Water-soluble non-effervescent pharmaceutical compositions comprising non-steroidal anti-inflammatory drugs

Abstract: Water-soluble non-effervescent pharmaceutical compositions comprising a water-soluble salt of a NSAID having an arylpropionic or arylacetic structure and a mixture of at least two pharmaceutically acceptable completely salified di- or tricarboxylic organic acids, in amounts and proportions as to mask the taste of the NSAID salt in aqueous solution are described. The compositions according to the present invention, even without flavors, provide perfectly drinkable aqueous solutions that, after ingestion, do not elicit the unpleasant irritating feeling typical of known formulation.

Description: The present invention relates to non-effervescent pharmaceutical compositions soluble in water and, in particular, to pharmaceutical compositions comprising a water-soluble salt of a non-steroidal anti-inflammatory drug (NSAID) in admixture with completely salified di- or tricarboxylic organic acids. NSAIDs are drugs that have been used for long time in therapy, mainly due to their anti-inflammatory and analgesic properties. Structurally they pertain to some general classes, among which those of arylpropionic and arylacetic acid derivatives are herein particularly relevant. Examples of said acids are ibuprofen, keoprofen, naproxen, flurbiprofen and diclofenac (Merck Index, 12 th edition, 1996). The oral formulations and, in particular, the drinkable aqueous solutions, of said NSAIDs could represent, in many cases, particularly advantageous means of administration, being easily ingested, painless and, due to the pre-dissolution of the active component, generally rapidly effective. However the preparation of aqueous oral formulation of NSAIDs is affected by both the low solubility of the drug, especially in its non-salified form, and by the unpleasant and stinging taste given by said substances to the solution. This problem is particularly relevant for pediatric pharmaceutical formulations in which even the slightest residue of taste or irritation may imply a total refusal of the drug for the child. In the literature, with the aim to obviate to that drawback, several effervescent and non-effervescent compositions have been studied, in which, besides solubilizing the drug, an attempt of masking the unpleasant taste by adding sweeteners, flavors or masking substances was made. Effervescent formulations, such as those based on ibuprofen described in the patent US4689218, allow a rapid disintegration of the pharmaceutical form by using admixtures of carbonates and /or bicarbonates together with organic acids that, when placed in water, evolve carbon dioxide. In general said formulations assure a satisfying solubilization of the active compound while do not solve the problem of palatability: in fact, anyhow, their aqueous solutions show an unpleasant and stinging taste when ingested. Among water-soluble non-effervescent NSAID formulations those described in the European patent applications EP906092 and EP418043 may be cited; the last one, in particular, describes compositions in which a water-soluble salt of ibuprofen is associated with a bicarbonate, a momohydrogenphosphate or a tribasic citrate with the aim to improve the low palatability in aqueous solution. The document, which underlines the use of bicarbonates and reports that momohydrogenphosphates and tribasic citrates have a less effective masking activity, neither mentions other suitable organic acids nor, least of all, suggests the use of mixtures of said acids. In addition EP418043 defines the use of additional excipients as optional, but solely exemplifies compositions which always include other taste-masking substances, such as sweeteners and flavors, in particular currant flavor, in addition to the masking agent above mentioned. However the corresponding aqueous solutions, although containing flavors, still show a low palatability that makes their ingestion unpleasant. In addition the presence of flavors is not always ideal, especially for pediatric formulations. In fact, if the chosen flavor is not particularly pleasant to the child, it is in practice impossible to mask it by adding milk or other drinks, making the administration of the drug difficult. In this case, therefore, it would be preferable to have a sweetened but not flavored solution, in order to adapt it to the child taste with specific corrections. In conclusion, as far as we know, the water-soluble NSAID compositions described in the art or available on the market do not satisfactorily solve the problem of palatability of NSAID aqueous solutions, notwithstanding the use of flavors. We have now surprisingly found that it is possible to effectively mask the unpleasant taste of aqueous solutions of water-soluble NSAID salts without using flavoring substances, with obvious advantages in terms of acceptance by patients, simplification of the preparation process and reduction of costs for the final pharmaceutical form. In the present contest the term "to mask" takes the meaning of significantly reduce or, preferably, eliminate the unpleasant feeling of irritation of the oral mucosa that usually follows the ingestion of classical NSAID aqueous solutions, comprising flavors and sweeteners. Therefore, object of the present invention is a solid non-effervescent water-soluble pharmaceutical composition, in particular a granulate, comprising a water-soluble salt of a NSAID having an arylpropionic or arylacetic structure and a mixture of at least two pharmaceutically acceptable di- or tricarboxylic organic acids, completely salified, optionally in admixture with pharmaceutically acceptable excipients, in which said organic acids are present in amounts and proportions as to mask the taste of the salt of said NSAID in the aqueous solution. A second object of the present invention is represented by palatable aqueous solutions obtainable by dissolving the above compositions in water; although the amount of water to be used is not binding, a solution according to the present invention is generally preparable by dissolving 900 to 3000 mg of composition, preferably 900 to 2000 mg, in 100-250 ml of water. A third object of the invention relates to a process for manufacturing water-soluble granulates according to the invention. Finally, a further object of the invention is represented by a method for masking the unpleasant taste of water-soluble NSAID salts in aqueous solution by dissolving a formulation according to the present invention in water. The compositions according to the present invention comprise a water-soluble NSAID salt having an arylpropionic or arylacetic structure. Non-limiting examples of said NSAIDs are ibuprofen, ketoprofen, naproxen, flurbiprofen, diclofenac, sulindac, fenoprofen, ibufenac, ketorolac, pranoprofen and aclofenac. Ibuprofen, ketoprofen, naproxen, flurbiprofen and diclofenac are preferred NSAIDs. Generally, water-soluble salts of said NSAIDs usable in the present invention, include sodium or potassium salts or salts of pharmaceutically acceptable nitrogenous substances such as aminoacids, for example lysine or arginine, or aminoalcohols, such as for example methylglucamine. Said salts may be previously formed or, alternatively, directly prepared in situ according to techniques known to the skilled in the art. The present compositions comprise a mixture of at least two pharmaceutically acceptable di- or tricarboxylic organic acids, completely salified, in addition to the water-soluble NSAID salt. Organic acids suitable for the above use are, for example, dicarboxylic acids such as succinic, malic, fumaric, adipic and tartaric acid and the tricarboxylic acids such as citric acid, fumaric, tartaric and citric acid being particularly preferred. However, apart from the above-mentioned acids, other pharmaceutically acceptable polycarboxylic organic acids can be successfully used which, suitably salified and dissolved in water, provide a solution having a pH from 7.2 to 8.5. Usually said acids are used in the form of alkaline metal salts or as salts with pharmaceutically acceptable organic bases, such as for example, basic aminoacids, optionally as mixed salts, preferably as sodium or potassium salts. In the compositions object of the present invention the above-defined salified organic acids are used in admixture, preferably as a binary mixture. Preferred binary mixtures are citric acid / tartaric acid and citric acid / fumaric acid mixtures. The organic acids composing the mixture can be salified with the same or different cations. Said organic acids can be used in variable proportions, depending on the kind of NSAID chosen too and however such as to confer a good palatability to the final aqueous solution. In particular, in the case of binary mixtures, the weight ratio between the two salified acids is generally comprised between 15:1 and 0.07:1, preferably between 11:1 and 2:1; instead, the weight ratio between the total amount of said salified organic acids and the salified active compound is generally comprised between 1:1 and 10:1, preferably between 2:1 and 7:1. In the preferred embodiment of the invention, the present formulation contains a tartaric acid / citric acid or fumaric acid / citric acid binary mixture, wherein the mutual weight ratio between the two above salified acids is comprised between 1:2 and 1:5 and, more preferably, said mixtures in which the weight ratio between the two above salified acids is comprised between 1:2 and 1:5 and in which the citric acid prevails. With respect to the single dosage unit of the active drug the total amount of salified organic acids is generally comprised between 100 and 4000 mg, preferably between 150 and 2000 mg, wherein with the term "dosage unit" the amount of the active drug taken in a single administration is intended. The optimization of the compositions in object, by selecting the kind of acid, their salts, optional sweeteners and the amounts thereof, falls within the normal capabilities of the skilled in the art and anyway is oriented to the achievement of the best possible technological result, that is palatability of the NSAID final aqueous solutions. Said choice, obviously, takes also into account that the final pH of the aqueous solution can not reach extreme values in that it is known that, at acidic values, the acid form of the NSAID could precipitate while, at basic values, damaging effects on the mucosae could occur. Generally, the pH of the aqueous solution deriving from the dissolution of the present compositions is comprised in the range from 7.0 to 8.5, preferably from 7.2 and 7.8, even more preferably at about 7.4. It is useful to underline that the better palatability of the present compositions with respect to those described in the art is a consequence not only of a simple action of pH buffering of the final aqueous solution, but comes just from the presence of said particular completely salified organic acids in admixture, as experimentally proven in the comparative example n. 10. In fact, in that experiment, a composition according to the present invention, even without flavors, results better than a known composition comprising tribasic citrate alone and having the same pH (example 8 of the patent EP418043) in the palatability test. The non-effervescent water-soluble compositions of the present invention may be under different solid oral pharmaceutical forms, for example, in the form of a powder, a granulate or a chewable tablet. In addition liquid oral formulations, such as syrups or drops, obtainable by dissolving the above solid compositions or, alternatively, preparable by dissolving in water single pre-weighted components and, if necessary, by correcting the volume up to the desired value, are also within the scope of the invention. A preferred composition, according to the present invention, is represented by granulates, in particular by a granulate comprising a mixture of sodium or potassium tartrate, tripotassium citrate and sodium or potassium diclofenac, in which said sodium or potassium tartrate and said tripotassium citrate are present in a weight ratio comprised from 1:1 to 2:1 and from 4:1 to 5:1, respectively, per unity of sodium or potassium diclofenac. The compositions object of the present invention, with the aim to make the administration of the product even more pleasant, may comprise additional non flavoring pharmaceutically acceptable excipients, i.e. saccharin, aspartame, cyclamate, acesulfame, saccharose, sorbitol, fructose and mixtures thereof, in such amount as to appropriately sweet the final solution. In addition, especially in the case of granulates and powders, it is possible to add suitable diluents such as mannitol, lactose, dextrose or other polyalcohols while, for chewable tablets, disintegrants or other excipients commonly used in the field may be included. The preparation of the solid compositions in object, in case of granulates, preferably occurs as described in the experimental part while in case of powders and chewable tablets it is performed by mixing the components and, for tablets, by the subsequent compression of the mixture, according to traditional techniques. With a purely exemplifying and not limiting scope, some preparative examples of the compositions object of the present invention are now reported. Examples Preparation of water-soluble granulates The NSAID salt is accurately mixed with 50% of the total weight of the chosen di- and tricarboxylic acids and with the sweeteners. The mixture is kneaded with the lowest amount of water, it is granulated and it is dried in a ventilated oven. The so obtained granulate is directly mixed with the remaining 50% of the mixture of acids and, optionally, with the reported diluent in a granular form. Thus the water-soluble granulates of the following examples 1-9 were prepared: Example 1 Sodium Diclofenac 50 mg 25 mg Dipotassium tartrate O.P. 100 mg 50 mg Tripotassium citrate O.P. 200 mg 100 mg Saccharin 10 mg 5 mg Aspartame 100 mg 50 mg Granular mannitol 940 mg 670 mg Total 1400 mg 900 mg Example 2 Potassium diclofenac 50 mg 25 mg Disodium tartrate hydrate O.P. 50 mg 25 mg Tripotassium citrate O.P. 250 mg 125 mg Saccharin 10 mg 5 mg Aspartame 100 mg 50 mg Granular mannitol 440 mg 670 mg Total 900 mg 900 mg Example 3 Potassium diclofenac 50 mg 25 mg Dipotassium tartrate O.P. 200 mg 100 mg Trisodium citrate O.P. 100 mg 50 mg Saccharin 10 mg 5 mg Aspartame 100 mg 50 mg Granular mannitol 440 mg 670 mg Total 900 mg 900 mg Example 4 Sodium ibuprofen dihydrate 256 mg Disodium tartrate O.P. 150 mg Tripotassium citrate O.P. 550 mg Saccharin 10 mg Aspartame 80 mg Granular mannitol 154 mg Total 1100 mg Example 5 Sodium ibuprofen dihydrate 512 mg Dipotassium tartrate O.P. 100 mg Tripotassium citrate O.P. 1.100 mg Saccharin 30 mg Aspartame 100 mg Granular mannitol 158 mg Total 2000 mg Example 6 Ibuprofen lysine salt 342 mg Disodium tartrate O.P. 100 mg Tripotassium citrate O.P. 450 mg Saccharin 10 mg Aspartame 80 mg Granular mannitol 118 mg Total 1100 mg Example 7 Sodium naproxen 257 mg Potassium fumarate O.P. 100 mg Tripotassium citrate O.P. 500 mg Saccharin 10 mg Aspartame 80 mg Granular mannitol 135 mg Total 1100 mg Example 8 Sodium naproxen 500 mg Potassium tartrate O.P. 350 mg Tripotassium citrate O.P. 800 mg Saccharin 20 mg Aspartame 160 mg Granular mannitol 170 mg Total 2000 mg Example 9 Ketoprofen lysine salt 80 mg Disodium tartrate O.P. 100 mg Tripotassium citrate O.P. 250 mg Saccharin 10 mg Aspartame 100 mg Granular mannitol 360 mg Total 900 mg The compositions of the above reported examples 1-9, when dissolved in water, provide drinkable solutions characterized by an excellent palatability. Example 10 (comparative example) In the present example the following compositions, according to EP418043 and to the invention, were prepared: EP418043 (ex. 8) Invention Sodium ibuprofen 512 mg 512 mg Disodium tartrate O.P. ----- 100 mg Tripotassium citrate O.P. ----- 1100 mg Trisodium citrate O.P. 600 mg ----- Saccharin 50 mg 50 mg Dextrose 2000 mg 1440 mg Current flavor 40 mg ----- Total 3202 mg 3202 mg The two compositions were dissolved in water (100 ml) providing clear solutions with a pH at about 7.4. The composition according to the present invention, even without flavors, provides a perfectly drinkable solution and shows a greater palatability than the one known. In fact, after ingestion, it does not cause the unpleasant feeling of irritation that results with the comparison formulation.

Claims: A water-soluble non-effervescent solid pharmaceutical composition comprising a water-soluble salt of a NSAID having an arylpropionic or arylacetic structure and a mixture of at least two pharmaceutically acceptable di- or tricarboxylic organic acids, completely salified, optionally in admixture with pharmaceutically acceptable excipients. A composition according to claim 1 in which said NSAID is selected from ibuprofen, ketoprofen, naproxen, flurbiprofen and diclofenac. A composition according to claim 1 in which said water-soluble salt of a NSAID is a sodium, potassium, lysine, arginine or metilglucamine salt. A composition according to claim 1 in which said organic acid salts are salts of alkaline metals or pharmaceutically acceptable organic basis or mixtures thereof, preferably sodium or potassium salts. A composition according to claim 1 in which said salified organic acids are present in an overall weight ratio comprised between 1:1 and 10:1 with respect to the salified NSAID, preferably between 2:1 and 7:1. A composition according to claim 1 in which said salified organic acids are present in an overall amount between 100 and 4000 mg, preferably between 150 and 2000 mg, per dosage unit. A composition according to claim 1 in which said mixture of di- or tricarboxylic organic acids comprises at least two acids selected among succinic, malic, fumaric, adipic, tartaric and citric acid. A composition according to claim 7 in which said mixture of organic acids is a binary mixture wherein the weight ratio between the two organic acids is comprised between 15:1 and 0.07:1, preferably between 11:1 and 2:1. A composition according to claim 7 in which said mixture of organic acids is a binary mixture of tartaric acid / citric acid or fumaric acid / citric acid in a reciprocal weight ratio comprised between 1:2 and 1:5. A composition according to claim 1 which, by dissolution, gives a pH comprised between 7.2 and 7.8, preferably a pH of about 7.4, to the aqueous solution. A composition according to claim 1 in which said excipients are sweeteners selected among saccharin, aspartame, cyclamate, acesulfame, saccharose, sorbitol, fructose and mixtures thereof. A composition according to claim 1 in a granular form. A composition in a granular form according to claim 12 comprising a mixture of sodium or potassium tartrate, tripotassium citrate and sodium or potassium diclofenac, in which said sodium or potassium tartrate and said tripotassium citrate are present in a weight ratio respectively comprised from 1:1 to 2:1 and from 4:1 to 5:1 per unity of sodium or potassium diclofenac. A liquid oral pharmaceutical composition obtainable by dissolution in water of the composition according to claim 1. A process for manufacturing a granulate according to claim 12 which comprises the steps of: a) mixing the water-soluble salt of the NSAID, the optional sweeteners and 50% by weight of the organic acid mixture, b) wet-granulating and drying the mixture, and c) blending the granulate with the remaining 50% by weight of the organic acid mixture and, optionally, with a diluent in a granular form.

Inventors: REINER ALBERTO, REINER GIORGIO, REINER, ALBERTO, REINER, GIORGIO
Applicants: APR APPLIED PHARMA RES S A, APR APPLIED PHARMA RESEARCH S.A.
Application year: 2001
Main classification: A61K9
IPC codes: A61K31, A61K9