Compounds Comprising Curcumin and Basic Amino Acids

Abstract

The present disclosure relates to: a solid compound formed by curcumin and arginine, which includes molar ratios between 5:1 and 1:5, with improved bioavailability properties, and which contains a solid compound comprising curcumin and arginine; the use thereof in complaints of inflammation, pain, stiffness and reduced range of movement, and in complaints that cause disability owing to the presentation of symptoms of pain, inflammation and stiffness and reduced range of movement, among others; and a pharmaceutical composition containing curcumin and L-arginine with a synergic effect in the therapeutic activity of the combination of curcumin and L-arginine, wherein the selected ratio allows a synergic effect in the therapeutic activity thereof to be obtained, and wherein an exemplary preferred ratio of curcumin to L-arginine is between 5:1 to 1:5.

Claims

1. A solid compound comprising curcumin and a basic amino acid, wherein said compound has a disordered molecular arrangement.

2. A solid compound of claim 1 wherein the basic amino acid is arginine and the molar ratio of curcumin and arginine is between 5:1 and 1:5 and is in a disordered molecular arrangement.

3. The solid compound according to claim 1, characterized in that it has better solubility or permeability properties.

4. The solid compound according to claim 1, wherein curcumin has improved properties that favor the enhancement of the analgesic and anti-inflammatory effect of curcumin and L-arginine.

5. The solid compound of claim 2, wherein the solid compound is co-amorphous.

6. A solid compound comprising curcumin and arginine in a crystalline arrangement.

7. The solid compound of claim 6 wherein the molar ratio of curcumin and arginine is between 5:1 and 1:5.

8. The solid compound according to claim 6, wherein said compound has better solubility or permeability properties.

9. A composition comprising the solid compound curcumin and arginine of any of claims 2 and 7, one or more pharmaceutical excipients.

10. The use of the composition of claim 9 in the manufacture of a medicament useful for conditions that require analgesic, anti-inflammatory, antioxidant, antitumor, antidiabetic activity, among others.

11. The use as claimed in claim 10 in the manufacture of a medicamenty useful in conditions of inflammation, pain, stiffness, decreased range of motion, as well as conditions that cause disability due to symptoms of pain, inflammation and stiffness, decreased range of motion, among others.

12. An amorphous solid compound with enhanced properties comprising curcumin and an organic compound as a co-former selected from the group consisting of arginine, alanine, glycine, lysine, histidine, azelaic acid, pimelic acid, 2,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, malonic acid, oxalic acid, and picolinamide.

13. A pharmaceutical combination comprising curcumin and arginine and/or their pharmaceutically acceptable salts.

14. A pharmaceutical composition comprising the combination of curcumin and L-arginine of claim 13 and pharmaceutically acceptable carriers and/or excipients.

15. The use of the pharmaceutical composition of claim 14 in the manufacture of a medicament useful in conditions of inflammation, pain, stiffness, decreased range of motion, as well as conditions that cause disability due to symptoms of pain, inflammation and stiffness, decreased range of motion, among others, or that require analgesic, anti-inflammatory, antioxidant, and antitumor activity, among others.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0042] The figures illustrate the characterization of the solids obtained and the performance of the invention when administered to the study subjects.

[0043] FIGS. 1a and 1b. Effect produced by oral administration of 100 and 320 mg/kg of curcumin (−1 h) on Complete Freund's Adjuvant (CFA)-induced inflammation. FIG. 1a corresponds to the temporary profile and FIG. 1b shows areas under the curve (AUC) (−1 h means administration 1 hour before).

[0044] FIGS. 2a and 2b. Effect produced by oral administration of 100 and 320 mg/kg of curcumin (−1 h) on carrageenan (CAR)-induced inflammation. FIG. 2a corresponds to the temporary profile and FIG. 2b shows the areas under the curve (AUC).

[0045] FIGS. 3a and 3b. Effect produced by oral administration of 100 and 320 mg/kg of L-arginine (−1 h) on CFA-induced inflammation. FIG. 3a corresponds to the temporary profile and FIG. 3b shows the areas under the curve (AUC).

[0046] FIGS. 4a and 4b. Effect produced by oral administration of 100 and 320 mg/kg of L-arginine (−1 h) on CAR-induced inflammation. FIG. 4a corresponds to the temporary profile and FIG. 4b shows the areas under the curve (AUC).

[0047] FIGS. 5a and 5b. Anti-inflammatory effect of oral administration of 10, 30 and 100 mg/kg of the co-amorphous formed by curcumin and L-arginine (ratio 1:2, −1 h) on the Complete Freund's Adjuvant (CFA) model. FIG. 5a corresponds to the temporary profile and FIG. 5b shows the areas under the curve (AUC).

[0048] FIGS. 6a and 6b. Anti-inflammatory effect of oral administration of 10, 30 and 100 mg/kg of the co-amorphous formed by curcumin and L-arginine (ratio 1:2, −1 h) on the CAR model. FIG. 6a corresponds to the temporary profile and FIG. 6b shows the areas under the curve (AUC).

[0049] FIGS. 7a and 7b. Effect produced by oral administration of 100 mg/kg of: the combination curcumin+L-arginine (Cur+L-Arg) in a 1:2 ratio; vehicle (Veh); celecoxib (Cel); diclofenac (Dic); and co-amorphous (Co-amo) formed by curcumin and L-arginine (1:2 ratio), on CFA-induced inflammation. FIG. 7a corresponds to the temporary profile and FIG. 7b shows the areas under the curve (AUC).

[0050] FIGS. 8a and 8b. Effect produced by oral administration of 100 mg/kg of: the combination curcumin+L-arginine (Cur+L-Arg) in a 1:2 ratio; vehicle (Veh); celecoxib (Cel); diclofenac (Dic); and co-amorphous (Coamo) formed by curcumin and L-arginine (1:2 ratio), on CAR-induced inflammation. FIG. 8a corresponds to the temporary profile and FIG. 8b shows the areas under the curve (AUC).

[0051] FIGS. 9a and 9b. Effect produced by oral administration of 100 mg/kg of curcumin (Cur), L-arginine (L-Arg), vehicle (Veh), and co-amorphous (Co-Amo) formed by curcumin and L-arginine (1:2 ratio) on CFA-induced thermal hyperalgesia. FIG. 9a corresponds to the temporary profile and FIG. 9b shows the areas under the curve (AUC).

[0052] FIGS. 10a and 10b. Effect produced by oral administration of 100 mg/kg of curcumin (Cur), L-arginine (L-Arg), vehicle (Veh), and co-amorphous (Co-Amo) formed by curcumin and L-arginine (1:2 ratio) on CAR-induced thermal hyperalgesia. FIG. 10a corresponds to the temporary profile and FIG. 10b shows the areas under the curve (AUC).

[0053] FIG. 11. UV absorption spectrum of a curcumin and L-arginine complex in dimethylsulfoxide solution at different concentrations.

[0054] FIG. 12. FT-IR spectrum of: I) L-arginine; II) curcumin and L-arginine co-amorphous 1:1 obtained by flash evaporation in ethanol; and III) highly pure curcumin (C3 complex).

[0055] FIG. 13. FT-IR spectrum of: I) L-arginine; II) curcumin and L-arginine co-amorphous 1:2 obtained by flash evaporation in ethanol; and III) high purity curcumin (C3 complex).

[0056] FIG. 14. FT-IR spectrum of: I) L-arginine; II) curcumin and L-arginine co-amorphous 2:1 obtained by flash evaporation in ethanol; and III) high purity curcumin (C3 complex).

[0057] FIG. 15. DSC-TGA thermogram of the amorphous curcumin obtained by flash evaporation in ethanol.

[0058] FIG. 16. DSC-TGA thermogram of curcumin and L-arginine co-crystal 1:1 obtained by mechanochemical reaction in water.

[0059] FIG. 17. DSC-TGA thermogram of the co-amorphous phase of curcumin and L-arginine 1:1 obtained by flash evaporation in ethanol.

[0060] FIG. 18. DSC-TGA thermogram of the co-amorphous phase of curcumin and L-arginine 1:2 obtained by flash evaporation in ethanol.

[0061] FIG. 19. DSC-TGA thermogram of the co-amorphous phase of curcumin and L-arginine 2:1 obtained by flash evaporation in ethanol.

[0062] FIG. 20. Powder diffraction pattern obtained from accelerated stability tests at 40° C. and 50° C. under dry conditions and at 40° C. with 75% relative humidity for the co-amorphous of curcumin and L-arginine 1:1.

[0063] FIG. 21. Powder diffraction pattern obtained from accelerated stability tests at 40° C. and 50° C. under dry conditions and at 40° C. with 75% relative humidity for the co-amorphous of curcumin and L-arginine 1:2.

[0064] FIG. 22. Powder diffraction pattern obtained from accelerated stability tests at 40° C. and 50° C. under dry conditions and at 40° C. with 75% relative humidity for the co-amorphous of curcumin and L-arginine 2:1.

[0065] FIG. 23. Solubility profile of co-amorphous forms of curcumin and L-arginine at different stoichiometries: a) 1:2, b) 1:1 and c) 2:1; as well as d) high purity curcumin (C3 complex) using water as dissolution medium and a temperature of 37.5° C.

[0066] FIG. 24. Solubility profile of co-amorphous form of curcumin and L-arginine 1:2 using as dissolution media HCl buffer at pH 1.2, acetate buffer at pH 4.5 and phosphate buffer at pH 6.8.

[0067] FIG. 25. Diffusion profiles obtained from permeability studies in water using pig membranes, for curcumin and the co-amorphous phase of curcumin and L-arginine 1:2.

DETAILED DESCRIPTION OF THE INVENTION

[0068] The present invention provides a combination comprising effective amounts of curcumin and L-arginine with an unexpected anti-inflammatory effect and with other beneficial effects such as pain reduction, wherein the drug ratio curcumin:L-arginine is from 3:1 to 1:3.

[0069] On the other hand, it refers to solid co-amorphous and co-crystalline compounds of curcumin and L-arginine with improved properties, and compositions containing sch compounds, as well as the process for preparing the composition and use thereof. It provides a new, valuable tool with enhanced physicochemical properties, such as enhanced solubility properties, resulting in enhanced bioavailability properties.

[0070] The present invention is a new alternative therapeutic support as antioxidant, anti-inflammatory, analgesic, antitumor, anticancer agent, among others. It exhibits an invention for the control or suppression of inflammation and pain that decreases or avoids the possible adverse effects of NSAIDs or opioids.

[0071] The use of pain models is a way to know the impact of curcumin and L-arginine compounds on the anti-inflammatory effect and even on the antinociceptive effect. Acute pain models use a physical or chemical stimulus with the purpose of determining the response latency of the animal being subjected to said stimulus. With the models, the nociceptive threshold of the animal is objectively determined, so that the obtained parameters are a consequence of the classic mechanism of pain as a reflection within a physiological mark.

[0072] By means of preclinical studies, the present invention demonstrates the pharmacodynamic course shown by the curcumin:L-arginine combination.

[0073] The localized inflammatory injury in joints may offer an intermediate model of inflammation between acute and chronic, whereas induction of generalized arthritis with Freund's adjuvant (CFA) is a model of chronic inflammation.

[0074] The carrageenan (CAR)-induced subplantar edema model was used in the evaluation of the acute effect.

[0075] Various methods have been developed to examine the anti-inflammatory properties of drugs in laboratory animals such as rodents. Each of these methods involves exerting a potentially painful (nociceptive) stimulus, followed by the measurement of a clearly observable response.

[0076] Preclinical studies were performed in rats with a chronic inflammation model using complete Freund's adjuvant (CFA) given intra-articularly (AIA), as well as an acute model induced by carrageenan (CAR) given in the subplantar region.

Preclinical Study Using Complete Freund's Adjuvant (CFA) Model

[0077] In the assessment of the pharmacological interaction, it must be considered that when two drugs are administered together, it is necessary to characterize the effect of the combination with respect to the individual effect of each drug, as shown in the figures.

[0078] The time course of the anti-inflammatory effect produced by orally administered curcumin alone, L-arginine alone and the co-amorphous solid compound of curcumin and L-arginine, was obtained in the complete Freund's adjuvant (CFA)-induced arthritis model by the intra-articular route (AIA) in Sprague-Dawley male rats (n=6).

[0079] The complete Freund's adjuvant (chronic inflammation) model and the carrageenan (acute inflammation) model were used for evaluating the possible anti-inflammatory effect of curcumin (FIGS. 1a, 1b, 2a and 2b), L-arginine (FIGS. 3a, 3b, 4a and 4b) or the co-amorphous compound of curcumin and L-arginine in a 1:2 ratio (FIGS. 5a, 5b, 6a, 6b).

[0080] In these models, the inflammation induced by the complete Freund's adjuvant and carrageenan is determined by the volume displacement measured with a plethysmometer. FIGS. 1a, 1b, 2a and 2b show that orally administered curcumin (100-320 mg/kg) is unable to reverse the inflammatory effect induced by complete Freund's adjuvant (FIG. 1b) or carrageenan (FIG. 2b). It can even be observed that curcumin shows an inflammatory effect with respect to the vehicle at 3 and 4 hours employing the 100 mg/kg dose, and between 2 and 6 hours employing the 320 mg/kg dose in the complete Freund's adjuvant model (FIG. 1a). The same phenomenon is observed with curcumin 320 mg/kg in the carrageenan model at 1 and 2 hours of evaluation. However, the two doses of curcumin (100 and 320 mg/kg) that were assessed in this model seem to reverse the inflammatory effect induced by carrageenan at 6 hours (FIG. 2a).

[0081] FIGS. 3a, 3b, 4a and 4b show that, just like curcumin, oral L-arginine at the assessed doses (100 and 320 mg/kg), was not able to reverse the inflammatory effect induced by the complete Freund's adjuvant (FIG. 3b) or carrageenan (FIG. 4b). On the contrary, L-arginine showed an inflammatory effect in relation to the vehicle between 2 and 4 hours of the assessment in the complete Freund's adjuvant model (FIG. 3a), whereas in the carrageenan model, L-arginine was inclined to show a proinflammatory effect during the first two hours of the assessment, however, at 4 and 6 hours of evaluation (FIG. 4a).

[0082] Contrary to the observations with the individual oral administration of curcumin or L-arginine, oral administration of the co-amorphous compound of curcumin and L-arginine 1:2 was able of reversing the inflammation induced by the complete Freund's adjuvant (FIGS. 5a and 5b) or carrageenan (FIGS. 6a and 6b) in a dose-dependent and statistically significant way with respect to the vehicle. In both models, the statistical difference with respect to the vehicle was reached at doses of 30 and 100 mg/kg (FIGS. 5b and 6b). Regarding the time courses, the 30 mg/kg dose reached a statistical difference since the eighth hour, whereas the 100 mg/kg dose was statistically significant with respect to the vehicle as of the sixth hour in the complete Freund's adjuvant model (FIG. 5a), while the dose of 10 mg/kg in the carrageenan model was significant since the fourth hour. P value is 0.05.

[0083] Additionally, we compared treatments with curcumin, L-arginine, and the co-amorphous compound of curcumin and L-arginine at a fixed dose of 100 mg/kg. In this comparison, only the oral administration of the co-amorphous compound of curcumin and L-arginine was able to significantly reverse the inflammation induced by the complete Freund's adjuvant or carrageenan. In the time courses, as of the sixth hour, the co-amorphous compound of curcumin and L-arginine, but not curcumin or L-arginine individually, reached a statistical difference with respect to the vehicle in the complete Freund's adjuvant model. Regarding the carrageenan model, the co-amorphous compound of curcumin+L-arginine shows an anti-inflammatory effect since the second hour, whereas curcumin or L-arginine reaches this difference only in the last measurement.

Verification of Combination Effectiveness.

[0084] 100 mg/kg of the co-amorphous compound of curcumin and L-arginine was compared against 100 mg/kg of a physical mixture of curcumin+L-arginine at a ratio of 1:2 (51.4 mg/kg of curcumin+48.6 mg/kg of L-arginine). FIGS. 7a, 7b, 8a and 8b show that the co-amorphous, but not the physical mixture, is capable of reversing the inflammatory effect induced by the complete Freund's adjuvant (FIGS. 7a and 7b) or carrageenan (FIGS. 8a, 8b). In addition, it can be observed that both celecoxib and diclofenac (positive controls) exhibited an anti-inflammatory effect at the same dose of 100 mg/kg in both models (FIG. 7a, 8a). When statistically comparing the treatments with celecoxib, diclofenac, and the co-amorphous compound of curcumin and L-arginine 1:2, there was no statistically significant difference among them, which suggests that the co-amorphous of curcumin and L-arginine 1:2 is as effective as the drugs clinically used for treating conditions that involve an inflammatory process. It is not possible to obtain such result with the physical mixture of curcumin+L-arginine.

[0085] In order to determine whether the co-amorphous compound of curcumin and L-arginine is capable of producing an antihyperalgesic effect, a dose of 100 mg/kg of the co-amorphous compound was assessed in the model of thermal hyperalgesia induced by complete Freund's adjuvant or carrageenan. FIGS. 9a, 9b, 10a and 10b show that the co-amorphous of curcumin and L-arginine can produce a statistically significant antihyperalgesic effect in the complete Freund's adjuvant model (FIG. 9a-b). In the carrageenan model, the three treatments produce an antihyperalgesic effect, however, the co-amorphous compound provides statistically greater relief for hyperalgesia with respect to the vehicle, curcumin or L-arginine.

Characterization of New Forms of Curcumin and L-Arginine

[0086] In the determination of the stoichiometry of the curcumin and L-arginine complex in solution, an absorption spectrum was obtained by the mole ratio method.

[0087] FIG. 11 shows UV absorption spectra obtained for a complex formed by curcumin and L-arginine in dimethylsulfoxide solution at different concentrations. The graph is obtained as follows: Curcumin is placed in dimethylsulfoxide (DMSO) solution, the UV spectrum is obtained and different aliquots of L-arginine (10 μL of a 0.0081M solution) are gradually added, obtaining the UV spectra for each addition. As a result, it is appreciated that the stability and union of the curcumin and L-arginine complex is preserved.

[0088] The image shows the absorption spectrum of curcumin at a concentration of 0.000027 M which corresponds to 0.03 absorbance units at 580 nm, and the spectra resulting from the addition of different aliquots of arginine to the curcumin solution. The image shows an absorption band at 580 nm, which is generated and increases with the addition of arginine to the curcumin solution. This absorption band does not correspond to curcumin or L-arginine, which do not exhibit UV-Vis activity at this wavelength, as shown in the raw materials spectra. This suggests that such absorption band corresponds to the formation of a supramolecular curcumin:L-arginine complex in solution. On the other hand, the graph shows the absorption of the curcumin and L-arginine complex at 580 nm as a function of the concentration of L-arginine, wherein the increase in the concentration of arginine favors the formation of a greater amount of the complex and results in increased absorption up to 0.2518 absorbance units, in agreement with the Lambert-Beer law. It is worth mentioning that, with the constant increase of the L-arginine concentration within the curcumin solution, the curcumin interaction sites become saturated and generate a smaller change until saturation, where no significant changes are further observed. According to this graph, the equilibrium constant for the complex formation is 9254.

[0089] On the other hand, for the characterization of the obtained solid forms, we analyzed the initial curcumin corresponding to the untreated curcumin, and/or the curcumin subjected to slurry treatment, rapid evaporation or mechanochemical reaction, as well as the untreated co-former.

[0090] In the X-ray Powder Diffraction (XRPD) test, the three amorphous phases of curcumin and L-arginine with 1:1, 1:2 and 2:1 stoichiometry exhibit the characteristic form of an amorphous compound.

[0091] FT-IR Spectroscopy of the Three Co-Amorphous Phases of Curcumin and L-Arginine with 1:1, 1:2 and 2:1 Stoichiometry.

[0092] FIGS. 12 to 14 show the FT-IR spectra obtained for the co-amorphous phases of curcumin and L-arginine 1:1, 1:2 and 2:1, respectively. Important changes are observed in the O—H and N—H vibration zone corresponding to the hydroxyl and amino groups of L-arginine (from 3510 to 3049 cm.sup.−1), which means that the hydroxyl groups of curcumin interact with the amine group of arginine.

[0093] The H—O stretching band of the initial curcumin shows a well-defined band at 3507 cm.sup.−1, which disappears completely in the curcumin and L-arginine co-amorphous phases, indicating that the hydroxyl groups of curcumin do not form an important interaction in the curcumin raw material, and the hydroxyl groups of curcumin, in the presence of L-arginine, establish an important interaction with the amino groups of L-arginine. The displacements of the carbonyl bands are shown in Table 1.

TABLE-US-00001 TABLE 1 Displacements (cm.sup.−1) of carbonyl bands in the amorphous NSF. v C═O v C═O Phase curcumin co-former Curcumin 1628 — L-arginine — 1675 Curcumin and L-arginine 1:1 1621 1668 Curcumin and L-arginine 1:2 1621 1667 Curcumin and L-arginine 2:1 1622 1675

[0094] Curcumin carbonyl groups (C═O) show a well-defined band at 1628 cm.sup.−1, which is not importantly shifted in the IR spectra obtained for the phases of curcumin and L-arginine 2:1, 1:1 and 1:2 (FIGS. 12, 13 and 14, respectively), shifting to 1621 cm.sup.−1. Possibly, this indicates that the interaction pattern established by the carbonyl groups in the initial curcumin remains unchanged when the co-amorphous phase with L-arginine is formed.

[0095] The band assigned to the C═O bond vibration of the carboxylic acid of L-arginine appears at 1675 cm.sup.−1. For the phases 1:1 (FIG. 13) and 1:2 (FIG. 14), the band appears at 1668 and 1667 cm.sup.−1 respectively. In the case of the phase 2:1, a shift of the C═O band of the carboxylic acid in L-arginine is not observed, which could be attributed to the fact that there is no significant interaction with curcumin.

[0096] It is important to mention that no intense and well-defined bands are observed between 1500 and 1600 cm.sup.−1, which are indicative of the formation of carboxylate ions in the arginine salt, so we can conclude that no proton transfer takes place from the co-former to the drug and that they are co-amorphous phases.

[0097] Characterization of NSF of Curcumin and L-Arginine, by Obtaining the Respective DSC and TGA Thermograms.

[0098] FIG. 15 shows a DSC-TGA thermogram of amorphous curcumin obtained by flash evaporation in ethanol.

[0099] FIG. 16 corresponds to the DSC-TGA thermogram of the co-crystalline phase obtained by mechanochemical reaction of curcumin and L-arginine 1:1 in water.

[0100] FIGS. 17 to 19 show DSC and TGA thermograms of the curcumin and L-arginine co-amorphous form in the ratios 1:1, 1:2 and 2:1. In all of the obtained phases, an endothermic event between 93 and 100° C. is observed, which according to the TGA is associated to dehydration of the phases with weight losses ranging from 3 to 5%, which correspond to 1.5 or 2 moles of water contained in the phases, concluding that they are hydrated co-amorphous phases.

[0101] After dehydration, at approximately 140° C., a possible exothermic event is observed in the DSC, which could be attributed to crystallization. However, the TGA shows another mass loss of the compound starting at such temperature. This can be attributed to the fact that at 140° C. the co-amorphous form begins to decompose, curcumin sublimes (melting point 183° C.), and arginine crystallizes and finally sublimes at approximately 250° C. (melting point of arginine 260° C.)

[0102] Characterization of the Co-Amorphous Phases by Determining the Density of the Obtained Solids.

[0103] We determined densities of the obtained solids, resulting in an insignificant increase in density. See Table 2.

TABLE-US-00002 TABLE 2 Density values of the obtained co-amorphous phases. Densities in g/cm.sup.3 Determination Determination Determination Phase 1 2 3 Average Curcumin Density 1.3688 1.3698 1.3575 1.3653 Std. Dev. 0.0037 0.0038 0.0075 0.005 Cur and Density 1.4966 1.4762 1.4982 1.4903 L-Arg Std. Dev. 0.0063 0.0142 0.0079 0.0094 1:1 Cur and Density 1.4181 1.4176 1.4078 1.4145 L-Arg Std. Dev. 0.0036 0.0031 0.0067 0.0044 1:2 Cur and Density 1.5427 1.5755 1.5497 1.5559 L-Arg Std. Dev. 0.0133 0.0195 0.0063 0.0130 2:1

[0104] Accelerated Stability, Solubility and Dissolution Tests

[0105] Accelerated stability studies were carried out by leaving the co-amorphous phases samples 1 month at 40° C. and 50° C. with 0% humidity and 40° C. with 75% RH. Subsequently, the samples were characterized by X-ray diffraction and compared with the respective initial phases and raw materials. FIGS. 20 to 22 show the diffractograms of the different co-amorphous phases subjected to the indicative stability test, showing that the phases are stable at 40 and 50° C. under dry conditions.

[0106] FIG. 23 shows the solubility profile of the co-amorphous forms of curcumin and L-arginine, a) 1:2, b) 1:1, c) 2:1 and d) high purity commercial curcumin (C3 complex) using water as dissolving medium at a temperature of 37.5° C. It is clearly observed that the phase of curcumin and L-arginine 1:2 has the highest solubility in water and at a temperature of 37.5° C., reaching a solubility of 350 to 400 mg per liter. The phases 1:1 and 2:1 achieved solubilities of 250 and 150 mg per liter, respectively. In addition to the above, high purity commercial curcumin did not solubilize at least under these conditions.

[0107] We carried out stability tests at physiologically relevant pH values.

[0108] FIG. 24 shows the solubility data of the phase of curcumin and L-arginine 1:2 employing dissolution medium of HCl buffer pH 1.2, acetate buffer pH 4.5 and phosphate buffer pH 6.8. Results show that the phase of curcumin and L-arginine 1:2 has low solubility in highly acidic media, such as HCl buffer pH 1.2. However, a good solubility is observed in acetate (pH 4.5) and phosphate (pH 6.8) buffers, in which a solubility of 13-15 g/L is reached at 30 minutes.

[0109] FIG. 23 shows a marked increase in the water solubility of the three co-amorphous phases with respect to curcumin alone.

[0110] Thermodynamic Solubility Studies

[0111] This test shows the equilibrium between the liquid phase corresponding to the saturated solution and the solid phase corresponding to the undissolved drug. It was performed by adding 2 g of the solid phase to LSS (sodium lauryl sulfate) medium, with stirring at 37.5° C., and taking aliquots at 3, 5, 10 and 30 minutes. Aliquots were filtered and measurements were made with UV-Vis spectroscopy at 420 nm. Due to the poor solubility of curcumin in water, the molar absorptivity coefficient was calculated in water with 1% LSS.

[0112] High concentration samples of the curcumin and L-arginine co-amorphous phases, curcumin lecithin liposomes (INDENA), high purity commercial sample (Complex C3) and a compound curcumin:L-lysine, were tested in water with 1% LSS.

[0113] It comes evident that the curcumin and L-arginine co-amorphous solids with stoichiometry 1:1 and 2:1 show a considerable increase in the solubility of curcumin, reaching values of 3.2 and 4.0 g/L, respectively.

[0114] Of all phases, curcumin and the compound curcumin:L-lysine show the lowest solubilities, solubilizing 0.11 and 0.34 g/L at 30 min.

[0115] It is important to mention that the solubility of curcumin alone could not be determined because it is almost insoluble in water.

[0116] We measured the solubility of the co-amorphous phases at a lower concentration of 0.05 g in 3.5 ml, for determining the effect of concentration on the aggregation phenomenon. This resulted in a decreased solubility because the amount required to saturate the phase was much lower. However, at low concentrations, the aggregation phenomenon was completely inhibited, and no reprecipitation was observed.

Permeability Studies

[0117] Permeability studies were carried out using pig membranes and water as dissolution medium. Diffusion profiles were obtained by plotting accumulated mg of drug vs time (h). The flux was obtained by using the formula J=Q/(A*t) where Q is the amount of drug that passes through the membrane, in accumulated mg; A is the exposed area of the membrane in cm.sup.2; and t is the time at which the measurement was made; the flux profile was obtained by plotting the flow (mg accum cm.sup.−2 t.sup.−1) vs time (h).

[0118] FIG. 25 shows the flow profile for curcumin and the phase of curcumin and L-arginine 1:2, using water as the diffusion medium. The graph shows a flow increase for the phase of curcumin and L-arginine 1:2, reaching its maximum flow at 10 min, and then reaching the stationary state. In contrast, regarding curcumin, it can be observed that the flow continues to increase until 45 min, then enters the stationary state.

[0119] This flow increase for the phase of curcumin and L-arginine 1:2 can be attributed to an increase of the solubility of the phase of curcumin and L-arginine 1:2 in water; since it is higher than curcumin, there is a greater amount of curcumin present in the medium, to permeate. In contrast, the solubility of curcumin in water is very low, thus the concentration of curcumin in water solution, which can permeate through the membrane, is almost insignificant.

[0120] As a result of these tests, the graphs in FIGS. 1-10 show that the co-amorphous form of curcumin and L-arginine has a surprising anti-inflammatory and/or antiallodynic effect; in addition, we demonstrated the existence of a compound formed by curcumin and arginine, which is stable (FIGS. 11-19); said compound confers different properties with respect to those exhibited by the initial components, reflecting an outstanding increase in solubility and permeability (FIGS. 23, 24 and 25).

[0121] The curcumin+L-arginine combination is administered in different compositions. It can be in the form of a suspension, pill, tablet, granulate, powder, capsule, semi-solid, ointment, cream or liquid.

[0122] A design of the solid composition can be as a tablet, pill, granulate, dragée, powder or powder for reconstituting a solution, and where appropriate, it may contain compressibility vehicle, binder, diluent, antistatic, lubricant, plasticizer and disintegrant in a compartment separated from the final outer layer. An insulating layer or coating is added on the active layer, such insulating layer is made up of a coating polymer that confers protection from factors such as humidity, light, among others.

[0123] The present invention additionally refers to a new co-amorphous form of curcumin and L-arginine with improved properties and compositions containing said form, and the process of making the composition and its use.

[0124] The new solid form has improved chemical, biological or physical properties, such as enhanced solubility, dissolution rate, bioavailability, pharmacokinetics, mechanical resistance, flow properties, particle size, melting point, among others.

[0125] A co-crystal is a crystalline solid formed by an active ingredient and a co-former, both of which are found in the same crystal cell. A co-amorphous form is a solid made up of an active ingredient and a co-former, which exist in a disordered molecular arrangement.

[0126] Methods for identifying a solid form, and distinguishing a co-crystal from a co-amorphous from, include X-ray Powder Diffraction (XRPD) analysis, Fourier Transform Infrared Spectrometry (FT-IR), and Differential Scanning calorimetry—Thermogravimetric Analysis (DSC-TGA).

[0127] The present invention provides the solid form of curcumin and arginine in different molar proportions or stoichiometric ratios selected from the group consisting of (1:1), (1:2), (2:1), (1:3) and (3:1).

[0128] The method used to prepare the solid form is selected from the group consisting of slurry, flash evaporation, and mechanochemical reaction. The solvent may be any solvent capable of dissolving the curcumin and the co-former. Preferably, a solvent having a non-toxic or low toxicity effect on the organism and/or a solvent which is easily evaporated, such as water or ethanol, is used.

[0129] In one embodiment, the condition or disease that can be treated by the methods of the present invention, or the uses of the present invention, can be any disease or condition that is treatable with an antitumor agent, an anticancer agent, an antioxidant, an anti-arthritic agent, a neuroprotective agent, an anti-inflammatory agent, an antiviral agent or an anti-infective.

[0130] In one embodiment, the pharmaceutical composition of the present invention comprises an amount of the solid form of curcumin and arginine that represents from about 90% to about 1%, by weight, based on the total weight of the composition.

[0131] In certain embodiments, the pharmaceutical composition may be presented in an appropriate dosage form. For example, the pharmaceutical composition may be suitable for tablets, powders, capsules, pills, liquids, syrups, suspensions, emulsions, elixirs, drops, ointments, gels, transdermal patches, parenteral dosage forms, and oral solution forms.