it has surprisingly been found that the substance omeprazole can exist in more than one crystal form . it is an object of the present invention to provide omeprazole form a . another object of the present invention is to provide a process for the preparation of omeprazole form a , substantially free from other forms of omeprazole . x - ray powder diffraction ( xrpd ) is used as a method of differentiating omeprazole form a from other crystalline and non - crystalline forms of omeprazole . additionally it is an object of the present invention to provide pharmaceutical formulations comprising omeprazole form a . omeprazole form a is a crystalline form exhibiting advantageous properties , such as being well - defined , being thermodynamically more stable and less hygroscopic than omeprazole form b , especially at room temperature . omeprazole form a does also show a better chemical stability , such as thermo stability and light stability , than omeprazole form b . omeprazole form b can under certain conditions , completely or partly , be converted into omeprazole form a . omeprazole form a is thereby characterized in being thermo - dynamically more stable than omeprazole form b . omeprazole form a is characterized by the positions and intensities of the peaks in the x - ray powder diffractogram , as well as by the unit cell parameters . the unit cell dimensions have been calculated from accurate guinier data . the x - ray powder diffractogram data as well as the unit cell parameters for omeprazole form b are different compared to omeprazole form a . omeprazole form a can thereby be distinguished from omeprazole form b , using x - ray powder diffraction . omeprazole form a , according to the present invention , is characterized in providing an x - ray powder diffraction pattern , as in fig1 exhibiting substantially the following d - values and intensities ; the peaks , identified with d - values calculated from the bragg formula and intensities , have been extracted from the guinier diffractogram of omeprazole form a . the relative intensities are less reliable and instead of numerical values the following definitions are used ; * the relative intensities are derived from diffractograms measured with fixed slits . omeprazole form a according to the present invention is further characterized by a triclinic unit cell with parameters ; omeprazole form a can also be characterized by raman spectroscopy , where omeprazole form a is characterized by the absence of a band at 1364 cm − 1 , which is observed for omeprazole form b , and by the ratio of the relative intensities of the 842 and 836 cm − 1 bands . the ratio ( intensity of 842 cm - 1 band / intensity of 836 cm - 1 band ) is & lt ; 1 for omeprazole form a , while the ratio is & gt ; 1 for omeprazole form b . according to the invention there is further provided a process for the preparation of omeprazole form a . omeprazole form a is obtained upon slow crystallization and omeprazole form b is obtained from fast crystallization . omeprazole form a may be prepared by reaction crystallisation or recrystallizing omeprazole of any form , or mixtures of any forms , in an appropriate solvent , such as for instance methanol , at around room temperature and for a prolonged time period . examples of prolonged time periods include , but are not limited to , a few hours , such as 2 hours , up to several weeks . suitable solvents are alkyl alcohols and especially a lower alcohol comprising 1 - 4 carbon atoms . omeprazole form a may also be prepared by suspending omeprazole of any form , or mixtures of any forms , in an appropriate solvent at around room temperature and for a prolonged time period . examples of appropriate solvents include , but are not limited to , methanol , ethanol , acetone , ethyl acetate , methyl tert , butyl ether , toluene , or any mixture thereof . examples of prolonged time periods include , but are not limited to , a few hours , such as 2 hours , up to several weeks . the omeprazole form a obtained according to the present invention is substantially free from other crystal and non - crystal forms of omeprazole , such as omeprazole form b . substantially free from other forms of omeprazole shall be understood to mean that omeprazole form a contains less than 10 %, preferably less than 5 %, of any other forms of omeprazole , e . g . omeprazole form b . omeprazole form a in mixture with other solid form / forms of omeprazole , e . g . omeprazole form b , also exhibits advantageous properties , such as being chemically more stable than pure omeprazole form b . mixtures comprising a certain amount of omeprazole form a , by weight , are also chemically more stable than other mixtures comprising a lesser amount of omeprazole form a , by weight . such mixtures comprising omeprazole form a can be prepared , for example , by mixing omeprazole form a prepared according to the present invention with other solid forms of omeprazole , such as form b , prepared according to prior art . the present invention also relates to mixtures comprising omeprazole form a in mixture with other solid forms of omeprazole . such mixtures comprising omeprazole form a include for instance mixtures containing a detectable amount of omeprazole form a , 1 %, 2 %, 5 %, 10 %, 20 %, 30 %, 40 %, 50 %, 60 %, 70 %, 80 %, 90 %, 95 %, 98 % or 99 % weight ), of omeprazole form a . examples of other solid forms of omeprazole include , but are not limited to , omeprazole form b , amorphous forms , and other polymorphs . a detectable amount of omeprazole form a is an amount that can be detected using conventional techniques , such as ft - ir , raman spectroscopy , xrpd and the like . the expression chemical stability includes , but is not limited to , thermo stability and light stability . the compound of the invention , i . e . omeprazole form a , prepared according to the present invention is analyzed , characterized and differentiated from omeprazole form b by x - ray powder diffraction , a technique which is known per se . another suitable technique to analyze , characterize and differentiate omeprazole form a from omeprazole form b is by raman spectroscopy : omeprazole form a is effective as a gastric acid secretion inhibitor , and is useful as an antiulcer agent . in a more general sense , it can be used for treatment of gastric - acid related conditions in mammals and especially in man , including e . g . reflux esophagitis , gastritis , duodenitis , gastric ulcer and duodenal ulcer . furthermore , it may be used for treatment of other gastrointestinal disorders where gastric acid inhibitory effect is desirable e . g . in patients on nsaid therapy , in patients with non ulcer dyspepsia , in patients with symptomatic gastro - esophageal reflux disease , and in patients with gastrinomas . the compound of the invention may also be used in patients in intensive care situations , in patients with acute upper gastrointestinal bleeding , pre - and postoperatively to prevent aspiration of gastric acid and to treat stress ulceration . further , the compound of the invention may be useful in the treatment of psoriasis as well as in the treatment of helicobacter infections and diseases related to these . the compound of the invention may also be used for treatment of inflammatory conditions in mammals , including man . any suitable route of administration may be employed for providing the patient with an effective dosage of omeprazole form a according to the invention . for example , peroral or parenteral formulations and the like may be employed . dosage forms include capsules , tablets , dispersions , suspensions and the like , e . g . enteric - coated capsules and / or tablets , capsules and / or tablets containing enteric - coated pellets of omeprazole . in all dosage forms omeprazole form a can be admixtured with other suitable constituents . according to the invention there is further provided a pharmaceutical composition comprising omeprazole form a , as active ingredient , in association with a pharmaceutically acceptable carrier , diluent or excipient and optionally other therapeutic ingredients . compositions comprising other therapeutic ingredients are especially of interest in the treatment of helicobacter infections . the invention also provides the use of omeprazole form a in the manufacture of a medicament for use in the treatment of a gastric - acid related condition and a method of treating a gastric - acid related condition which method comprises administering to a subject suffering from said condition a therapeutically effective amount of omeprazole form a . the compositions of the invention include compositions suitable for peroral or parenteral administration . the compositions may be conveniently presented in unit dosage forms , and prepared by any methods known in the art of pharmacy . in the practice of the invention , the most suitable route of administration as well as the magnitude of a therapeutic dose of omeprazole form a in any given case will depend on the nature and severity of the disease to be treated . the dose , and dose frequency , may also vary according to the age , body weight , and response of the individual patient . special requirements may be needed for patients having zollinger - ellison syndrome , such as a need for higher doses than the average patient . children and patients with liver diseases as well as patients under long term treatment will generally benefit from doses that are somewhat lower than the average . thus , in some conditions it may be necessary to use doses outside the ranges stated below . such higher and lower doses are within the scope of the present invention . in general , a suitable oral dosage form may cover a dose range from 5 mg to 250 mg total daily dose , administered in one single dose or equally divided doses . a preferred dosage range is from 10 mg to 80 mg . the compound of the invention may be combined as the active component in intimate admixture with a pharmaceutical carrier according to conventional techniques , such as the oral formulations described in wo 96 / 01623 and ep 247 983 , the disclosures of which are hereby incorporated as a whole by reference . combination therapies comprising omeprazole form a and other active ingredients in separate dosage forms , or in one fixed dosage form , may also be used . examples of such active ingredients include anti - bacterial compounds , non - steroidal anti - inflammatory agents , antacid agents , alginates and prokinetic agents . the examples which follow will further illustrate the preparation of the compound of the invention , i . e . omeprazole form a , but are not intended to limit the scope of the invention as defined hereinabove or as claimed below . omeprazole ( 55 . 8 g ) is added at room temperature to methanol ( 348 ml ) containing ammonia ( 1 . 3 ml ; 25 %). the suspension is thereafter stirred in darkness for approximately 45 hours and then filtered . the filtrate is dried 18 hours at 30 ° c . under reduced pressure (& lt ; 5 mbar ). yield : 43 . 9 g . omeprazole ( 50 g ) is added to methanol ( 750 ml ) containing ammonia ( 0 . 7 ml ; 25 %) at 50 ° c . the solution is thereafter filtered and cooled in about 20 minutes to approximately 0c . the formed crystals are filtered and washed with ice cooled methanol and then dried . the filtrate was dried 24 hours at 40 ° c . under reduced pressure (& lt ; 5 mbar ). yield : 39 g . characterization of omeprazole form a and omeprazole form b using x - ray powder diffraction x - ray diffraction analysis was performed according to standard methods which can be found in e . g . bunn , c . w . ( 1948 ), chemical crystallography , clarendon press , london ; or klug , h . p . & amp ; alexander , l . e . ( 1974 ), x - ray diffraction procedures , john wiley and sons , new york . the unit cell parameters for omeprazole form a and b have been calculated from the guinier x - ray powder diffractograms using the program “ treor ” by wemer , p .- e ., eriksson , l . and westdahl , m ., j . appl . crystallogr . 18 ( 1985 ) 367 - 370 . the fact that the positions of all peaks in the diffractograms for omeprazole form a and form b may be calculated using the respective unit cell parameters , proves that the unit cells are correct and that the diffractograms are indicative of the pure forms . the diffractogram of omeprazole form a , prepared according to example 1 in the present application , is shown in fig1 and the diffractogram of omeprazole form b , prepared according to example 2 in the present application is shown in fig2 . the peaks , identified with d - values calculated from the bragg formula and intensities , have been extracted from the diffractograms for omeprazole forms a and form b , and are given in table 1 . in this table the unit cell parameters for omeprazole forms a and b are also given . the relative intensities are less reliable and instead of numerical values the following definitions are used ; some additional weak or very weak peaks found in the diffractograms have been omitted from table 1 . table 1 . x - ray powder diffraction data for omeprazole form a and form b shown in fig1 and 2 . all peaks noted for omeprazole form a and form b can be indexed with the unit cells given below .
the present invention relates to a novel crystalline form of 5 - methoxy - 2 - methyl ] sulfinyl - 1h - benzimidazole , known under the generic name omeprazole . further , the present invention also relates to the use of the novel crystalline form of 5 - methoxy - 2 - methyl ] sulfinyl ]- 1h - benzimidazole for the treatment of gastrointestinal disorders , pharmaceutical compositions containing it as well as processes for the preparation of the novel crystalline form of 5 - methoxy - 2 - methyl ] sulfinyl ]- 1h - benzimidazole .