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GB2190291A - Rumen bolus - Google Patents
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GB2190291A - Rumen bolus - Google Patents

Rumen bolus Download PDF

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Publication number
GB2190291A
GB2190291A GB08711704A GB8711704A GB2190291A GB 2190291 A GB2190291 A GB 2190291A GB 08711704 A GB08711704 A GB 08711704A GB 8711704 A GB8711704 A GB 8711704A GB 2190291 A GB2190291 A GB 2190291A
Authority
GB
United Kingdom
Prior art keywords
segments
bolus
electrically conductive
plastics
support rod
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08711704A
Other versions
GB8711704D0 (en
GB2190291B (en
Inventor
Derek James Whitehead
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Castex Products Ltd
Original Assignee
Castex Products Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Castex Products Ltd filed Critical Castex Products Ltd
Publication of GB8711704D0 publication Critical patent/GB8711704D0/en
Publication of GB2190291A publication Critical patent/GB2190291A/en
Application granted granted Critical
Publication of GB2190291B publication Critical patent/GB2190291B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61KPREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00Medicinal preparations characterised by special physical form
    • A61K9/0012Galenical forms characterised by the site of application
    • A61K9/0053Mouth and digestive tract, i.e. intraoral and peroral administration
    • A61K9/0068Rumen, e.g. rumen bolus
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23KFODDER
    • A23K20/00Accessory food factors for animal feeding-stuffs
    • A23K20/20Inorganic substances, e.g. oligoelements
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23KFODDER
    • A23K40/00Shaping or working-up of animal feeding-stuffs
    • A23K40/20Shaping or working-up of animal feeding-stuffs by moulding, e.g. making cakes or briquettes
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23KFODDER
    • A23K40/00Shaping or working-up of animal feeding-stuffs
    • A23K40/30Shaping or working-up of animal feeding-stuffs by encapsulating; by coating
    • A23K40/35Making capsules specially adapted for ruminants
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61JCONTAINERS SPECIALLY ADAPTED FOR MEDICAL OR PHARMACEUTICAL PURPOSES; DEVICES OR METHODS SPECIALLY ADAPTED FOR BRINGING PHARMACEUTICAL PRODUCTS INTO PARTICULAR PHYSICAL OR ADMINISTERING FORMS; DEVICES FOR ADMINISTERING FOOD OR MEDICINES ORALLY; BABY COMFORTERS; DEVICES FOR RECEIVING SPITTLE
    • A61J3/00Devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms
    • A61J3/06Devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms into the form of pills, lozenges or dragees
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61MDEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M31/00Devices for introducing or retaining media, e.g. remedies, in cavities of the body
    • A61M31/002Devices for releasing a drug at a continuous and controlled rate for a prolonged period of time

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Medicinal Chemistry (AREA)
  • Zoology (AREA)
  • Veterinary Medicine (AREA)
  • Food Science & Technology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Pharmacology & Pharmacy (AREA)
  • Physiology (AREA)
  • Nutrition Science (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Biomedical Technology (AREA)
  • Epidemiology (AREA)
  • Anesthesiology (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Hematology (AREA)
  • Inorganic Chemistry (AREA)
  • Animal Husbandry (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Medicinal Preparation (AREA)

Abstract

A bolus for the controlled release of a biologically active ingredient to ruminants comprises a plurality of annular plastics segments 11 pressed onto a magnesium alloy support rod 12. End segment 14 is extended at the rear to form an annular cavity containing a weighting material 18 and has a releasable cap 13 engagable with an end of the support rod 12 to seal the cavity and contain the weighting material 18 therein. Each segment 11 is provided with a recess and a ring shaped tablet 15 located therein, the tablet 15 containing an active ingredient. The segments 11, 14 are of a plastics material containing dispersed therein an electrically conductive material such that the segments 11, 14 are electrically conductive and coupled to the support rod 12 to cause galvanic corrosion thereof. To enhance the galvanic corrosion rate an exterior coating of an electrically conductive material can be applied to the segments. <IMAGE>

Description

SPECIFICATION Bolus This invention relates to a device, in the form of a bolus, suitable for the controlled release of therapeutic or nutrient substance(s) to ruminants. European Patent Application No.
85303461.9 (Published under No. 0 164 927) describes boluses which essentially depend for their action on the corrosion of a magnesium alloy/member in the rumen juices. The magnesium alloy parts of these devices act as time fuses the degradation of which releases controlled amounts of the desired therapeutic or nutrient substance(s) over a period of several months.
One commercial type of such a bolus consists of a central magnesium alloy support rod which carries several segments, of plastics material, which are an interference fit on the rod. Each such segment provides a respective annular recess which contains a ring-form tablet of anthelmintic or other biologically active material. The adjacent plastics segments abut closely to prevent ingress of liquid, and rubber sealing washers may be provided between the segments. In order that the device may be retained by the animal, it must be weighted to provide a minimum density of about 2.2gm/m1. In addition, it has been found that with the usual magnesium-aluminium-copper alloys which are used for these devices the magnesium alloy rod must be electrically coupled to a more electro-negative material to give the required corrosion rate.For these purposes, a steel end weight has been used, which is also carried by the magnesium alloy support rod and functions both as weight and as a cathode. In action, the magnesium rod corrodes progressively from the end remote from the weight, releasing the plastics segments and their contained tablets of drug at regular intervals. A disadvantage of this design is that the steel end weight is retained indefinitely by the animal and is undesirable in that it may eventually damage the animal and the machinery used to process the carcass.
It is an object of the present invention therefore to provide a bolus of the previously described type providing for galvanic corrosion of the magnesium rod without the use of a solid steel end weight.
With this object in view the present invention provides a bolus having a central magnesium alloy support rod carrying a plurality of annular segments which are an interference fit on the rod, each such segment providing a respective annular recess containing a ringform tablet of a biologically active material and abutting closely its adjacent segments to prevent the ingress of liquid, characterised in that the segments are of a plastics material having, dispensed therein an electrically conductive material such that the secments are electrically conductive and galvanically coupled to the magnesium alloy support rod.
It will be readily understood that this construction will cause galvanic corrosion of the magnesium rod releasing the segments and their respective tablets at regular intervals. Although the steel end weight is not required for galvanic coupling it is still preferable to weight the bolus to ensure its retention by the animal. Advantageously therefore one end segment is extended at its rear to form an annular cavity which is filled with a weighting material and a releasable cap, also of electrically conductive plastics, is provided engagable with one end of the mangesium support rod to seal the cavity in the end segment.
Preferably the weighting material is fine iron shot or finely divided iron-tungston alloy.
The electrically conductive material dispersed in the plastics segments is preferably metal granules, the metal being more electronegative than magnesium such as iron, copper, nickel or zinc. Advantageously the material is carbon or graphite powder.
Although the plastics segments are electrically conductive the produced galvanic corrosion rate may be lower than would be obtained with a steel end weight due to the lower effectiveness of the electrical contact with the rumen liquor (providing the electrolyte). This contact is advantageously improved by providing a coating of an electrically conductive material on the plastics segments exterior surfaces for example an iron or iron based coating.
The invention will be described further, by way of example with reference to the accompanying drawing in which the single figure is a sectional elevation illustrating a preferred embodiment of the bolus of the invention.
Referring to the drawing the bolus shown therein comprises a plurality of annular-shaped plastics segments 11 which are injection moulded using a rigid polypropylene containing about 40% by weight of conductive carbon in powder form. The segments 11 are pressed onto a magnesium alloy core rod 12 which is made from an alloy containing 12% aluminium and 2% copper, the percentages being by weight. Each segment 11 contains a ringshaped tablet 15 containing an active ingredient consisting of Igm of oxfendazole. End segment 14 is similar to the segments 11 save that it is extended at the rear to form a long annular cavity which is filled with weighting material 18 in the form of fine iron shot, e.g.
S170 grade, or finely divided iron-tungsten alloy. A cap 13 on the segment 14 is also moulded from carbon-filled polypropylene and engages with the extreme end of the magnesium support rod 12 to seal the end of the segment 14.
The device is suitable for administration to cattle and may, for example, weigh about 100 gms. The bolus is administered using a balling gun. In the animal's rumeno-reticular sac, corrosion of the magnesium rod 12 proceeds from the exposed end as a result of contact with the rumen juices. The plastics segments 11 fall away at about 4 week intervals, each exposing a fresh drug-containing tablet 15 to the rumen contents. When corrosion of the magnesium rod 12 has extended beyond the position indicated approximately by the numeral 17, the closing cap 13 becomes dislodged and the finely-divided weighting material 18 escapes from its enclosure provided by the segment 14, to be eliminated from the animal along with the plastic parts.
The device depends for its success on maintaining a liquid-tight seal between the adjacent segments at the points indicated at 16, and rubber or like washers may be inserted here to facilitate this.
To increase the electrical coupling between the segments and the rumen liquor a coating (not shown) of iron or an iron based electrically conductive compound may be applied to the segments exterior surfaces. This will bring about a faster galvanic corrosion rate than would otherwise be possible.
The foregoing details are descriptive and variations may be made thereto within the scope of the invention. For example other electrically conductive materials could be substituted for the carbon powder such as granu íated iron, copper nickel or zinc and the proportions used may vary from that specified.
The biologically active ingredient contained in the ring-form tablets can be any desired or required agent and need not be oxfendazole.
The composition of the magnesium alloy support rod may be different from that described and the iron or iron based conductive coating on the segments exterior could be omitted or a different electrically conductive material used instead. The rate at which the drug containing tablets are released will vary according to the galvanic corrosion rate and the diameter of the support rod and need not be at 4 week intervals. Other variations are also possible.

Claims (8)

1. A bolus having a central magnesium alloy support rod carrying a plurality of annular segments which are an interference fit on the rod, each such segment providing a respective annular recess containing a ring-form tablet of a biologically active material and abutting closely its adjacent segment to prevent the ingress of liquid characterised in that the segments are of a plastics material having dispersed therein an electrically conductive material such that the segments are electrically conductive and galvanically coupled to the magnesium alloy support rod.
2. A bolus as claimed in claim 1 wherein one end, segment is extended at its rear to form an annular cavity containing a weighting material and has a releasable cap, also of electrically conductive plastics, engagable with one end of the magnesium support rod to seal the cavity.
3. A bolus as claimed in claim 2 wherein the weighting material is iron shot.
4. A bolus as claimed in claims 1, 2 or 3 wherein a coating of an electrically conductive material is provided on the segments exterior surfaces.
5. A bolus as claimed in any preceding claim wherein the electrically conductive material dispersed in the plastics segments is carbon powder.
6. A bolus as claimed in claims 1, 2, 3 or 4 wherein the electrically conductive material dispersed in the plastics segments is granulated metal, the metal being lower in the electro-chemical series than magnesium.
7. A bolus as claimed in claim 6 wherein the electrically conductive material is iron granules.
8. A bolus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
GB8711704A 1986-05-17 1987-05-18 Controlled release bolus for ruminants. Expired - Fee Related GB2190291B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB868612054A GB8612054D0 (en) 1986-05-17 1986-05-17 Bolus

Publications (3)

Publication Number Publication Date
GB8711704D0 GB8711704D0 (en) 1987-06-24
GB2190291A true GB2190291A (en) 1987-11-18
GB2190291B GB2190291B (en) 1990-03-28

Family

ID=10598031

Family Applications (2)

Application Number Title Priority Date Filing Date
GB868612054A Pending GB8612054D0 (en) 1986-04-17 1986-05-17 Bolus
GB8711704A Expired - Fee Related GB2190291B (en) 1986-05-17 1987-05-18 Controlled release bolus for ruminants.

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB868612054A Pending GB8612054D0 (en) 1986-04-17 1986-05-17 Bolus

Country Status (1)

Country Link
GB (2) GB8612054D0 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2012203345B2 (en) * 2004-09-09 2013-07-18 Argenta Manufacturing Limited Delivery devices and their uses

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2012203345B2 (en) * 2004-09-09 2013-07-18 Argenta Manufacturing Limited Delivery devices and their uses

Also Published As

Publication number Publication date
GB8711704D0 (en) 1987-06-24
GB2190291B (en) 1990-03-28
GB8612054D0 (en) 1986-06-25

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19940518