Method and device for buffering anaesthetic agents

Abstract

A device for compounding two solutions contained within multiple cartridges, one of which serves as a mixing container, is disclosed. The device can be used by physicians to buffer anesthetics prior to use, including, but not limited to, by dentists to buffer local anesthetics prior to use. In various embodiments, a buffer solution container can be incorporated into the device, which maintains the buffer solution in a stable state. The device can be used to buffer anesthetics within one or more cartridges, and when the buffer solution within the device is depleted, the device can be reloaded or discarded.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application No. 63 / 410,524, filed September 27, 2022, which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION The field of the invention is medical devices, in particular medical devices for buffering anesthetic agents. [Background technology]

[0003] Background of the Invention Local anesthetics such as lidocaine are commonly used in dentistry, usually in combination with epinephrine in an aqueous solution, to numb a patient's tissues before performing various procedures such as filling a tooth, placing a crown, or endodontic therapy, among others.

[0004] When unbuffered, aqueous solutions containing lidocaine and epinephrine typically have a pH of about 3.5. At that pH, anesthetics typically produce a burning and tingling sensation in patients. At pH 3.5, the amount of lipid-soluble anesthetic molecules (base or "active" form) that can cross nerve membranes is about 1 in 25,000 molecules, which is too low to produce nerve anesthesia. At neutral pH, the proportion of the active form is 4 times higher, or about 6,000 times higher, which is sufficient to produce anesthesia, taking into account the considerations described in the following paragraphs.

[0005] It can take as long as 45 minutes of the patient's buffering capacity to raise the pH of the injected anesthetic solution to the point where there is enough active anesthetic available to cross the nerve membrane and produce analgesia. Furthermore, some patients may not have the buffering capacity to raise the pH to the point where analgesia is achieved.

[0006] Buffering anesthetics to a neutral pH with bicarbonate solution before injection not only immediately increases the concentration of active anesthetic molecules in solution, but also provides additional anesthetic properties from dissolved CO2. Also, after entering the nerve, the base form of the anesthetic must be converted back to its acidic form to block the nerve receptor sites. High levels of CO2 inside the nerve create an acidic environment, and therefore the base form of the anesthetic is converted to its acidic form after successfully crossing the nerve membrane. Blocking receptor sites within the nerve reduces the nerve's ability to transmit pain signals.

[0007] Aqueous solutions containing bicarbonate ions are used in a variety of medical applications, including, but not limited to, antidotes, dialysis solutions, artificial cerebrospinal fluid, intraocular irrigation solutions, cardiac perfusion solutions, cardioplegia solutions, peritoneal irrigation solutions, and solutions for organ preservation. Of particular interest in this application, bicarbonate solutions are used to buffer dental and other anesthetics to control pH. One of the most commonly used medical bicarbonate solutions consists of sodium bicarbonate (NaHCO) mixed with water (H2O). In medical bicarbonate solutions, the bicarbonate ion is represented by the following formula: It is in equilibrium as represented in TIFF2025532435000002.tif4128.

[0008] When a reaction occurs in a closed system, the amounts of reactants remain constant and reach equilibrium. However, in an open system, carbon dioxide gas escapes and the reaction proceeds from left to right, with bicarbonate (2HCO3) releasing carbon dioxide gas (CO2), carbonate (CO3), and water (HO), gradually decreasing the concentration of bicarbonate ions and increasing the concentration of carbonate ions. Because carbonate ions are more alkaline than bicarbonate ions, the pH of the solution gradually increases as CO2 is released from solution.

[0009] The clinical effectiveness of medical bicarbonate solutions often depends on maintaining a specific pH range (typically 7-9). For some applications, maintaining the pH within a narrower range is beneficial. To stabilize the pH and CO2 content, sodium bicarbonate solutions are traditionally packaged in airtight containers that limit the release of CO2 from the solution to the atmosphere. By limiting the loss of released CO2, pH changes can be reduced. As CO2 leaves the solution and enters the "headspace" of the container (the gas-filled region above the solution), the partial pressure of the released CO2 increases, eventually establishing equilibrium between the CO2 leaving the solution and the CO2 returning to the solution.

[0010] The most commonly used airtight container for storing medical bicarbonate solution is a glass vial with a pierceable rubber cap, called a septum. Such vials allow the physician to puncture the septum with a hypodermic needle and withdraw, or "draw up," the desired amount of bicarbonate solution into a syringe. To facilitate bicarbonate withdrawal, the vial typically contains a significant headspace, which allows gas within the headspace to expand to compensate for the withdrawn fluid and prevents a vacuum lock from forming when the practitioner attempts to draw up the fluid. Once the bicarbonate solution is drawn up into a syringe, the syringe can be used to deliver the fluid to another container, catheter, or blood vessel. A partially filled syringe can be used to draw up a second solution, including but not limited to a local anesthetic, from another vial to mix with the sodium bicarbonate, with the syringe serving as a mixing and delivery vessel for the resulting pH-buffered local anesthetic solution. One drawback of using such a vial and syringe system to store, mix, and / or deliver bicarbonate solution is that as the solution is drawn from the vial into the syringe, the partial pressure of CO2 in the syringe decreases, causing CO2 to leave solution and generate CO2 bubbles in the solution during transfer. Additionally, the solution can be significantly agitated as the bubbles enter the syringe, further dissipating CO2 from solution. Similarly, as the solution is drawn from the vial, the partial pressure of CO2 in the vial's headspace decreases, causing CO2 to leave solution and enter the headspace, reestablishing equilibrium between the partial pressure of CO2 in the solution and the partial pressure of CO2 in the headspace. Thus, as each dose of bicarbonate is withdrawn from the vial, CO2 leaves solution and enters the headspace, increasing the pH of the bicarbonate solution remaining in the vial. For these reasons, even if the pH of the sodium bicarbonate buffer in the vial storage container is estimated or confirmed prior to delivery, the drawing, mixing, and / or delivery of the bicarbonate system may undesirably alter the pH of the solution.

[0011] One particular device for mixing a buffer solution, including but not limited to sodium bicarbonate, with an anesthetic, including but not limited to a dental anesthetic, in a conventional cartridge is described in U.S. Patent No. 5,603,695. The device includes a buffer solution cartridge with a needle capable of piercing a septum in the anesthetic cartridge. The buffer solution is stored in a cartridge with sufficient headspace and no provision for maintaining volatile CO2 in solution with the bicarbonate anesthetic. Furthermore, no provision is made for displacing the anesthetic from the anesthetic cartridge once the buffer solution is introduced.

[0012] For these reasons, it would be desirable to provide an improved method and apparatus for mixing buffers with anesthetics or other medical solutions, particularly when the buffers are held in conventional glass cartridges. The present method and apparatus would be particularly beneficial when using buffer cartridges that maintain the buffer, particularly the sodium bicarbonate solution, in a stable state with minimal pH change and carbon dioxide loss prior to use. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] U.S. Patent No. 5,603,695 Summary of the Invention

[0014] Some embodiments of the present disclosure relate to an apparatus, comprising: a buffer cartridge containing a buffer solution, the buffer cartridge including a first septum and a plunger; a buffer compartment configured to receive may include:

[0015] This device is an anesthetic cartridge containing an anesthetic agent and including a second septum; an anesthetic compartment configured to receive may include:

[0016] The device may also include an overflow compartment. In some embodiments, the overflow compartment comprises: an absorbent member configured to absorb at least a portion of the fluid released from the anesthetic cartridge; Additionally or alternatively, the overflow compartment may include: a plurality of granules configured to absorb fluids, including but not limited to fluids that are not absorbed or retained by the absorbent member when the absorbent member is present; may include:

[0017] In some embodiments, the buffer compartment may be proximal to a first end of the device, the anesthetic compartment may be proximal to a second end of the device, and the overflow compartment may be positioned between the buffer compartment and the anesthetic compartment.

[0018] The device also a needle assembly including a transfer needle having a first end and a second end, and a discharge needle having a first end and a second end; a compressible member configured to compress upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein compression of the compressible member causes a first end of the transfer needle to pierce the first septum, a second end of the transfer needle to pierce the second septum, and a second end of the drainage needle to pierce the second septum, wherein the first end of the drainage needle resides in the overflow compartment; and In some embodiments, the first end of the discharge needle enters the overflow compartment. In some embodiments, the first end of the discharge needle is already present in the overflow compartment. In some embodiments, the second end of the transfer needle extends further into the anesthetic cartridge than the second end of the discharge needle. In some embodiments, the anesthetic compartment can include at least one retention member configured to retain the anesthetic cartridge after receiving it, such that the compressible member remains compressed until the anesthetic cartridge is removed from the anesthetic compartment. In some embodiments, when the anesthetic cartridge is removed from the anesthetic compartment and the compressible member is no longer compressed by the anesthetic cartridge, the first end of the transfer needle is withdrawn from the first septum, the second end of the transfer needle is withdrawn from the second septum, and the second end of the discharge needle is withdrawn from the second septum. In some embodiments, when the anesthetic cartridge is removed from the anesthetic compartment, the first end of the discharge needle is also withdrawn from the overflow compartment. In one embodiment, the first end of the discharge needle remains in the overflow compartment. In one embodiment, the first end of the discharge needle always resides in the overflow compartment. In one embodiment, the transfer needle is offset to ensure effective dispensing. In one embodiment, the second end of the transfer needle extends further into the interior volume of the anesthetic cartridge than the second end of the discharge needle.

[0019] The device also an advancement member configured to engage a plunger in the buffer cartridge such that, upon receipt of the anesthetic cartridge by the anesthetic compartment, advancement of the advancement member expels buffer fluid from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; For example, the advancement member may include a dial, rotation of which advances the plunger. Alternatively or additionally, the advancement member may include: A ratchet and pawl mechanism configured to ensure that the dial can only be rotated in one direction The device may include a ratchet and pawl mechanism that releases a predetermined dose of buffer solution upon rotation or partial rotation of the dial. Alternatively or additionally, the ratchet and pawl mechanism may be configured such that the ratchet and pawl mechanism are engaged and function to release a dose of buffer solution only when an anesthetic cartridge is inserted into the anesthetic compartment. Alternatively or additionally, the advancement member may include a plurality of detent notches, e.g., toothed notches. Additionally or additionally, the device may include a clutch that will slip when the advancement member is engaged when no anesthetic cartridge is present in the anesthetic compartment or when the transfer needle is not engaged with a buffer cartridge. This can reduce or prevent excessive pressure that could damage one or more components of the device. Furthermore, the clutch, or slip clutch, may frictionally lock the distal portion of the screw with the external knob, allowing the buffer solution to be released from the device. Furthermore, the detent notch is configured to allow the user to rotate the dial in only one direction. The device may include an arrow or other symbol indicating to the user the direction in which the external knob should be rotated to operate the device.

[0020] Additionally or additionally, the ratchet or clutch mechanism may be configured to provide a tactile or audible indicator when the dial has been rotated from its start position to its end position for a single operation of the device.

[0021] In some embodiments, the device can be used to operate with multiple instances of the buffered anesthetic cartridge, with each instance further depleting the buffer cartridge. In some or additional embodiments, the device can include an indicator of the remaining number of instances available before the buffer cartridge is depleted. In one embodiment, the device includes a window through which the user can view the advancement member and determine, by an indicator on the device, whether additional doses remain or whether the device has delivered the last dose.

[0022] In some embodiments, the device can be cylindrical.

[0023] Some embodiments of the present disclosure relate to a method, the method comprising: Providing an apparatus; a buffer cartridge including a first septum, a plunger, and containing a buffer; and an anesthetic cartridge containing an anesthetic agent and including a second septum; and providing a needle assembly including a transfer needle having a first end and a second end and a discharge needle having a first end and a second end; attaching an anesthetic cartridge to the device; compressing the compressible member, wherein a first end of the transfer needle penetrates the first septum, a second end of the transfer needle penetrates the second septum, and a second end of the discharge needle penetrates the second septum, wherein the discharge needle resides within the overflow compartment; In some embodiments, the first end of the discharge needle enters the overflow compartment. In some embodiments, the first end of the discharge needle is already in the overflow compartment.

[0024] The method comprises: advancing the plunger, thereby expelling buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; In some embodiments, the transfer needle extends further into the anesthetic cartridge than the evacuation needle so that when the buffer solution is released into the anesthetic cartridge, the fluid simultaneously released through the evacuation needle consists mostly of local anesthetic.

[0025] In some embodiments, advancing the plunger can include rotating a dial. In some further embodiments, rotating the dial can engage a ratchet and pawl mechanism, and releasing the buffer can include releasing a predetermined dose of buffer upon engagement of the ratchet and pawl mechanism. In further embodiments, a mechanism disposed relative to the plunger during assembly of the device prevents the plunger from moving outward within the buffer cartridge, thereby preventing gas from escaping from solution in the buffer cartridge and creating a headspace within the buffer cartridge. In another embodiment, a mechanism disposed relative to the plunger generates pressure within the buffer cartridge, which also prevents gas from escaping from solution and creating a headspace within the buffer cartridge. In further embodiments, a slip clutch mechanism can be provided to hold the plunger in place and / or facilitate pressurization of the buffer during assembly of the device.

[0026] The method may further include absorbing at least a portion of the fluid released into the overflow compartment with an absorbent member, and / or absorbing fluid not absorbed or retained by the absorbent member with a plurality of granules.

[0027] Alternatively, or in addition, the method may further include holding the anesthetic cartridge in a position to maintain compression of the compressible member.

[0028] In some embodiments, the method can further include withdrawing the anesthetic cartridge from the device. In one embodiment, the method can further include detaching the transfer needle from the buffer cartridge when the anesthetic cartridge is disconnected from the device. In one embodiment, the transfer needle is offset to ensure effective dispensing. In still further embodiments, the method can further include providing a second or additional instance of the anesthetic cartridge and repeating the above-described mounting, compressing, advancing, transferring, and detaching with the second or additional instance of the anesthetic cartridge. For example, the buffer cartridge, the needle assembly, the compressible member, and an advancing member configured to advance the plunger can be positioned within the housing, and the method can further include discarding the device when the buffer cartridge is substantially emptied of buffer. In one embodiment, the anesthetic cartridge is locked into place upon correct insertion. In one embodiment, correct insertion is accompanied by an audible click. In one embodiment, the anesthetic cartridge is inserted by placing the anesthetic cartridge into the device and applying light pressure until the anesthetic cartridge is locked into place.

[0029] Some embodiments of the present disclosure relate to a second method. The second method may include providing a device, including but not limited to the devices summarized above, and inserting a buffer cartridge into the buffer compartment. The second method may further include packaging the device after inserting the buffer cartridge in combination with instructions for practicing the method summarized above. In some embodiments, the instructions may further include instructions for inserting and withdrawing the anesthetic cartridge from the device. In some still further embodiments, the instructions may further include instructions for providing a second or additional instance of the anesthetic cartridge and instructions for repeating the compression and advancement with the second or additional instance of the anesthetic cartridge.

[0030] The devices and methods disclosed herein can provide buffer solutions, including but not limited to sodium bicarbonate solutions, in a stable state with minimal pH change and minimal carbon dioxide loss prior to use. They can also provide for the introduction and combination of a buffer solution with an anesthetic solution and the withdrawal or expulsion of an equal amount of anesthetic from the cartridge without delivering excessive amounts of buffer to the anesthetic cartridge when the anesthetic solution is held in a conventional cartridge. The devices can also be provided to practitioners, including but not limited to dentists, in a ready-to-use form. The devices and methods can also provide for combining a buffer solution with a local anesthetic formulated as a hypotonic solution, such that the addition of a hypertonic buffer solution results in the buffered anesthetic reaching an isotonicity or an osmolality approximating that of the human body. In one embodiment, the buffer solution is hypertonic and the anesthetic is hypotonic, so that when the buffer and anesthetic are combined, the combination has the intended target osmolality. In one embodiment, the target osmolality is between 200 mOsm / L and 416 mOsm / L. In one embodiment, the target osmolality is 308 mOsm / L, substantially isotonic.

[0031] In one embodiment, the method includes compounding the agent.

[0032] Incorporation by Reference All publications, patents, and patent applications mentioned in this specification, including but not limited to U.S. Pat. Nos. 8,162,917, 8,690,853, and 8,303,566, are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. [Brief explanation of the drawings]

[0033] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and that is accompanied by the following drawings.

[0034] [Figure 1] 1 shows an external perspective view of the device. [Figure 2] 1 shows a cutaway perspective view of the device. [Figure 3] The cross-sectional views of a portion of the device are shown "near-sighted" and "far-sighted" in that they illustrate portions of some elements that are behind or in front of the cross-section and would not be visible in a strict cross-sectional view. [Figure 4A] FIG. 1 shows a cutaway perspective view of a portion of the device during the first stage of use before the anaesthetic cartridge is connected. [Figure 4B] 1 shows a cutaway perspective view of a portion of the device in a second stage of use when the anaesthetic cartridge is connected and fully seated within the anaesthetic compartment. [Figure 4C] 1 shows a cutaway perspective view of a portion of the device including a retention member. [Figure 5A] 1 shows a perspective view of a portion of the device in a first stage of a second use. [Figure 5B] 1 shows a perspective view of a portion of the device in a second stage of a second use. [Figure 6] 1 shows a cutaway perspective view of a portion of the device. [Figure 7] 1 shows a cutaway perspective view of a portion of the device. [Figure 8] 1 shows a longitudinal cross-sectional view of the distal portion of the device. [Figure 9] 9 shows a cross section perpendicular to the longitudinal cross section shown in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0035] Detailed Description of the Invention Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0036] The present invention provides a method and apparatus for buffering anesthetic or other medical solutions. The apparatus is particularly useful for dispensing anesthetics and other therapeutic agents. Previously, anesthetic or other medical solutions could be buffered by being held in conventional cartridges, particularly cartridges having a pierceable septum and a slidable plunger or plug, including, but not limited to, those generally described in U.S. Pat. No. 5,603,695, the full disclosure of which is incorporated herein by reference. Such cartridges are commonly used in dental practice, where a disposable cartridge containing, in particular, a local anesthetic is loaded into a reusable syringe to which a disposable needle is attached, and the assembly is then used to deliver the local anesthetic to a patient's tissue to produce analgesia prior to a dental procedure. Such disposable anesthetic cartridges were traditionally loaded into a reusable stainless steel dental syringe or other delivery device, which engaged the cartridge plunger to administer the anesthetic through the disposable needle attached to the syringe, one end of which penetrated the anesthetic cartridge through the septum when the cartridge was loaded into the dental syringe. In this manner, the cartridge can be loaded into a syringe, which is then used to deliver the local anesthetic via injection. The cartridge and disposable needle can be removed from the syringe and discarded, leaving the syringe available to be reloaded and reused for that procedure, or sterilized and used for a subsequent procedure.

[0037] To optimize anesthetic effectiveness and reduce injection pain, it is desirable to buffer conventional anesthetics toward physiological pH immediately before use. Dental anesthetics, including but not limited to lidocaine, articaine, prilocaine, or mepivacaine, are typically formulated and stored in an acidic form to enhance shelf life. To ensure consistent and reliable use of sodium bicarbonate solutions or other buffered solutions, it is crucial that the buffered anesthetic consistently and reliably buffers the local anesthetic to physiological pH, ensuring optimal efficacy and minimal injection pain. The buffer itself has a predictable and stable pH and chemical composition.

[0038] Containers that hold solutions under pressure or that do not readily allow for headspace prevent CO2 from leaving solution, thereby preventing pH changes. In applications where minimal or no change in pH is desired for solutions used as buffers, it is desirable to prevent CO2 from leaving solution each time the solution is served as a buffer.

[0039] It would be desirable to provide an improved method and apparatus for mixing a buffer solution with an anesthetic or other medical solution, particularly when the buffer solution is held in a conventional glass cartridge. The method and apparatus would be particularly beneficial when using a buffer cartridge that maintains the buffer solution, particularly a sodium bicarbonate solution, in a stable state with minimal pH change and carbon dioxide loss prior to use. It would also be desirable if the method and system provided for introducing and combining a buffer solution with an anesthetic solution and withdrawing or draining an equal amount of anesthetic from the cartridge, without delivering an excessive amount of buffer solution to the anesthetic cartridge, when the anesthetic solution is held in a conventional cartridge. It would also be desirable if the system could be provided to practitioners, including, but not limited to, dental professionals, in a ready-to-use form.

[0040] In an embodiment, the present disclosure relates to an apparatus, the apparatus comprising: a buffer cartridge containing a buffer solution, the buffer cartridge including a first septum and a plunger; a buffer compartment configured to receive an anesthetic cartridge containing an anesthetic agent and including a second septum; an anesthetic compartment configured to receive an anesthetic agent; an overflow compartment; a needle assembly including a transfer needle having a first end and a second end, and a discharge needle having a first end and a second end; a compressible member configured to compress upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein compression of the compressible member causes a first end of the transfer needle to pierce the first septum, a second end of the transfer needle to pierce the second septum, and a second end of the drainage needle to pierce the second septum, wherein the first end of the drainage needle resides within the overflow compartment; an advancement member configured to engage the plunger upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein advancement of the advancement member expels buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; In some embodiments, the first end of the discharge needle enters the overflow compartment. In some embodiments, the first end of the discharge needle is already in the overflow compartment.

[0041] FIG. 1 shows a perspective view of an exemplary device 100. Device 100 includes a housing 110. The housing has a first end 110a and a second end 110b. Housing 110 can be made of plastic, metal, other materials, or any combination thereof. Desirably, housing 110 can be made from a material(s) that can be easily sterilized.

[0042] In embodiments in which the second end 110b is open, including but not limited to, the one shown in Figure 1, the housing 110 may include a stiffening band 111 positioned around the opening in the second end 110b. The stiffening band 111 may include a metal.

[0043] In the embodiment shown in FIG. 1 , the housing 110 includes a window 112. In one embodiment, the window 112 can be free of any material. In other embodiments, the window 112 can be made from any transparent material, including, but not limited to, glass or clear plastic, or can be glass-free, keeping in mind that it is desirable that any material(s) of the window 112, and the device 100 as a whole, be easily sterilizable. The window 112 can allow a user of the device 100 to visually observe the contents of the buffer compartment 120. However, in other embodiments (not shown), the window 112 can reveal only a portion of the contents of the buffer compartment, can be omitted, or can be replaced with a mechanical, electrical, electromechanical, or electronic device configured to report information regarding the contents of the buffer compartment 120 to the user of the device 100.

[0044] The embodiment shown in FIG. 1 also includes a dial 172 and a retaining member 180, which are described in more detail below.

[0045] 2 shows a cutaway perspective view of device 100. Housing 110 includes three compartments 120, 130, and 140: buffer compartment 120, anesthetic compartment 130, and overflow compartment 140. In the illustrated embodiment, buffer compartment 120 is proximal to dial 172, anesthetic compartment 130 is distal to dial 172, and overflow compartment 140 is intermediate buffer compartment 120 and anesthetic compartment 130. However, in other embodiments (not shown), compartments 120, 130, and 140 can be positioned in other arrangements relative to one another.

[0046] These figures depict the housing 110 as essentially cylindrical. Furthermore, the compartments 120, 140, and 130 are shown as continuous and collinear from the first end 110a to the second end 110b. While a cylindrical shape is a convenient shape and a continuous and collinear arrangement of the compartments is a convenient configuration, in other embodiments (not shown), the housing 110 can have any three-dimensional shape, including, but not limited to, a cylinder, a rectangular parallelepiped, a cube, a square pyramid, a regular square pyramid, a triangular pyramid, a sphere, or another shape. Alternatively, or in addition, the arrangement of the compartments 120, 130, and 140 need not be continuous and / or collinear, but can be selected to be parallel, partially parallel, partially non-collinear, non-collinear, or have any other configuration.

[0047] The buffer compartment 120 is configured to receive a buffer cartridge 220 that includes a first septum 222 that seals one end of the buffer cartridge 220 and a plunger 224 that slidably seals the other end of the buffer cartridge 220, and contains a buffer within an internal volume 226 of the buffer cartridge.

[0048] The buffer cartridge can be of any desired size. For example, the buffer cartridge can have an internal volume 226 of 3 mL or 1.7 mL, among other volumes.

[0049] The walls of the buffer cartridge 220 can be formed from any suitable material, including but not limited to glass or plastic. The first septum 222 can be formed from rubber or any other suitable material. The plunger 224 can be formed from any suitable material, including but not limited to rubber.

[0050] Typically, the buffer solution is a bicarbonate buffer, although the disclosure is not so limited. In an embodiment, the buffer cartridge 220 is filled with a bicarbonate buffer solution that releases carbon dioxide at room temperature and pressure. Carbon dioxide release is inhibited by storing the buffer cartridge 220 in a configuration that prevents the plunger from displacing outward when carbon dioxide is released from the solution. One method can be to apply a force to the plunger 224, sufficient to pressurize the bicarbonate buffer solution to a pressure that inhibits carbon dioxide release, thus stabilizing the pH and composition of the buffer solution. In an exemplary embodiment, the buffer solution contains sodium bicarbonate having a pH in the range of 7.5 to 7.8, and the applied pressure is greater than 1.2 atmospheres. In a further exemplary embodiment, the force is applied by using a spring, impeller, or other compression member against the plunger to load the buffer cartridge 220 into the buffer compartment 120 and maintain the pressure until the buffer cartridge 220 is used. In one embodiment, the impeller 178 is in contact with the plunger 224. Preferably, the buffer cartridge 220 is filled with all evacuated gases (headspace eliminated) to further stabilize the pH and carbonate content of the solution.

[0051] In embodiments, the buffer is sodium bicarbonate, including but not limited to about 8.4% sodium bicarbonate in water. Buffers that can increase the pH of the anesthetic to about 7.4 can be utilized.

[0052] In the illustrated embodiment, device 100 can be configured such that buffer cartridge 220 is disposed within buffer compartment 120 during manufacturing, and subsequent manufacturing steps render buffer cartridge 220 substantially unremovable by human hands. However, in other embodiments (not shown), device 100 can be configured such that buffer cartridge 220 can be disposed within buffer compartment 120 after manufacturing and / or can be user removable.

[0053] The anesthetic compartment 130 includes a second septum 232 and is configured to receive the anesthetic cartridge 230, which contains an anesthetic agent within an internal volume 236 of the anesthetic cartridge 230. In the illustrated embodiment, the anesthetic compartment 130 is open at the second end 110b of the housing 110, and the anesthetic compartment 130 is configured to receive the anesthetic cartridge 230 by inserting the anesthetic cartridge 230 into the open second end 110b. In one embodiment, the anesthetic cartridge 230 locks into place upon correct insertion. In one embodiment, correct insertion is accompanied by an audible indication, such as a click. In one embodiment, the anesthetic cartridge 230 is inserted by placing the anesthetic cartridge 230 into the device through the open second end 110b and applying gentle pressure until the anesthetic cartridge 230 locks into place. In other embodiments (not shown), the device 100 may be configured to allow the anesthetic cartridge 230 to be inserted into the anesthetic compartment 130 from the side of the device 100, including, by way of example only and not limitation, through a door that can be reversibly flipped, slid, or otherwise moved between an open configuration and a closed configuration.

[0054] The anesthetic cartridge 230 can have many features in common with the buffer cartridge 220. For example, the anesthetic cartridge 230 can have any desired size. Also, for example, the anesthetic cartridge 230 can have an internal volume 236 of 1.8 mL or more, among other volumes. In another example, the walls of the anesthetic cartridge 230 can be formed from any suitable material, including, but not limited to, glass or plastic. The second septum 232 can be formed from rubber or any other suitable material. The anesthetic cartridge 230 also includes a plunger 237, which can be formed from any suitable material, including, but not limited to, rubber.

[0055] The anesthetic cartridge 230 can contain an anesthetic formulation, typically a solution containing about 2% to about 4% of the desired anesthetic. In embodiments, the anesthetic formulation can be about 2% lidocaine, 1:100,000 epinephrine; about 2% lidocaine, 1:50,000 epinephrine; about 2% articaine, 1:100,000 epinephrine; about 2% articaine, 1:200,000 epinephrine; about 2% mepivacaine; about 4% prilocaine; or about 2% prilocaine, 1:200,000 epinephrine. In various embodiments, the anesthetic can be formulated as a hypotonic solution so that the addition of a hypertonic buffer results in the desired osmolality, which can be isotonic, or close to or equal to the osmolality of the human body. In one embodiment, the buffer is hyperosmolar and the anesthetic is hypoosmolar so that when the buffer and anesthetic are combined, the combination has an intended target osmolality. In one embodiment, the target osmolality is between 200 mOsm / L and 416 mOsm / L. In one embodiment, the target osmolality is 308 mOsm / L, which is substantially isotonic.

[0056] In a further embodiment of the invention, the local anesthetic cartridge will contain an anesthetic formulated as a hypotonic solution (when compared to the osmolality of human blood or tissue), such that when a hypertonic buffer, such as sodium bicarbonate, is combined with a hypotonic local anesthetic solution, the combined solution will be closer to isotonic, and a greater degree of pH buffering will be possible with the more readily tolerated buffer solution.

[0057] The overflow compartment 140 is configured to receive anesthetic agent released from the anesthetic agent cartridge 230 during operation of the device 100. Desirably, the overflow compartment 140 has a volume at least as large as the interior volume 226 of the buffer cartridge 220. The overflow compartment 140 is described in more detail herein.

[0058] 3 shows that the buffer compartment 120, the anesthetic compartment 130, and the overflow compartment 140 are defined by the housing 110 and inter-compartment walls, e.g., first inter-compartment wall 113a and second inter-compartment wall 113b. Both inter-compartment walls 113a and 113b include needle passageways, e.g., first inter-compartment wall needle passageway 114a and second inter-compartment wall needle passageway 114b. Generally, needle passageways 114a and 114b have a size, shape, and position such that a transfer needle 152 can reversibly puncture a septum 222 to provide a fluid connection from the internal volume 226 of the buffer cartridge 220 to the internal volume 236 of the anesthetic cartridge 230, and a drain needle 154 can penetrate inter-compartment wall 113b to provide a fluid passageway between the internal volume 236 of the anesthetic cartridge 230 and the interior of the overflow compartment 140 during use of the device 100, as described in more detail herein.

[0059] 3, there can be an assembly 150 including a transfer needle 152 having a first end 152a and a second end 152b, which also includes an evacuation needle 154 having a first end 154a and a second end 154b. In one embodiment, as shown, the needles 152 and 154 are oriented parallel to one another, with the second end of the transfer needle 152b extending further into the interior volume 236 of the anesthetic cartridge 230 than the second end of the evacuation needle 154b.

[0060] In a first configuration of the device, the anesthetic chamber 130 is empty of the anesthetic cartridge 230, including but not limited to, that shown in FIG. 4A. The second ends 152b and 154b of the transfer needle 152 and the drain needle 154 are positioned within the anesthetic chamber 130. The transfer needle 152 is positioned to pass through the needle passage 114a, and the first end 154a of the drain needle 154 is positioned within the overflow compartment 140.

[0061] 2 and 3 also show compressible member 160. As shown, compressible member 160 can include a pusher plate 162 and a spring 164. Spring 164 is positioned to compress when pressure is applied to pusher plate 162, including, but not limited to, pressure applied by an anesthetic cartridge 230 inserted into anesthetic compartment 130.

[0062] The compressible member 160 can be configured to maintain a fixed position and orientation of the transfer needle 152 and the discharge needle 154 relative to the pusher plate 162, regardless of the compression state of the spring 164. As the spring 164 compresses and expands, the position of the transfer needle 152 and the discharge needle 154 can move relative to other features of the device 100, including, but not limited to, the buffer compartment 120 and the overflow compartment 140.

[0063] 4B shows a second configuration of the device 100, in which the anesthetic chamber 130 includes an anesthetic cartridge 230 that compresses the compressible member 160. The second end 152b of the transfer needle 152 penetrates the septum 232 and is positioned within the internal volume 236 of the anesthetic cartridge 230. The first end 152a of the transfer needle 152 penetrates the first septum 222 of the buffer cartridge 220 and is positioned within the internal volume 226 of the buffer cartridge 220. The second end 154b of the discharge needle 154 penetrates the septum 232 and is positioned within the internal volume 236 of the anesthetic cartridge 230. The first end 154a of the discharge needle 154 remains positioned within the overflow compartment 140. In other words, the discharge needle 154 does not penetrate the septum 222 on the buffer cartridge 220.

[0064] Thus, upon compression of the compressible member 160 by the anesthetic cartridge 230, a first fluid communication channel is established between the internal volume 226 of the buffer cartridge 220 containing the buffer solution and the internal volume 236 of the anesthetic cartridge 230 containing the anesthetic liquid. Also, a second fluid communication channel is established between the internal volume 236 of the anesthetic cartridge 230 and the overflow compartment 140.

[0065] As shown in Figures 4B and 4C, the retaining member 180 can hold the anesthetic cartridge 230 in place so that the first and second fluid communication channels are maintained until the user disengages the retaining member 180.

[0066] 5A and 5B, the device 100 may also include an advancement member 170 configured to engage the impeller 178 with the plunger 224 upon receipt of the buffer cartridge 220 by the buffer compartment 120. Advancement of the impeller 178 relative to the plunger 224 of the buffer cartridge 220 may expel buffer fluid from the buffer cartridge 220 via the transfer needle 152 and into the anesthetic cartridge 230, thereby expelling fluid from the anesthetic cartridge 230 via the discharge needle 154 and into the overflow compartment 140. By introducing buffer into the anesthetic cartridge and simultaneously expelling anesthetic into the overflow compartment, a predetermined volume of buffer may be introduced into the anesthetic cartridge 230 without increasing the volume of, or overfilling, the anesthetic cartridge 230.

[0067] In an embodiment, the advancement member 170 includes a dial 172, and rotation of the dial 172 about the central axis of the housing 110 advances the impeller 178 relative to the plunger 224, thereby expelling buffer solution from the internal volume 226 of the buffer cartridge 220. Figures 5A and 5B illustrate such an embodiment in a first stage before the dial 172 rotates (Figure 5A), and a second stage after the dial 172 rotates (Figure 5B).

[0068] 5A, 5B, and 6, the advancement member 170 can include an impeller 178. The impeller 178 can be meshed with the dial 172 at any desired gear ratio, such that rotating the dial 172 a first rotational distance advances the impeller 178 a second, proportional axial distance. The volume of buffer released from the buffer cartridge 220 can then be a function of the cross-sectional area of ​​the internal volume 226 of the buffer cartridge 220 in a plane perpendicular to the advancement axis of the impeller 178 and the second distance. Thus, the volume of buffer released from the buffer cartridge 220 can be controlled by controlling the amount of rotation of the dial 172.

[0069] The amount of rotation of the dial 172 can be further controlled by a ratchet and pawl mechanism, including a ratchet 175 and a pawl 176. The dial 172 can be rotated relative to the ratchet 175 in the direction of allowed movement of the pawl 176 until the pawl 176 enters the detent notch 174. The ratchet 175 can be constructed with a single detent notch 174 (as shown in FIG. 6 ) or with fixed spacing between multiple detent notches 174 (not shown). In one embodiment, one or more of the detent notches can be toothed notches. Thus, each relative rotational advancement of the pawl 176 from a first detent notch 174 of the ratchet 175 to the next detent notch 174 can be substantially constant, and the corresponding advancement of the impeller 178 and the corresponding amount of buffer released from the buffer cartridge into the anesthetic cartridge 230 are also substantially constant. Thus, each rotation of the dial 172 to the next detent notch 174 allows a substantially consistent amount of buffer to be mixed into the anesthetic liquid in the anesthetic cartridge 230. Thus, repeatability of the buffering of the anesthetic liquid from one use of the device 100 to the next can be maintained.

[0070] In an embodiment of the device, a slip clutch mechanism 300 is designed to hold the plunger 224 in place. See FIGS. 8 and 9. When an anesthetic cartridge is not present in the device to establish a fluid path, the incompressibility of the fluid overcomes the frictional force, and the distal portion of the screw 306 rotates, providing an audible indicator that engagement is not occurring. See FIGS. 8 and 9. In one embodiment, the slip clutch mechanism 300 prevents the screw 306 from back-rotating and allowing pressure on the buffer solution to be released. In the embodiment shown in FIG. 8, the slip clutch mechanism 300 resides within the knob 302. The proximal portion of the screw 306 functions as an impeller to advance against the plunger 224 of the buffer solution cartridge 220 when an anesthetic cartridge is present. During use of the device with an anesthetic cartridge, the distal portion of the screw 306 is locked with the knob 302. A portion of the screw 306 threadably interacts with the casing 304 relative to at least a portion of the body of the screw 306. The frame 308 is located inside the knob 302 and outside the casing 304. Figure 9 is a cross-sectional view of the distal end of the device. The screw 306 can be seen interacting with the casing 304. The frame 308 is located outside the casing 304. The knob 302 is located around the periphery of the frame 308. The retaining member 180 and grip 310 can be seen in circumferential position on the device.

[0071] In embodiments of the device 100, the buffer cartridge 220 can contain enough buffer to buffer up to approximately 30 anesthetic cartridges, including, but not limited to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, or more doses of buffer. The device 100 can be discarded when all or substantially all of the buffer in the buffer cartridge 220 has been dispensed, or when only a portion of the buffer in the buffer cartridge 220 has been dispensed. If a window 112 (FIG. 1) is included in the housing 110, the amount of buffer remaining in the buffer cartridge 220 can be monitored. Thirty doses of buffer is generally sufficient for a dental practitioner's use for one week. In other embodiments, upon first use, buffer cartridge 220 may contain more or less buffer.

[0072] As buffer solution is expelled from the buffer cartridge 220 into the anaesthetic cartridge 230 by the action of the advancement member 170 , a corresponding amount of anaesthetic liquid must be expelled from the anaesthetic cartridge 230 into the overflow compartment 140 .

[0073] The overflow compartment 140 may be otherwise empty. In such an embodiment, the released anesthetic liquid may have complete fluid access to the entire volume of the overflow compartment 140. In doing so, the released anesthetic liquid may find a way to exit the overflow compartment 140, for example, the solution may traverse one or more of the inter-compartment wall needle passages 114a and 114b.

[0074] In embodiments, the device 100 may further include an absorbent member 142. The absorbent member 142 may be configured to absorb at least a portion of the fluid released from the anesthetic cartridge 230. For example, in the embodiments shown in FIGS. 3 and 7, the absorbent member 142 is positioned within the overflow compartment 140. Alternative locations (not shown) for the absorbent member 142 may be used. The absorbent member 142 may comprise any material capable of absorbing anesthetic liquid. Exemplary materials include, but are not limited to, sponge, cotton, and synthetic polymers, among others.

[0075] In one embodiment, the device 100 can further include a plurality of granules 144 configured to absorb fluid not absorbed or retained by the absorbent member 142. As shown in FIG. 7, the granules 144 can be positioned within the overflow compartment 140, although alternative locations (not shown) can be used. In one embodiment, the granules have a diameter large enough that they do not fit into the end of the discharge needle 154a. In some embodiments, the granules 144 can include any polymer capable of absorbing anesthetic fluid. Exemplary materials include, but are not limited to, polyacrylate, ethylene maleic anhydride, cross-linked carboxymethyl cellulose, polyvinyl alcohol copolymer, and cross-linked polyethylene oxide.

[0076] An alternative embodiment may include only granules 144 in the overflow compartment 140 without any absorbent member 142 in the overflow compartment 140. In one embodiment, the granules have a diameter large enough that they do not fit into the end of the discharge needle 154a.

[0077] The present disclosure also relates to methods of manufacturing devices, including but not limited to the above-described device 100. For example, a method is disclosed herein, the method comprising: a buffer cartridge containing a buffer solution, the buffer cartridge including a first septum and a plunger; a buffer compartment configured to receive an anesthetic cartridge containing an anesthetic agent and including a second septum; an anesthetic compartment configured to receive an anesthetic agent; an overflow compartment; a needle assembly including a transfer needle having a first end and a second end, and a discharge needle having a first end and a second end; a compressible member configured to compress upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein compression of the compressible member causes a first end of the transfer needle to pierce the first septum, a second end of the transfer needle to pierce the second septum, and a second end of the drainage needle to pierce the second septum, wherein the first end of the drainage needle resides within the overflow compartment; an advancement member configured to engage the plunger upon receipt of the buffer cartridge by the buffer compartment, wherein advancement of the advancement member expels buffer from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; In some embodiments, the first end of the discharge needle enters the overflow compartment. In some embodiments, the first end of the discharge needle is already in the overflow compartment.

[0078] Although the description of inserting the buffer cartridge into the buffer compartment follows the description of providing a device including the buffer compartment and other elements, the insertion is not limited to being performed after the device is otherwise fully assembled. For example, the insertion can be performed when the device is in an incomplete state of manufacture, but the location and position of the buffer compartment have been established and subsequent manufacturing steps will not be hindered by the buffer cartridge.

[0079] In a further example, the housing can be a cylindrical housing formed of two halves, e.g., split into two semi-cylinders across the longitudinal axis of the housing. The first half of the housing can sufficiently define a buffer compartment into which a buffer cartridge can be inserted. Insertion of the buffer cartridge can occur before, after, or simultaneously with the placement of various other elements within the buffer compartment, anesthetic compartment, and / or overflow compartment, such as a needle assembly, absorbent member, granules, compressible member, pressure plate, spring, advancement member, pawl, ratchet, slip clutch, impeller, and / or retention member.

[0080] After all elements that can be disposed on the first half of the housing are disposed, the second half of the housing can be disposed and joined to the first half by one or more screws, including but not limited to, snap-fitting, adhesive, or other joining devices, or a combination thereof. A reinforcing band can be added to further secure the first and second halves of the housing. A dial can be positioned above the end of the housing in engagement with one or more of the advancement member, ratchet, slip clutch, and / or impeller.

[0081] After the buffer cartridge is inserted and the device is assembled, the device can be sterilized and / or packaged. For example, the device can be packaged in combination with instructions for carrying out a method, the method comprising: an anesthetic cartridge containing an anesthetic agent and including a second septum; and compressing the compressible member with the anesthetic cartridge, whereby a first end of the transfer needle penetrates the first septum, a second end of the transfer needle penetrates the second septum, and a second end of the drainage needle penetrates the second septum, wherein the first end of the drainage needle resides in the overflow compartment; advancing the plunger, thereby expelling buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; In some embodiments, the first end of the discharge needle enters the overflow compartment. In some embodiments, the first end of the discharge needle is already in the overflow compartment. In other words, the device can be packaged with instructions on how to use it.

[0082] In embodiments, the instructions may further include instructions for withdrawing the anesthetic cartridge from the transfer and drainage needles.

[0083] In embodiments, the instructions may further include instructions for providing a second or additional instance of the anesthetic cartridge and instructions for repeating the compression and advancement with the second or additional instance of the anesthetic cartridge.

[0084] The present disclosure also relates to methods of using the above-described apparatus, including but not limited to the apparatus 100. For example, a method is disclosed herein, the method comprising: a buffer cartridge including a first septum, a plunger, and containing a buffer; and an anesthetic cartridge containing an anesthetic agent and including a second septum; and providing a needle assembly including a transfer needle having a first end and a second end and a discharge needle having a first end and a second end; compressing the compressible member with the anesthetic cartridge, whereby a first end of the transfer needle penetrates the first septum, a second end of the transfer needle penetrates the second septum, and a second end of the drainage needle penetrates the second septum, wherein the first end of the drainage needle resides within the overflow compartment; advancing the plunger, thereby expelling buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; In some embodiments, the first end of the discharge needle enters the overflow compartment. In some embodiments, the first end of the discharge needle is already in the overflow compartment.

[0085] In embodiments, the method may further include one or more additional actions and / or steps of the method, which may be characterized by one or more additional features, including, but not limited to, one, two, three, four, five, six, seven, eight, or nine or more of the following:

[0086] In the method, advancing the plunger can include rotating a dial or knob.

[0087] In the method, rotating the dial or knob can engage a ratchet and a pawl mechanism, and in embodiments, releasing the buffer solution includes releasing a predetermined dose of the buffer solution upon engagement of the ratchet and the pawl mechanism.

[0088] In this method, a slip clutch mechanism present within the dial or knob prevents the screw from rotating backwards and releasing pressure on the buffer. In embodiments, the slip clutch mechanism is present within the dial or knob.

[0089] The method may further include absorbing at least a portion of the fluid released into the overflow compartment with an absorbent member or other absorbent material.

[0090] The method may further include absorbing fluid not absorbed or retained by the absorbent member with a plurality of granules.

[0091] The method may further include holding the anesthetic cartridge in a position to maintain compression of the compressible member.

[0092] The method may further include withdrawing the anesthetic cartridge from the transfer needle and the drainage needle.

[0093] The method may further include providing a second instance of the anesthetic cartridge and repeating the compression and advancement with the second instance of the anesthetic cartridge.

[0094] In the method, the buffer cartridge, the needle assembly, the compressible member, and the advancing member configured to advance the plunger can be positioned within a housing, and the method can further include disposing of the housing when the buffer cartridge is substantially emptied of buffer.

[0095] The devices and methods disclosed herein provide one or more desirable results for dental practitioners and their supporting personnel. These devices are generally simpler to use than previous devices, thereby reducing the amount of training time required by dental practitioners and the burden on customer support personnel. The devices can have buffers built into them from the start, thereby reducing the number of separate items a dentist or dental office staff must purchase and keep track of. The devices, through the methods of use described herein, allow for very rapid buffering of anesthetic agents using buffers maintained under conditions that generally maintain pH throughout the unit's intended service life. In one embodiment, the devices are disposable, allowing for convenient disposal at the end of their service life without the need for assembly, disassembly, or cleaning by the dental practitioner. The devices generally have simpler, more integrated mechanisms than previous devices, thereby improving reliability.

[0096] Although specific dental embodiments have been described herein, it will be apparent to one skilled in the art that the devices and methods disclosed herein can be used to buffer any anesthetic liquid for any medical or other application where accurate and repeatable pH buffering is desired.

[0097] While the above is a description of embodiments, various alternatives, modifications, additions, and substitutions are possible without departing from the scope thereof, as defined by the claims.

Claims

1. below: a buffer cartridge including a first septum and a plunger and containing a buffer; a buffer compartment configured to receive the an anesthetic cartridge containing an anesthetic agent and including a second septum; an anesthetic compartment configured to receive an anesthetic agent; an overflow compartment; a needle assembly including a transfer needle having a first end and a second end, and a discharge needle having a first end and a second end; a compressible member configured to compress upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein compression of the compressible member causes the first end of the transfer needle to pierce the first septum, the second end of the transfer needle to pierce the second septum, and the second end of the discharge needle to pierce the second septum, wherein the first end of the discharge needle resides within the overflow compartment; an advancement member configured to engage the plunger upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein advancement of the advancement member expels buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; An apparatus comprising:

2. 10. The device of claim 1, wherein the advancing member includes a dial, rotation of the dial advancing the plunger.

3. The advancing member a ratchet and pawl mechanism configured to ensure that the dial rotates in only one direction and to release a predetermined dose of the buffer solution upon rotation or partial rotation of the dial; The apparatus of claim 2 , comprising:

4. The device of claim 2 , wherein the advancement member includes one or more detent notches.

5. 3. The device of claim 2, wherein the ratchet and pawl mechanism is arranged to provide an audible indication when the dial is fully rotated.

6. a slip clutch mechanism that locks a screw with a knob on the advancement member when the anesthetic cartridge is present in the device; The apparatus of claim 1 further comprising:

7. The overflow compartment is an absorbent member configured to absorb at least a portion of the fluid released from the anesthetic cartridge; The apparatus of claim 1 , comprising:

8. The overflow compartment comprises: A plurality of granules configured to absorb a fluid The apparatus of claim 1 , comprising:

9. 2. The device of claim 1, wherein the anesthetic compartment includes at least one retention member configured to retain the anesthetic cartridge after receiving it such that the compressible member remains compressed until the anesthetic cartridge is removed from the anesthetic compartment.

10. 2. The device of claim 1, wherein the buffer compartment is proximal to a first end of the device, the anesthetic compartment is proximal to a second end of the device, and the overflow compartment is positioned between the buffer compartment and the anesthetic compartment.

11. The device of claim 1 which is cylindrical.

12. below: providing a device; a buffer cartridge including a first septum, a plunger, and containing a buffer; providing an anesthetic cartridge containing an anesthetic agent and including a second septum; providing providing a needle assembly including a transfer needle having a first end and a second end and a discharge needle having a first end and a second end; attaching the anesthetic cartridge to the device; compressing a compressible member on the anesthetic cartridge, thereby causing the first end of the transfer needle to pierce the first septum, the second end of the transfer needle to pierce the second septum, and the second end of the discharge needle to pierce the second septum, wherein the first end of the discharge needle resides within the overflow compartment; advancing the plunger, thereby expelling buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; A method comprising:

13. 13. The method of claim 12, wherein an audible indication occurs when the anesthetic cartridge is properly inserted into the device.

14. The method of claim 12 , wherein the step of advancing the plunger comprises rotating a dial.

15. Rotation of the dial engages the ratchet and pawl mechanism, and releasing the buffer solution includes releasing a predetermined dose of the buffer solution upon engagement of the ratchet with a pawl mechanism.

15. The method of claim 14.

16. a slip clutch mechanism that locks the screw with the knob of the advancement member when the anesthetic cartridge is present; The process of providing The method of claim 12 further comprising:

17. absorbing at least a portion of the fluid released into the overflow compartment with an absorbent member. The method of claim 12 further comprising:

18. absorbing fluids, such as fluids not absorbed or retained by the absorbent member, if present, with the plurality of granules. The method of claim 12 further comprising:

19. holding the anesthetic cartridge in a position to maintain the compression of the compressible member; The method of claim 12 further comprising:

20. withdrawing the anesthetic cartridge from the device. The method of claim 12 further comprising:

21. The process of compounding medicines 13. The method of claim 12, comprising:

22. 13. The method of claim 12, wherein the buffer is hypertonic and the anesthetic is hypotonic, such that when the buffer and the anesthetic are combined, the combination has an intended target osmolality.

23. 23. The method of claim 22, wherein the target osmolality is between 200 mOsm / L and 416 mOsm / L.

24. 24. The method of claim 23, wherein the target osmolality is substantially isotonic at 308 mOsm / L.

25. an advancement member configured to advance the buffer cartridge, the needle assembly, the compressible member, and the plunger is positioned within a housing; The method comprises: disposing of the housing when the buffer cartridge is substantially empty of buffer. further comprising: The method of claim 12.

26. below: Providing an apparatus, said apparatus comprising: a buffer cartridge including a first septum and a plunger and containing a buffer; a buffer compartment configured to receive an anesthetic cartridge containing an anesthetic agent and including a second septum; an anesthetic compartment configured to receive an anesthetic agent; an overflow compartment; a needle assembly including a transfer needle having a first end and a second end, and a discharge needle having a first end and a second end; a compressible member configured to compress upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein compression of the compressible member causes the first end of the transfer needle to pierce the first septum, the second end of the transfer needle to pierce the second septum, the second end of the drainage needle to pierce the second septum, and the first end of the drainage needle to reside within the overflow compartment; and an advancement member configured to engage the plunger upon receipt of the anesthetic cartridge by the anesthetic compartment, wherein advancement of the advancement member expels buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; the providing step comprising: inserting the buffer cartridge into the buffer compartment; packaging the device in combination with instructions for practicing the method; The method comprises: an anesthetic cartridge containing an anesthetic agent and including a second septum; and providing compressing the compressible member with the anesthetic cartridge, thereby causing the first end of the transfer needle to pierce the first septum, the second end of the transfer needle to pierce the second septum, and the second end of the discharge needle to pierce the second septum, wherein the first end of the discharge needle resides in the overflow compartment; advancing the plunger, thereby expelling buffer solution from the buffer cartridge through the transfer needle and into the anesthetic cartridge, thereby expelling fluid from the anesthetic cartridge through the drain needle and into the overflow compartment; the packaging step comprising: A method comprising:

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