JP2774135B2 - Solid, rapidly disintegrating dosage form - Google Patents

Description

The present invention relates to an effervescent tablet for producing an aqueous suspension of diclofenac or a salt thereof, which is suitable for oral administration.
The tablets provide a rapid or sustained release of the active drug. The invention furthermore relates to a suspension obtainable by disintegrating this dosage form in the aqueous phase, in micronized form in effervescent tablets and in an aqueous suspension obtainable therefrom. Furthermore, the present invention relates to diclofenac or a salt thereof having osmotic swellability, a method for preparing the effervescent tablet, and use thereof.

[Problems to be solved by conventional technology and invention]

A variety of medicaments with different structures are useful for treating painful inflammatory conditions, such as rheumatism, for example, obtaining non-steroidal anti-inflammatory drugs (NSAIDs). The poorly water-soluble drug, diclofenac, belongs to this class of drugs and is also a poorly water-soluble and its sodium salt poorly water-soluble, also available under the name VOLTAREN (Ciba-Geigy).

For example, oral dosage forms of NSAIDs, tablets that disintegrate in the stomach, pose the problem of too slow diffusion as a local overconcentration, and furthermore, poor distribution of the active drug in gastric juices
It occurs during disintegration and poses a risk of irritation to the gastric mucosa and a risk of ulceration with prolonged administration. For this reason,
NSAIDs in the form of tablets should be administered at the time of meal, so that the distribution that usually only takes place by diffusion,
It occurs more quickly and uniformly due to the convection of the active drug.

NSAIDs that, even when administered outside of mealtime, can provide a uniform dispersion of the active ingredient in gastric juice, ignoring time and thereby reduce the risk of gastric mucosal irritation required by the increased concentration There is a need to provide new oral dosage forms. In addition, such a dosage form also allows for more effective use of diclofenac as an analgesic by administering immediately when pain symptoms occur, without having to wait for the first dose before a meal can be taken. Bring.

An effervescent formulation containing acetylsalicylic acid as a poorly soluble NSAID having a definite analgesic effect is available, for example, from Alkazelzer effervescent tablets (Bayer) containing calcium carbonate as a stabilizer. When such effervescent tablets dissolve, a water-soluble calcium salt having a neutral taste is formed. The complete dispersion of this soluble salt in water, after ingestion of the solution, initiates a rapid analgesic effect in the gastric juice and reduces the risk of irritation of the gastric mucosa due to the low concentration in the large volume of liquid.

To date, similar effervescent formulations as well as other rapidly disintegrating formulations such as powders or granules have not been available for the NSAID diclofenac and its salts. The reason for this is that if such dosage forms were to disintegrate, the active ingredient could not be converted to a pharmaceutically suitable form of a water-soluble salt having a neutral taste. Usually, the bitter taste of the active ingredients renders such forms unsuitable.

[Means for solving the problem, operation and effect of the invention]

It is an object of the present invention to provide a new and therapeutically more effective formulation for diclofenac, a poorly soluble drug, which disintegrates rapidly and improves taste. This formulation provides a homogeneous dispersion of the active ingredient in the aqueous phase without disturbing its taste upon disintegration.

This object has been achieved by the present invention, which provides a solid, effervescent tablet in order to produce an aqueous suspension.
For a rapidly disintegrating dosage form, this is micronized diclofenac or a corresponding coated pharmaceutically acceptable salt of diclofenac, which is suitable for oral administration and has a water-permeable swellable coating, as well as a pharmaceutically acceptable salt Contains excipients.

The present invention relates to effervescent tablets containing diclofenac, preferably having an average particle size of less than 200 μm, more preferably less than 100 μm, suitable for effervescent formulations, a suspending agent and optionally also a pharmaceutical excipient. About.

When water is added to the effervescent tablet, a suspension is formed, accompanied by the evolution of carbon dioxide. The suspension is stable for about 5 to 10 minutes required for ingestion without fixed sedimentation and has a neutral or favorable taste. After the dosage form has disintegrated, the diclofenac can be suspended in water and coated with a coating of high permeability to diclofenac, for example a dimethylaminoethyl methacrylate / methacrylate copolymer of polyvinylpyrrolidone or Eudragit E type (Rhm pharma) at the appropriate thickness. Upon release, it is released into the stomach, and this coating is stable in gastric juice. Rapid release of the active drug is important whenever pain symptoms should be treated immediately in a short time if they occur and a rapid onset of action is desirable at higher doses, while gastric mucosa The danger of irritation to should be substantially eliminated. Non-mouth permeable coatings, such as Eudragit E
The choice of the type of acrylate / methacrylate copolymer, and optionally the choice of a thicker thickness, can extend the duration of action and delay the release of the active ingredient in the stomach. When using diclofenac as an antirheumatic drug in long-term treatment, the persistence of the active drug is important. Because of their easier and more convenient ingestion, aqueous suspensions giving sustained release of diclofenac for oral administration can favorably replace conventional tablets with resistant film coatings. . The terms and expressions used in the present invention are presented as follows within the scope of the present invention.

The effervescent tablet of the present invention disintegrates in water, with the generation of carbon dioxide within 3 minutes, preferably within 1 minute, and has a neutral or pleasant taste suitable for drinking a slightly turbid aqueous drink. Give a suspension of the drug. This suspension can be taken directly after the effervescent tablet has completely disintegrated.

Effervescent tablets contain diclofenac, o- (2,6-dichloroanilino) phenylacetic acid, in free form or as a pharmaceutically acceptable salt thereof.

Particularly preferred salts of diclofenac are the sodium and potassium salts (METAX INDEX, 10th edition N
o.3066).

The micronized diclofenac salt has a preferred average particle size of less than 200 μm, preferably less than 100 μm. Particles having this particle size can be obtained by crushing in a usual crushing means, for example, in an air jet mill, a ball mill or a vibrator mill. Micronization is preferably performed using an ultrasonic disintegrator, such as J.
Pharm. Sci 53 (9), 1040-1045 (1965) by a method known per se having a Branson sonifier type or alternatively a high-speed stirrer, for example a homolex type stirrer (Broglyand Co. Basel) ) By stirring the suspension using a commercially available stirrer.

Microparticulate diclofenac, or a pharmaceutically acceptable salt thereof, is provided with a permeable, swellable coating that is made of an elastic material, which can be used in aqueous bodily fluids such as, for example, gastric fluid or interstitial fluid. It is permeable to water or to water and is also swellable and / or soluble in this body fluid.

The water-permeable elastic film-like material is typically a hydrophilic mixture of polyvinylpyrrolidone or a copolymer of polyvinylpyrrolidone and polyvinylacetate with hydroxymethylcellulose, a mixture of polyvinylpyrrolidone and a polysorbate, such as polysorbate 80, shellac and It is a mixture with hydroxypropylmethylcellulose, polyvinyl acetate or a copolymer thereof with polyvinylpyrrolidone, or a mixture with a water-soluble cellulose derivative such as hydroxypropylmethylcellulose and water-insoluble ethylcellulose. These actual coating agents can be used, if desired, in admixture with other auxiliaries, for example talc or wetting agents, for example sorbates (for example to facilitate application).

Elastic film-like materials are in particular hydrophilic polyvinylpyrrolidone (PVP-povidone) having an average molecular weight of 10,000 to 700,000, hydrophilic partially etherified cellulose derivatives and hydrophilic polyacrylates, such as acrylic acid polymers or acrylic acid / methacrylate copolymers It is.

Examples of hydrophilic partially etherified cellulose derivatives are
A lower alkyl ether of cellulose having an average degree of substitution (MS) of greater than 1 and less than 3 and a degree of polymerization of about 100-5000.

The degree of substitution is the degree of substitution of a hydroxy group with a lower alkoxy group per glucose unit. The average degree of substitution (MS) is an average and indicates the number of lower alkoxy groups per glucose unit in the polymer.

The average degree of polymerization (DP) is also an average and indicates the average number per glucose unit in the cellulose polymer.

Lower alkyl ethers of cellulose are, for example, cellulose derivatives, which are replaced by hydroxymethyl groups (primary hydroxy groups) on glucose units to form cellulose chains and, in some cases, the second and the second. the C ₁ -C ₄ alkyl group as the third secondary hydroxy group, preferably or also substituted C ₁ ~ by methyl or ethyl
C ₄ alkyl group, such as 2-hydroxyethyl, 3-hydroxypropyl -n- propyl, carboxymethyl or 2-
Substituted by carboxyethyl.

Suitable lower alkyl ethers of cellulose are preferably cellulose derivatives, which are the hydroxymethyl groups (primary hydroxy groups) of the glucose units and the above C ₁
The -C ₄ alkyl, or by also substituted C ₁ -C ₄ alkyl group, more if the second th Moreover certain substituted by methyl or ethyl group at the second hydroxy group of the third.

Preferred lower alkyl ethers of Cesulose are methylcellulose (DP: about 200 to 1000, MS: about 1.4 to 2.0), ethylcellulose (DP: about 150 to 1000, MS: about 1.2 to 1.8),
For example, Aquacoat ™ type (FMC) cellulose, hydroxyethyl cellulose (DP: about 120-1200, M
S: 1.2-1.5), hydroxypropylcellulose (DP: about 2
00-3000, MS: about 1.0-3.0) and methylhydroxypropylcellulose (DP: about 200-1000, MS: about 1.4-2.0),
For example, Pharmacoat ™ type cellulose (Shin-Etsu).

The hydrophilic polyacrylate has an average molecular weight of about 1.0 × 10 ^{5 to} 1.0 × 10 ⁶ and further comprises an acrylic acid polymer or an acrylic acid / methacrylic acid copolymer. The acidic groups of the acrylic and / or methacrylic acid monomers are partially or completely esterified by C ₁ -C ₄ alkyl groups, especially methyl and / or ethyl groups, the ester groups being hydrophilic groups, preferably May be replaced by trimethylammoniumethyl.

Preferred polyacrylates are available from Rohm Pharma (We
iterstadt, Germany) under the registered trademark EUDRAGIT. Particularly preferred are rapidly disintegrating film coatings, such as acrylate / methacrylate copolymers, especially ethyl acrylate / methyl methacrylate copolymers, preferably those having an average molecular weight of 800,000, such as swellable types based on EUDRAGIT NE30D, Or for rapidly disintegrating film coatings of the type that can be dissolved in gastric juice such as EUDRAGIT E
EUDRAGIT is in commercial form. When using a type that resists dissolution in gastric juices, such as EUDRAGITL or S, sustained release can be achieved.

Pharmaceutically acceptable excipients are, for example, viscosity index improvers which are suitable for stabilizing aqueous suspensions and inhibit the sedimentation of the coated active drug diclofenac, for example the natural index known as karaya gum. Polymer,
For example, carrageenan or biscalin Viscarin ™ (marine colloid) type, guar gum, eg Meyproga
t (TM) type (Myhal Chemical) galactomannans, especially the standard types 30,60,90,120 and 150 of "Myprogats (TM)", gum arabic,
Sodium alginate or tragacanth, a semi-synthetic polymer such as Avicel ™ Avicel ™ type (FMC)
Microcrystalline cellulose, such as the above cellulose ethers, for example methylcellulose, ethylcellulose or propylcellulose, with or without functional groups such as hydroxy or carboxy groups or propylene glycol alginate, polyoxyethylene, for example Polyox (Polyox (Polyox)). Trademark)) (Union Carbide), Carbowax (Carbowax®)
(Goodrich) or Polyglycol ™ (Dow Chemical) type, carboxypolymethylene, such as Carbopol ™ (Goodrich) type, polyvinyl alcohol (PVA), such as Polyviol (Polyviol ™) )) (Worker) or Mowiol (TM) (Hoechst) type, or polyvinylpyrrolidone (PVP) such as Collidion (C
ollidion ™ (BASF) or Plasdone
(TM)) (GAF) type, or a synthetic polymer selected from the group consisting of:
o-Sil ™ (Cabot) type colloidal silica.

In addition to the excipients commonly used for preparing tablets, effervescent tablets contain an agent that acts as a source of carbon dioxide as well as an agent that triggers the release of carbon dioxide. Agents acting as a source of carbon dioxide include pharmaceutically acceptable mono- and dibasic salts of carboxylic acids, such as alkali metal carbonates or alkali metal bicarbonates,
For example, sodium or potassium carbonate or sodium bicarbonate, and alkaline earth metal carbonates, such as calcium or magnesium carbonate, or sodium glycine carbonate. Sodium bicarbonate is preferred as a source of carbon dioxide.

The agents which trigger the release of carbon dioxide are preferably pharmaceutically acceptable organic acids and their anhydrides or salts of acids, which are in solid form and without the premature evolution of carbon dioxide, It can be formulated into granules or tablets containing the coated active drug and other excipients described above.

Pharmaceutically acceptable acids are, for example, organic acids such as tartaric acid, malic acid, fumaric acid, adipic acid, succinic acid,
Ascorbic acid and maleic acid. The preferred acid is citric acid.

Pharmaceutically acceptable acid anhydrides are the corresponding anhydrides of the above organic acids, for example citric anhydride or succinic anhydride.

Examples of pharmaceutically acceptable acidic salts are solid salts of polybasic acids, wherein at least one acidic function is present in the acid, for example, sodium hydrogen phosphate or hydrogen hydrogen phosphate. Disodium.

Surfactants or wetting agents (surfactants) can also be used to produce effervescent tablets, such as anionic surfactants of the alkyl sulfate type, such as sodium, potassium or magnesium of n-dodecyl sulfate; Or non-ionic surfactants of the fatty acid / polyhydroxy alcoholate type, such as sorbitan monostearate or sorbitan palmitate or sorbitan tristearate.

Further examples of excipients are fillers in powder form, such as lactose, sucrose, sorbitol, mannitol,
Starch, for example potato starch, rice starch, corn starch, wheat starch or amylopectin, or cellulose, preferably microcrystalline cellulose.

In addition, the ingredients can improve the appearance and taste of the aqueous suspension obtainable by disintegration of the effervescent tablet. Examples of such ingredients are colorants, sugars or sweeteners.

The use of colorants is effective for enhancing the appearance of the composition as well as for its purpose of disintegration. Colorants approved for use in pharmacies are, for example, carotenoids, iron oxides or chlorophyll.

Examples of sugars and sweeteners are scroll, xylitol, D
-Xylose, D-glycose, sorbitol, mannitol or lactose, and saccharin sodium,
Dultin, ammonium lysinate or sodium cyclamate.

Effervescent tablets are prepared by micronizing solid particles of diclofenac, imparting a permeable, swellable coating to the micronized particles, and tableting the coated composition. If desired, a pharmaceutical excipient may be added.

Coating of micronized diclofenac with the above coating agent is a conventional technique for coating finely particulate material, such as water or organic solvent or a mixture thereof, such as ethanol, isopropanol, acetone or methylene chloride in a desired ratio. By suspending or dissolving it, and then adding a desired additive. This preferred 4-6% solution or suspension is applied onto diclofenac powder or other excipients and mixtures thereof, for example in a known manner, for example in a fluidized bed, for example aeromatically.
Sprayed by spray coating with Worcester air suspension technology using a Glatt or Hüterin (Kugel coater) system.

Agents capable of releasing carbon dioxide, such as sodium bicarbonate, as well as corresponding agents that induce the release of carbon dioxide, for example, flowable granules that can be mixed with citric acid, remove the solvent slowly and completely. The residue can be obtained by sieving to a preferred average grain size of about 50-200 μm.

The coated active drug granules are mixed in the manner described above with the acid and fillers necessary for preparing effervescent tablets, such as lactose and cellulose, and a lubricant, such as polyethylene glycol, and then mixing the mixture with the effervescent tablet. Press. Because of the high content of excipients, tablet machines
Those suitable for the production of large tablets with a diameter of about 3.5 cm and a maximum thickness of about 1 cm are used. Tableting is carried out under moisture-free conditions or in an inert gas atmosphere. Tablets may be individually filled into foils.

The present invention preferably comprises diclofenac with an average particle shape of less than 200 μm and a permeable, swellable coating preferably having a thickness of less than 100 μm, excipients suitable for effervescent formulations, suspending agents and It further relates to an effervescent tablet optionally containing a pharmaceutical excipient.

The present invention is further non-limitingly described by the following examples.

〔Example〕

Example 1: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Myprogat (Meyprogat ™ 150) 32 mg Colloidal silica Aerosil (Aerosil ™ 2)
00) 1 mg Eudragit (TM), NE 30 D, solid 7 mg polyethylene glycol 8000 50 mg sodium bicarbonate 825 mg citric acid, anhydride 1160 mg galactomannan myprogat (Meyprogat (TM) 150) 75 mg microcrystalline cellulose Avicel (Avic)
el ™ pH 102) 200 mg 2400 mg Diclofenac, a first part of Meyprogat ™ 150 and a mixture of Aersoil ™ 200 are flowed with an aqueous dispersion of Eudragit ™ NE Sprinkle on the floor and dry. The coated active drug is mixed with an outer phase consisting of polyethylene glycol 8000, sodium bicarbonate, citric acid, a second portion of Meyprogat ™ 150 and microcrystalline cellulose, and then mixing the homogeneous mixture, usually To obtain effervescent tablets (diameter: 19 mm, thickness: 6 mm).

Example 2: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Meprogat (TM) 150 33 mg Eudragit (Eudragit (TM)) NE 30 D, solid 7 mg ground lactose 400 mg polyvinylpyrrolidone (PVP (TM) K 30) 10 mg polyethylene glycol 8000 50 mg sodium bicarbonate 700 mg citric acid, anhydride 975 mg galactomannan myprogat (Meyprogat (TM) 150) 75 mg microclestalin cellulose azecel (Avicel)
(Trademark) pH102) 100 mg 2400 mg Diclofenac and Meyprogat
The mixture of the first portion of 150) is sprayed with an aqueous suspension of Eudragit NE 30D in a fluidized bed and dried. The coated active drug is mixed with ground lactose and PVP ™ K30 and the mixture is granulated with water. Dry kneader granules,
The polyethylene glycol 8000, sodium carbonate, citric acid, a second part of Meyprogat® 150 and microcrystalline cellulose are mixed with the external phase and the mixture is then compressed into effervescent tablets.

Example 3: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Meprogat ™ 150 mg 33 mg Eudragit ™ NE 30 D, solid 7 mg ground lactose 400 mg polyvinylpyrrolidone (PVP ™ K) 30) 10mg polyethylene glycol 8000 50mg sodium bicarbonate 700mg citric acid, anhydride 950mg microcrystalline cellulose cellulose Avicel (Avic
el ™ pH102) 200 mg 2400 mg Diclofenac and Meyprogat
(TM)) in a fluidized bed in Eudragit (E
sprinkle with an aqueous suspension of udragit ™ NE 30 D and dry. The coated active drug is mixed with ground lactose and PVP ™ K30 and the mixture is granulated with water. The dried kneader granules are mixed with an outer phase consisting of polyethylene glycol 8000, sodium bicarbonate, citric acid, and microcrystalline cellulose, and the mixture is compressed into effervescent tablets.

Example 4: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Myprogat (Meyprogat (TM) 150) 32 mg Colloidal silica Aerosil (Aerosil (TM) 2
00) 1 mg Eudragit ™ NE 30 D, solid 7 mg polyethylene glycol 8000 50 mg sodium bicarbonate 855 mg citric acid, anhydride 1205 mg microcrystalline cellulose cellulose azecel (Avic
el ™ pH 102) 200 mg 2400 mg A mixture of diclofenac, Meyprogat ™ 150 and Aerosil ™ Aerosil ™ 200 in a fluidized bed in aqueous suspension of Eudragit ™ NE 30 Spray with liquid and dry. Coated active drug, polyethylene glycol 8000,
The outer phase consisting of sodium bicarbonate, citric acid and microcrystalline cellulose is mixed and the homogeneous mixture is compressed into effervescent tablets in a tablet machine.

Example 5: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Myprogat (Meyprogat 150) 32 mg Colloidal silica Aerosil (Aerosil 2)
00) 1 mg Eudragit ™ NE 30 D, solid 25 mg polyethylene glycol 8000 50 mg sodium bicarbonate 825 mg citric acid, anhydride 1142 mg galactomannan Myprogat (Meyprogat ™ 150) 75 mg microcrystalline cellulose cellulose azecel (Avic)
el ™ pH 102) 200 mg 2400 mg Preparation of effervescent tablets is as in Example 1.

Example 6: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Myprogat (Meyprogat (TM) 150) 33 mg Colloidal silica Aerosil (Aerosil (TM) 2
00) 1 mg Aquacoat EDC, solid 25 mg polyethylene glycol 8000 50 mg sodium bicarbonate 825 mg citric acid, anhydride 1142 mg microcrystalline cellulose cellulose azecel (Avic
el ™ pH 102) 200 mg 2400 mg Mixture of diclofenac, Meyprogat ™ 150 and Aerosil ™ 200 in a fluidized bed with Aquacoat ™ ED
Sprinkle with an aqueous suspension of C30 and dry. The coated active drug is mixed with an outer phase consisting of polyethylene glycol 8000, sodium bicarbonate, citric acid and microcrystalline cellulose, and the homogeneous mixture is compressed in a tablet machine to give effervescent tablets.

Example 7: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Myprogat (Meyprogat (TM) 150) 36.7 mg Colloidal silica Aerosil (Aerosil (TM) 2
00) 1.1 mg cellulose HPM-603 Pharmacoat
(Trademark) 5.5 mg polyethylene glycol 8000 50 mg sodium hydrogen carbonate 850 mg citric acid, anhydride 1206.7 mg microcrystalline cellulose cellulose azecel (Avic
el ™ pH 102) 200 mg 2400 mg Mixture of diclofenac, Meyprogat ™ 150 and Aerosil ™ Aerosil ™ 200 in a fluid bed in an aqueous suspension of Pharmacoat ™ Spray with the suspension and dry. The coated active drug is mixed with an outer phase consisting of polyethylene glycol 8000, sodium bicarbonate, citric acid and microcrystalline cellulose, and the homogeneous mixture is compressed in a tablet machine to give effervescent tablets.

Example 8: Effervescent tablet of diclofenac (50 mg) Diclofenac 50 mg Galactomannan Myprogat (Meyprogat (TM) 150) 35 mg Colloidal silica Aerosil (Aerosil (TM) 2
00) 1 mg Eudragit NE 30 D 50 mg polyethylene glycol 8000 50 mg sodium bicarbonate 830 mg citric acid, anhydride 1184 mg microcrystalline cellulose cellulose azecel (Avic
el ™ pH 102) 200 mg 2400 mg Preparation is carried out as in Example 4.

Determination of Disintegration Rate Method-US Puzzle, 50 rpm medium-60 min, 0.1 N HCl, pH 1.0-60 min, phosphate buffer, pH 6.8 Result: Percent (%) of diclofenac 60 min 4 120 min 50 240 After 77 minutes After 420 minutes 93 Example 9: Effervescent tablet of diclofenac (50 mg) Diclofenac 46.5 mg Galactomannan Myprogat (Meyprogat (TM) 150) 37 mg Colloidal silica Aerosil (Aerosil (TM) 2
00) 1 mg polyvinylpyrrolidone K 30 10 mg polysorbate 80 0.8 mg polyethylene glycol 8000 powder 60 mg sodium bicarbonate 700 mg citric acid, anhydride 1344.7 mg mybitol 200 mg 2400 mg diclofenac, meprogat (trade mark) 150 and A mixture of Aerosil ™ 200 is sprinkled with an aqueous suspension of polyvinylpyrrolidone K30 and polysorbate 80 in a fluidized bed and dried. Coated active drug, polyethylene glycol 8000,
Mix with an outer phase consisting of sodium bicarbonate, citric acid and malbitol, then compress the homogeneous mixture in a tablet machine to obtain effervescent tablets.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI A61K 47/38 A61K 47/38 A (56) References JP-A-63-54316 (JP, A) JP-B-48-38844 ( JP, B1) JP 48-26204 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) A61K 31/195 A61K 9/20 CA (STN)

Claims (7)

(57) [Claims] A solid, rapidly disintegrating effervescent tablet for the preparation of an aqueous suspension of oral dosage forms, comprising finely divided diclofenac or water-permeable swellable coatings or Such a tablet comprising a coated pharmaceutically acceptable salt of diclofenac, and a pharmaceutically acceptable excipient. 2. Micronized diclofenac having an average particle size of less than 200 μm and having a coating of polyvinylpyrrolidone, a lower alkyl ether of cellulose or a permeable, swellable acrylate / methacrylate copolymer, solid foaming 2. The effervescent tablet according to claim 1, which contains excipients suitable for formulation, suspending aids and optionally pharmaceutical excipients. 3. The effervescent tablet according to claim 2, which contains micronized diclofenac having an average particle size of less than 100 μm. 4. Micronized diclofenac with a coating of osmotic ethylcellulose or methylhydroxypropylcellulose or osmotic swellable ethyl acrylate / methyl methacrylate copolymer, excipients suitable for solid effervescent formulations, suspending agents The effervescent tablet according to claim 2 or 3, further comprising an excipient, if desired. 5. A finely divided diclofenac having a coating of a permeable, swellable acrylate / methyl methacrylate copolymer having an average particle size of less than 200 μm and an average molecular weight of about 800,000, a pharmaceutically acceptable carbonate salt and The effervescent tablet according to claim 4, further comprising an organic acid, a cold-water-soluble hydrocolloid as a suspending agent, and optionally an excipient. 6. An aqueous suspension suitable for oral administration of diclofenac, obtained by disintegrating the solid rapidly disintegrating tablet according to claim 1 in an aqueous phase. 7. The process for preparing a solid rapidly disintegrating tablet according to claim 1, wherein the solid particles of diclofenac are micronized and permeable and swellable to the micronized diclofenac. Such a method, comprising applying a coating and tableting the coated active drug with a pharmaceutical excipient.