AU3175293A

AU3175293A - Substituted benzimidazoles, process for their preparation as well as their use

Info

Publication number: AU3175293A
Application number: AU31752/93A
Authority: AU
Inventors: Karl Bjorn Christer Holstein; Gunnel Elisabeth Sunden
Original assignee: Astra AB
Current assignee: AstraZeneca AB
Priority date: 1991-12-19
Filing date: 1992-12-08
Publication date: 1993-07-19
Anticipated expiration: 2012-12-08
Also published as: CA2124689A1; ZA928836B; AP9200463A0; SK73594A3; JPH07502503A; CN1031827C; AP397A; SI9200402A; IS3960A; HUT68270A; SE9103776D0; FI942912A; MA22746A1; HRP921400A2; FI942912A0; TW224100B; HU9401840D0; NO942230L; KR940703840A; EP0628049A1

Description

SUBSTITUTED BENZIMIDAZOLES, PROCESS FOR THEIR

PREPARATION AS WELL AS THEIR USE.

DESCRIPTION

Field of the invention

The object of the present invention is to provide novel compounds, which inhibit exogenously or endogenously stimulated gastric acid secretion and thus can be used in the prevention and treatment of peptic ulcer.

The present invention also relates to the use of the compounds of the invention for inhibiting gastric acid secretion in mammals including man. In a more general sense, the compounds of the invention may be used for prevention and treatment of gastrointestinal

inflammatory diseases, and gastric acid-related

diseases in mammals including man, such as gastritis, gastric ulcer, duodenal ulcer, reflux esophagitis, and Zollinger-Ellison syndrome. Furthermore, the compounds may be used for treatment of other gastrointestinal disorders where gastric antisecretory effect is

desirable e.g. in patients with gastrinomas, and in patients with acute upper gastrointestinal bleeding. They may also be used in patients in intensive care situations, and pre- and postoperatively to prevent acid aspiration and stress ulceration. The compounds of the invention may also be used for treatment or prophylaxis of inflammatory conditions in mammals, including man, especially those involving lysozymal enzymes .

Conditions that may be specifically mentioned are rheumatoid arthritis and gout. The invention also relates to pharmaceutical compositions containing the compounds of the invention, as active ingredient. In a further aspect, the invention relates to processes for preparation of such new compounds and to the use of the active compounds for the preparation of pharmaceutical compositions for the medical use indicated above. The compounds of the invention will not block the uptake of iodine into the thyroid gland. It has earlie been disclosed in several lectures from the company, where the inventors are working that thyroid toxicity depends on if the compounds are lipophilic or not. The inventors have now unexpectedly found that it is not the lipophilicity that is the critical parameter. The claimed compounds, which include rather hydrophilic compounds, do not give any thyroid toxic effect and have at the same time high acid secretion inhibitory effect.

The compounds of the invention will also exhibit a high solubility and a high chemical stability in water. Background of the invention

Similar disubstituted 2-[[(3,4-dialkoxy-2-pyridinyl)- methyl]sulfinyl]-1H-benzimidazole-1-yl compounds are described in PCT/SE91/00415, which was not publically available at the time of filing the basic application in Sweden, but was published shortly thereafter.

Prior art Benzimidazole derivatives intended for inhibiting gastric acid secretion are disclosed in numerous patent documents.

Among these can be mentioned GB 1 500 043,

GB 1525 958, US 4182766, US 4255 431, US 4 599 347, BE 898 880, EP 124 495, EP 208 452, EP 221 041,

EP 279 149, EP 176 308 and Derwent abstract

87-294449/42. Benzimidazole derivatives proposed for use in the treatment or prevention of special

gastrointestinal inflammatory diseases are disclosed in US 4 359 465. The invention

The compounds of the invention are effective as

inhibitors of gastric acid secretion in mammals

including man and in addition do not block the uptake of iodine into the thyroid gland.

Further, the compounds of the invention exhibit a high solubility and a high chemical stability in water. The compounds of the invention are therefore

particularly suitable for parenteral, especially intravenous and intramuscular administration. The high solubility and chemical stability also render the compounds of the invention suitable for other

administration routes, such as for instance oral and rectal administration.

The compounds of the invention are of the following formula I:

I wherein

R¹ and R², which are different, is each methyl, -C(O)-

CH₃ or -C(O)-OCH₃ and whereby one of R¹or R² is always methyl, and M is a physiologically acceptable counter cation.

The structural isomers of the compounds of the formula I may be used separately, or in equal or unequal mixtures.

The compounds of the invention of the formula I have an asymmetric centre in the sulfur atom, i.e. exists as two optical isomers (enantiomers). Both the pure enantiomers, racemic mixtures (50% of each enantiomer) and unequal mixtures of the two are within the scope of the present invention.

It is believed that compounds of formula I are

metabolized before exerting their effect. Such

metabolism occur in the N-substituent, the phosphorous containing group, in position 1 in the benzimidazole nucleus. Preparation

The compounds of the invention may be prepared

according to the following methods: a) Reacting a compound of the formula II wherein R¹ and R² are as defined under formula I, and

Z, is halogen such as CI, Br or I or a functionally equivalent group, with a compound of the formula III

O

|

HO-P-O Q III

|

O Q wherein Q is a counter ion such as Na⁺, K⁺, Ag⁺ or trialkylammonium.

Salts obtained may be transformed to a therapeutically suitable salt such as sodium and potassium salts, by addition of NaOH and KOH, respectively or by ion exchange. b) Oxidizing a compound of the formula IV

wherein R¹, R² and M have the meanings given, to give a compound of formula I.

This oxidation may be carried out by using an oxidizing agent such as nitric acid, hydrogen peroxide,

(optionally in the presence of vanadium compounds), peracids, peresters, ozone, dinitrogentetraoxide, iodosobenzene, N-halosuccinimide, 1- chlorobenzotriazole, t-butylhypochlorite, diazabicyclo- [2,2,2]-octane bromine complex, sodium metaperiodate, selenium dioxide, manganese dioxide, chromic acid, cericammonium nitrate, bromine, chlorine, and sulfuryl chloride. The oxidation usually takes place in a solvent such as halogenated hydrocarbons, alcohols, ethers, ketones.

The oxidation may also be carried out enzymatically by using an oxidizing enzyme or microbiotically by using a suitable microorganism.

The structural isomers obtained, may be separated by means of crystallization or chromatography.

Racemates obtained can be separated according to known methods, e.g. recrystallization from an optically active solvent.

For clinical use the compounds of the invention are formulated into pharmaceutical formulations for oral, rectal, parenteral or other mode of administration. It is especially preferred to formulate the compounds of the invention into pharmaceutical formulations for parenteral administration. The pharmaceutical

formulation contains a compound of the invention in combination with a pharmaceutically acceptable carrier. The carrier may be in the form of a solid, semi-solid or liquid diluent, or a capsule. These pharmaceutical preparations are a further object of the invention.

Usually the amount of active compounds is between 0.1- 95% by weight of the preparation, between 0.2-20% by weight in preparations for parenteral use and between 1 and 50% by weight in preparations for oral

administration. In the preparation of pharmaceutical formulations containing a compound of the present invention in the form of dosage units for oral administration the compound selected may be mixed with a solid, powdered carrier, such as lactose, saccharose, sorbitol, mannitol, starch, amylopectin, cellulose derivatives, gelatin, or another suitable carrier, as well as with lubricating agents such as magnesium stearate, calcium stearate, sodium stearyl fumarate and polyethylenglycol waxes. The mixture is then processed into granules or pressed into tablets. Granules and tablets containing

sulfoxides may be coated with an enteric coating, which protects the active compound from acid catalyzed degradation as long as the dosage form remains in the stomach. The enteric coating is chosen among

pharmaceutically acceptable enteric-coating materials e.g. beeswax, shellac or anionic film-forming polymers such as cellulose acetate phtalate, hydroxypropyl- methylcellulose phthalate, partly methyl esterified methacrylic acid polymers and the like, if preferred in combination with a suitable plasticizer. To this coating various dyes may be added in order to

distinguish among tablets or granules with different active compounds or with different amounts of the active compound present.

Soft gelatine capsules may be prepared with capsules containing a mixture of the active compound or

compounds of the invention, vegetable oil, fat, or other suitable vehicle for soft gelatine capsules. Soft gelatine capsules may also be enteric-coated as described above. Hard gelatine capsules may contain granules or enteric-coated granules of the active compound. Hard gelatine capsules may also contain the active compound in combination with a solid powdered carrier such as lactose, saccharose, sorbitol,

mannitol, potato starch, amylopectin, cellulose

derivatives or gelatine. The hard gelatine capsules may be enteric-coated as described above. Dosage units for rectal administration may be prepared in the form of suppositories which contain the active substance mixed with a neutral fat base, or they may be prepared in the form of a gelatine rectal capsule which contains the active substance in a mixture with a vegetable oil, paraffin oil or other suitable vehicle for gelatine rectal capsules, or they may be prepared in the form of a ready-made micro enema, or they may be prepared in the form of a dry micro enema formulation to be reconstituted in a suitable solvent just prior to administration.

Liquid preparation for oral administration may be prepared in the form of syrups or suspensions, e.g.

solutions or suspensions containing from 0.2% to 20% by weight of the active ingredient and the remainder consisting of sugar or sugar alcohols and a mixture of ethanol, water, glycerol, propylene glycol and

polyethylene glycol. If desired, such liquid

preparations may contain colouring agents, flavouring agents, saccharine and carboxymethyl cellulose or other thickening agents. Liquid preparations for oral

administration may also be prepared in the form of a dry powder to be reconstituted with a suitable solvent prior to use.

Solutions for parenteral administration may be prepared as a solution of a compound of the invention in a pharmaceutically acceptable solvent, preferably in a concentration from 0.1% to 10% by weight. These

solutions may also contain stabilizing agents and/or buffering agents and may be manufactured in different unit dose ampoules or vials. Solutions for parenteral administration may also be prepared as a dry

preparation to be reconstituted with a suitable solvent extemporaneously before use.

The typical daily dose of the active substance varies within a wide range and will depend on various factors such as for example the individual requirement of each patient, the route of administration and the disease. In general, oral and parenteral dosages will be in the range of 5 to 500 mg per day of active substance.

The invention is illustrated by the following examples.

Example 1. Preparation of phosphoric acid, [5-acetyl- 6-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt or phosphoric acid, [6-acetyl-5- methyl-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]- 1H-benzimidazole-1-yl]methyl ester, disodium salt.

Tributylamine (1.7 ml, 7.0 mmol) was added with stirring to a solution of phosphoric acid, 85 per cent (0.24 ml, 3.6 mmol) in ethanol (2 ml). The solvent was evaporated and the residue taken up in methylene chloride (2.5 ml). The organic phase was dried over sodium sulphate, filtered and evaporated. 5-acetyl-1- chloromethyl-6-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole or 6- acetyl-1-chloromethyl-5-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole (0.12 g, 0,28 mmol) and the tributylammonium salt of phosphoric acid, prepared above, were dissolved in methylene chloride (6 ml). The methylene chloride was distilled off and the residue was heated on a waterbath for 5 minutes at 60°C. The residue was dissolved in

methylene chloride (6 ml) and again the methylene chloride was distilled off and the oily product mixture was heated on a waterbath for 5 minutes at 60°C. This procedure was repeated four times until the reaction was completed. The residue was dissolved in methylene chloride (4 ml) and washed with three (4 ml) portions of water. A solution of sodium hydroxide (0.2M), was added to the organic phase with stirring while pH of the aqueous layer was carefully controlled. When pH reached 9-9.5 in the aqueous phase the mixture was centrifuged. The aqueous layer was washed with three portions (4 ml) of methylene chloride and then freeze dried to give 40 mg, 27% of the title compound.

NMR data are given below.

Example 2. Preparation of phosphoric acid, [5-carbo methoxy-6-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt or phosphoric acid, [6- carbomethoxy-5-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt.

Tributylamine (1.8 ml, 7.8 mmol) was added with

stirring to a solution of phosphoric acid, 85%

(0.26 ml, 3.9 mmol) in ethanol (2.5 ml). The solvent was evaporated and the residue taken up in methylene chloride (3 ml). The organic phase was dried over sodium sulphate, filtered and evaporated. 5- carbomethoxy-1-chloromethyl-6-methyl-2-[[(3,4- dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole or 6-carbomethoxy-1-chloromethyl-5-methyl-2-[[(3,4- dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole (0.14 g, 0.32 mmol, and the tributylammonium salt of phosphoric acid, prepared above, were dissolved in methylene chloride (6.5 ml). The methylene chloride was distilled off and the residue was heated on a waterbath for 5 minutes at 60°C. The residue was dissolved in methylene chloride (6.5 ml) and again the methylene chloride was distilled off and the oily product mixture was heated on a waterbath for 5 minutes at 60°C. This procedure was repeated four times until the reaction was completed. The residue was dissolved in methylene chloride (4 ml) and washed with three (4 ml) portions of water. A solution of sodium hydroxide (0.2M), was added to the organic phase with stirring while pH of the aqueous layer was carefully controlled. When pH reached 9-9.5 in the aqueous phase the mixture was centrifuged. The aqueous layer was washed with three portions (4 ml) of methylene chloride and then freeze dried to give 11 mg, 6% of the title compound. NMR date are given below.

Table 1

Protons in water set to 4.80.

Ex. Solvent NMR data 6 ppm

₁ D₂O 2.67 (s,3H), 2.78 (s, 3H), 3.85

(s, 3H),

(300 MHz) 3.98 (s, 3H), 4.98 (d, 1H), 5.08 (d

1H), 5.98 (m, 2H), 7.15 (d, 1H), 7.

(s, 1H), 8.12 (d, 1H), 8.18 (s, 1H)

2 D₂O 2.75 (s, 3H), 3.83 (s, 3H), 3.97 (s

3H),

(300 MHz) 4.05 (s, 3H), 4.98 (d, 1H), 5.08 (d

1H), 5,95 (m, 2H), 7.15 (d, 1H), 7.

(s, 1H), 8.15 (d, 1H), 8.28 (s, 1H)

Preparation of intermediates

Example I 1 Preparation of 5-acetyl-1-hydroxymethyl-6-methyl-2-[[(3 dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole 6-acetyl-1-hydroxymethyl-5-metyl-2-[[(3,4-dimethoxy-2-p dinyl)methyl]sulfinyl]-1H-benzimidazole To a mixture of 5-acetyl-6-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole (2.00 g,

5.4 mmol) and methylene chloride (100 ml) aqueous 5 M formaldehyde (5.0 ml, 25 mmol) was added. The mixture was shaken for 3 minutes. After separation the organic solution was dried over Na₂SO₄ and evaporated under reduced pressure giving a red syrup (1.7 g, 78%). The product consisted mainly of one of the structure isomers of the title

compound as well as small amounts of starting material. NMR data are given below.

Example I 2

Preparation of 5-acetyl-1-chloromethyl-6-methyl-2-[[(3,4- dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole or 6-acetyl-1-chloromethyl-5-methyl-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole

A suspension of 5-acetyl-1-hydroxymethyl-6-methyl-2-[[(3,4- dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole and 6-acetyl-1-hydroxymethyl-5-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole (1.7 g,

4.2 mmol) in acetonitrile (40 ml) was chilled to -15°C.

Thionyl chloride (0.50 g, 4.2 mmol) and triethylamine

(0.50 g, 4.2 mmol) were added dropwise in the given order. The mixture was stirred at room temperature for five minutes and then evaporated under reduced pressure. The residue was chromatographed on silica gel (70 g) using a mixture of ethyl acetate and methylene chloride as eluent. The amount of ethyl acetate was increased during the chromatography. The product 0.14 g (8%) consisted mainly of one of the structure isomers.

NMR data are given below. Example I 3

Preparation of 5-carbomethoxy-1-hydroxymethyl-6-methyl-2- [[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benzimidazole or 6-carbomethoxy-1-hydroxymethyl-5-methyl-2- [[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benziraidazole

To a solution of 5-carbomethoxy-6-methyl-2-[[(3,4- dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole (0.34 g, 0.87 mmol) in methylene chloride (25 ml) 5 M aqueous formaldehyde (1.7 ml, 8.5 mmol) was added. The mixture was shaken for 3 minutes. After separation the organic solution was dried over Na₂SO₄ and evaporated under reduced pressure giving a red syrup (0.36 g, 100%). The product consisted mainly of one of the structure isomers of the title compound as well as small amounts of starting material. NMR data are given below.

Example I 4

Preparation of 5-carbcfnethoxy-1-chloromethyl-6-methyl-2- [[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benzimidazole or 6-carbomethoxy-1-chloromethyl-5-methyl-2- [[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benzimidazole A solution of 5-carbomethoxy-1-hydroxymethyl-6-methyl-2- [[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benzimidazole and 6-carbomethoxy-1-hydroxymethyl-5-methyl- 2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benzimidazole (0.36 g, 0.87 mmol) in aσetonitril (20 ml) was chilled to -20°C. Thionyl chloride (0.066 ml. 0.90 mmol) and triethylamine (0.10 g, 1.0 mmol) were added dropwise in the given order. The mixture was stirred at room temperature for five minutes and then evaporated under reduced pressure. The residue was chromatographed on silica gel (20 g) using a mixture of ethyl acetate and methylene chloride as eluent. The amount of ethyl acetate was

increased during the chromatography. The product 0.16 g (43%) consisted mainly of one of the structure isomers. NMR data are given below.

Table 2

Ex Solvent NMR data δ ppm

I 1 CDCl₃ 2.60 (s, 3H), 2.70(s, 3H), 3.90 (s, 3H),

3.95 (s, 3H), 4.8-5.1 (m, 2H), 5.70 (d,

1H), 6.10 (d, 1H) 6.75 (d, 1H), 7.40 (s, 1H),

7.90 (d, 1H), 8.10 (s, 1H).

I 2 CDCl₃ 2.66 (s, 3H), 2.72 (s, 3H), 3.90 (s, 3H) ,

3.91 (s, 3H), 4.91 (d, 1H), 5.02 (d, 1H),

6.23 (d, 1H), 6.55 (d, 1H), 6.80 (d, 1H), 7.39 (s, 1H), 8.15 (d, 1H), 8.20 (s, 1H) .

I 3 CDCl₃ 2.75 (s, 3H), 3.8-4.0 (m, 9H), 4.7-5.1 (m,

2H), 5.75 (d, 1H), 6.10 (d, 1H),

6.75 (d, 1H), 7.40 (s, 1H), 7.90 (d, 1H), 8.30 (s, 1H).

I 4 CDCl₃ 2.79 (s, 3H), 3.89 (s, 3H), 3.91 (s, 3H),

3.93 (s, 3H), 4.90 (d, 1H), 5.02 (d, 1H),

6.23 (d, 1H), 6.57 (d, 1H), 6.80 (d, 1H), 7.39 (s, 1H), 8.15 (d, 1H), 8.40 (s, 1H) . Table 3

Examples of compounds included in the formula I are given in the following table.

ric re

The best mode of carrying out the invention known at present is to use a compound according to Example 2.

Pharmaceutical preparations containing a compound of the invention as active ingredient are illustrated in the following formulations.

Syrup

A syrup containing 1% (weight per volume) of active

substance was prepared from the following ingredients: Compound according to Example 1 1 . 0 g

Sugar, powder 30 . 0 g

Saccharine 0. 6 g

Glycerol 5 . 0 g

Flavouring agent 0 . 05 g

Ethanol 96% 5. 0 g

Distilled water q.s. to a final volume of 100 ml

Sugar and saccharine were dissolved in 60 g of warm

water. After cooling the active compound was added to the sugar solution and glycerol and a solution of

flavouring agents dissolved in ethanol were added. The mixture was diluted with water to a final volume of 100 ml. Enteric-coated tablets

An enteric coated tablet containing 20 mg of active

compound was prepared from the following ingredients: I Compound mixture according to

Example 2 200 g

Lactose 700 g

Methyl cellulose 6 g

Polyvinylpyrrolidone cross-linked 50 g

Magnesium stearate 15 g

Sodium carbonate 6 g

Distilled water q.s.

II Cellulose acetate phthalate 200 g

Cetyl alcohol 15 g

Isopropanol 2000 g

Methylene chloride 2000 g I Compound according to Example 1, powder, was mixed with lactose and granulated with a water solution of methyl cellulose and sodium carbonate. The wet mass was forced through a sieve and the granulate dried in an oven. After drying the granulate was mixed with

polyvinylpyrrolidone and magnesium stearate. The dry mixture was pressed into tablet cores (10 000 tablets), each tablet containing 20 mg of active substance, in a tabletting machine using 6 mm diameter punches. II A solution of cellulose acetate phthalate and cetyl alcohol in isopropanol/methylene chloride was sprayed onto the tablets in an Accela Cota^R, Manesty coating equipment. A final tablet weight of 110 mg was obtained.

Solution for intravenous administration

A parenteral formulation for intravenous use,

containing 4 mg of active compound per ml, was prepared from the following ingredients: Compound according to Example 2 4 g

Sterile water to a final volume of 1000 ml

The active compound was dissolved in water to a final volume of 1000 ml. The solution was filtered through a 0.22 μm filter and immediately dispensed into 10 ml sterile ampoules. The ampoules were sealed. Tablets

Tablets containing 30 mg of active compound were prepared from the following ingredients: Compound according to Example 3 in Table 3 300 g

Lactose 700 g

Methyl cellulose 6 g Polyvinyl pyrrolidone, cross-linked (PVP-XL) 62 g

Disodium hydrogen phosphate 2 g Magnesium stearate 30 g

Purified water q.s.

The active compound was mixed with lactose and part of the PVP-XL and granulated with a solution of methyl cellulose and disodium hydrogen phosphate. The wet mass was forced through a screen and dried in a fluidized bed dryer. After adding magnesium stearate and the remainder in PVP-XL and mixing, the drug mixture was compressed into tablets with a mean weight of 110 mg, each tablet containing 30 mg of the active compound.

Enteric coated tablets

500 g of the tablets above were enteric-coated. A solution of the composition below was sprayed onto the tablets in a fluidized bed apparatus using Wurster coating technique.

Coating solution:

Cellulose acetate phthalate 40 g

Cetyl alcohol 2 g

Isopropanol 400 g

Dichloromethane 400 g The final coated tablet weighed 117 mg.

Suppositories

Suppositories were prepared from the following

ingredients using a welding procedure. Each suppository contained 40 mg of active compound.

Compound mixture according to Example 4

in Table 3 4 g Witepsol H-15 180 g

The active compound mixture was homogenously mixed with Witepsol H-15 at a temperature of 41°C. The molten mass was volume filled into pre-fabricated suppository packages to a net weight of 1.84 g. After cooling the packages were heat sealed. Each suppository contained 40 mg of active compound.

Just before use, the active compound dissolved in 10 ml of sterile water is transferred into 100 ml of normal saline solution for infusion to give a total volume of about 110 ml. The solution is administered as an intravenous infusion during a time period of about 30 minutes. Syrup

A syrup containing 1% of active substance was prepared from the following ingredients:

Compound according to Example 3 in

Table 3 1.0 g

Sugar, powder 30.0 g Saccharine 0.6 g

Flavouring agent 0.05 g

Ethanol 96% 5.0 g Purified water q.s. to 100 ml Sugar and saccharine were dissolved in 60 g of warm water. After cooling the active compound was added to the sugar solution and a solution of flavouring agents dissolved in ethanol was added. The mixture was diluted with water to a final volume of 100 ml.

Solution for intravenous or intramuscular injection

Compound according to Example 1 60 g

Water for injection to make 1000 ml

The active compound was dissolved in water to a final volume of 1000 ml. The solution was filtered through a sterile 0.22 μm filter and aseptically dispensed into 1 ml sterile ampoules. The ampoules were sealed.

Formulation for intravenous infusion

Sterile compound according to Example 2 60 mg Sterile injection vials and stoppers Sterile active compound, 60 mg, was dispensed into 10 ml sterile injection vials. The vials were stoppered with sterile rubberstoppers. The vokale filling operation was performed under aseptic conditions in a sterile production area under vertical laminar flow.

Biological Effects

Effects on the uptake of iodine into the thyroid gland

The effect of a compound within the invention of the formula I on the uptake of iodine into the thyroid gland is measured as an effect on the accumulation of

¹²⁵ I in the thyroid gland of the active compounds generated in the metabolism of the compounds within the invention.

Effect on the accumulation of ¹²⁵I in the thyroid gland The accumulation of ¹²⁵I in the thyroid gland was studied in male, Sprague-Dawley rats which were

deprived of food for 24 hours before the test. The experimental protocol of Searle, CE et al. (Biochem J

1950; 47:77-81) was followed.

Test substances, suspended in 0.5% buffered (pH 9) methocel, were administered by oral gavage in a volume of 5 ml/kg body weight. After 1 hour, ¹²⁵I (300kBq/kg,

3ml/kg) was administered by intraperitoneal injection. Four hours after ¹²⁵I-administration, the animals were killed by CO₂-asphyxiation and bled. The thyroid gland together with a piece of the trachea was dissected out and placed in a small test tube for the assay of radioactivity in a gamma counter (LKB-Wallac model 1282 Compugamma). Percentage inhibition was calculated according to the formula 100 ( 1-T/P) , where T and P is the mean radioactivity of thyroid glands from animals treated with test agent and placebo (buffered

methocel), respectively. The statistical significance for a difference between test agent- and placebo- treated animals was assessed with the Mann-Whitney U- test (two-tailed). P<0.05 was accepted as significant.

Results of biological tests

Table 4 give the test data available for the compounds of the invention.

Table 4, Biological Test Data

Test compound Per cent inhibition of

(number of animals) 400 μmol/kg on the uptake

ooff ¹²⁵I in the thyroid

gland

Active metabolite of

Examples No 1, 3 and 5

(n = 5) -7 Active metabolite of

Examples No 2, 4 and 6

(n = 5) 0

Claims

CLAIMS:

1. Compounds of the formula I

wherein

R¹ and R², which are different, is each methyl, -C(O)-CH₃ or -C(O)-OCH₃ and whereby one of R¹ or R² is always methyl and M is a physiologically acceptable counter cation.

2. A compound according to claim 1 wherein M is Na, K, Ag or trialkylammonium.

3. Compounds according to formula I of claim 1, namely a mixture of phosphoric acid, [5-acetyl-6-methyl-2- [[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H- benzimidazole-l-yl]methyl ester, disodium salt and phosphoric acid, [6-acetyl-5-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt.

4. Compounds as according to formula I of claim 1, namely a mixture of phosphoric acid, [5-carbomethoxy-6- methyl-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]- 1H-benzimidazole-1-γl]methγl ester, disodium salt and pho phoric acid, [6-carbomethoxy-5-methyl-2-[[(3,4- dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole2 1-yl]methyl ester, disodium salt.

5. A compound according to claim 1, namely phosphoric acid, (5-acetyl-6-methyl-2-[[(3,4-dimethoxy-2-pyridinyl)- methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt.

6. A compound according to claim 1, namely phosphoric acid, [6-acetyl-5-methyl-2-[[(3,4-dimethoxy-2-pyridinyl)- methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt.

7. A compound according to claim 1 namely phosphoric acid, [5-carbomethoxy-6-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt.

8. A compound according to claim 1, namely phosphoric acid, [6-carbomethoxy-5-methyl-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl]methyl ester, disodium salt.

9. A pharmaceutical composition containing as active ingredient a compound according to claim 1.

10. A compound as defined in claim 1 for use in therapy.

11. A compound as defined in claim 1 for use in

inhibiting gastric acid secretion in mammals including man.

12. A compound as defined in claim 1 for use in the treatment of gastrointestinal inflammatory diseases in mammals including man.

13. A method for inhibiting gastric acid secretion by administering to mammals including man a compound as defined in claim 1.

14. A method for the treatment of gastrointestinal inflammatory diseases in mammals including man by administering a compound as defined in claim 1.

15. Use of a compound according to claim 1 in the manufacture of a medicament for inhibiting gastric acid secretion in mammals including man.

16. Use of a compound according to claim 1 in the manufacture of a medicament for the treatment of

gastrointestinal infiammatory diseases in mammals

including man.

17. A process for the preparation of a compound of the formula I according to claim 1, by

a) reacting a compound of the formula II

wherein R¹ and R² are as defined under formula I and Z halogen such as CI, Br or I or a functionally equivalent group, with a compound of the formula III O

II HO-P-O Q III

I O Q wherein Q is a counter ion such as Na⁺, K⁺, Ag⁺ or trialkylammonium, or b) Oxidizing a compound of the formula IV

18. A compound of the formula II

^{wherein R1} and R² are as defined under formula I and Z is halogen, such as CI, Br or I or a functionally equivalent group.

19. A compound according to claim 18, wherein R¹ and

R² are as defined above and Z is CI or OH.