Process to prepare water-dispersable tablets containing diclofenac

Abstract: A new procedure to prepare a new formulation of dispersible diclofenac tablets is described. It is characterized by the compression of a mixture consisting of granules containing a hydrophilic lubricant and a disintegrant, in addition to micronized diclofenac as the active principle and other excipients, and a powder that contains, also in addition to other excipients, a hydrophilic lubricant and a disintegrant. By weight, the total amount of hydrophilic lubricants is from 2.5 to 5% and the total amount of disintegrants is from 13 to 17%.

Description: The present invention concerns a dispersible tablet formulation comprising diclofenac. The invention is also directed to a process for the preparation of such a dispersible tablet formulation. The invention also concerns a dispersible tablet formulation for use in administering finely divided diclofenac. From a. biopharmaceutical point of view, solid pharmaceutical dosage forms, such as tablets and capsules, which are orally administered by swallowing, provide an accurate dosage of the active principle; but, since they have to disintegrate in the gastrointestinal tract prior to their dissolution, the absorption tends to be slower than if the drug is administered in a dispersed form, such as suspensions and powders or granules dispersed in water. In addition, some people are unable or unwilling to swallow tablets and capsules, and thus dipersible tablets are advantageous because are well-accepted specially by children, patients who find the medicine difficult to swallow, the elderly, and patients with mental illness. The active principle of the dispersible tablets to which this invention refers is diclofenac, a non-steroidal anti-inflammatory compound that also has analgesic properties, in therapeutic doses, usually between 23 and 93 mg per tablet. Its use is indicated in a variety of processes that cause pain and inflammation. In many pharmaceutical specialties, already on the market in numerous countries, it is included as a salt, for example sodium diclofenac or diethylamonium diclofenac. Its usefulness has been proved in long-term therapy of several illnesses with inflammatory component, and it is recommended in the treatment of the rheumatic processes. The formulation of diclofenac in the form of dispersible tablets is of great interest since, as indicated, diclofenac is useful to treat processes that old people, in particular, suffer from. On the other hand, diclofenac in this galenic form is more rapidly absorbed, and therefore, its therapeutic effect is more quickly perceived. This is very important when dealing with pain. The European patent number 0 365 480 A1 of Ciba-Geigy AG describes a dispersible formulation of the active principle diclofenac, as well as a procedure for preparing it. The document DE-A 14 92 019 is concerned with additives for drug tablets in the process of manufacturing such tablets. The granulation step in said process was tried to be avoided by adding to the tablet formulations a mixture of carboxymethylcellulose and at least one of the substances of a group containing polyethylene glycol 6000, together with usual lubricants like stearic acid and magnesium stearate. The document EP-A 0 408 273 is addressing the field of tabletting compositions of Fosinopril which compositions are described in the prior art as moisture sensitive and only marginally stable and as requiring the use of a protective package in order to allow a practically useful shelf life. The present invention refers to a new formulation of dispersible diclofenac tablets, that disintegrate in less than 3 minutes after dropped into water at room temperature, and its preparation process. This dispersible tablet in water results in a fine dispersion, which facilitates oral administration of the drug and achieves a good dissolution rate and bioavailability of the active principle. The present invention concerns a dispersible tablet formulation comprising finely divided diclofenac having a particle size of less than 10 µm; a disintegrant selected from polyvinylpolypyrrolidone and carboxymethylstarch and combinations thereof; a hydrophilic lubricant selected from polyethyleneglycol 6000 and sodium stearylfumarate and combinations thereof; one or more of common excipients for solid formulations; and colloidal silicon dioxide as a glidant. The invention also concerns a process for the preparation of a dispersible tablet formulation comprising the steps of (a) wet granulation of a solid mixture of finely divided diclofenac having a particle size of less than 10 µm, polyvinylpolypyrrolidone and one half of the total amount of carboxymethylstarch in the presence of a granulation liquid consisting of 5 % hydroalcoholic polyethyleneglycol 6000 solution to obtain dry granules containing the active principle; (b) incorporation of the remainder of said carboxymethylstarch, sodium stearylfumarate, colloidal silicon dioxide and one or more common excipients for solid formulations as a powder to said dry granules to obtain a mixture of granules in a powder; and (c) compression of said mixture. The invention also relates to the dispersible tablet formulation as described above for use in administering finely divided diclofenac. These dispersible tablets can also be used as traditional tablets; in this case, their dispersion in the gastrointestinal tract is also faster than for traditional tablets. Micronized diclofenac, with a particle size of less than 10 µm, is used, thus improving dissolution and bioavailability as compared to tablets in which the active principle is not micronized. In order to obtain the dispersible tablets referred to in this invention, a compression process is carried out in 3 phases: a) Wet granulation of the active principle and part of the excipients, representing ca. 85% of the total weight of the product to be compressed; b) Incorporation of the rest of the excipients as a pulverulent solid to the dry granules obtained in the first phase; c) compression of the mixture. Excipients have been carefully selected to get a mixture to be compressed with suitable compressibility characteristics, and also so that the tablets obtained be immediately dispersible in water with a satisfactory particle size. These dispersible tablets disintegrate in less than three minmutes when they are subjected to the disintegration test for tablets and capsules as per Appendix XIIA of the 1988 British Pharmacopoeia, and comply with the test for uniformity of dispersion and uniformity of weight. Common excipients for solid formulations, such as microcrystalline cellulose, corn starch and lactose, are used as diluents to increase the volume of the mass to be compressed and facilitate the compression process. In order to fulfil the requirements for dispersibility of the tablet when dropped in water, polyvinylpolypyrrolidone and carboxymethylstarch are used in combination as disintegrants; the total amount of disintegrants represents 13 to 17% of the final weight of the tablet. The disintegrants are incorporated into the mass to be compressed as follows: The polyvinylpoly-pyrrolidone and half of the carboxymethylstarch of the formulation are added before the wet granulation process, in order to promote disintegration directly in the primary particles that make up the granules. The rest of the carbonxymethylstarch is added after the granulation process, blended with the remaining ingredients and then compressed. In the process to prepare these dispersible tablets conventional hydrophobic lubricants are not used; instead, two hydrophilic products have been selected: Polyethylenglycol 6000, which is added dissolved in the granulation liquid, and sodium stearylfumarate, which is added in a fine powder form before proceeding to compression. Sodium stearylfumarate is preferred over more hydrophobic lubricants because suitable hard tablets of uniform contents, disintegration and dissolution rate are achieved. Sodium stearylfumarate contributes in an important manner to the characteristics of the tablets. The polyethylenglycol 6000 dissolved in the granulation liquid helps to obtain a good quality unabrasive granulated mass, thus causing less deteriotation in the machine used and easier to handle. An important aspect of this invention is the use of these lubricants as indicated. A glidant can also be added included in the formulation, preferably colloidal silicon dioxide, which provides suitable flow properties to the mixture to be compressed. The glidant is added in the proportion of 0.5% of the final tablets weight. A flavour and a sweetener are also added in order to provide adequate organoleptic characteristics. To illustrate the scope of the invention, but without limiting it as there are several possible variations thereof, the following examples are offered. Example 1 Composition per dispersible tablet: Micronized diclofenac 46.5 mg Microcrystalline cellulose 156.5 mg Corn starch 30 mg Plyethylenglycol 6000 8 mg Polyvinylpolypyrrolidone 15 mg Carboxymethylstarch 30 mg Sodium saccharine 4.5 mg Orange flavour 10 mg Sodium stearylfumarate 6 mg Colloidal silicon dioxide 1.5 mg Manufacturing process: A granulation solution, consisting of a 5% hydroalcoholic polyethylenglycol 6000 solution, is prepared. The micronized diclofenac, The microcrystalline cellulose, the corn starch, The polyvinylpyrrolidone, and half of the total amount of carboxymethylstarch are mixed, after passed through a 0.6 mm mesh sieve. Once a homogeneous mixture is obtained, it is moistened with the 5% hydroalcoholic polyethylenglycol 6000 solution. The moistened mass is passed through a 1 mm mesh sieve, and the obtained granules are dried and passed through a 0.6 mm mesh sieve. The dry, sieved granules are placed in a suitable mixer, and the flavour, the sweetener and half of the carboxymethylstarch of the formulation, previously passed through a 0.6 mm mesh sieve, are added. Colloidal silicon dioxide and sodium stearylfumarate, previously sieved through 0.6 mm, are added. It is all mixed until a homogeneous mixture is obtained, which is then compressed. Example 2 Composition per dispersible tablet: Micronized diclofenac 46.5 mg Microcrystalline cellulose 178 mg Polyethylenglycol 6000 8 mg Polyvinylpolypyrrolidone 15 mg Carboxymethylstarch 30 mg Sodium saccharin 3 mg Orange flavour 20 mg Sodium stearylfumarate 6 mg Colloidal silicon dioxide 1.5 mg Manufacturing process: The micronized diclofenac, the microcrystalline cellulose, the polyvinylpolypyrrolidone and half of the carboxymethylstarch are mixed. Once a homogeneous mixture is obtanined, it is moistened with the granulation solution, consisting of a 5% hydroalcoholic solution of polyethylenglycol 6000. This is granulated, and the dry granulation is mixed with the sodium saccharin, the orange flavour, the rest of the carboxymethylstarch, the colloidal silicon dioxide, and the sodium stearylfumarate. The mixture thus obtained is compressed. Example 3 Composition per dispersible tablet: Micronized diclofenac 46.5 mg Microcrystalline cellulose 143 mg Lactose 38.5 mg Polyethylenglycol 6000 8 mg Polyvinylpolypyrrolidone 15 mg Carboxymethylstarch 35 mg Sodium saccharin 2 mg Flavour 17 mg Sodium stearylfumarate 3 mg Manufacturing process: The micronized diclofenac, the microcrystalline cellulose, the lactose, the polyvinylpolypyrrolidone, and half of the carboxymethylstarch are mixed. This mixture is moistened with the 5% hydroalcoholic polyethylenglycol 6000 solution. The granulation obtained is dried and then the rest of the carboxymethylstarch, the sodium saccharin, the flavour and lastly the sodium stearylfumarate, are added to it. Once a homogeneous mixture is obtained, it is compressed. Described the nature of the invention and the way to put it into practice, it should be noted that the foregoing is subject to detail modifications, provided they do not alter its fundamental principle which is characterized by the following claims.

Claims: A dispersible tablet formulation comprising finely divided diclofenac having a particle size of less than 10 µm; a disintegrant selected from polyvinylpolypyrrolidone and carboxymethylstarch and combinations thereof; a hydrophilic lubricant selected from polyethyleneglycol 6000 and sodium stearylfumarate and combinations thereof; one or more of common excipients for solid formulations; and colloidal silicon dioxide as a glidant. The dispersible tablet formulation according to claim 1, wherein said finely divided diclofenac is present in an amount of from 7 to 23 % by weight. The dispersible tablet formulation according to any of the claims 1 or 2, wherein the total amount of said hydrophilic lubricants is from 2.5 to 5 % by weight. The dispersible tablet formulation according to any of the claims 1 to 3, wherein the total amount of said disintegrants is from 13 to 17 % by weight. A process for the preparation of a dispersible tablet formulation comprising the steps of (a) wet granulation of a solid mixture of finely divided diclofenac having a particle size of less than 10 µm, polyvinylpolypyrrolidone and one half of the total amount of carboxymethylstarch in the presence of a granulation liquid consisting of 5 % hydroalcoholic polyethyleneglycol 6000 solution to obtain dry granules containing the active principle; (b) incorporation of the remainder of said carboxymethylstarch. sodium stearylfumarate, colloidal silicon dioxide and one or more common excipients for solid formulations as a powder to said dry granules to obtain a mixture of granules in a powder; and (c) compression of said mixture. The process according to claims 5, wherein said sodium stearylfumarate is added in an amount of 2.5 to 5 % by weight. The process according to any of the claims 5 or 6, wherein said finely divided diclofenac is added in an amount of from 7 to 23 % by weight. The process according to any of the claims 5 to 7, wherein said colloidal silicon dioxide is added in an amont of 0.5 % by weight. The process according to any of the claims 5 to 8, wherein the total amount of polyvinylpolypyrrolidone and carboxymethylstarch is adjusted to a range of from 13 to 17 % by weight. The dispersible tablet formulation according to any of the claims 1 to 4 for use in administering finely divided diclofenac.

Inventors: BEASCOA-ALZOLA ESPERANZA, LUCERO-DE PABLO MA LUISA, ORJALES-VENERO AURELIO, BEASCOA-ALZOLA, ESPERANZA, LUCERO-DE PABLO, MA LUISA, ORJALES-VENERO, AURELIO
Applicants: ESPANOLA DE PRODUCTOS FAB, FABRICA ESPANOLA DE PRODUCTOS
Application year: 1993
Main classification: A61K9
IPC codes: A61K9, A61K31