Dissolution therapy for pyrophosphate containing crystals

Abstract

A medical dissolvent is provided for use as a medical treatment for calcium pyrophosphate deposition disease (pseudo-gout). The medical dissolvent is capable as functioning as a solubilizing agent for crystalline structures containing calcium pyrophosphate due to its unique chemical complex structure, which is formed by a chelating agent bound to metal cations. The chemical structure is both deliverable and removable through a solution or a medical insert.

Description

DISSOLUTION THERAPY FOR PYROPHOSPHATE CONTAINING CRYSTALSRELATED APPLICATIONS

[0001] This application claims the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Serial No. 63 / 664,066 entitled “DISSOLUTION THERAPY FOR PYROPHOSPHATE CONTAINING CRYSTALS,” filed June 25, 2024, the entire disclosure of which is incorporated herein by reference.BACKGROUND1. Field of the Invention

[0002] The present teachings are generally directed towards a chemical dissolvent and, more particularly, a medical dissolvent capable of solubilizing crystalline structures that contain pyrophosphate in the human body. The chemical dissolvent is capable of being delivered to the treatment region through means of aqueous delivery or through an insertable delivery structure.2. Description of the Related Art

[0003] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0004] Pseudo-gout is a disease that affects millions of people in the USA. It is caused by the development of highly insoluble crystals of calcium pyrophosphate dihydrate (“CPPD”) in joints. This leads to pain and inflammation, which can be debilitating. Currently, there is no effective strategy to treat this disease, only manage symptoms. Thus, there is a desire to identify a method to specifically dissolve CPPD deposits.

[0005] A main challenge with developing such methods is that the two ions in CPPD (Ca+2and pyrophosphate) are highly charged (+2 and -4, respectively), so the two ions bind to each other very tightly. This makes CPPD very insoluble, as water can not compete for these strong charge-charge interactions. A second challenge is that there is a very similar mineral present in or near joints, namely hydroxy apatite (“HA”), which is the mineral that forms the vast majority of the inorganic portion of bones. HA also contains Ca+2ions, but these are combined with phosphate anions, which have a -3 charge. Thus, the challenge is to dissolve CPPD, while not dissolving HA.

[0006] Research articles and scientific papers hypothesize that the crystals could be dissolved by a litany of reagents, but all are still theoretical or failures when tested. For example, cyclic amines were tested to dissolve CPPD, with the idea that their multiple positive charges could specifically recognize the -4 charge of the pyrophosphate and remove it from contact from the Ca +2 ions. However, none of these molecules have proved effective in treating CPPD.SUMMARY

[0007] One or more embodiments of the present disclosure generally concern a method for treating calcium pyrophosphate deposition disease. Generally, the method comprises: (a) providing a medical dissolvent comprising a chelating agent bound to two cationic metals, wherein each of the cationic metals has a charge of greater than +1; (b) introducing the medical dissolvent into a location in an afflicted individual comprising pyrophosphate-containing crystalline structures; and (c) dissolving at least a portion of the pyrophosphate-containing crystalline structures with the medical dissolvent to thereby form a pyrophosphate-bound complex.

[0008] One or more embodiments of the present disclosure generally concern a medical dissolvent for treating calcium pyrophosphate deposition disease. Generally, the medical dissolvent is in the form of a solution or a solid construct and the medical dissolvent comprises a chelating agent bound to two cationic metals, wherein each of the cationic metals has a charge of greater than +1. The medical dissolvent is capable of removing pyrophosphate from the pyrophosphate-containing crystalline structures.

[0009] One or more embodiments of the present disclosure generally concern a method for treating calcium pyrophosphate deposition disease. Generally, the method comprises: (a) providing a medical dissolvent comprising l-[3-[[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]- N,N-bis(pyridin-2-ylmethyl)methanamine bound to two cationic metals, wherein each of the cationic metals has a charge of greater than +1, wherein the medical dissolvent is in the form of a solution or a solid construct; (b) introducing the medical dissolvent into a location in an afflicted individual comprising calcium pyrophosphate dihydrate crystals; and (c) dissolving at least a portion of the calcium pyrophosphate dihydrate crystals with the medical dissolvent to thereby form a pyrophosphate-bound complex.BRIEF DESCRIPTION OF THE FIGURES

[0010] Embodiments of the present invention are described herein with reference to the following drawing figures, wherein:

[0011] FIG. 1 depicts the conceptual basis for CPPD crystal dissolution;

[0012] FIG. 2 depicts an exemplary Skeletal Chemical Diagram of PPS-1 Synthesis;

[0013] FIG. 3 depicts an exemplary di-zinc PPS-1 complex and a modeled complex of PPS-1 and pyrophosphate;

[0014] FIGS. 4A and 4B provide high-resolution Q-TOF mass spectral analyses of an exemplary PPS-1 in complex with pyrophosphate;

[0015] FIG. 5 provides comparative graphs demonstrating the solubilizing effect of an exemplary PPS-1 on HA in comparison to CPPD; and

[0016] FIG. 6 is a graph demonstrating the dissolution of CPPD over time while using an exemplary PPS-1 as a dissolvent.DETAILED DESCRIPTION

[0017] The embodiments disclosed in the following disclosure are chosen and described so that others skilled in the art would be able to recreate or use the invention without undue experimentation. Uses that are listed are not exhaustive and are not intended to limit potential applications of the invention in any way.

[0018] As noted above, calcium pyrophosphate deposition disease (pseudo-gout) is an arthritic condition that is caused by the formation of highly insoluble calcium pyrophosphate dihydrate (“CPPD”) crystals. These crystals form in the joints of patients and cause pain, inflammation, and joint degeneration.

[0019] We have identified a family of pyrophosphate-specific molecules that effectively dissolves CPPD and minimally dissolves HA. This family of pyrophosphate-specific molecules does this by specifically binding to the pyrophosphate ion (“PPi”), thereby removing it from the calcium in CPPD. More particularly, we have discovered that the combination of a pyrophosphate-specific chelating agent and two bound cationic metals can allow for the effective dissolution and removal of CPPD in joints afflicted with calcium pyrophosphate deposition disease (pseudo-gout). As used herein, “PPS-1” and “Pyrophosphate Solubilizer- 1” may be usedinterchangeably and refer to the combination of the chelating agent and the cationic metal(s) described herein.

[0020] We have observed that the PPS-1 described herein is able to dissolve CPPD due to the PPS-l’s ability to satisfy all the electrostatic interactions that the calcium ions normally provide for pyrophosphate in the CPPD crystals and do so in a single molecular complex. PPS- 1, as a single molecular complex, has an entropic advantage over independent ions, which is one of the factors that gives PPS-1 the competitive advantage over calcium ions.

[0021] While not wishing to be bound by theory, FIG. 1 provides the conceptual basis for CPPD dissolution with PPS-1. As shown in FIG. 1, a highly insoluble CPPD is stabilized by charge-charge interactions of the calcium cations. PPS-1 can act as a crystal lattice surrogate and provide similar interactions to the calcium cations, thereby forming a soluble pyrophosphate complex, which allows removal of the pyrophosphate from the crystal lattice. More particularly, molecule complexes, such as the PPS-1 described herein, will be able to effectively compete with the two calcium ions in CPPD, thereby binding tightly to pyrophosphate and, therefore, cause dissolution. It is believed that the PPS-1 can cause this dissolution of CPPD, and the removal of the pyrophosphate from the calcium cations in the associated crystal lattice, due to the chemical complex of the PPS-1, which is formed by an organic chelating agent and two cationic metals. In this chemical complex of PPS-1, the chelating agent binds the cationic metals within a fixed range of distances.

[0022] The key characteristics associated with the ability to dissolve pyrophosphate, particularly CPPD, are generally based on presenting positive charges in the correct spacing of the PPS-1, which allow interaction with the highly negatively charged pyrophosphate, driven by coulombic attraction. In one or more embodiments, in the case of PPS-1, this presentation may be generally affected by two cationic metals (e.g., Zinc +2) that have been chelated by a complex amine. Generally, in many embodiments, this structure of the PPS-1 preferentially binds pyrophosphate over phosphate due to at least one factor: pyrophosphate is exactly complementary in charge (-4 on pyrophosphate compared to +4 on PPS-1). In contrast, phosphate at neutral pH has only a -1 to -3 charge. Furthermore, phosphate is more compact and may not interact as effectively with PPS-1 as does pyrophosphate. If the cationic metals have smaller ionic charges (e.g., +1), then the PPS-1 won’t be able to interact strong with the -4 charged pyrophosphate.

[0023] Generally, the metal cations each need to be bound tightly to the chelating agent that complexes them. This is affected by the organic structure of the chelating agent. In one or more embodiments, the chelating agent presents three to five oxygen atoms, nitrogen atoms, sulfur atoms and / or phosphorous atoms per metal cation. Any less than three atoms and the metal won’t be held tight enough to make a stable complex; however, more than five and there will be no sites remaining to allow the metals to interact with the pyrophosphate.

[0024] Furthermore, it has been observed that spacing of the metal cations within the PPS-1 can be critical in affecting dissolution of CPPD. Generally, in various embodiments, the metal cations have to be spaced at least 3.5, 4, or 4.5 angstroms and / or less than 12, 11, or 10 angstroms, preferably between 3.5 to 12 angstroms, apart from each other. Any less than 3.5 angstroms, there will be insufficient space for the pyrophosphate to complex with PPS-1; however, spaces greater than 12 angstroms will weaken the interaction between the PPS-1 and the pyrophosphate. Therefore, spacing the metal cations in the PPS-1 can be critical for its functionality in dissolving CPPD.

[0025] When CPPD is treated with PPS-1, it is dissolved, whereas a common buffer alone will not appreciably dissolve CPPD. Equally importantly, there was little additional dissolution of hydroxy apatite (“HA”) when it was treated with PPS-1, versus buffer alone. Further studies analyzing these properties are summarized in the article entitled, “Selective Dissolution of Calcium Pyrophsophate Dihydrate Crystals Using a Pyrophosphate Specific Receptor," by Paine et al., the entire disclosure of which is incorporated herein by reference.

[0026] In one or more embodiments, the PPS-1 described herein can comprise a chelating agent and at least one, preferably two, cationic metals bound to the chelating agent. Generally, each of the cationic metals have a charge of greater than +1, +2, or +3. In certain embodiments, each of the cationic metals have a charge of +2 and / or +3.

[0027] In various embodiments, the PPS-1 described herein can comprise a chelating agent bound to two cationic metals having a charge of +2 and / or +3.

[0028] Additionally, we have discovered that the chemical reagent, l-[3-[[bis(pyridin-2- ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine, may effectively function as a chelating agent when bound to two cationic metals with charges greater than +1. Thus, in various embodiments, the chelating agent can be an amine compound, such as l-[3- [[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine.

[0029] It was discovered that a class of molecules that had been used as detectors of pyrophosphate may also function as chelating agents and be effective to dissolve the pyrophosphate in close association with calcium ions in CPPD. However, this class of molecules has not been used to selectively solubilize CPPD. One such class uses a framework to bind two metal cations (e g., zinc), each of which has a +2 charge to thereby provide a net +4 charge. These are perfectly arranged to interact with the -4 charge of the pyrophosphate, and detect it over other ions, such as phosphate. Through this binding, the PPS-1 can then effectively remove the pyrophosphate from contact with the +2 charge of the calcium ions found in CPPD. Consequently, this would effectively remove the PPi from the CPPD crystal lattice and, in so doing, dissolve the CPPD.

[0030] This class of molecules can include the chemical complex, l-[3-[[bis(pyridin-2- ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine, as a chelating agent bound to two cationic metals. This amine compound was first identified by Kawahara and Uchimaru in their research paper, “Dinucleotide Hydrolysis Promoted by Dinuclear Zn Complexes - The Effect of the Distance between Zn Ions in the Complexes on the Hydrolysis Rate,” (“Kawahara”), the contents of which are incorporated by reference in its entirety. This chemical reagent was determined to be able to bind to pyrophosphate by Han and Kim in their research paper, “Visual Detection of Di-and Tri-phosphates in Aqueous Solution of Neutral pH,” which is also incorporated hereby reference in its entirety. Han and Kim used [Z (1,3- bis[bis(2-pyridylmethyl)aminomethyl]benzene)] 4+ to detect the binding of ATP, ADP, and anions, such as pyrophosphate. However, we have discovered that this chemical complex’s ability to bind so strongly to pyrophosphate could be harnessed for dissolving CPPD crystals. Thus, the use of the aforementioned amine compound bound to two metal cations for the dissolution of CPPD provided a unique use and application of a chemical complex investigated for other applications. In other words, even though the previous amine complex existed, no one had the insight that this complex would effectively dissolve calcium pyrophosphate.

[0031] For the PPS-1 to dissolve CPPD, it was necessary to determine whether the PPS-1 complex became water soluble when bound to pyrophosphate. To determine PPS-1’ s solubility, a solution of PPS-1 in buffer may be prepared and the solution can be added to a potassium pyrophosphate solution. If no precipitate is formed, this indicates that the PPS-1 is able to makea pyrophosphate complex that was soluble. This is a necessary component for the removal of PPS-1 and pyrophosphate complex from the treatment site within an afflicted individual.

[0032] Accordingly, PPS-1 is representative of an overall approach, in which molecules that are effective at detecting pyrophosphate may also be effective at competing for the pyrophosphate present in CPPD crystals. Furthermore, this detection and binding of pyrophosphate may translate into dissolution of CPPD. Other molecules that have this property of recognizing pyrophosphate and distinguishing it from phosphate may also have this property of dissolving CPPD.

[0033] The methodologies used to produce PPS-1 containing l-[3-[[bis(pyridin-2- ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine are summarized in FIG. 2. FIG. 2 depicts a Skeletal Chemical Diagram of the synthesis of PPS-1 containing l-[3- [[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine. As shown in FIG. 2, (a) MXDB, DPA, and DIEA are combined in methylene chloride to create the precursor amine; and (b) the precursor amine is combined with zinc (II) nitrate in methanol to create the PPS-1.

[0034] FIG. 3 depicts: (a) di-zinc PPS-1 complex (PPS-1) comprising l-[3-[[bis(pyridin- 2-ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine, (b) a simplified schematic of the PPS-1, and (c) a modeled complex of PPS-1 and pyrophosphate (right figure).

[0035] While not wishing to be bound by theory, there are possibly other potential motifs that can work with the treatments described herein. For example, rather than using metals with positive charges, a related compound could use positively charged organic groups, such as amines, guanidines, and / or amidines.

[0036] As described below in greater detail, a medical dissolvent comprising the PPS-1 can be provided and used to treat joints afflicted with calcium pyrophosphate deposition disease (pseudo-gout). Such treatment methodologies can include, for example, irrigating at least a portion of a joint with a medical dissolvent in the form of a solution that dissolves and removes the CPPD. Additionally, or alternatively, the pyrophosphate binding motifs of the medical dissolvent, particularly the PPS-1, can be grafted onto a solid construct support and temporarily implanted into or near a joint to slowly absorb the pyrophosphate. For example, the solid construct support may be implanted near the joint cartilage, which contains the CPPD, in the directly adjacent synovial fluid. Either treatment pathway provides a way to directly treatcalcium pyrophosphate deposition disease, which currently has no current treatment method. PPS-l’s ability to be readily delivered into a location comprising pyrophosphate-containing crystalline structures in an afflicted individual and readily removed after dissolution of the crystalline structures is described further below.

[0037] In various embodiments, the PPS-1 described herein is intended for use as a dissolution treatment therapy for CPPD crystals in the human body, which cause pseudo-gout. This treatment can involve: (1) providing a medical dissolvent comprising the PPS-1; (2) introducing the medical dissolvent into a location in an afflicted individual comprising pyrophosphate-containing crystalline structures; and (3) dissolving at least a portion of the pyrophosphate-containing crystalline structures with the medical dissolvent to thereby form a pyrophosphate-bound complex. The resulting PPS-1 pyrophosphate bound complex can be removed from the location by: (1) using aspiration, drainage, or other fluid removal technologies to remove the PPS-1 pyrophosphate bound complex (when a solution of PPS-1 is used) or (2) removing the solid construct now containing the PPS-1 pyrophosphate bound complex. Generally, the “location” is a joint afflicted with calcium pyrophosphate deposition disease, which causes the joint to contain calcium pyrophosphate dihydrate crystals.

[0038] In one or more embodiments, this treatment can be performed through the injection of PPS-1 into the affected joint (directly or in the form of a solution) followed by joint aspiration to remove the PPS-1 and pyrophosphate soluble complex. In alternative embodiments, PPS-1 can also be administered through the use of an insertable solid construct, which also has absorption capabilities.

[0039] Generally, there are two main ways that the medical dissolvents described herein can be used to treat joints with CPPD deposits. Under the first methodology, delivery to an afflicted site, such as a knee joint, can be facilitated using joint irrigation of a solution of PPS-1. In the second methodology, the PPS-1 can be chemically linked to an insoluble polymer, which can then be formed into an injectable insert, such as solid construct. The resulting solid construct can be introduced into the afflicted joint and left temporarily. It can then act as a “pyrophosphate sponge,” soaking up specifically the pyrophosphate in the joint, and in so doing, dissolve the CPPD present. Once sufficient CPPD has been removed, the insert can be removed. The polymer can include any thermoplastic or thermoset polymer that is insoluble and may be usedfor such purposes. In certain embodiments, the polymer forming the solid construct can be a biocompatible polymer.

[0040] In one or more embodiments, the medical dissolvent described herein for CPPD can comprise a PPS-1 containing a chelating agent and at least one, preferably two, cationic metals bound to the chelating agent. Generally, each of the cationic metals have a charge of greater than +1, +2, or +3. In certain embodiments, each of the cationic metals have a charge of +2 and / or +3.

[0041] In various embodiments, the medical dissolvent described herein for CPPD can comprise a PPS-1 containing a chelating agent bound to two cationic metals having a charge of +2 and / or +3.

[0042] In various embodiments, the present disclosure is based on the novel production of a medical dissolvent of pyrophosphate-based crystalline structures that comprises a PPS-1 which contains l-[3-[[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2- ylmethyl)methanamine as a chelating agent bound to two cationic metals, such as zinc cations.

[0043] In various embodiments, a medical dissolvent in the form of a solution can contain at least 0.0001, 0.001, 0.01 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99 weight percent of PPS-1, based on the total weight of the solution. Additionally or alternatively, a medical dissolvent in the form of a solution can contain less than 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 6, 5, 4, or 3 weight percent of PPS-1, based on the total weight of the solution.

[0044] In various embodiments, a medical dissolvent in the form of a solution can contain at least 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99 weight percent of at least one buffer, based on the total weight of the solution. Additionally or alternatively, a medical dissolvent in the form of a solution can contain less than 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 6, 5, 4, or 3 weight percent of at least one buffer, based on the total weight of the solution. In one or more embodiments, the buffer can be any aqueous buffer, including a buffer having a pH of 7±1. In certain embodiments, the buffer can exhibit at or near isotonic ionic strength (i.e., 0.154 mol / liter ± 0.05 mol / liter). An exemplary buffer can include HEPES bufferand / or water. For example, the solution can be an aqueous delivery system when water is utilized.

[0045] In various embodiments, a medical dissolvent in the form of the solid constructs can contain at least 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99 weight percent of PPS-1, based on the total weight of the construct. Additionally or alternatively, a medical dissolvent in the form of the solid constructs can contain less than 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 6, 5, 4, or 3 weight percent of PPS-1, based on the total weight of the construct.

[0046] In various embodiments, a medical dissolvent in the form of the solid constructs can contain at least 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99 weight percent of at least one polymer, based on the total weight of the construct. Additionally or alternatively, a medical dissolvent in the form of the solid constructs can contain less than 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 6, 5, 4, or 3 weight percent of at least one polymer, based on the total weight of the solution. The polymers can include any water-insoluble bio-compatible polymers, including thermoplastic polymers or thermoset polymers.

[0047] Accordingly, the two treatment methodologies can be broken down into two different treatment strategies. Under the first treatment strategy, the aforementioned solution of containing PPS-1 can be introduced into an afflicted joint via a needle or other injection means to irrigate the joint, in order to selectively dissolve the CPPD deposits located within the joint, while not disturbing the HA around the joint. Under the second treatment strategy, a solid support construct that is covalently linked to the PPS-1 may be provided. This support may be temporarily implanted into a joint, where it would slowly absorb the pyrophosphate from the region, and thus clear the deposits. Afterwards, the solid construct may be removed from the patient.

[0048] Both of these conceptions are linked to the same idea: that the interactions which allow PPS-1 to recognize pyrophosphate will also allow the same molecule to remove pyrophosphate from the crystal lattice it is embedded in where it binds to calcium tightly. The idea is that the conceived molecules bind stronger to the pyrophosphate than does the calcium, thus dissolving the CPPD (which, again, is made of calcium bound to pyrophosphate).

[0049] While the PPS-1 described herein is effective at dissolving CPPD and treating pseudo-gout, there are a wide range of ways that its efficacy can be improved. For example, metals besides zinc can be used. In certain embodiments, metals with greater than a +2 charge can be used, such as Al+3, Fe+3, and / or Co+3. Additionally, or alternatively, the chelating group can be made more conformationally restricted. This can then increase both the affinity and specificity of the resulting species, by lowering conformational entropy barriers. Any modification that improves recognition of pyrophosphate should translate into more effective dissolution of CPPD.

[0050] This invention can be further illustrated by the following examples of embodiments thereof, although it will be understood that these examples are included merely for the purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.EXAMPLESExample 1

[0051] A PPS-1 containing l-[3-[[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]-N,N- bis(pyridin-2-ylmethyl)methanamine as the chelating agent was created. The m-xylene dibromide, di-(2 picolyl) amine, calcium (II) nitrate, zinc (II) nitrate, potassium pyrophosphate, ammonium molybdate, ascorbic acid, sulfuric acid, and disodium hydrogen phosphate used for this study were purchased from chemical companies and used in the creation of this PPS-1. These chemicals are depicted in TABLE 1, below. The precursor amine was synthesized from m-xylene dibromide (“MXDB”) and di-(2 picolyl) amine (“DPA”), as previously described by Kawahara. MXDB (1.289 g, 4.88 mmol) was then combined with 1.757 mL of DPA (9.76 mmol) and 1.700 mL of di-isopropyl ethyl amine (9.76 mmol) in 48.8 mL of methylene chloride. This was allowed to react overnight at which time the solution was extracted twice with distilled water and brine, followed by drying of the methylene chloride solution with magnesium sulfate, and solution concentration under vacuum. The crude product was purified using silica column chromatography, resulting in a viscous oil, which was confirmed as the desired product using electrospray mass spectrometry. To isolate the target di-zinc PPS-1 complex, a solution of the precursor amine (20 mL of a 34.1 mM solution in methanol) was combined with a 2 to 1 ratio of zinc (II) nitrate (6.83 mL of a 200 mM solution in methanol). Immediately upon mixing, a whitesolid began to form and settle on the floor of the vessel. This powder was suspended, filtered, and washed with cold methanol, yielding 546 mg (91% of expected).TABLE 1

[0052] The final compound (PPS-1) was confirmed by both combustion analysis and high-resolution electrospray mass spectrometry. FIGS. 4A and 4B provide high resolution Q- TOF mass spectral analyses of 10 pM of this PPS-1 in complex with 100 pM pyrophosphate. The inset closeup images isotopic peaks for PPS-1 complexed with pyrophosphate (right hand cluster due to PPS-1 -PPiH+, left hand cluster due to PPS-1 -PPi (H+)2).Example 2

[0053] The PPS-1 from Example 1 was further analyzed in order to determine how its ability to competitively bind to phosphate anions could affect the treatment protocols described herein. As discussed above, hydroxy apatite (“HA”) is the main inorganic component in human bones, and it contains a phosphate anion partnered with calcium cations like CPPD. In previous research, PPS-1 was shown to have a preference for binding to pyrophosphate instead of phosphate. To test this, CPPD was placed into a solution of PPS-1 and HEPES buffer (Solution 1), while another CPPD sample was placed into a solution of only HEPES buffer (Solution 2). One sample of HA was also placed into Solution 1, while another sample of HA was also placed into Solution 2. The CPPD and HA samples were then vortexed for one hour and centrifuged for 15 minutes. The resulting test samples were then observed and photographed. It was observed that only the CPPD sample in Solution 1 (with PPS-1) showed near complete dissolution, while the HA was still evident in Solution 1 and both HA and CPPD were clearly evident in Solution 2.

[0054] FIG. 5 provides graphs showing the amounts of CPPD and HA dissolved through treatment with Solution 1 (“PPS-1” - dark bars) and Solution 2 (“Buffer” - light bars). Phosphorous release was determined by molybdate assay and converted to corresponding amount of CPPD and HA. The total amount dissolved was summed over four rounds of treatment (n=3, sd indicated, * indicates significance by t-test).

[0055] As shown in FIG. 5, the solubilities of CPPD in Solution 1 and CPPD in Solution 2 were compared, and it was observed that there was a 761% increase in solubility of CPPD in Solution 1 relative to Solution 2. Furthermore, as shown in FIG. 5, the HA solubilities of Solution 1 and Solution 2 were also compared, and only a 44% increase in solubility was observed for Solution 1 (labeled “PPS-1”).

[0056] FIG. 6 provides a graph demonstrating the dissolution of CPPD over time for Solution 1 (“PPS-1 Treated”) and Solution 2 (“Buffer Treated”). Phosphorous release was determined by molybdate assay and converted to corresponding amount of CPPD. As shown in FIG. 6, PPS-1 was significantly superior at dissolving CPPD relative to the buffer alone.

[0057] From this study it was concluded that PPS-1 would have a minimal effect on the bone structure of patients who were treated with this reagent.DEFINITIONS

[0058] It should be understood that the following is not intended to be an exclusive list of defined terms. Other definitions may be provided in the foregoing description, such as, for example, when accompanying the use of a defined term in context.

[0059] As used herein, the terms “a,” “an,” and “the” mean one or more.

[0060] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

[0061] As used herein, the terms “comprising,” “comprises,” and “comprise” are open- ended transition terms used to transition from a subject recited before the term to one or moreelements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.

[0062] As used herein, the terms “having,” “has,” and “have” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

[0063] As used herein, the terms “including,” “include,” and “included” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.NUMERICAL RANGES

[0064] The present description uses numerical ranges to quantify certain parameters relating to the invention. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claim limitations that only recite the upper value of the range. For example, a disclosed numerical range of 10 to 100 provides literal support for a claim reciting “greater than 10” (with no upper bounds) and a claim reciting “less than 100” (with no lower bounds).CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS

[0065] The preferred forms of the invention described above are to be used as illustration only, and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.

[0066] The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as it pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.

Claims

What is claimed is:

1. A method for treating calcium pyrophosphate deposition disease, the method comprising:(a) providing a medical dissolvent comprising a chelating agent bound to two cationic metals, wherein each of the cationic metals has a charge of greater than +1;(b) introducing the medical dissolvent into a location in an afflicted individual comprising pyrophosphate-containing crystalline structures; and(c) dissolving at least a portion of the pyrophosphate-containing crystalline structures with the medical dissolvent to thereby form a pyrophosphate-bound complex.

2. The method according to claim 1, wherein each of the cationic metals is a zinc cation.

3. The method according to claim 1, wherein the chelating agent is an amine compound.

4. The method according to claim 1, wherein the medical dissolvent is in the form of a solution or a solid construct, wherein the solid construct further comprises a water-insoluble polymer.

5. The method according to claim 4, wherein the introducing comprises injecting the solution into the location of the afflicted individual.

6. The method according to claim 5, further comprising removing the pyrophosphate-bound complex from the afflicted individual via aspiration.

7. The method according to claim 5, wherein the solution comprises at least 0.001 weight percent and less than 10 weight percent of the medical dissolvent.

8. The method according to claim 7, wherein the solution comprises at least one buffer, wherein the buffer is water and / or HEPES buffer.

9. The method according to claim 5, wherein the introducing comprises irrigating at least a portion of the location with the solution.

10. The method according to claim 4, wherein the introducing comprises placing the solid construct into the location of the afflicted individual, further comprising removing the solid construct after the dissolving.

11. The method according to claim 10, wherein the solid construct comprises at least 0.1 weight percent of the medical dissolvent.

12. The method according to claim 1, wherein the location is a joint.

13. The method according to claim 1, wherein the chelating agent is l-[3- [[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine.

14. The method according to claim 1, wherein each of the cationic metals has a charge of +2 or greater.

15. The method according to claim 1, wherein the chelating agent comprises 3 to 5 oxygen atoms, nitrogen atoms, sulfur atoms, and / or phosphorous atoms per cationic metal.

16. The method according to claim 1, wherein the distance between the cationic metals is in the range of 3.5 to 12 angstroms.

17. A medical dissolvent for treating calcium pyrophosphate deposition disease, the medical dissolvent is in the form of a solution or a solid construct, wherein the medical dissolvent comprises a chelating agent bound to two cationic metals, wherein each of the cationic metals has a charge of greater than +1, wherein the medical dissolvent is capable of removing pyrophosphate from the pyrophosphate-containing crystalline structures.

18. The medical dissolvent according to claim 17, wherein each of the cationic metals is a zinc cation.

19. The medical dissolvent according to claim 17, wherein the chelating agent is an amine compound.

20. The medical dissolvent according to claim 17, wherein the solid construct further comprises a water-insoluble polymer.

21. The medical dissolvent according to claim 17, wherein the solution comprises at least 0.001 weight percent and less than 10 weight percent of the medical dissolvent.

22. The medical dissolvent according to claim 21, wherein the solution comprises at least one buffer, wherein the buffer is water and / or HEPES buffer.

23. The medical dissolvent according to claim 17, wherein the solid construct comprises at least 0.1 weight percent of the medical dissolvent.

24. The medical dissolvent according to claim 17, wherein the chelating agent is l-[3- [[bis(pyridin-2-ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine.

25. The medical dissolvent according to claim 17, wherein each of the cationic metals has a charge of +2 or greater.

26. The medical dissolvent according to claim 17, wherein the chelating agent comprises 3 to 5 oxygen atoms, nitrogen atoms, sulfur atoms, and / or phosphorous atoms per cationic metal.

27. The medical dissolvent according to claim 17, wherein the distance between the cationic metals is in the range of 3.5 to 12 angstroms.

28. A method for treating calcium pyrophosphate deposition disease, the method comprising:(a) providing a medical dissolvent comprising l-[3-[[bis(pyridin-2- ylmethyl)amino]methyl]phenyl]-N,N-bis(pyridin-2-ylmethyl)methanamine bound to two cationic metals, wherein each of the cationic metals has a charge of greater than +1, wherein the medical dissolvent is in the form of a solution or a solid construct; and(b) introducing the medical dissolvent into a location in an afflicted individual comprising calcium pyrophosphate dihydrate crystals; and(c) dissolving at least a portion of the calcium pyrophosphate dihydrate crystals with the medical dissolvent to thereby form a pyrophosphate-bound complex.

29. The method according to claim 28, wherein each of the cationic metals is a zinc cation.

30. The method according to claim 29, wherein the introducing comprises injecting the solution into the location of the afflicted individual.

31. The method according to claim 30, further comprising removing the pyrophosphate-bound complex from the afflicted individual via aspiration.

32. The method according to claim 28, wherein the solution comprises at least 0.001 weight percent and less than 10 weight percent of the medical dissolvent.

33. The method according to claim 28, wherein the solution comprises at least one buffer, wherein the buffer is water and / or HEPES buffer.

34. The method according to claim 28, wherein the introducing comprises irrigating at least a portion of the location with the solution.

35. The method according to claim 28, wherein the introducing comprises placing the solid construct into the location of the afflicted individual, further comprising removing the solid construct after the dissolving.

36. The method according to claim 28, wherein the solid construct comprises at least 0.1 weight percent of the medical dissolvent.

37. The method according to claim 28, wherein the location is a joint.

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