Improved slip cap for cannula use

Abstract: An applicator for administering a veterinary pharmacological composition comprises a container having a cannula extending therefrom and a two-piece cap for releasably covering the cannula. The cap has an internal seal for sealing the cannula against leakage and contamination.

Description: Field of the Invention This invention relates to an applicator for administering a veterinary pharmacological composition. Background of the Invention It is known to treat mastitis and/or other diseases of the udder by injecting into the udder of the animal being treated a veterinary pharmacological composition containing, for example, penicillin. For this purpose, a cannula including a teat through which the composition is injected into the udder, is used. The cannula preferably has a smooth surface and it is made of a non-abrasive, physiologically-inert, synthetic resin, such as polyethylene, so that the cannula will not abrade or irritate the animal's tissue. The cannula should be sealed from the ambient air prior to use thereof, in order to prevent leakage and contamination of the composition. It has been customary to use a slip-type cap which frictionally engages the external surface of the cannula. Slip-type caps are apt to slip off cannulas accidentally, and they do not provide as tight a seal as is desirable. US-A-2848997 on which the preamble of Claim 1 is based, discloses a squeeze bottle, suitable for use in treating mastitis by adding the contents of the bottle to milk in vitro before injecting the mixture into the animal, which comprises a cannula and a one-piece sleeve adapted to seal and protect the cannula during storage and handling prior to use. US-A-3434473 discloses a hypodermic needle unit having a two-part needle guard adapted to limit the penetration of the needle to a predetermined depth. Summary of the Invention A novel applicator, for administering a veterinary pharmacological composition, comprises a container having a cannula extending therefrom and adapted for dispensing the veterinary pharmacological composition into the teat or the udder of an animal undergoing treatment. A two-part, tubular, slip cap system or sheath is releasably connected to the cannula and covers substantially the cannula's entire length. When one part of the slip cap system has been removed, only the outer portion of the cannula is exposed, so that the cannula can be inserted only part-way into the teat of the animal. When both parts of the slip cap system have been removed, the entire length of the cannula is exposed so that the entire length of the cannula can be inserted into the udder. The slip cap system has an internal seal structure for releasably sealingly engaging the outer surface of the cannula, to prevent leakage of the composition from the cannula and to prevent contamination of the contents of the cannula and the container. Further, the tip cap comprises an inner cylindrical portion of enlarged diameter sleeved on the outer portion of the base cap, an outer cylindrical portion of reduced diameter sleeved on the said outer end portion of the cannula and a radially-extending shoulder extending between adjacent ends of the inner and outer cylindrical portions and abutting against the outer end of the base cap; and the tip cap has an internal, inwardly-projecting, annular, sealing ring which has a smaller internal diameter than the external diameter of the outer end portion of the cannula, so that the sealing ring resiliently deforms the external wall of the outer end portion of the cannula into conformity with the shape of the ring, to provide a releasable liquid seal therebetween. Description of the Invention In a preferred embodiment of the invention, the cannula is made of relatively resiliently deformable, low density polyethylene having a density of from about 0.91 to about 0.94. At least the inner part or base cap of the slip cap system is made of high density polyethylene having a density of about 0.940 to about 0.965 and higher than the density of the low density polyethylene of which the cannula is made. The outer part or tip cap of the slip cap system is made of either high density polyethylene or low density polyethylene. The high density polyethylene used to make the base cap of the slip cap system has a higher strength and greater hardness and it is less easily resiliently deformable than the low density polyethylene of which the cannula is made. The outer part or tip cap of the slip cap system has an internal annular ring or ridge which has an interference fit with the external surface of the cannula. The outer part or tip cap of the slip cap system is press-fit on the axially outer end of the cannula so that the ring resiliently deforms and sealingly engages the external wall of the cannula, whereby to prevent leakage of material from the cannula and to prevent contamination of the cannula. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded view of a container having a cannula and a two-part slip cap systems for the cannula, according to the invention; Fig. 2 is a central cross-sectional view of the cannula and slip cap of Figure 1; Fig. 3 is an enlarged view of the upper portion of Fig. 2; and Fig. 4 is a view like Fig. 2 and showing a modification of the invention. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Fig. 1, the applicator 10, according to the invention, generally comprises an elongated container 11 having a cannula 12 extending axially therefrom, and a two-part slip cap system or sheath 13 comprising a main body or base cap 14 and a tip cap 16. The container 11 can be of any suitable type for parenteral administration of veterinary pharmacological compositions and it is of a size sufficient for holding the required dosage of the veterinary pharmaceutical composition. For example, the container 11 can be a sterile, disposable, hypodermic syringe barrel made of low density polyethylene. The container 11 has an integral, axially outwardly extending hub 17 at one end thereof. The hub 17 has a laterally outwardly projecting, annular rib 18 (Figs. 1 and 2) on the external surface thereof, and has a central opening 19 extending longitudinally therethrough. The hub 17 has a flat wall 20 spaced downwardly a short distance from the rib 18 to define a groove 25 therewith. The opening 19 communicates with the interior chamber of the container 11. The cannula 12 extends axially from the hub 17 in a direction away from the container 11. The cannula 12 is an elongated, smooth-surfaced, tubular member and it has a central opening 21 extending lengthwise from the opening 19 in the hub 17. The opening 21 in the cannula is open at its longitudinally outer end. The longitudinally inner end of the opening 21 communicates with the opening 19 in the hub 17 and thence with the interior chamber of the container 11 so that the contents of the container can be dispensed through the cannula 12. The cannula 12 should be as long as is required for the deepest intended penetration into the udder of the animal to be treated. The cannula 12 preferably is slightly tapered in the longitudinally outward direction so that the external wall thereof extends at an angle of about 2° relative to the longitudinal axis of the cannula. This facilitates insertion and removal of the cannula. The container 11, hub 17 and cannula 12 preferably are parts of a one-piece, monolithic, molded shape made of low-density polyethylene, as described in greater detail hereinbelow. The main body or base cap 14 of the two-piece slip cap system 13 is generally cylindrical and elongated, and it has a laterally enlarged inner section 26 surrounding and releasably secured to the hub 17 of the container 11. Preferably, the main body 14 tapers in a direction away from the container 11. The enlarged inner section 26 of the main body 14 has an annular, laterally inwardly projecting ridge 27 at its longitudinally inner end and an end wall 30. An internal, annular, axially elongated groove 28 extends axially outwardly from adjacent to the ridge 27. When the main body 14 is releasably secured to the cannula 12, the end wall 30 of the main body 14 abuts against the flat wall 20 of the hub 17, the annular rib 18 on the hub 17 is received in the groove 28 and the ridge 27 underlies the rib 18 in order releasably to secure the main body 14 of the cap 13 to the hub 17 by a snap-lock effect. The axially outer end of the main body 14 of the cap 13 has a laterally inwardly extending shoulder 29 which defines an opening through which extends the axially outer end portion 31 of the cannula 12. The internal wall of the main body 14 is spaced from the external wall of the cannula 12, except at the ridge 27 and shoulder 29 so that these parts can be more easily flexed, relative to one another, as needed to effect removal of the cap. The tip cap 16 has an axially inner tubular sleeve portion 33 which is sleeved on the axially outer portion of the main body 14 and an axially outer portion 34 of reduced diameter and which is sleeved on the axially outer end portion 31 of the cannula 12. The portion 34 is closed at its outer end and it covers the axially outer end portion 31 of the cannula 12. The inner surface of the sleeve portion 33 of the tip cap 16 is provided with an annular, laterally inwardly projecting, retaining ring 35 at its axially inner end for releasible engagement with the annular, laterally outwardly projecting, lock ring 36 on the main body 14 whereby the tip cap 16 is releasably engaged and held in place on the main body 14 of the cannula 12 by a snap-lock type of coupling. In this position, as shown in Fig. 3, the shoulder 37 of the tip cap 16, which shoulder extends laterally between the portions 31 and 34, abuts against the shoulder 29 on the main body 14 of the slip cap system 13. A laterally outwardly projecting flange 38 is provided at the axially inner end of the tip cap 16. When the contents of the container 11 are to be dispensed, the user can manually engage the flange 38 with a finger or thumb and flip off the tip cap 16 from the main body 14, whereby the end portion 31 of the cannula becomes exposed and the contents of the container 11 can be dispensed. When the entirety of the slip cap system 13 is to be removed to expose the entire length of the cannula 12, the user can grasp the main body 14 and flex it to disengage the ridge 27 and rib 18 and then slide the entire slip cap system 13 axially off the cannula. The inner surface of the axially outer portion 34 of the tip cap 16 has an annular, laterally inwardly projecting, sealing ring 41 which resiliently deforms the opposing portion of the external wall of the axially outer portion 31 of the cannula 12 whereby to form a complementary groove 42 therein. In this way, the ring 41 and groove 42 provide an effective, resilient seal between the tip cap 16 and the axially outward end portion 31 of the cannula 12. This serves to prevent leakage of the contents of the container 11 and to keep said contents sterile. For this purpose, the cannula 12 is preferably made of low density polyethylene having a density of from about 0.91 to about 0.94. The tip cap 16 is made of said low density polyethylene or high density polyethylene having a density of about 0.940 to about 0.965. Because high density polyethylene has a higher strength and hardness than the low density polyethylene, when the tip cap 16 is made of high density polyethylene and it is placed on the axially outer end of the cannula 12 and then is pushed axially inwardly therealong, the sealing ring 41 on the tip cap 16 will elastically deform successive portions of the external wall of the end portion 31 of the cannula 12 as it moves therepast until shoulder 37 abuts against shoulder 39. In that position, the ring 41 forms the groove 42 and the opposing wall portions of said ring and groove resiliently press against each other to form a tight seal between those parts and to hold the tip cap 16 in place. When the tip cap 16 is made of low density polyethylene, the ring 41 will be resiliently flattened more and the groove 42 will be less deep, but the opposing walls of the ring 41 and the groove 42 will still press against each other to form a tight seal between the tip cap 16 and the cannula 12. In a typical embodiment of the invention, in which the external diameter of the axially outer end 31 of the cannula 12 is about 2.50 mm. and the wall thickness of the cannula is about 0.5 mm., the radial depth D of the sealing ring 41 is about 0.22 mm. In this example, the tip cap 16 is made either of high density polyethylene which is commercially available under the designation "MARTEX BMN TR-880" or low density polyethylene, which is commercially available under the designation "Tenite 800A" and the cannula 12 is made of low density polyethylene which is commercially available under the designation "Tenite 800A". The main body 14 of the slip cap system 13 is made of high density polyethylene which is commercially available under the designation "Marlex BMNTR880". When the tip cap 16 is secured to the outer end 31 of the cannula 12 and to the main body 14 of the slip cap system, the cannula 12 is protected from exposure and contamination and the entire applicator unit 10 can be safely stored and transported. When the pharmaceutical composition in the container 11 is to be administered, the tip cap 16 can be flipped-off by manually engaging the flange 38 whereby to expose the outer end portion 31 of the cannula. If a relatively shallow depth of penetration of the cannula 12 is desired, the outer end portion 31 of the cannula 12 can be inserted until the shoulder 29 abuts against the flesh of the animal. The shoulder 29 limits the depth of penetration of the cannula into the animal. When it is desired to expose a greater length of the cannula, then the main body 14 of the slip cap system can be removed by flexing and pulling said main body upwardly relative to the cannula 12. When the main body portion 14 is removed, then the entire length of the cannula 12 is exposed and the cannula can be inserted into the animal to the maximum extent. A modified slip cap system is shown in Fig. 4. The parts of this figure which correspond to parts in the embodiment of Figs. 1 to 3 are identified by the same reference numbers with the suffix "a" applied thereto. This modification differs from the modification of Figs. 1 through 3 by the provision of a cylindrical skirt 51 which extends downwardly from the flange 38a to cover a greater portion of the length of the main body portion 14a of the slip cap system. Also, the interengaging lock ring and sealing ring 35a and 36a are provided at the inner end of the tip cap 16a. Further, the ring 41a and complementary cavity 42a are provided substantially at the juncture of the shoulder 37a with the outer cap portion 34a. Also, the hub 17a flares in a direction toward the container 11, the rib 18 is omitted and the groove 25a is formed between the inner end of hub 17a and the shoulder 20a. The applicator according to the invention protects the cannula from damage and contamination during storage, shipment and use. It permits the cannula to be inserted into the body of the animal to various depths, as needed for proper administration of the veterinary pharmaceutical composition. Because the end portion 31 and the remainder of the cannula 12 are completely covered by the tip cap 16 and the main body 14, respectively, the cannula is maintained in a sterile condition and is not exposed until the tip cap and/or main body are removed. Also, because the surfaces of shoulder 29 and hub 17, which are likely to contact the skin of the animal, are maintained in a sterile condition, there is a lower possibility of infection.

Claims: An applicator adapted for administering a mastitis treatment medication to a cow, comprising: a container (11) for the medication; extending from the container, an elongate cannula (12) having a blunt outer end and adapted to be slidably receivable in a teat canal of the cow; and a tubular cap releasably connected to and sealingly covering the cannula; characterised in that the cap is a two-part system (13) comprising a base cap (14) and a tip cap (16); wherein the base cap is shorter than the cannula, has an inner end releasably secured to the cannula, extends from the container partway along the length of the cannula, and terminates in an outer end having a substantially flat annular end wall adapted to prevent the base cap from entering into the teat canal of the cow, and through which the outer end portion of the cannula extends; wherein the tip cap is releasably secured to the base cap and covers the outer end portion of the cannula, whereby removal of the tip cap, but not the base cap, allows the medication to be deposited directly into the teat canal, while removal of the base cap and the tip cap allows the cannula to be received, through the teat canal, into the udder of the cow; wherein the tip cap comprises an inner cylindrical portion (33) of enlarged diameter sleeved on the outer portion of the base cap, an outer cylindrical portion (34) of reduced diameter sleeved on the said outer end portion of the cannula and a radially-extending shoulder (37) extending between adjacent ends of the inner and outer cylindrical portions and abutting against the outer end of the base cap; and the tip cap has an internal, inwardly-projecting, annular, sealing ring (41) which has a smaller internal diameter than the external diameter of the outer end portion of the cannula, so that the sealing ring resiliently deforms the external wall of the outer end portion of the cannula into conformity with the shape of the ring, to provide a releasable liquid seal therebetween. An applicator as claimed in claim 1, in which the sealing ring is located closer to the shoulder than to the outer end of the cannula. An applicator as claimed in claim 1, in which the sealing ring is located substantially at the shoulder. An applicator as claimed in any preceding claim, which additionally comprises a first snap-lock joint for releasably connecting the inner end of the base cap to the container and a second snap-lock joint for releasably connecting the tip cap to the base cap. An applicator as claimed in claim 4, in which the second snap-lock joint comprises a radially-outwardly-projecting ridge (36) on the base cap and a radially-inwardly-projecting ridge (35) on the tip cap, the ridges having an interference fit with each other, so that the tip cap can be removed by elastic deformation thereof. An applicator as claimed in any preceding claim, in which the cannula is made of low-density polyethylene and the tip cap is made of low-density polyethylene or high-density polyethylene. An applicator as claimed in any preceding claim, in which the external diameter of the blunt outer end of the cannula is about 2.5 mm.

Inventors: GALLAGHER JAMES L, PYRET THOMAS W, GALLAGHER, JAMES L., PYRET, THOMAS W.
Applicants: UPJOHN CO, THE UPJOHN COMPANY
Application year: 1989
Main classification: A61D1
IPC codes: A61D1