DICLOFENAC/GAMMA-CYCLODEXTRIN INCLUSION COMPOUNDS

Abstract: The object of the present invention is an oral drug preparation containing the g-cyclodextrin complex of diclofenac (or pharmaceutically acceptable salts thereof, especially sodium salt) prepared by known methods and by which the gastro-intestinal irritancy of diclofenac - at the same or improved bioavailability - can be considerably decreased.

Description: DICLOFENAαGAMMA-CYCLODEXTRIN INCLUSION COMPOUNDS Diclofenac. sodium (chemical name 2-[(2.6- dichlorophenyl )aminojbenzeneacetic acid sodium salt) is an effective and widely used non-steroid anti-inflammatory agent marketed as Voltaren® (Ciba Geigy) in several countries. Diclofenac is applied in different formulations such as tablet, film tablet, dragee, capsule, retard preparations, injection, suppository, ophthalmic solution , gel. The most frequently applied tablet formulation - similarly to other poorly soluble, slowly absorbed non-steroid anti- inflammatory drugs - causes local irritation in the stomach especially in case of chronic treatment. Cyclodextnns are cyclic oligosaccharides consisting of 6 . 7 or 8 α-D-glucopiranose units in which the glucose units are linked by α 1→4 linkage The eight-member ring is called γ- cyclodextrin Cyclodextnns form inclusion complexes with the hydrophobic guest molecules of appropriate size Cyclodextnns. cyclodextπn derivatives, inclusion complexation process and characterization of complexes are widely discussed by Sze]tlι (Cyclodextnns and Their Inclusion Complexes, Akademiai kiadό Budapest, 1982 Cyclodextnn Technology, luwer Academic Publishers, Dordrecht, 1988) and Frommmg and Sze * jtlι (Cyclodextnns in Pharmacy Kluwer Academic Publishers Dordrecht/Boston, 1994 ) Diclofenac - similarly to other non-steroidal anti- mflammatory drugs - shows toxic side effects, it irritates the gastro-intestinal mucosa, bleedings, ulcers and perforations may develop. The development of ulcers is a complex process, involving many factors damage of the mucosal barrier, inhibition of the mucoεal prostanoid synthesis, direct effect on the cellular enzymes, increased acid secretion, slowing down of repair processes etc Dose of the given drug, route of administration, metabolism etc may also play a role The effect of a certain factor may change from drug to drug Preparation and pharmaceutical applications of diclofenac/cyclodextπn complexes are described in several patents Eye drops containing diclofenac sodium and β-cyclodextπn for enhancement of the solubility of the poorly soluble diclofenac are described in a Japan Kokai 58174310 (Wakamoto Pharm Co , Ltd . 1982) The Japan Kokai 590848821 (Teikoku Chemical Industry Co . Ltd 1982) describes sustained-release analgesics containing diclofenac and β-cyclodextπn The Japan Kokai 62289515 (Ishida, K. , 1986) describes lint cloth coated with medicine containing diclofenac and cyclodextπn A medical preparation used for treatment of lschaemic brain diseases is discussed in the Japan Kokai 62198616 (Shmgijutsu Kaihatsu K.K. , 1986), the preparation contains a prostaglandin synthesis inhibitor e.g diclofenac and cyclodextrin Suppositories containing steroid and non-steroid anti- inflammatory drugs - e.g. diclofenac and cyclodextrin are described in the Japan Kokai 87.138,437 (Nakamshi. M , 1987) . Cyclodextrin is used as an absorption promoter. EP 371431 (Vectorpharma International S.p.A , 1988) describes the preparation of supported drugs with increased dissolution rate. The drug and the support material are co-ground in a mill with its grinding chamber saturated with solvent vapour. The solvent solubilizes the drug or promotes its adsorption onto the support material This technology decreases the extent of drug crystallinity. The drug can be e.g diclofenac, the support material may be cyclodextrin polymer or water-soluble cyclodextπn The EP 446753 (Vectorpharma International S.p.A. , 1990) deals with therapeutic compositions with controlled release of medicaments. The drug is supported on crosslmked polymer matrix which is insoluble but swellable in water. The drug can be e g diclofenac, the polymer matrix is. for example, water-insoluble cyclodextrin polymer The WO 92/00725 paten.t application (Farcon AG. 1990) describes oral topical liquid pharmaceutical compositions of non-steroidal anti-inflammatory drugs e.g. diclofenac. Combining the drugs with cyclodextrins or cyclodextrin derivatives (physical mixture, complex, coprecipitate) is suggested. Cyclodextrins can be α-, β-, γ-cyclodextrin or hydroxypropyl-β-cyclodextrin . The objects of the EP 510561 patent (Poli Industria Chimica S.p.A. , 1991) are oral, dermal and intravaginal liquid pharmaceutical compositions in the form of foam.The drug can be - among many others - diclofenac. or its cyclodextrin complex. The DE 4207922 German patent (Pharmatech GmbH) describes the water soluble inclusion complex of diclofenac sodium with methylated β-cyclodextrins or with hydroxypropyl-β- cyclodextrin . The Japan Kokai 06016547 (Wakamoto Pharm. Co . . Ltd.. 1992) describes eye-drops containing diclofenac sodium and enzymatically or chemically modified β-cyclodextrin derivatives. The patent of Takeda Chemical Industies, Ltd (EP 519.428, 1992) describes a pharmaceutical composition containing a cyclodextrin and a poorly water soluble drug e.g. diclofenac. The composition contains water-soluble organic solvent, ©specially for injections. The WO 94/28936 patent application (Ciba-Geigy. 1993) relates to a novel advantageous process for the preparation of an oral solid dosage containing diclofenac (or salts thereof) . The dosage form is obtainable by direct compression of the γ- cyclodextrin inclusion complex of diclofenac and the salts thereof The examples describe complexes of 1 1 molar ratio The EP 647451 patent (South African Druggist Ltd , 1993) describes the inclusion complex of diclofenac (or salts thereof) and non-substituted β-cyclodextπn The WO 95/01781 (APR Applied Pharma Research SA. 1993) describes ultilayered controlled-release oral solid pharmaceutical forms The drug can be diclofenac sodium In the first layer which is intended to release a drug portion in short times there is a polymer e g β-cyclodextπn The EP 658347 patent describes the method of preparing an m]ectable pharmaceutical or veterinary composition (South African Druggist Ltd . 1993) containing diclofenac (or salts thereof) and 2-hydroxypropyl-β-cyclodextrιn The in]ectable composition is applied for the inhibition of prostaglandm synthesis The composition may contain an inclusion complex or the mixture of drug and cyclodextrin Pharmacokmetic studies performed on human volunteers have shown that the preparation formulated by cyclodextrin and administered intramuscularly is bioequivalent with the marketed diclofenac sodium miection, but in case of the cyclodextπn-containing injection higher plasma concentration can be attained within a shorter time The WO 95/32737 patent application (South African Druggist Ltd , 1994) describes the preparation method of a solid pharmaceutical composition consisting of β-cyclodextπn or a derivative thereof (hydroxypropyl or methyl βCD) and a poorly water soluble non-steroid anti-inflammatory drug e g diclofenac sodium The composition which is an inclusion complex of the drug is prepared by the kneading method and dried at 40 S C The solid product, when dissolved in water. gives a clear or slightly opalescent solution which is suitable for oral use All these inventions and patents describe preparation methods of inclusion complexes of diclofenac with a cyclodextπn which methods have been well-known for a long time and widely applied The aim verified empirically in each case is to achieve a faster dissolution and higher solubility of the drug which, according to the general experiences with the inclusion complexes of drugs is expressed in faster biological absorption and n improved bioavailability as well The inventions patents and other publications related to diclofenac discussed above comprise several further results of physico-chemical studies such as X-ray diffraction studies of the crystal structure of diclofenac/cyclodextnn complexes, the study of interactions between diclofenac and cyclodextrin molecules m solution by nuclear magnetic resonance, Fourier-transformed infrared spectroscopic, differential-scanning caloπmetπc studies etc , The overwhelming majority of the above mentioned inventions and patents applies β-cyclodextπn for co plexation of diclofenac At the time when these patents were worked out it had not been known yet that - according to the JECFA recommendations - the daily oral dose of β-cyclodextrm should not be beyond 6 mg/kg body weight Namely a small part of β-cyclodextrin is absorbed from the gastro-intestinal tract and may cause irreversible damage of the kidneys Therefore oral diclofenac formulations containing β- cyclodextπn are not feasible since in case of all diclofenac/β-cyclodextnn complexes recommended for oral us© this 6 mg/kg limit would be far exceeded Several reports deal with the preparation and characterization of diclofenac/cyclodextπn inclusion complexes (E g Backensfeld T Mueller B W Arch Pharm 222 690 1990. Backensfeld T Mueller B W Kolter, K Int J Pharm , 24 (2-3) 85 1991 Devi, S G , Prakasam K , Udapa, H Indian J Pharm Sci ϋ_(6), 259. 1992 Oπenti I Cavallaπ C ecchi V Arch Pharm 322 207 1989 Orienti , I , Fini A Bertasi, V Zecchi, V Eur J Pharm Biopharm . 21 ( 2 ) 110 1991 Singh. U V Pandey, S , Udupa N Indian J Pharm 55 f 41 145, 1993 The object of our invention is to decrease the side effect namely the gastro-mtestinal irritant stomach and intestinal ulcer inducing effect of diclofenac by applying diclofenac in a formulation providing a fast dissolution and an enhanced bioavailability of the drug The mam object of our invention is an oral pharmaceutical composition containing diclofenac in form of a diclofenac/γ- cyclodextr complex prepared by known methods by which the gastro-intestinal irritant effect of diclofenac can be significantly decreased The problem underlaying the invention is solved by a chemical composition comprising at least 50 % by weight of or consisting of an inclusion compound formed from diclofenac and γ-cyclodextπn at a molar ratio of about 1 2 A specific embodiment of the invention concerns a chemical composition consisting of at least 50 % by weight of the above mentioned inclusion compound the remainder being diclofenac and/or an inclusion compound formed from diclofenac and a cyclodextrin other than an inclusion compound formed from diclofenac and γ-cyclodextrin at a molar ratio of about 1 2 Further, a specific embodiment of the invention concerns a chemical composition, wherein the remainder is an inclusion compound formed from diclofenac and γ-cyclodextπn at a molar ratio of about 1 1 Further, a specific embodiment concerns a chemical composition, wherein the composition comprises at least 80, preferably at least 90 and especially at least 95 % by weight of the inclusion compound formed from diclofenac and γ- cyclodextnn at a molar ratio of about 1 2 Further, a specific embodiment concerns a chemical composition, characterized in that diclofenac is present as a pharmaceutically acceptable salt thereof, especially as its sodium salt The problem underlaying the invention is further solved by a pharmaceutical preparation consisting of a chemical composition according to the invention or comprising same, optionally besides usual pharmaceutical adjuvants Further, a specific embodiment of the invention concerns a pharmaceutical preparation, wherein the preparation is a dry preparation at solid state Further, a specific embodiment of the invention concerns a pharmaceutical preparation, wherein the preparation is for oral purposes Finally, a specific embodiment of the invention concerns a pharmaceutical preparation, wherein the preparation is a granulate, a tablet or an effervescent tablet The diclofenac/γ-cyclodextrm complexes used for the irritation studies and for verification of absorption enhancement were prepared by two different, otherwise well- known methods "A"' composition Diclofenac sodium/γ-cyclodextπn complex of 1 2 molar ratio 0 708 g diclofenac sodium and 6 98 g γ-cyclodextrm were added to 34 ml distilled water and mixed with Ultra-Turrax T25 equipment for 4x2 minutes The suspension was freeze dried Weight of the solid product 7 6 g Diclofenac sodium content 9.5±0.5% ''B'' composition Diclofenac sodium/γ-cyclodextπn complex of 1 2 molar ratio 805 g diclofenac sodium and 87 0 g γ-cyclodextπn powders were mixed, then under continuous stirring they were added to 60 ml 60 S C distilled water and stirred for 10 minutes The creamy suspension was poured onto trays and dried at 50 β C During drying the substance was mixed several times in order to get a granulated product At 4-5 % water content the substance was meshed through a 2 mm sieve and dried further Weight of the solid product. 94 g Water content 6.15% Diclofenac sodium content 7 9% The advantages of our invention are demonstrated by the following in vitro and in vivo results Example 1 The gastric irritancy of diclofenac sodiu /γCD complex ( "B" composition molar ratio 1 2) and that of diclofenac sodium were compared on Wistar male rats The average body weight of the animals was 230 g Fasted rats were treated with a single 10 mg/kg body weight oral dose related to diclofenac To one group of rats (20 rats) diclofenac sodium to another group (20 rats) diclofenac sodium/γ-cyclodextπn complex and to a third group (10 rats) distilled water was given per os Rats were dissected 4 hours after the treatment and the number and size of ulcers in the stomach were determined The ulcers were divided into four groups according to their size a / the largest diameter is < 1 mm, b / the largest diameter s between 1-2 mm c / the largest diameter is between 2-4 mm d / the largest diameter is > 4 mm The number of ulcers was counted and the ulcer index was calculated as follows total number of ulcers <lmm was multiplied by 0 5 total number of ulcers between 1 to 2 mm was multiplied by 1 total number of ulcers between 2 to 4 mm was multiplied by 2 total number of ulcers >4mm was multiplied by 3 The ulcer index was determined for each animal and total and mean values were given for the different groups (Table I and II ) Table I . Gastroirri taηcy of diclofenac sodium dose .10 mg/kg No ulcers were found in nine out of 20 rats treated with diclofenac sodium Ulcers larger than 1 mm were observed in 5 rats severe ulceration was found in one rat (No 11 ulcer index 50) The mean ulcer index was 4 m this group Table II Gastroirritancy of Diclofenac sodium/γ- cyclodextπn complex dose related to di clofenac sodium 10 mg/kg No ulcers were found in 11 rats, ulcers larger than 1 mm were observed in the stomach of 4 animals The highest ulcer index was 13 5 the mean value was 1 7 No ulcers were found in any of the control animals The number of ulcers was significantly lower in the diclofenac sodium/γ-cyclodextπn complex-treated group than in the free diclofenac sodium-treated group Therefore γ-cyclodextπn decreased the gastroirntant effect of diclofenac sodium considerably when applied as a single 10 mg/kg (related to diclofenac sodium) dose Example 2 The gastro-intestinal irritancy of diclofenac sodium/γ- cyclodextπn complex ( "A'' composition) and that of free diclofenac sodium was compared in a subacute experiment on rats Male Wistar rats weighing 220 g average were used Animals were kept on a standard LATI rat and mouse chow before and during the experiment Animals were treated orally with 15 mg/kg dose diclofenac sodium (10 rats) or the complex containing an equivalent amount of diclofenac sodium (10 rats) for 4 days as follows, 1st day 15 mg/kg at 8 a m 2nd day 15 mg/kg at 8 a m 3rd day 15 mg/kg at 8 a.m and at 8 p m 4the day 15 mg/kg at 8 a m Control rats were given 0.5 % ethylcellulose solution (5 animals) . Four hours after the last treatment animals were dissected . Ulcers, perforations and peritonitis developed as a result of this treatment and were evaluated according to the following scale : 0: normal condition 0.5: signs of inflammation in the small intestine, greyish-reddish discoloration of the intestinal wall, no perforation 1: at least 1 perforation, small adhesions 2: 2 or more perforations, larger adhesion parts in the intestine 3: perforations, large adhesions in the intestine including a few other organs 4: severe peritonitis, including practically all organs in the abdomen Results are shown in Table III. Both in complex- and diclofenac sodium-treated groups perforations were observed in the jejuno-ileal part of the small intestine. However, the irritancy index was signi icantly lower in case of complex-treated rats (1.5) than in the diclofenac sodium-treated group (2.3). Therefore, it can be concluded that the diclofenac sodium/γ-cyclodextrin complex proved to be less toxic than diclofenac sodium in the subacute experiment. Table III. : Intestinal irritancy of diclofenac sodium and diclofenac sodium/γ-cyclodextrin complex of 1.2 molar ratio subacute experiment, dose related to diclofenac sodium: 15 mg/kg Example 3 230 mg of diclofenac sodium/γ-cyclodextrin complex ( '"A" composition) were added to 20 ml simulated gastric juice (pH 1.2 HCI) and stirred for 30 minutes at 25 °C. Samples of 4 . 4 ml each were taken at 0,5, 10 and 30 minutes, filtered across a 0.45 μm membrane filter and dissolved diclofenac concentration was determined by UV-spectrophotometry. Results are shown in Table IV. Table IV Dissolution of diclofenac sodium/γ-cyclodextrm complex in pH 1.2 HCI Complexation increased the dissolution of diclofenac in pH 1.2 HCI (Under similar conditions, dissolution of non- complexed diclofenac sodium is less than 2 μg/ml in 30 minutes ) The complex of 1.2 molar ratio offered a concentration of dissolved diclofenac more than one order of magnitude higher than that of free diclofenac sodium in the first 10 minutes. Example 4 Fasted New Zealand white male rabbits weighing 2 4 kg average were treated orally with diclofenac sodium/γ-cyclodextπn complex ( "B' ' composition) or diclofenac sodium. Dose related to diclofenac sodium was 0.5 mg/kg. Heparinized blood samples were taken from the animals by heart punction and diclofenac concentration was determined from the plasma separated by centrifugation following appropriate purification (solid phase extraction) and analysis by HPLC Results are shown in Table V. The plasma concentration of diclofenac in rabbits treated with the complex was higher at every time point (between 0.5-4 hours) than that of diclofenac -treated animals. Table V. : Absorption of diclofenac in rabbits following oral administration of diclofenac sodium and diclofenac sodium/g- cyclodextrin complex of 1:2 molar ratio dose related to diclofenac sodium: 0.5 mg/kg The results of the absorption study indicate that both absorption and bioavailability as well of diclofenac can be improved by γ-cyclodextrin complexation of the drug. Example 5 From the diclofenac sodium/γ-cyclodextrin complex ( ''B'' composition) tablets were prepared by the usual method, direct compression and using the usual excipients as follows diclofenac sodium/γ-cyclodextrin complex (25 mg diclofenac sodium) 31.6 kg (73.49%) microcrystalline cellulose 9.0 kg (20.93%) crosslinked polyvinyl pyrrolidone 2.0 kg ( 4.65%) 43 . 0 kg ( 1 00% ) The complex and the qxcipients were homogenized and pressed to tablets directly. The amount given above is enough for production of 100 000 tablets.

Claims: Claims 1. Chemical composition comprising at least 50 % by weight of or consisting of an inclusion compound formed from diclofenac and gamma-cyclodextrm at a molar ratio of about 1:2. 2. Chemical composition according to claim 1 consisting of at least 50 % by weight of the inclusion compound according to claim 1, the remainder being diclofenac and/or an inclusion com¬ pound formed from diclofenac and a cyclodextrin other than an inclusion compound formed from diclofenac and gamma-cyclodextrm at a molar ratio of about 1:2. 3. Chemical composition according to claim 2 , wherein the remainder is an inclusion compound formed from diclofenac and gamma-cyclodextrm at a molar ratio of about 1:1. 4. Chemical composition according to any of the preceding claims, wherein the composition comprises at lease 80, preferably at least 90 and especially at least 95 % by weight of the inclusion compound according to claim 1. 5 Chemical composition according to any of the preceding claims, characterized in that diclofenac is present as a pharma¬ ceutically acceptable salt thereof, especially as its sodium salt . 6. Pharmaceutical preparation consisting of a chemical composi¬ tion according to any of the preceding claims or comprising same, optionally besides usual pharmaceutical adjuvants. 7. Pharmaceutical preparation according to claim 6, wherein the preparation is a dry preparation at solid state 8. Pharmaceutical preparation according to claim 6 or 7, wherein the preparation s for oral purposes. 9. Pharmaceutical preparation according to any of claims 6 to 8, wherein the preparation is a granulate, a tablet or an effer¬ vescent tablet

Inventors: FISCHER WILFRIED, SENDL-LANG ANNA, FISCHER, WILFRIED, SENDL-LANG, ANNA
Applicants: FISCHER WILFRIED, HEXAL AG, SENDL LANG ANNA, FISCHER, WILFRIED, SENDL-LANG, ANNA
Application year: 1997
Main classification: A61K31
IPC codes: A61K9, A61K31, A61K47