A veterinary drug delivery device based on a drug sustained-release stick and its application.

Abstract

This invention discloses a veterinary drug delivery device based on a drug sustained-release stick and its application. The drug delivery device includes an ear tag fixing base and a drug sustained-release stick. The ear tag fixing base includes a male component and a female component, and a connecting pin for connecting the male component and the female component. A first receiving cavity is provided axially inside the connecting pin, and a sustained-release port is provided on the side wall of the connecting pin. The drug sustained-release stick is disposed in the first receiving cavity and includes a sustained-release matrix material and an active drug. This invention abandons the traditional methods of daily oral medication and subcutaneous implants, and creatively adopts a "drug sustained-release stick" delivery strategy. Wearing the ear tag enables immediate drug delivery, and removing the ear tag immediately stops drug delivery, realizing "on / off" controllable drug delivery and solving the problems of missed oral doses and the inability to quickly interrupt traditional implants.

Description

Technical Field

[0001] This invention belongs to the field of veterinary drug delivery technology, and relates to a veterinary drug delivery device based on a drug sustained-release rod, its preparation method and application, specifically a microneedle-allylprogesterone long-acting drug delivery system for estrus synchronization in sows. Background Technology

[0002] For a long time, in traditional animal husbandry practices, the industry has generally adopted non-continuous drug administration methods such as manual injection, oral administration, or group feed mixing for animal disease prevention and control, growth promotion, and nutritional regulation. However, these methods have several inherent drawbacks: on the one hand, they easily induce significant stress responses in animals; on the other hand, it is difficult to accurately control the dosage and timing of drug administration, and in large-scale farming scenarios, they also face prominent problems such as high labor costs and low operational efficiency. Taking sow farming as an example, in order to induce sows to synchronously come into estrus and be mated in a concentrated manner within a predetermined cycle, thereby achieving batch production goals, farmers usually choose to feed allylprogesterone to induce group estrus, as follows: The industry standard and only commercially available route of administration is daily oral administration for 18 consecutive days. The traditional method involves mixing acetaminophen (20 mg daily) into the feed or drinking water for sows to consume. However, this traditional administration method has revealed numerous insurmountable technical bottlenecks and management challenges in practical large-scale farming applications, specifically in the following aspects: Poor accuracy and reliability of drug administration can easily lead to production failure: Sows often exhibit anorexia, picky eating, or uneven feed intake due to individual differences, health conditions, or stress responses. During daily feeding, operators are highly susceptible to oversight or chaotic group management, resulting in missed feedings, repeated administrations, or inaccurate dosages. A stable blood concentration of acetaminophen is crucial for effectively inhibiting the release of pituitary gonadotropins. Missed feedings or insufficient dosages will directly lead to asynchronous estrus and decreased ovulation rates in sows, disrupting the breeding, pregnancy, and farrowing plans for the entire production batch, causing significant time delays and economic losses for farms.

[0003] The high cost and heavy management burden of manual operation: This plan requires farmers to operate and observe each sow at a fixed time for more than 18 consecutive days. This not only consumes a lot of human resources, but also brings enormous mental stress and operational burden to the operators. In large-scale farms, it is difficult to guarantee the stability and accuracy of each operation in the long term, and staff fatigue can easily lead to errors.

[0004] The hidden overall costs are enormous: In traditional methods, the cost of the drug itself accounts for only a small portion; behind this lies extremely high labor and management costs, as well as potential production losses due to operational errors. The chain reaction caused by a single synchronization failure results in losses far exceeding the cost of the drug itself.

[0005] The pharmacokinetic performance has inherent defects: under oral administration, the drug is absorbed through the gastrointestinal tract and undergoes the first-pass effect in the liver, resulting in relatively low bioavailability and large individual variability, leading to significant fluctuations in blood drug concentration. This pulsed drug exposure pattern makes it difficult to maintain a blood drug level above the minimum effective concentration (MEC>2 ng / mL) continuously and stably over a period of up to 18 days, affecting the stability and uniformity of the estrus suppression effect.

[0006] To address the challenge of daily drug administration, those skilled in the art have attempted other technologies, but all have significant limitations, such as: Traditional subcutaneous implants: Although they can achieve long-lasting sustained release, most require invasive implantation with the help of special implanters, and removal often requires a second surgery or forceful pulling, making removal difficult, causing significant stress and tissue damage to animals, and the drug release cannot be stopped immediately after removal, posing a risk of drug residue.

[0007] Transdermal patches: face the problem of poor adhesion and easy fall-off in the breeding environment, and for allylprogesterone, which has a high lipid solubility, its transdermal penetration rate and drug loading capacity are often difficult to meet the needs of continuous drug delivery for up to 18 days.

[0008] Biodegradable implants: While avoiding the removal step, their release process cannot be stopped midway. If adverse reactions occur or breeding plans need to be adjusted, there is no way to proactively discontinue the medication, resulting in poor flexibility. Furthermore, degradation products and residues may trigger local tissue inflammation.

[0009] In summary, current technologies, whether mainstream oral regimens or alternative sustained-release attempts, fail to achieve a satisfactory balance between ease of administration, release stability, treatment interruptibility, and animal welfare. Therefore, there is an urgent need to develop a novel drug delivery system capable of "one-time operation, long-lasting release, on-demand discontinuation, and convenient management" to help achieve efficient and precise low-cost animal drug administration. Summary of the Invention

[0010] To address the aforementioned problems of existing technologies, this invention provides a veterinary drug delivery device based on a drug sustained-release stick, along with its preparation method and application. It aims to solve the problems of cumbersome operation and easy missed doses associated with existing oral drug delivery methods, as well as the inconvenience of interrupting drug delivery with traditional subcutaneous implants. Through innovative structural design and pharmacokinetic regulation, this system achieves long-acting, stable, and controllable transdermal delivery of hormonal drugs such as acetaminophen.

[0011] A veterinary drug delivery device based on a drug sustained-release stick includes: an ear tag fixing base and a drug sustained-release stick. The ear tag fixing base includes a male component, a female component, and a connecting pin for connecting the male component and the female component; the connecting pin has a first receiving cavity along the axial direction and a slow-release port is provided on the side wall of the connecting pin; the drug slow-release rod is disposed in the first receiving cavity and includes a slow-release matrix material and an active drug.

[0012] Furthermore, the drug loading capacity of the sustained-release stick is 0.1-200 mg.

[0013] For drug sustained-release sticks, active drug molecules can be continuously and stably released into the interstitial fluid through the sustained-release port set on the connecting needle via diffusion, and then absorbed into the systemic circulation to achieve systemic drug delivery.

[0014] Furthermore, the slow-release matrix material includes at least one of polydimethylsiloxane, silica gel, ethylene-vinyl acetate copolymer, and polylactic-co-hydroxyacetic acid copolymer.

[0015] Preferably, the slow-release matrix material is at least one of polydimethylsiloxane and silica gel.

[0016] Furthermore, the specific type of active drug can be selected according to actual needs. For example, in order to ensure that sows come into estrus and are bred within a predetermined time, thereby achieving batch production, farmers can choose allylprogesterone as the active drug.

[0017] Furthermore, the drug release stick also includes pharmaceutical excipients.

[0018] Furthermore, the surface of the drug-release stick is coated with a pharmaceutical excipient film.

[0019] Furthermore, the pharmaceutical excipient is polylactic acid-glycolic acid copolymer.

[0020] Pharmaceutical excipients are polymeric materials capable of controlling the rate of drug release. The use of pharmaceutical excipients allows for better control of the release rate of the active drug in a drug release stick, helping to more precisely "program" the drug release profile and ensuring stable and complete drug release over a long period.

[0021] Furthermore, the cross-section of the drug-release rod is at least one of the following: circular, elliptical, rectangular, polygonal, or irregular shape.

[0022] Preferably, the cross-section of the drug release stick is circular or elliptical.

[0023] Furthermore, the length of the drug-releasing rod can be slightly longer than the height of the release port provided on the side wall of the connecting needle. The drug-releasing rod is placed into the first receiving cavity through the release port. After the drug delivery device is fixed to the animal's ear, the drug-releasing rod is completely fixed.

[0024] Furthermore, the aforementioned drug sustained-release rods can be prepared by solvent evaporation or melt extrusion, and it is necessary to ensure a high degree of uniform dispersion of the drug in the sustained-release matrix material or a mixture of sustained-release matrix material and pharmaceutical excipients.

[0025] Further, the preparation of drug sustained-release rods by solvent evaporation includes the following steps: (1) dissolving the dried sustained-release matrix material or a mixture of sustained-release matrix material and pharmaceutical excipients with the active drug in proportion, and stirring to obtain a homogeneous mixed solution; (2) pouring the mixed solution onto a glass plate or release film, and scraping it flat with a scraper to obtain a wet film; (3) removing the solvent from the wet film under suitable conditions to obtain a dry film; (4) lightly hot-pressing the film, and then precisely cutting it to obtain a drug sustained-release rod.

[0026] Further, the preparation of drug sustained-release rods by melt extrusion includes the following steps: (1) premixing the dried sustained-release matrix material or a mixture of sustained-release matrix material and pharmaceutical excipients with the active drug in a twin-screw extruder in proportion, then heating it to a molten state, and obtaining a uniform blended melt through shearing and mixing by the screw; (2) extruding the blended melt using a die, and obtaining drug sustained-release rods through solidification molding and precision cutting.

[0027] For drug components with poor stability, solvent evaporation is the preferred method for preparation.

[0028] Furthermore, the drug delivery device also includes a microneedle assembly or a drug-loaded pad, which is detachably connected to the ear tag fixing base.

[0029] Furthermore, the microneedle assembly includes a fixedly connected substrate and multiple microneedles arranged in an array.

[0030] Furthermore, the microneedle assembly also includes a drug coating disposed on the outer surface of the microneedle.

[0031] Microneedle components are used to rapidly increase the blood drug concentration in animals in the early stages to quickly relieve symptoms.

[0032] Furthermore, the drug loading of the drug coating is 0.1-50 mg.

[0033] Furthermore, the type of active drug in the drug coating can be selected according to actual needs. For example, to ensure that sows come into estrus and are mated within a predetermined time, thereby achieving batch production, farmers can choose allylprogesterone as the active drug.

[0034] Furthermore, the drug coating on the microneedle assembly is achieved by applying a solution containing an active drug to the surface of the microneedle and then curing it. Specifically, the drug and a biocompatible polymer (such as polyvinylpyrrolidone or hydroxypropyl methylcellulose) are dissolved in a suitable solvent to prepare a coating solution, which is then uniformly applied to the surface of the microneedle using a micro-spraying or dip-coating process. The thickness and uniformity of the drug coating are controlled, and after curing, a microneedle with a drug coating on its surface is obtained.

[0035] Furthermore, the number of microneedles on the microneedle assembly is 10-1500.

[0036] Furthermore, the microneedle has a tapered structure that is wider at the bottom and narrower at the top, with a height of 0.3-1.5 mm, a bottom diameter of 0.2-0.7 mm, and a tip diameter of less than 50 μm.

[0037] Furthermore, the substrate thickness of the microneedle assembly is 0.1-1 mm.

[0038] Furthermore, the drug delivery device also includes a drug-loaded pad, which is detachably connected to the ear tag fixing base. The thickness of the drug-loaded pad is 0.1-3mm, and the bottom diameter of the drug-loaded pad is 10-40mm.

[0039] Furthermore, the raw materials for preparing drug-loaded pads include sustained-release matrix materials and active drugs.

[0040] Drug-loaded pads are used to rapidly increase the blood drug concentration in animals in the early stages to quickly relieve symptoms.

[0041] Furthermore, the slow-release matrix material includes at least one of polydimethylsiloxane, silica gel, ethylene-vinyl acetate copolymer, and polylactic-co-hydroxyacetic acid copolymer.

[0042] Preferably, the slow-release matrix material is at least one of polydimethylsiloxane and silica gel.

[0043] Furthermore, the specific type of active drug can be selected according to actual needs. For example, in order to ensure that sows come into estrus and are bred within a predetermined time, thereby achieving batch production, farmers can choose allylprogesterone as the active drug.

[0044] Furthermore, the drug loading capacity of the drug-loaded pad is 0.1-100mg.

[0045] Furthermore, the drug-loaded pad also includes glycerin to enhance drug delivery efficiency.

[0046] Further, the drug-loaded pad includes the following preparation steps: (1) dissolving the sustained-release matrix material in an appropriate amount of solvent and pouring it onto a glass plate or release film, then scraping it flat with a scraper to obtain a wet film; (2) removing the solvent from the wet film under suitable conditions to obtain a dry film; (3) lightly hot-pressing the film, and then precisely cutting it to obtain a pad; (4) dissolving the active drug and biocompatible polymer (such as polyvinylpyrrolidone, hydroxypropyl methylcellulose) in a suitable solvent to prepare a coating solution, which is then uniformly coated onto the surface of the pad by roller coating, spraying or dipping processes. After curing, the drug-loaded pad is obtained.

[0047] Furthermore, the type and load of active drug on the drug-release rod may be the same as or different from the type and load of drug in the microneedle assembly and / or drug-loaded pad. The specific selection and parameters can be combined according to actual needs.

[0048] Furthermore, an annular groove is provided on the side of the male component near the female component. The depth and area of ​​the annular groove are adapted to the thickness and area of ​​the base or drug-loaded pad, and the base or drug-loaded pad can be fitted into the annular groove. Furthermore, an annular groove is provided on the side of the female component near the male component. The depth and area of ​​the annular groove are adapted to the thickness and area of ​​the base or drug-loaded pad, and the base or drug-loaded pad can be fitted into the annular groove.

[0049] Furthermore, the annular groove allows for the secure connection of the microneedle assembly or drug-loaded pad to the ear tag fixing base. Similarly, clearance holes are provided on both the base and the drug-loaded pad, positioned at the center of the base or pad. These clearance holes serve two purposes: firstly, to allow the connecting needle to pass through, and secondly, to limit the movement of the base or drug-loaded pad, preventing lateral displacement.

[0050] Furthermore, the male component is provided with a first fixing hole, one end of the connecting pin is connected to the male component through the first fixing hole, and the other end is connected to the female component.

[0051] Furthermore, a locking element is provided on the female component, and the other end of the female component and the connecting pin are detachably connected by the locking element.

[0052] Furthermore, the locking component includes a second fixing groove on the side of the female component near the male component. The other end of the connecting pin can be accommodated in the second fixing groove, and the connecting pin and the second fixing groove are interference-fitted, with the second fixing groove securing the connecting pin. During the disassembly of the female component, if the female component is made of resin material, the second fixing groove has a certain elasticity, allowing the female component to detach from the connecting pin under external force.

[0053] Furthermore, a connector is installed between the female component and the male component to reduce the risk of component loss.

[0054] Furthermore, the mother component has a second receiving cavity. The locking mechanism includes a metal cup, a spring component, and three steel balls disposed within the second receiving cavity. The metal cup has three limiting holes, the positions of which correspond to the positions of the steel balls. The spring component restricts the movement of the metal cup towards itself. Specifically, the limiting holes, in conjunction with the second receiving cavity, restrict the position of the steel balls. When the connecting pin is inserted radially, the downward force of the spring component presses against the metal cup, causing the three steel balls to lock the connecting pin in place, thus fixing the connecting pin to the mother component. When it is necessary to remove the mother component, a strong magnet is placed above it. Under the attraction of the magnet, the metal cup moves the steel balls upward, and the spring component compresses upward. Because the inner diameter of the second receiving cavity gradually increases from bottom to top (the diameter increases closer to the spring component), the steel balls gradually release the connecting pin as the metal cup moves upward, allowing the mother component to be removed from the connecting pin. This is similar to the anti-theft magnetic tags used on clothing in supermarkets.

[0055] Furthermore, the male and female components are installed and removed via a magnetic attraction mechanism. This mechanism includes permanent magnets on both the male and female components, arranged symmetrically with polarity. The magnetic force of the permanent magnets attracts and locks the male and female components together. By setting permanent magnets on the ear tag fixing base, the magnetic structure can be quickly installed and removed, allowing for rapid installation and removal of ear tags. This extremely convenient operation greatly improves the efficiency of the farm and reduces the labor intensity of operators. The detachable connection between the drug-loaded microneedle assembly and the ear tag fixing base allows for the replacement of the microneedle assembly, enabling the same drug delivery device to be adapted to various treatment protocols, demonstrating strong scalability.

[0056] Furthermore, blind holes are provided on both the male and female components. The magnet is accommodated within the blind hole and is interference-fitted with it. A stop is provided at the edge of the blind hole to fix the permanent magnet inside, preventing it from falling out under strong pulling. Alternatively, an ultrasonic welding process can be used to fix the permanent magnet and the blind hole together, preventing the permanent magnet from falling out under strong pulling.

[0057] Furthermore, an elastic barb is provided at the end of the connecting needle near the mother component, and a barb groove is provided at the corresponding position on the mother component. When the connecting needle and the mother component are connected, the elastic barb is accommodated in the barb groove. The setting of the elastic barb and the barb groove ensures that the system will not be accidentally opened in extreme cases, thereby improving the stability of the connection between the drug delivery device and the animal's ear.

[0058] The preparation method of the above-mentioned veterinary drug delivery device based on a drug sustained-release stick includes the following steps: S1. Prepare drug sustained-release rods by solvent evaporation or melt extrusion; S2. The drug release rod is housed in the first receiving cavity of the connecting needle, and the connecting needle is fixedly installed on the male component; S3. Inspect, sterilize, and package all components.

[0059] Furthermore, the testing includes: a full inspection of the ear tag fixing base and the connecting pin with the drug release rod, including inspection of appearance, key dimensions, total weight, magnetic attraction and drug loading, to exclude non-conforming products.

[0060] Furthermore, sterilization includes: sterilization using ethylene oxide sterilization to ensure a sterility assurance level (SAL) of 10. -6 Furthermore, there were no significant changes in drug content and related substances.

[0061] Furthermore, the packaging includes: immediately packaging the sterilized qualified products in individual blister packs (aluminum foil blister packs) with good barrier properties and filling them with nitrogen for protection.

[0062] The above-mentioned veterinary drug delivery device based on a drug sustained-release stick is used in animal drug administration. In use, the device is clipped to the animal's ear for precise drug delivery. For example, to ensure sows come into estrus and mate within a predetermined timeframe, farmers can use a veterinary drug delivery device containing acetaminophen to clip onto the sow's ear for long-term continuous drug administration, which can be stopped at any time as needed, thus enabling batch production of sows.

[0063] The beneficial effects of this invention are: 1) The drug delivery device of this application abandons the traditional daily oral administration and subcutaneous implant methods, and creatively adopts a "drug sustained-release stick" delivery strategy. The drug is delivered directly into the animal's body through contact between the drug sustained-release stick and the animal's ear tissue. When the ear tag is removed, the drug sustained-release stick detaches from the skin, and the drug delivery stops immediately. This achieves "on / off" controllable drug delivery and solves the problems of easy missed doses with traditional oral administration and the difficulty in removing traditional subcutaneous implants.

[0064] 2) By simultaneously incorporating microneedles or drug-loaded pads with a sustained-release drug stick within the drug delivery device, the drug can be rapidly released into the animal's body in the early stages via the microneedles or drug-loaded pads to quickly alleviate symptoms. The sustained-release drug stick is responsible for continuous drug delivery to the animal, ensuring an effective drug concentration within the animal's body during the administration period. Furthermore, different drugs can be selected to treat different diseases based on specific circumstances.

[0065] 3) Microneedles or drug-loaded pads act only on the surface of the skin, causing far less trauma than traditional subcutaneous implants, greatly reducing pain and stress in animals, and promoting animal welfare and healthy growth.

[0066] 4) Polydimethylsiloxane, silica gel, and other materials have excellent biocompatibility as sustained-release matrix materials. They do not degrade in vivo, have low risk of tissue residue during administration, and are highly safe, which helps to ensure the safety of animal-derived foods. Attached Figure Description

[0067] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0068] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0069] Figure 1 This is a perspective view of a veterinary drug delivery device based on a drug sustained-release stick according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of an ear tag fixing base according to an embodiment of the present invention; Figure 3 This is another perspective view of a veterinary drug delivery device based on a drug sustained-release rod according to an embodiment of the present invention; Figure 4 This is a perspective view of a veterinary drug delivery device based on a drug sustained-release rod, according to another embodiment of the present invention. Figure 5 This is a perspective view of a microneedle assembly according to another embodiment of the present invention; Figure 6 This is a perspective view of a microneedle according to another embodiment of the present invention; Figure 7 This is a cross-sectional view of a veterinary drug delivery device based on a drug sustained-release rod according to another embodiment of the present invention; Figure 8 This is a perspective view of a male component according to an embodiment of the present invention; Figure 9 This is a perspective view of a veterinary drug delivery device based on a drug sustained-release rod, according to another embodiment of the present invention. Figure 10 Another perspective view of a veterinary drug delivery device based on a drug sustained-release rod according to yet another embodiment of the present invention; Figure 11 This is a cross-sectional view of a veterinary drug delivery device based on a drug sustained-release rod according to an embodiment of the present invention; Figure 12 This is a partial perspective view of a veterinary drug delivery device based on a drug sustained-release rod according to an embodiment of the present invention; Figure 13This is a blood drug concentration curve of a veterinary drug delivery device based on a drug sustained-release stick according to an embodiment of the present invention.

[0070] In the diagram: 1. Male component; 11. First fixing hole; 12. Annular groove; 2. Female component; 21. Second fixing groove; 22. Second receiving cavity; 23. Metal cup; 231. Limiting hole; 24. Steel ball; 25. Spring component; 3. Connecting needle; 31. First receiving cavity; 32. Slow-release port; 33. The other end of the connecting needle; 4. Connector; 5. Base; 51. Alternating hole; 6. Microneedle; 7. Drug coating; 8. Drug-loaded pad. Detailed Implementation

[0071] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0072] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0073] This embodiment describes a veterinary drug delivery device based on a drug sustained-release stick, such as... Figure 1-3 As shown, it includes an ear tag fixing base and a drug release rod. The ear tag fixing base includes a male component 1, a female component 2, and a connecting pin 3 for connecting the male component 1 and the female component 2. The connecting pin 3 has a first receiving cavity 31 along the axial direction inside, and a release port 32 is provided on the side wall of the connecting pin 3. The drug release rod is disposed in the first receiving cavity 31 and includes a release matrix material and an active drug.

[0074] For drug delivery rods, active drug molecules are continuously and stably released into the interstitial fluid via diffusion through the release port on the connecting needle, and are subsequently absorbed and enter the systemic circulation to achieve systemic drug delivery.

[0075] In some embodiments, the drug-release stick has a drug loading capacity of 0.1-200 mg.

[0076] In some embodiments, the sustained-release matrix material includes at least one of polydimethylsiloxane, silica gel, ethylene-vinyl acetate copolymer, and polylactic-co-hydroxyacetic acid copolymer.

[0077] In some embodiments, the sustained-release matrix material is at least one of polydimethylsiloxane and silica gel.

[0078] In some embodiments, the specific type of active drug can be selected according to actual needs. For example, in order to ensure that sows come into estrus and are bred within a predetermined time to achieve batch production, farmers may choose allylprogesterone as the active drug.

[0079] In some embodiments, the drug release stick also includes pharmaceutical excipients.

[0080] In some embodiments, the surface of the drug release stick is coated with a pharmaceutical excipient film.

[0081] Pharmaceutical excipients are polymeric materials capable of controlling the rate of drug release, such as polylactic acid-glycolic acid copolymers. The use of pharmaceutical excipients allows for better control of the release rate of the active drug in drug-release rods, helping to more precisely "program" the drug release profile and ensuring stable and complete drug release over long periods.

[0082] In some embodiments, the cross-section of the drug release stick is at least one of the following: circular, elliptical, rectangular, polygonal, or irregular shape.

[0083] In some embodiments, the cross-section of the drug release stick is circular or elliptical.

[0084] In some embodiments, the length of the drug release stick may be slightly longer than the height of the release port 32 provided on the side wall of the connecting needle 3. The drug release stick is placed into the first receiving cavity 31 through the release port 32. After the drug delivery device is fixed to the animal's ear, the drug release stick is completely fixed.

[0085] In some embodiments, the above-mentioned drug sustained-release rods can be prepared by solvent evaporation or melt extrusion, and it is necessary to ensure that the drug is highly uniformly dispersed in the sustained-release matrix material or a mixture of sustained-release matrix material and pharmaceutical excipients.

[0086] In some embodiments, the preparation of drug sustained-release rods by solvent evaporation includes the following steps: (1) dissolving a dry sustained-release matrix material or a mixture of sustained-release matrix material and pharmaceutical excipients with an active drug in proportion, and stirring to obtain a homogeneous mixed solution; (2) pouring the mixed solution onto a glass plate or release film, and scraping it flat with a scraper to obtain a wet film; (3) removing the solvent from the wet film under suitable conditions to obtain a dry film; (4) lightly hot-pressing the film, and then precisely cutting it to obtain a drug sustained-release rod.

[0087] In some embodiments, the specific steps for preparing drug sustained-release rods by solvent evaporation include: (1) drying the sustained-release matrix material or a mixture of sustained-release matrix material and active drug under vacuum conditions to remove moisture, and then dissolving the precisely weighed sustained-release matrix material or a mixture of sustained-release matrix material and active drug together in an organic solvent, and stirring to form a homogeneous and clear mixed solution; (2) pouring the mixed solution onto a flat glass plate or release film, and scraping it flat with a scraper to obtain a wet film, the thickness of which is adjusted by controlling the scraper parameters; (3) transferring the glass plate or release film carrying the wet film to a temperature-controlled and well-ventilated solvent evaporation cabinet, and programmed controlling the temperature and wind speed to allow the solvent to evaporate safely and slowly to form a uniform and dry film; (4) subjecting the dried film to light hot pressing to enhance its density, and then cutting it into the specified size using a precision cutting mold or laser cutting system to obtain the drug sustained-release rod.

[0088] In some embodiments, the preparation of drug sustained-release rods by melt extrusion includes the following steps: (1) premixing dried sustained-release matrix material or a mixture of sustained-release matrix material and pharmaceutical excipients with active drug in a twin-screw extruder, then heating to a molten state, and obtaining a uniform blended melt through shearing and mixing by the screw; (2) extruding the blended melt using a die, and obtaining a sustained-release implant by solidification molding and precision cutting.

[0089] In some embodiments, the specific process steps for preparing drug sustained-release rods by melt extrusion include: (1) drying the sustained-release matrix material or the mixture of sustained-release matrix material and active drug under vacuum conditions to remove moisture, and then pre-mixing the precisely weighed sustained-release matrix material or the mixture of sustained-release matrix material and active drug in a twin-screw extruder, heating it to a molten state in a precisely temperature-controlled barrel, and forming a highly uniform blended melt through the shearing and mixing action of the screw; (2) extruding the blended melt through a precisely designed specific die, solidifying it through a cooling water tank or cooling air duct, and then cutting it into a specified size using a precision cutting die or laser cutting system to obtain the drug sustained-release rod.

[0090] For drugs with poor stability, the solvent evaporation method is preferred for preparing drug sustained-release rods.

[0091] In some embodiments, such as Figure 4 As shown, the drug delivery device also includes a microneedle assembly, which is detachably connected to the ear tag fixing base. The microneedle assembly includes a fixedly connected base and multiple microneedles arranged in an array.

[0092] In some embodiments, such as Figure 5As shown, there are multiple microneedles 6, specifically 10-1500. The dosage can be adjusted by changing the number of microneedles. When a larger dosage is needed, the number of microneedles is increased; when a smaller dosage is needed, the number of microneedles is decreased. The microneedles 6 are arranged in a ring array, rectangular array, or other shaped array on the substrate 5. The microneedle assembly is a modular design that enhances flexibility. It can be pre-loaded and replaced according to treatment needs (such as different drugs or dosages), allowing the same drug delivery device to be adapted to multiple treatment regimens, demonstrating strong scalability.

[0093] The microneedle array is preferably a ring array. The ring design helps to create a uniform drug release zone on the skin of the ear and facilitates tissue fluid circulation, reducing local pressure. The ring array arrangement and precise structural design ensure that all microneedles can penetrate the skin synchronously and evenly when pressure is applied, avoiding drug delivery failure caused by uneven force on a single needle.

[0094] In some embodiments, the material used for microneedles 6 needs to be a polymer with excellent biocompatibility and sufficient mechanical strength, such as polycarbonate, and then the microneedles are prepared by molding or 3D printing. Alternatively, the material used for microneedles 6 can be medical-grade stainless steel (compliant with GB 4234.1-2017), and the microneedles are prepared by precision cutting to ensure that the microneedles 6 can penetrate the stratum corneum of animal skin.

[0095] In some embodiments, the microneedle 6 is a tapered structure that is wider at the bottom and narrower at the top, with a height of 0.3-1.5 mm, to ensure that it can penetrate the stratum corneum of the animal skin and effectively reach the microvascular distribution area of ​​the dermis, ensuring efficient drug absorption while avoiding excessive penetration that could cause discomfort.

[0096] In some embodiments, the bottom diameter of the microneedle 6 is 0.2-0.7 mm to ensure that the needle body has sufficient structural strength and is not easily bent or broken.

[0097] In some embodiments, the microneedle 6 has a needle tip diameter of less than 50 μm, forming a sharp needle tip to ensure a rapid puncture process, minimal trauma, and low animal stress response.

[0098] In some embodiments, the thickness of the substrate 5 of the microneedle assembly is 0.1-1 mm.

[0099] In some embodiments, such as Figure 6 As shown, the microneedle 6 is a solid structure, and the drug coating 7 is disposed on the outer surface of the microneedle 6. In the preparation process, the drug and biocompatible polymer (such as polyvinylpyrrolidone, hydroxypropyl methylcellulose) are dissolved in a suitable solvent to form a coating solution, which is uniformly coated on the surface of the microneedle by micro-spraying or dip coating process. The thickness and uniformity of the drug coating are controlled, and after curing, the microneedle 6 with the drug coating 7 on the surface is obtained.

[0100] In some embodiments, the drug loading of the drug coating is 0.1-50 mg.

[0101] When the drug delivery microneedles 6 puncture the skin tissue, bypassing the outermost keratin barrier, they deliver the drug directly to the vascularized dermis, resulting in high absorption efficiency, significantly improved bioavailability, and rapid attainment of effective concentrations. Microneedle puncture only affects the skin surface, causing far less trauma than traditional subcutaneous implants, greatly reducing pain and stress in animals, thus promoting animal welfare and healthy growth.

[0102] In some embodiments, such as Figure 7 As shown, the drug delivery device also includes a drug-carrying pad, which is detachably connected to the ear tag fixing base. The thickness of the drug-carrying pad 8 is 0.1-3mm, and the bottom diameter of the drug-carrying pad is 10-40mm, which is adapted to the annular groove on the male part 1 and / or the female part 2.

[0103] In some embodiments, the raw materials for preparing the drug-loaded pad include sustained-release matrix materials and active pharmaceutical ingredients; In some embodiments, the sustained-release matrix material includes at least one of polydimethylsiloxane, silica gel, ethylene-vinyl acetate copolymer, and polylactic-co-hydroxyacetic acid copolymer.

[0104] In some embodiments, the sustained-release matrix material is at least one of polydimethylsiloxane and silica gel.

[0105] In some embodiments, the specific type of active drug can be selected according to actual needs. For example, in order to ensure that sows come into estrus and are bred within a predetermined time to achieve batch production, farmers may choose allylprogesterone as the active drug.

[0106] In some embodiments, the drug-loaded pad also includes glycerin to enhance drug delivery efficiency.

[0107] In some embodiments, the drug-loaded pad has a drug loading capacity of 0.1-100 mg.

[0108] In some embodiments, the preparation of drug-loaded pads by solvent evaporation includes the following steps: (1) dissolving the sustained-release matrix material in an appropriate amount of solvent and pouring it onto a glass plate or release film, then scraping it flat with a scraper to obtain a wet film; (2) removing the solvent from the wet film under suitable conditions to obtain a dry film; (3) lightly hot-pressing the film and then precisely cutting it to obtain a pad; (4) dissolving the active drug and a biocompatible polymer (such as polyvinylpyrrolidone, hydroxypropyl methylcellulose) in a suitable solvent to prepare a coating solution, which is then uniformly coated onto the surface of the pad by roller coating, spraying or dipping processes. After curing, the drug-loaded pad is obtained.

[0109] In some embodiments, other suitable carriers may be selected as pads. The active drug and biocompatible polymer (such as polyvinylpyrrolidone, hydroxypropyl methylcellulose) are dissolved in a suitable solvent to prepare a coating solution. The solution is then uniformly coated onto the surface of the pad by roller coating, spraying or dipping. After curing, the drug-loaded pad is obtained.

[0110] In some embodiments, the type and amount of active drug on the drug-release rod may be the same as or different from the type and amount of drug in the microneedle assembly and / or drug-loaded pad. The specific selection and parameters can be combined according to actual needs.

[0111] In some embodiments, such as Figure 8 As shown, an annular groove 12 is provided on the surface of the male component 1 that contacts the skin of the ear. The depth and area of ​​the annular groove 12 are adapted to the thickness and area of ​​the base 5 of the microneedle assembly or the drug-loaded pad 8. The annular groove 12 can stably fit the base 5 or the drug-loaded pad 8, thereby connecting the microneedle assembly or the drug-loaded pad 8 to the female component 2.

[0112] In some embodiments, an annular groove 12 is provided on the surface of the female component 2 that contacts the skin of the ear. The depth and area of ​​the annular groove 12 are adapted to the thickness and area of ​​the base 5 or the drug-loaded pad 8. The annular groove 12 can securely fit the base 5 or the drug-loaded pad 8, thereby connecting the microneedle assembly or the drug-loaded pad 8 to the male component 1.

[0113] The annular groove allows for the secure connection of the microneedle assembly or drug-loaded pad to the ear tag fixing base. Similarly, a clearance hole 51 is provided on the base 5, and the drug-loaded pad 8 is also provided on the base 5. The clearance hole is located at the center of the base 5 or the drug-loaded pad 8, serving two purposes: firstly, to allow the connecting needle 3 to pass; and secondly, to limit the movement of the base 5 or the drug-loaded pad 8, preventing lateral displacement.

[0114] In some embodiments, the fixation between the male component 1 and the female component 2 fixes the microneedle assembly or the drug-loaded pad 8 between the two. Alternatively, adhesives or double-sided tapes can be used to pre-adhere and fix the base 5 of the microneedle assembly or the drug-loaded pad 8 in the annular groove 12.

[0115] In some embodiments, such as Figure 9-10 As shown, a connector 4 can be provided between the male component 1 and the female component 2 to reduce the risk of parts loss. The connector 4 has a certain degree of flexibility and can be bent. When the ear tag fixing base is fixed to the animal's ear, the connecting needle 3 pierces the ear, bends the connector 4, and connects the ends of the female component 2 and the connecting needle 3.

[0116] In some embodiments, such as Figure 8As shown, one end of the connecting pin 3 is connected to the male component 1, which can be either a fixed connection or a detachable connection. For example, a first fixing hole 11 is provided on the side of the male component 1 near the female component 2. The bottom end of the connecting pin 3 can be accommodated in the first fixing hole 11, and the connecting pin 3 and the first fixing hole 11 are interference-fitted, so that the first fixing hole 11 can fix the connecting pin 3. The other end of the connecting pin 3 extends towards the female component 2. A locking member is provided on the female component 2. The female component 2 and the other end of the connecting pin 3 are detachably connected through the locking member. The female component 2 can be installed on the connecting pin 3 or removed from the connecting pin 3.

[0117] In some embodiments, the first fixing hole 11 is a threaded hole, and the bottom end of the connecting needle 3 is provided with an external thread, so that the connecting needle 3 is threadedly connected to the male component 1 through the first fixing hole 11. When disassembling, the connecting needle 3 and the male component 1 can be rotated apart. During the wearing of the device, the rotation between the connecting needle 3 and the male component 1 can be restricted by the connector 4 to prevent it from falling off. When it needs to be removed, the connector 4 can be cut first, and then the connecting needle 3 and the male component 1 can be rotated apart to remove the drug delivery device.

[0118] In some embodiments, the first fixing hole 11 is a threaded blind hole, the bottom end of the connecting pin 3 is provided with an external thread and the bottom is hollowed out, the drug sustained-release rod is placed into the first receiving cavity 31 through the bottom hollow of the connecting pin 3, and then the connecting pin 3 is threadedly connected to the male component 1 through the first fixing hole 11.

[0119] In some embodiments, such as Figure 2 As shown, the female component 2 has a second fixing groove 21 on its side near the male component 1. The other end of the connecting pin 3 can be accommodated in the second fixing groove 21, and the connecting pin 3 and the second fixing groove 21 are interference-fitted, so the second fixing groove 21 can fix the connecting pin 3. During the disassembly of the female component 2, if the female component 2 is made of resin material, the second fixing groove 21 has a certain elasticity, and under the action of external force, the female component 2 can detach from the connecting pin 3.

[0120] In some embodiments, such as Figure 11 As shown, the mother component 2 has a second receiving cavity 22. The locking component includes a metal cup 23, three steel balls 24, and a spring component 25 disposed within the second receiving cavity 22. Three limiting holes 231 are formed on the side wall of the metal cup 23, and the positions of the three limiting holes 231 are adapted to the positions of the steel balls 24. The bottom end of the spring component 25 contacts the top surface of the metal cup 23, and the top end... It contacts the top surface of the second receiving cavity 22 to restrict the movement of the metal cup 23 toward the spring component 25. Specifically, as shown... Figure 11-12As shown, the limiting hole 231, in conjunction with the second receiving cavity 22, restricts the position of the steel balls 24. When the connecting pin 3 is inserted radially, the downward force of the spring component 25 presses against the metal cup 23, causing the three steel balls 24 to lock the connecting pin 3 in place, thus fixing the connecting pin 3 and the female component 2. When it is necessary to remove the female component 2, a strong magnet is placed above it. Under the attraction of the magnet, the metal cup 23 moves the steel balls 24 upward, and the spring component 25 compresses upward. Since the inner diameter of the second receiving cavity 22 gradually increases from bottom to top, as the metal cup 23 moves the steel balls 24 upward, the steel balls 24 gradually release the connecting pin 3, allowing the female component 2 to be removed from the connecting pin 3. For a similar example, refer to the anti-theft magnetic tags used on supermarket clothing.

[0121] In some embodiments, male component 1 and female component 2 are installed and disassembled via a magnetic attraction mechanism. The magnetic attraction mechanism includes permanent magnets respectively disposed on male component 1 and female component 2, with the permanent magnets arranged symmetrically in polarity. The magnetic force of the permanent magnets attracts and locks male component 1 and female component 2. A magnetic cavity is provided inside male component 1 and female component 2, located in the central region of the mating surface of male component 1 and female component 2. High-strength permanent magnets are embedded in the magnetic cavity, arranged symmetrically in polarity. By using the magnetic force of the permanent magnets in the magnetic cavity to attract and lock male component 1 and female component 2, quick installation ("one-click") and quick disassembly ("one-pull") can be achieved, making operation extremely convenient, greatly improving the work efficiency of the farm, and reducing the labor intensity of operators.

[0122] In some embodiments, blind holes are provided on both the male component 1 and the female component 2. The magnet is accommodated within the blind hole and is interference-fitted with the blind hole. A stop is provided at the edge of the blind hole to fix the permanent magnet within the blind hole and prevent the permanent magnet from falling out of the blind hole under strong pulling. Alternatively, an ultrasonic welding process is used to fix the permanent magnet and the blind hole together and prevent the permanent magnet from falling out of the blind hole under strong pulling.

[0123] In some embodiments, an elastic barb is provided at the end 33 of the connecting needle 3 near the mother component 2, and a barb groove is provided at the corresponding position of the mother component 2. When the connecting needle 3 and the mother component 2 are connected, the elastic barb is accommodated in the barb groove. The setting of the elastic barb and the barb groove ensures that the system will not be accidentally opened in extreme cases, thereby improving the stability of the connection between the drug delivery device and the animal's ear.

[0124] The preparation method of the above-mentioned veterinary drug delivery device based on a drug sustained-release stick includes the following steps: S1. Prepare drug sustained-release rods by solvent evaporation or melt extrusion; S2. The drug release rod is housed in the first receiving cavity of the connecting needle, and the connecting needle is fixedly installed on the male component; S3. Inspect, sterilize, and package all components.

[0125] In some embodiments, the testing includes: conducting a full inspection of the ear tag fixing base and the connecting pin equipped with the drug release rod, including inspection of appearance, key dimensions, total weight, magnetic attraction and drug loading, and excluding non-conforming products.

[0126] In some embodiments, sterilization includes sterilization using an ethylene oxide sterilization method to ensure a sterility assurance level (SAL) of 10. -6 Furthermore, there were no significant changes in drug content and related substances.

[0127] In some embodiments, the packaging includes: immediately encapsulating the sterilized qualified product in a barrier-resistant individual blister pack (aluminum foil blister pack) and filling it with nitrogen for protection.

[0128] The above-mentioned veterinary drug delivery device based on a drug sustained-release stick is used in animal drug administration. In use, the device is clipped to the animal's ear for precise drug delivery. For example, to ensure sows come into estrus and mate within a predetermined timeframe, farmers can use a veterinary drug delivery device containing acetaminophen to clip onto the sow's ear for long-term continuous drug administration, which can be stopped at any time as needed, thus enabling batch production of sows.

[0129] When the scheduled dosing cycle is completed or dosing needs to be stopped early, the operator can simply separate the male and female parts by hand or with the help of simple, non-specialized tools, and remove the entire drug delivery system from the pig's ear. The drug release source is physically removed, and the dosing process is immediately stopped.

[0130] To better understand, this application uses the promotion of batch production in sows as an example. The selected drug is allengestrol, also known as tetraethrin, a synthetically produced oral active progestin that directly inhibits the development, maturation, and ovulation of follicles in the ovary, thus maintaining the sow's physiological state stably in the anestrus period. Once the device is removed, the blood drug concentration drops rapidly, its inhibitory effect on the pituitary gland is relieved, and gonadotropin release resumes in pulses, thereby simultaneously initiating follicle development and estrus behavior in the entire herd of sows, achieving precise batch production management. The specific design and verification details are as follows: I. The core objective of the pharmacokinetic design in this case is to maintain the blood concentration of endoprogesterone in sows above the minimum effective concentration (MEC = 2 ng / mL) for its estrus-inhibiting effect during a dosing period of up to 18 days.

[0131] II. Design and Calculation of Key Pharmacokinetic Parameters: ① Target steady-state concentration (Css): set to >2 ng / mL, with a certain safety margin.

[0132] ② Clearance rate of endoprogesterone in pigs (CL): Based on existing literature data and preliminary experimental results, the conservative estimate for a 135kg pig is 162 L / day.

[0133] ③ Calculation of the required release rate (R): According to the steady-state dosing formula, R = CL × Css / F. Where F is bioavailability. Benefiting from transdermal delivery bypassing the first-pass effect of the liver, the F value is estimated to be significantly higher than that for oral administration, and is set at 70%. Substituting into the calculation: R = (162 L / day) × (2 ng / mL) / 0.7 ≈ 463 μg / day. This is the ideal daily release required to maintain the target concentration.

[0134] ④ Determination of total required dosage: To achieve effective treatment for 18 days, the theoretical minimum required dosage = 162 μg / day × 18 days = 8.33 mg.

[0135] III. Based on the above requirements, the drug delivery device design for this case is as follows: Cylindrical drug-release rods with a diameter of 2 mm and a length of 5 mm are prepared using silicone and allylprogesterone as raw materials via melt extrusion. Each drug-release rod contains approximately 50 mg of allylprogesterone. The microneedle assembly has 50 microneedles with a height of 0.6 mm, a bottom diameter of 0.3 mm, and a tip diameter of 20 μm. The drug coating contains 2 mg of allylprogesterone.

[0136] IV. The method of using the drug delivery device is as follows: Use the connecting needle of the drug delivery device to pierce the ear of a 135kg female pig, move the male part to the side that is close to the pig's ear, align the female part with the male part, lock them together, and apply stable pressure to make the microneedle assembly perpendicular and in close contact with the ear skin, ensuring that all microneedles are simultaneously inserted into the pig's ear skin to the predetermined depth, and the use is complete.

[0137] V. Blood drug concentration test: Blood samples are taken at fixed times every day to measure blood drug concentration and plot drug concentration curves.

[0138] When the above-mentioned drug delivery device was applied to 135kg sows in estrus, it significantly inhibited estrus within 24 hours (specifically manifested as the absence of typical estrus symptoms in sows: vulvar redness and swelling, mucus discharge, and standing reflex). This is because the microneedles effectively increased the blood concentration of acetaminophen in the animals within a short period, thereby rapidly stopping estrus. During the drug delivery period, blood samples were taken at fixed times daily to measure the blood drug concentration; the drug concentration curve is shown in the appendix. Figure 13 As shown, the minimum effective concentration (MEC) of endoprogesterone sustained release over 18 days is >2 ng / mL, and the cumulative absorption of endoprogesterone is >8.33 mg, which can meet the dosage requirements of sows. At the same time, the release curve is relatively flat and the release is continuous, which meets the requirements for sustained efficacy in the body.

[0139] When production plans are adjusted or drug administration is terminated, the operator can simply use their bare hands or simple tools to apply a pulling force sufficient to overcome the magnetic force or locking mechanism to separate the male and female parts, physically remove the drug release source, and then remove the drug administration device from the pig's ear, thus immediately stopping the drug administration process.

[0140] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0141] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A medicated wick based veterinary dosing device, characterized in that, include: An ear tag fixing base, comprising a male component (1), a female component (2), and a connecting pin (3) for connecting the male component (1) and the female component (2), wherein the connecting pin (3) has a first receiving cavity (31) axially arranged inside, and a slow-release port (32) is provided on the side wall of the connecting pin (3); and A drug release stick is disposed in the first receiving cavity (31) and includes a sustained-release matrix material and an active drug.

2. The medicated, slow-release rod-based, veterinary dosing device of claim 1, wherein, The sustained-release matrix material includes at least one of polydimethylsiloxane, silica gel, ethylene-vinyl acetate copolymer, and polylactic acid-hydroxyacetic acid copolymer.

3. The veterinary drug delivery device based on a drug sustained-release rod according to claim 1, characterized in that, The cross-section of the drug sustained-release stick is at least one of the following: circular, elliptical, rectangular, polygonal, or irregular shape; the drug loading capacity of the drug sustained-release stick is 0.1-200 mg.

4. The veterinary drug delivery device based on a drug sustained-release rod according to claim 1, characterized in that, The drug delivery device also includes a microneedle assembly or a drug-loaded pad (8), which is detachably connected to the ear tag fixing base.

5. The veterinary drug delivery device based on a drug sustained-release rod according to claim 4, characterized in that, The microneedle assembly includes a fixedly connected substrate (5) and a plurality of microneedles (6), and a drug coating (7) disposed on the outer surface of the microneedles (6), wherein the plurality of microneedles (6) are arranged in an array.

6. The veterinary drug delivery device based on a drug sustained-release rod according to claim 5, characterized in that, The number of microneedles (6) on the microneedle assembly is 10-1500; The microneedle (6) has a tapered structure that is wider at the bottom and narrower at the top. The height of the microneedle (6) is 0.3-1.5 mm. The thickness of the base (5) of the microneedle assembly is 0.1-1 mm. The bottom diameter of the microneedle (6) is 0.2-0.7 mm. The tip diameter of the microneedle (6) is less than 50 μm. The drug coating (7) has a drug loading of 0.1-50 mg.

7. The veterinary drug delivery device based on a drug sustained-release rod according to claim 4, characterized in that, The thickness of the drug-loaded pad (8) is 0.1-3 mm, and the bottom diameter of the drug-loaded pad (8) is 10-40 mm; the drug loading of the drug-loaded pad (8) is 0.1-100 mg.

8. The veterinary drug delivery device based on a drug sustained-release rod according to claim 5, characterized in that, The male component (1) and / or female component (2) have an annular groove (12) on the surface that contacts the skin of the ear. The depth and area of ​​the annular groove (12) are adapted to the thickness and area of ​​the base (5) or the drug-loaded pad (8) so that the base (5) or the drug-loaded pad (8) can be fitted into the annular groove (12).

9. The veterinary drug delivery device based on a drug sustained-release rod according to claim 1, characterized in that, The male component (1) is provided with a first fixing hole (11). One end of the connecting pin (3) is connected to the male component (1) through the first fixing hole (11), and the other end is connected to the female component (2).

10. The use of the veterinary drug delivery device based on a drug sustained-release stick according to any one of claims 1-9 in animal drug delivery.

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