Patent Application
20160045440
The present invention relates to a stabilized mixture of amorphous calcium L-5-methyltetrahydrofolate and cysteine and to the use of said stabilized mixture in the production of a dosage form.
Calcium L-5-methyltetrahydrofolate is the Nonproprietary Name of N-{4-[[((6S)-2-amino-1,4,5,6,7,8-hexahydro-5-methyl-4-oxo-6-pteridinyl)methyl]amino]benzoyl}-L-glutamic acid, calcium salt.
Calcium L-5-methyltetrahydrofolate is commercialized by Merk Eprova under the trademark METAFOLIN® for use in the manufacture of foods for particular nutritional uses.
Calcium L-5-methyltetrahydrofolate is predominantly used in nutritional formulations for pregnant women indicated for the prevention of neural tube defects of the fetus. Is also used for the treatment of high risk recurrent pregnancy loss; risk of anemia due to impaired folic acid absorption; for the treatment of early memory loss, mild to moderate cognitive impairment and vascular dementia or Alzheimer disease.
Additionally, calcium L-5-methylfolate has been used as component of contraceptive compositions comprising a progestogen such as drospirenone and a estrogen such as ethinyl estradiol indicated for raise folate levels in women who choose to use an oral contraceptive for contraception for the purpose of reducing the risk of a neural tube defect and other congenital malformations caused by folate deficiency, in a pregnancy conceived while taking the product or shortly after discontinuing the product.
L-5-methylfolate is the predominant natural form of folates in many foods. It is also the essential form in which folates occur and are stored in the human body. In some foods (e.g. orange juice) it is the only folate present.
During absorption, all natural folates are converted to L-methylfolate which is the only form of folate to enter the human circulation. Unlike folic acid, L-5-methylfolate has to be converted to tetrahydrofolate (THF) via the vitamin B-12-dependent enzyme methionine synthase before it can participate in other folate-dependent reactions. When vitamin B-12 is deficient, L-5-methylfolate is not converted to tetrahydrofolate and thus is not able to ameliorate megaloblastic anemia. For that reason, L-5-methylfolate is the only reduced form of folate that does not mask vitamin B-12 deficiency.
Main problem associated with the pharmaceutical use of calcium L-5-methylfolate is that it is extremely unstable, and it is highly susceptible to oxidation by air, and it is therefore difficult to formulate as a pharmaceutical active ingredient of food additive.
U.S. Pat. No. 6,441,168 solves this problem by providing crystalline forms I, II, III and IV of calcium L-5-methylfolate. These crystalline forms are stable at room temperature, practically without limitation and are therefore suitable for the production of pharmaceutical compositions or food additives.
Main problem associated with the use of crystalline forms of a compound in the production of dosage forms is the inter-conversion of the crystalline forms during the process for its production. It is well known that the physical stability of polymorphs, in particular of hydrates and anhydrous forms may depend upon the relative humidity and/or temperature of the environment, and the most stable form may switch as the humidity/temperature is varied. Transitions between crystalline forms can occur and thus affect the dissolution rate and perhaps bioavailability of the drug in the dosage form.
For example, U.S. Pat. No. 6,441,168 teaches that crystalline form II of calcium L-5-methylfolate can be converted into form I by adding water to the crystals, e.g. by treatment with water in a humidity cabinet at 90° C. Additionally, form I of calcium L-5-methylfolate can be converted into forms II, III or IV by drying under vacuum at 70° C. (conversion into form II), or by thermal treatment at a temperature above 90° C. (conversion into form III) or above 95° C. (conversion into form IV).
Thus, in order to avoid the conversion of the crystalline form during the production process, careful control of the conditions used (humidity, temperature) should be made to avoid the inter-conversion between polymorphic forms.
Furthermore, patent application US 2008160004 teaches that Metafolin (commercialized crystalline form of calcium L-5-methylfolate) is degraded during granulation with the other components of the composition. Further, only 60% of Metafolin remains in the compositions obtained by granulation after a storage time of one month at 40° C. Dry admixture of Metafolin after the completion of the granulation process is necessary to stabilize Metafolin in the formulations disclosed.
The alternative to the crystalline forms of calcium L-5-methylfolate, i.e. the amorphous form of calcium L-5-methylfolate can be obtained according to the process disclosed in patent application US 2010168117. However, in the presence of oxygen, amorphous calcium L-5-methylfolate is very unstable and therefore, it is considered as less suitable for the production of dosage forms.
U.S. Pat. No. 5,223,500 discloses tablets comprising an active compound selected from racemic 5-methyltetrahydrofolic acid or its sodium, calcium or magnesium salt and 5 to 50% of an organic compound of biological origin containing at least on —SH group as stabiliser. The stabilizer can be selected from cysteine, pantetheine and reduced glutathione. It is highlighted that said patent is directed to stabilize a composition containing a racemic 5-methyltetrahydrofolic acid or its sodium, calcium or magnesium salt.
Thus, problems in respect of the physical and chemical stability of calcium L-5-methylfolate are not yet satisfactorily solved. There is still a need for improving the stability of calcium L-5-methylfolate, by sufficiently suppressing decomposition and conversion between crystalline forms when it is formulated into an oral dosage form, and during the storage time.
The dosage form of the invention resolves the aforesaid disadvantages, among others the instability of amorphous calcium L-5-methylfolate to the oxidation by air, presenting other advantages that will be described.
Present inventors have surprisingly found that amorphous calcium L-5-methylfolate may be stabilized by mixing it with cysteine. Said mixture can be processed into a dosage form, thus providing stabilized preparations comprising amorphous calcium L-5-methylfolate.
Thus, the object of this invention is to provide stabilized dosage forms of amorphous calcium L-5-methylfolate.
Thus, an aspect of the present invention refers to a dosage form which comprises amorphous calcium L-5-methylfolate and cysteine as stabilizing agent and optionally, further auxiliary agents.
Another aspect of the present invention refers to a process for the production of a dosage form comprising amorphous calcium L-5-methylfolate by mixing amorphous calcium L-5-methylfolate with cysteine and then processing the mixture to produce a stable dosage form.
Another aspect of the invention is the use of the dosage form of the invention for the production of a pharmaceutical composition, for example, of contraceptive compositions or for the production of nutraceutical compositions.
Another aspect of the invention is the use of cysteine as stabilizing agent for the stabilization of amorphous L-5-methylfolate.
All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning as known in the art. Other more specific definitions for certain terms as used in the present application are set forth below and are intended to apply uniformly through-out the specification and claims unless otherwise expressly set out definition provides a broader definition.
After numerous assays, the present inventors have found that cysteine is capable of stabilizing amorphous calcium L-5-methylfolate. Additionally, the present inventors have surprisingly found that the amorphous calcium L-5-methylfolate is stable maintained in the dosage forms containing the mixture of amorphous calcium L-5-methylfolate and cysteine.
Present inventors have tested the stabilization effect on amorphous calcium L-5-methylfolate of several reducing agents and antioxidants, such as methionine, sodium ascorbate, calcium ascorbate, ascorbyl palmitate, cytric acid, trisodium dihydrated citrate, α-tocopherol (vitamin E), propyl gallate, lipoic acid, butylhydroxytoluene (BHT), butylhydroxyanisol (BHA), butylhydroxytoluene (BHT), polacrilin potassium and mixtures thereof.
None of the agents listed above provide a satisfactorily practical stabilizing effect of amorphous calcium L-5-methylfolate compared as the cysteine one, as it can be seen in Tables 1 to 6 included below on the Example section, specifically at the end of example 6.
Additionally, present inventors have also tested the stabilization effect of other compounds that also contains a —SH group, such as cysteamine or reduced glutathione. None of them provide a satisfactorily practical stabilizing effect of amorphous calcium L-5-methylfolate compared as the cysteine one, as it can be seen in Example 7.
The present inventors have surprisingly found that is possible to stabilize amorphous calcium L-5-methylfolate by mixing it with cysteine, as it is shown in Tables 1 to 6 (see example 6). Furthermore, said mixture can be processed into a stable dosage form, thus providing stabilized formulations comprising amorphous calcium L-5-methylfolate. The incorporation of cysteine as stabilizing agent into the dosage form of the invention allows stabilization of amorphous calcium L-5-methylfolate during the blending, granulation, spray-drying or compression process. Additionally, the amorphous form of calcium L-5-methylfolate is maintained stable in the final dosage form.
Thus, the present invention relates to a dosage form comprising effective amount of amorphous calcium L-5-methylfolate as active ingredient, cysteine as stabilizing agent and optionally further auxiliary agents.
In a preferred embodiment, the present invention relates to a dosage form comprising a spray-dried mixture of amorphous calcium L-5-methylfolate with cysteine and, optionally, further auxiliary agents.
As used herein, the term “spray-dried mixture of amorphous calcium L-5-methylfolate with cysteine”, unless otherwise specified, refers to a mixture of amorphous calcium L-5-methylfolate with cysteine that has been subjected to a spray-drying process.
As used herein “multiparticulate”, unless otherwise specified, refers to the mixture of discrete particles obtained by spray-drying a mixture of amorphous calcium L-5-methylfolate with cysteine in a suitable solvent.
As used herein, the term “dosage form” applies to any solid or semi-solid composition designed to contain a specific pre-determined amount or dose of a certain ingredient, for example amorphous calcium L-5-methylfolate as active ingredient as defined above.
The active substance of the dosage form of this invention is the amorphous calcium L-5-methylfolate, which may be prepared, for instance, in accordance to the process disclosed in patent application US 2010168117, as a general process on pages 1 to 2, paragraphs [0027]-[0034], and specifically disclosed in example 3.
Dosage forms may include, but are not limited to: a) pharmaceutical drug delivery systems, including those for oral administration, buccal administration, rectal administration, topical or mucosal delivery, implants for subcutaneous delivery or other implanted drug delivery systems; or b) compositions for delivering minerals, vitamins and other nutraceuticals, oral care agents, flavorants, and the like.
The dosage forms of the present invention are typically considered to be solid; however, they may contain liquid or semi-solid components. Suitable “dosage forms” of the present invention include, but are not limited to granules, pellets, multiparticles, tablets, caplets, capsules, lozenges, sachets, dispensable powders and the like.
In a preferred embodiment, the dosage form according to the invention comprises a relative weight amount of amorphous calcium L-5-methylfolate to cysteine of at least 1:2, preferably of at least 1:4, more preferably of at least 1:10. Preferably, the relative weight amount of amorphous calcium L-5-methylfolate to cysteine is of 1:2 to 1:40. More preferably, the relative weight amount of amorphous calcium L-5-methylfolate to cysteine is of 1:2 to 1:33. As used herein, the relative weight amount of amorphous calcium L-5-methylfolate to cysteine means the same that the weight ratio of amorphous calcium L-5-methylfolate to cysteine.
Amorphous calcium L-5-methylfolate may be present in an amount from about 0.1% to 60%, preferably from about 0.2% to 40%, more preferably from 0.3% to 30% of the total weight of the dosage form.
Typically, the amount used of amorphous calcium L-5-methylfolate is between 0.1 and 10 mg, preferably 0.4 to 1 mg, particularly preferred 0,451 mg of the total weight of the dosage form.
Cysteine may be present in an amount from about 0.2% to about 70%, preferably from about 0.5% to 60%, more preferably from about 1% to 50% of the total weight of the dosage form.
The dosage form of the invention may, if desired, further include one or more auxiliary agents which may be added during the appropriate step so as to afford the appropriate mechanical and release properties. All such auxiliary agents must be compatible with the other ingredients of the dosage form and not injurious to the human being.
The auxiliary agent may be selected from the group consisting of diluents, binders, lubricants, and disintegrating, antiadherent, colouring, sweetening, flavouring agents, and/or mixtures thereof.
Suitably, the dosage form according to the invention comprises a diluent. Diluents are inert excipients that facilitate compression of pulverulent materials and provide resistance to tablets. Suitable diluents include corn starch, microcrystalline cellulose, powdered cellulose, silicified cellulose, lactose monohydrate, anhydrous lactose, mannitol, sorbitol, sucrose, fructose, dextrose, and/or mixtures thereof. Preferably lactose monohydrate and microcrystalline cellulose are used.
Diluents may be presents in a an amount from about 30% to about 95%, preferably from 40% to 90%, and more preferably form 50 to 87% of the total weight of the dosage form.
Suitably, the dosage form according to the invention comprises a binder. Binders are compounds that are able to provide cohesive properties to pulverulent material, in such a way that the fluidity of the composition is improved. The binding agent is selected from the group consisting of hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, methylcellulose, polyvinylpyrrolidone, sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, and/or mixtures thereof. Preferably polyvinylpyrrolidone is used.
Binders may be present in an amount from about 0.5% to about 10% by weight, preferably from about 2% to about 9% by weight, and more preferably from 2.5% to 7.5% by weight of the total weight of the dosage form.
Disintegrating agents are excipients that promote the rapid breakup of the tablet in an aqueous medium, as well as the rapid disintegration of the granule in order to release more quickly the active substance. Disintegrating agents may be selected from the group consisting of low-substituted hydroxypropyl cellulose, sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, crospovidone, sodium croscarmellose, and/or mixtures thereof. Preferably sodium croscarmellose is used.
Disintegrating agents may be present in an amount from about 1% to about 15% by weight, preferably from about 2% to about 12% by weight, and more preferably from 3% to 10% by weight of the total weight of the dosage form.
Lubricants and antiadherent agents are excipients that reduce interparticular friction and prevent adhesion of drug particles, and improve fluidity of granular or pulverulent compositions. Lubricants may be selected from the group consisting of talc, alkaline earth salts of stearic acid, specially magnesium and calcium stearate, stearic acid, glycerin palmitostearate, stearyl fumarate, and/or mixtures thereof. Colloidal silica is most preferred as an antiadherent agent.
The lubricant may be present in an amount from about 0% to 5% by weight, preferably from about 0% to about 3% based on the total weight of the dosage form.
The antiadherent agent may be present in an amount from about 0% to 5% by weight, preferably from about 0% to about 3% based on the total weight of the dosage form.
The dosage forms of this invention may also contain sweetening and flavouring agents in order to provide acceptable organoleptic properties (flavour and taste) for patients. Suitable sweetening agents include sodium saccharin, aspartame, mannitol, xylitol, sucrose, sorbitol and ammonium glycyrrhizinate. Suitable flavouring agents include fruit and plant flavours, for example orange, anise, mint, etc. Suitable colouring agents, which may be incorporated into the tablets of the invention, may be selected from those approved for oral use.
The tablets may be coated using conventional methods known to a person skilled in the art, as those described in Remington: The Science and Practice of Pharmacy, 20th Edition, Philadelphia, Lippincott, Williams & Wilkins, 2000 [ISBN 0 683 306472]. Among the film-forming agents which are used for coating the tablets, polyvinylpyrrolidone, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, hypromelose, solid polyethyleneglycol, and polyvinyl alcohol may be included.
Information on the characteristics of auxiliary agents is described in reference handbooks available to those skilled in the art, for example in Handbook of Pharmaceutical Excipients, 4th Edition, London, Pharmaceutical Press, 2003 [ISBN 0 85369 472 9] wherein, in addition, the trade names of commercially available auxiliary agents are included. It will be apparent for a skilled person in the art that an auxiliary agent as used herein may be also named a pharmaceutical acceptable excipient.
The dosage form of the invention may, if desired, include further active ingredients. In a preferred embodiment, said further active ingredient is selected from the group of estrogens and progestagens. Suitable estrogens are ethinyl estradiol, mestranol, quinestranol, estradiol, estrone, estrane, estriol, estetrol and conjugated equine estrogens. Ethinylestradiol is particularly preferred.
Examples of suitable progestogens include levonorgestrel, norgestimate, norethistreone, drospirenone, desogestrel, dienogest cyproterone acetate, chlormadinone, gestodene, progesterone and dihydrogesterone. Drospirenone is particularly preferred.
Preferred amounts of ethinyl estradiol used in the dosage form according to the invention are for example 10 to 50 μg, preferably 10 to 30 μg, and more preferably 20 to 30 μg.
Preferred amounts of drospirenone used in the dosage form according to the invention are for example 0.5 to 5 mg, preferably 3 mg of drospirenone.
In a preferred embodiment, the dosage form according to the invention comprises:
In a more preferred embodiment, the dosage form according to the invention comprises:
Another aspect of the invention is the use of the dosage form of the invention for the production of a pharmaceutical composition, for example, contraceptive composition or for the production of compositions for delivering minerals, vitamins and other nutraceuticals, such as multivitamin preparations.
Still another aspect of the present invention refers to a process for the production of a dosage form comprising amorphous calcium L-5-methylfolate comprising blending amorphous calcium L-5-methylfolate with cysteine and optionally one or more auxiliary agents and then forming the dosage form from the blend.
Dosage forms of the invention may be formed from the blend of amorphous calcium L-5-methylfolate with cysteine using standard techniques, and using standard equipment, known to the skilled person, including direct compression/compaction, wet or dry granulation, spray drying, milling, mixing, drying, encapsulation and coating, as well as combinations of these processes.
In a preferred embodiment, the process of the invention comprises the following steps:
In a preferred embodiment, the blend of amorphous calcium L-5-methylfolate with cysteine is produced by spray-drying a mixture of amorphous calcium L-5-methylfolate with cysteine and, optionally one or more pharmaceutically acceptable excipients in a suitable solvent.
In a preferred embodiment, the process of the invention comprises the following steps:
Solvents suitable for spray-drying can be any organic solvent in which amorphous calcium L-5-methylfolate and cysteine are soluble. Preferred solvents include alcohols such as methanol, ethanol, n-propanol, iso-propanol, and butanol; ketones such as acetone, methyl ethyl ketone and methyl iso-butyl ketone; esters such as ethyl acetate and propylacetate; and various other solvents such as acetonitrile, methylene chloride, toluene, and 1,1,1-trichloroethane. Lower volatility solvents such as dimethyl acetamide or dimethylsulfoxide can also be used. Mixtures of solvents can also be used.
Another aspect of the invention is the use of a dosage form according to the invention for the production of a pharmaceutical or nutraceutical composition for reducing the risk of a neural tube defect and other congenital malformations caused by folate deficiency, such as cardiac or urogenital defects, cleft lip, jaw and palate.
Another aspect of the invention, is the use of a dosage form according to the invention for the production of a pharmaceutical or nutraceutical composition for the treatment of high risk recurrent pregnancy loss; for reducing the risk of malignant disorders; for reducing the risk of cardiovascular disorders; for reducing the risk of anemia due to impaired folic acid absorption; for the treatment of early memory loss, mild to moderate cognitive impairment and vascular dementia or Alzheimer disease.
The following examples are given only to illustrate the invention in a sufficiently complete manner.
In order to determine whether the amorphous form of calcium L-5-methylfolate is maintained in the final dosage form, an X-ray diffraction study of the tablet obtained was made. See also
The diffraction measurements were performed at ambient conditions on a PANalytical X'Pert PRO diffractometer with reflection θ-θ geometry, equipped with Cu K-alpha radiation and a PIXcel deterctor, operated a 45 KV and 40 mA.
The detection of very small amounts of crystallized calcium L-5-methylfolate in the final tablets requires the existence of peaks of calcium L-5-methylfolate not interfering with the diffraction signals of the other tablets components (excipients). A tablet containing 0.45 mg of amorphous calcium L-5-methylfolate was diffracted in order to have a preliminary idea of the position of these diffraction signals.
The recorded diffractogram was compared with the diffractograms of previously known crystalline forms of calcium L-5-methylfolate: I, II, III and IV disclosed in U.S. Pat. No. 6,441,168. Best peaks considered for crystalline calcium L-5-methylfolate detection were those found at about 6.5 to 6.9 2θ positions for each of the crystalline forms I, II, III and IV of calcium L-5-methylfolate. For all of them the peak showed at this 2θ position is one of the most intense peaks. Additionally, these signals are located in a position where the background signal of the tablet obtained according to example 1 is less intense.
Based on the above, as is shown in
Powder mixtures of amorphous calcium L-5-methylfolate with each of the stabilizing agents disclosed in the following table were prepared. In all the cases, the mixture contained a weight amount of calcium L-5-methylfolate to stabilizing agent of 1:10. Table 1 shows the amount of Calcium L-5-methylfolate that remains in the mixture after storage at 5° C. for one month.
1HO-MeTHFA: 4α-hydroxy-5-methyltetrahydrofolic acid
2D-Mefox: D-pyrazino-S-triazine derivative
3L-Mefox: L-pyrazino-S-triazine derivative
The results show that the cysteine is the only agent able to stop the degradation of Amorphous Calcium L-5-methylfolate.
In order to confirm the stabilization effect of cysteine on amorphous Calcium L-5-methylfolate, additional test were conducted with both substances, at weight ratios of from 1:0 to 1:33.
The results show that the Cysteine is able to improve the stability of amorphous Calcium L-5-methylfolate. The impurities amount found without cysteine is significantly higher than when cysteine is not used. No significant differences are observed between the tested weight ratios for each condition.
The most significant degradation was found at the most aggressive storage conditions (40° C./75% HR). However, even in this case, the degradation of the LC was reduced when cysteine was used, for all the weight ratios.
The results obtained at the other tested conditions show also that cysteine is able to stabilize amorphous Calcium L-5-methylfolate during the time: no significant increase of the impurities or decrease on the assay value was found between storage at 1 month or 3 months at 25° C./60% HR when cysteine was used.
In case of storage at 5° C., the effect of the cysteine over the time is less important, however it is important to note that the impurities amount is significantly higher than when cysteine is used.
In order to compare the stabilization effect of cysteine on amorphous Calcium L-5-methylfolate in comparison with other compounds containing at least one mercapto group (—SH), such as cysteamine and reduced glutathione, additional test were conducted with both substances, at a relative weight amount of amorphous Calcium L-5-methylfolate:cystamine or reduced glutathione of 1:10.
Stability tests on storage were conducted in the following conditions:
The blend of amorphous Calcium L-5-methylfolate-cysteamine is not stable physically, since at the temperature of the tests the physical state of the samples changes from the solid state to liquid/melt state. This change in the physical properties of the mix is not desired because in case it would be included in the tablets the active could leak out from the tablets leading to a decrease in the drug content.
The blends of amorphous Calcium L-5-methylfolate-reduced glutathione were analyzed in order to monitor the stabilization effect of reduced glutathione on amorphous Calcium L-5-methylfolate.
In both conditions tested (25° C./60% RH and 40° C./75% RH) after just 14 days less than 75% of Amorphous Calcium L-5-methylfolate remains in the mixture. Thus, reduced glutathione does not stabilize amorphous Calcium L-5-methylfolate.
The stability test confirmed again that cysteine is the only agent able to stop the degradation of Amorphous Calcium L-5-methylfolate. The mechanism is not already clear but it is postulated that the cysteine has a particular effect compared with others stabilizing agents and that this effect is enhanced in an enantiomeric compound compared with in a racemic mixture.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13382106.6 | Mar 2013 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/055026 | 3/13/2014 | WO | 00 |
