a dump dose of medicament to be held between the overcap and one end of the capsule. A piston within the body of the capsule can be modified to enable it to accommodate an exit dose of medicament within its hollow interior which is aligned with an aperture at the end of the capsule which enables release of the medicaments to the rumen. After insertion of the capsule in the animal the overcap (if present) dissolves and separates from the capsule to release the dump dose of medicament. The sustained release medicament is then dispensed via the apertured end, followed by the release of the exit dose of medicament (if present).
1. A sustained release capsule comprising:
a) a hollow tubular body sealed at a first end,
b) a movable piston within the body,
c) a spring biasing the piston towards a second end of the body,
d) an apertured cover at the second end to define a first chamber between the movable piston and the apertured cover capable of containing a first dose of material within the hollow tubular body for subsequent sustained release through the apertured cover into a rumen of an animal, and
wherein the movable piston has an end face facing towards the first dose, a hollow central sleeve extending rearwardly from the end face to assist in locating a spring, an aperture in the end face into a hollow interior of the central sleeve, the central sleeve having a closed portion distal from the end face to create a void capable of containing an exit dose of material.
2. The capsule of claim 1 further comprising an overcap which is releasably attached to the second end to form a void between the apertured cover and the overcap capable of containing a second dose of material within the void so that in use the second dose of material is delivered to the rumen when the overcap is breached or detaches from the second end.
3. The capsule of claim 2 wherein the overcap is releasably attached to the device by a dissolvable attachment.
4. The capsule of claim 2 wherein the overcap is made of a material which will dissolve or breakup in the rumen.
5. The capsule of claim 2 wherein the overcap is made of a material selected from the group consisting of cellulosic fibre, cardboard, paper, a water soluble plastics material and starch.
6. The capsule of claim 2 wherein the capsule is loaded with a second dose of material in the overcap.
7. The capsule of claim 6 , wherein the second dose of material in the overcap comprises copper needles.
8. The capsule of claim 1 wherein the body has at least one external protrusion adapted in use to assist in retaining the capsule in the rumen of an animal.
9. The capsule of claim 8 wherein the at least one protrusion consists of a pair of foldable wings.
10. The capsule of claim 1 wherein the capsule is loaded with a first dose of material.
11. The capsule of claim 1 wherein the capsule is loaded with an exit dose of material.