Background of the invention and prior art Acid labile H, K-ATPase inhibitors also named as gastric proton pump inhibitors are for instance compounds known under the generic names omeprazole, lansoprazole, pantoprazole, rabeprazole and leminoprazole. Some of these compounds are disclosed in EP-A1-0005129, EP-A1-124495, WO 94/27988, EP-A1-174726, EP-A1-166287 and GB 2163747.

These pharmaceutical substances are useful for inhibiting gastric acid secretion in mammals including man by controlling gastric acid secretion at the final step of the acid secretory pathway and thus reduce basal and stimulated gastric acid secretion irrespective of stimulus. In a more general sense, they may be used for prevention and treatment of gastric-acid related diseases in mammals and man, including e. g. reflux oesophagitis, gastritis, duodenitis, gastric ulcer, duodenal ulcer and Zollinger-Ellison syndrom.

Furthermore, they 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, and in patients with symptomatic gastro-oesophageal reflux disease

(GORD). They may also be used in patients in intensive care situations, in patients with acute upper gastrointestinal bleeding, pre-and post-operatively to prevent aspiration of gastric acid and to prevent and treat stress ulceration. Further, they may be useful in the treatment of psoriasis as well as in the treatment of Helicobacter infections and diseases related to these.

Therapeutic control of gastric acid secretion is fundamental in all these disease, but the degree and duration of acid inhibition required for optimal clinical effect is not fully understood.

It has been proposed by the Applicant in W097/48380, (published 24 December, 1997 i. e. after the priority date of the instant application,) that an administration regimen that gives blood plasma levels extending from 2-12 hours (by any of several means) will result in a larger fraction of proton pumps being inhibited. Thus, an extended blood plasma level should result in more effective inhibition of acid secretion resulting in improved efficacy in GORD, more rapid healing of gastric ulcer and improved eradication of H. Pylori. The present invention provides pharmaceutically dosage forms which achieve such extended plasma levels by releasing the drug in two or more separate pulses.

A pharmaceutical dosage form of omeprazole or any other proton pump inhibitor is best protected from contact with acidic gastric juice by an enteric coating layer. In US 4,786,505 and US 4,853,230 such enteric coated preparations are described. These preparations have a core comprising an alkaline salt of the drug or a core comprising the drug together with an alkaline reacting compound, the core is coated with a water soluble or in water rapidly disintegrating separating layer and then with an enteric coating layer.

WO 96/01623 and WO 96/01624 describe tableted dosage forms of omeprazole and other proton pump inhibitors, wherein enteric coating layered pellets are compressed into a multiple unit tableted dosage form. It is essential in these tableted formulations that the enteric coating layer can withstand the compression forces. None of these by the Applicant previously described formulations gave a dissolution of two or more pulses separated in

time, i. e. in the meaning pulsed release of the proton pump inhibitor which resulted in an extended blood plasma profile.

There are different technologies and pharmaceutical formulations described in the prior art which aim at a delayed release of an administered drug. Such pharmaceutical formulations are for instance formulations providing different lag times, constructions based on osmotic differences, slow-eroding/dissolving layers, time controlled explosion systems or any combinations thereof. In the following some of these principles are described.

Gazzaniga et al (Proceed. 12* Pharm. Int. Techn. Conf., described tablets which were spray-coated or press-coated with HPMC layers to obtain delayed release preparations of ketoprofen or verapamil. The HPMC layer may also contain an insoluble filler. Gazzaniga et al have also described press-coated tablets containing antipyrine with HPMC layers to obtain delayed release, having an outer enteric coating comprising Eudragit L30D applied thereon. (Proc. Inter. Symp. Control. Rel. Bioact. Mater. 1996,23, 571-2.) EP-A1-0629398 describes a dosage form comprising a drug and an organic acid in a core surrounded by a film that controls the start of release, and further covered by an enteric coating layer. This dosage form is not suitable for substances that are sensitive to acidic degradation as the core comprises an organic acid.

Osmotic systems are described by Fox ("Colon-Targeted Osmotic System for Oral delivery of Peptides and Proteins", In; Oral Delivery of Proteins, Peptides and other Biopharmaceutical Agents; Proceedings Technology Management Group, Wakefield, MA, USA, Sept. 1991). A colon release system, OROS-CT, is used to obtain delayed extended release after a lag time. The dosage form had an enteric coating which dissolved in the small intestines, the drug release started after a desired lag time and the release was maintained during some hours.

EP 0384642 and EP 0384646 (as well as Pharm. J., July 27"', 1991 pp. 137-9) introduced the PULSINCAPTM dosage form both for enteric coated system and non-enteric coated system. The system comprises a capsule composed of a water insoluble body and a water soluble cap. The drug formulation was contained within the capsule body and sealed within this region by means of a hydrogel plug.

Conte et al (Drug Development and Industrial Pharmacy, 1989, vol 15, pp. 2583-96) described a three-layer tablet giving a double pulse system suitable for ibuprofen. The first layer contained a rapidly releasing formulation, and was separated from the layer comprising the second dose by a swellable polymeric barrier layer. The second dose was coated with an impermeable film of ethyl cellulose. This construction releases the drug in an acidic medium.

A dosage form for diltiazem was described in US 5,567,441 comprising a mixture of one fraction of enteric coated pellets with slow release and another fraction of delayed pulse release membrane coated pellets, the latter fraction of pellets were not enteric coated. Such a dosage form will not be suitable for acidic sensitive drugs such as omeprazole or the like.

There are two newly published patent applications which propose controlled release formulations comprising a proton pump inhibitor, i. e. in WO 97/02020 a dosage form for pantoprazole in combination with an antibacterial substance is proposed. At least a part of the pantoprazole dose shall be in slow-release form with a continuous release of pantoprazole during time. The preparation has one intermediate layer which will remain intact as a layer and is releasing the dose of pantoprazole continuously so as a pantoprazole plasma level persists as long as possible. WO 97/02021 discusses a very similar dosage form of a reversible proton pump inhibitor in combination with an antibacterial substance.

Detailed description of the drawings

Figures 1-5 show graphs illustrating the dissolution profiles for some of the inventive pharmaceutical formulations prepared in the examples. The graphs show the released amount of substance with respect to time. The amount of released substance is identified by registration of the absorbance at 292 nm in a buffer solution.

Figure 1 shows the dissolution profile for single dose layered pellets prepared in Example 1.

Figure 2 shows the dissolution profile for single dose layered pellets prepared in Example 2.

Figure 3 shows the dissolution profile for single dose layered pellets prepared in Example 3.

Figure 4 shows the dissolution profile for single dose layered tablets prepared in Example 5.

Figure 5 shows the dissolution profile for multiple dose layered tablets prepared in Example 6.

Summary of the invention The therapeutic effect of omeprazole and similar substances may be improved by providing an extended plasma profile by once daily administration of a dosage form. The present invention obtains such an extended plasma profile by a pharmaceutical dosage form capable of releasing the drug in discrete pulses separated in time, i. e. a dosage form with a discontinuous release pattern. The present invention provides such dosage forms comprising an acid susceptible H+K+-ATPase inhibitor, such as omeprazole or any other proton pump inhibitor. A specific problem is that the pharmaceutical dosage forms suitable for a H K-ATPase inhibitor must fulfill certain requirement with respect to gastric acid resistance for enteric coated articles specified in the US Pharmacopeia (Edition 23).

According to one aspect of the invention the extended plasma profile of a proton pump inhibitor is provided by once daily administration of a dosage form which, in the small

and/or large intestines (but not in the stomach), releases the proton pump inhibitor in two or more discrete pulses separated in time by from 0.5 up to 12 hours, preferably separated in time by from 0.5 and up to 8 hours, and more preferably by from 0.5 and up to 4 hours.

According to another aspect of the invention a discontinuous release pattern of the proton pump inhibitor by once daily administration of a dosage form is provided wherein a part of the dosage form gives a pulsed delayed release, and other parts of the dosage form release the proton pump inhibitor instantly. The dosage form provides at least two consecutive pulses for release of substance, the pulses should be separated in time by from 0.5 and up to 12 hours, preferably by from 0.5 and up to 8 hours, and more preferably by from 0.5 and up to 4 hours interval.

The present pulsed release formulations show an improved patient compliance over an administration regimen comprising consecutive administration of two or more unit doses within specified time intervals.

Detailed description of the invention Activesubstance.

Compounds of interest for the novel pharmaceutical formulations according to the present invention are compounds of the general formula I, an alkaline salt thereof, one of the single enantiomers thereof or an alkaline salt of one of the enantiomers wherein

Met} is Het2 is X= wherein N in the benzimidazole moiety means that one of the ring carbon atoms substituted by R6- Rg optionally may be exchanged for a nitrogen atom without any substituents; RI, R2 and R3 are the same or different and selected from hydrogen, alkyl, alkoxy optionally substituted by fluorine, alkylthio, alkoxyalkoxy, dialkylamino, piperidino, morpholino, halogen, phenyl and phenylalkoxy; R4 and Rs are the same or different and selected from hydrogen, alkyl and arylalkyl;

R6'is hydrogen, halogen, trifluoromethyl, alkyl or alkoxy; R6-R9 are the same or different and selected from hydrogen, alkyl, alkoxy, halogen, halo- alkoxy, alkylcarbonyl, alkoxycarbonyl, oxazolinyl, and trifluoroalkyl, or adjacent groups R6-Rg form ring structures which may be further substituted; Rlo is hydrogen or forms an alkylene chain together with R3 and Rl l and Rl2 are the same or different and selected from hydrogen, halogen or alkyl.

Examples of specifically interesting compounds according to formula I are

OCH3<BR> OCH<BR> OCHF2#O <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> #<BR> <BR> <BR> <BR> N #S <BR> <BR> <BR> <BR> <BR> N<BR> <BR> <BR> <BR> H<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> OCH2CH2CH20CH3<BR> # CH3<BR> #O<BR> N<BR> #<BR> S#NCH2 <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> N<BR> #<BR> CHUS<BR> CH3 NCH2CH(CH3)2 #O N #<BR> #CH2S <BR> <BR> <BR> <BR> <BR> <BR> H<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> # H #N<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> N#O <BR> <BR> <BR> <BR> <BR> CH3O # S #<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> #N<BR> <BR> <BR> <BR> <BR> CL3<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> #CH3<BR> N<BR> ##S <BR> <BR> <BR> <BR> CH3<BR> #<BR> O # N O N<BR> <BR> <BR> H

The compound suitable to be used in the pulsed release formulations according to the present invention may be used in neutral form or in the form of an alkaline salt, such as for instance the Mg2+, Ca2+, Na or K salts, preferably the Mg2+ salts. The compounds may also be used in the form of one of its single enantiomers or an alkaline salt of the single enantiomer.

Especially preferred compounds for the oral pharmaceutical preparation according to the present invention are omeprazole, a magnesium salt of omeprazole or a magnesium salt of the (-)-enantiomer of omeprazole. Omeprazole and related substances as well as their preparations are described in EP 5129, EP 124 495, WO 95/01977, WO 94/27988 hereby incorporated in a whole by references.

The above compounds are susceptible to degradation/transformation in acidic and neutral media. Generally, the degradation is catalyzed by acidic reacting compounds and the active compounds are stabilized with alkaline reacting compounds. There are different enteric coating layered preparations comprising omeprazole as well as other proton pump

inhibitors described in the prior art, see for instance US-A 4,853,230, WO 95/01783, and WO 96/01623. Especially, the latter describes alternative manufacturing methods for the preparation of enteric coating layered pellets comprising omeprazole and similar compounds.

The dosage forms according to the invention provide at least a part of the dose with a pulsed delayed release of the drug and another part of the formulation with rapid or instant release. The instant and pulsed delayed release of the drug can be achieved according to different principles, such as -by single dose layered pellets or tablets, -by multiple dose layered pellets or tablets, or -by two or more different fractions of single or multiple dose layered pellets or tablets, optionally in combination with pellets or tablets having instant release.

Multiple dose layered pellets, or two or more different populations of single or multiple dose layered pellets prepared according to any of the below described principles, are filled into a capsule or together with tablet excipients compressed into a multiple unit tablet.

Alternatively, a multiple dose layered tablet may be prepared.

Single dose layered pellets or tablets.

According to one aspect of the invention, pellets or tablets giving one single delayed release pulse of the drug are prepared. The single dose layered pellets or tablets may be constructed as to comprise the following parts: -a core material, optionally layered on a seed/sphere, the core material comprises the drug together with a water swellable substance, and optionally pharmaceutically acceptable excipients, and the core material is being free from acidic compounds, and thereupon the following sequence of layers: -a surrounding lag time controlling layer, and finally

-an enteric coating layer positioned to cover the lag time controlling layer.

According to an alternative aspect of the invention, it is also possible to construct the layered pellets or tablets as to comprise the following parts: -a core material, optionally layered on a seed/sphere, the core material comprises the drug optionally together with pharmaceutically acceptable excipients, and the core material is being free from acidic compounds, and thereupon the following sequence of layers: -a surrounding layer comprising a water swellable substance, and thereupon -a surrounding lag time controlling layer, and finally -an enteric coating layer positioned to cover the lag time controlling layer.

Multiple dose layered pellets or tablets.

According to another aspect of the invention, multiple dose layered pellets or tablets giving two or more delayed release pulses of the drug are prepared. These pellets or tablets may be constructed as to comprise the following parts: -a core material (I), optionally layered on a seed/sphere, the core material comprises the drug together with a water swellable substance, and optionally pharmaceutically acceptable excipients, and the core material is being free from acidic compounds, and thereupon the following sequence of layers: -a surrounding lag time controlling layer (II), and -a layer (III) comprising the drug optionally together with a water swellable substance, and/or pharmaceutically acceptable excipients; the layer is being free from acidic compounds, and -optionally a separating layer (IV) which is water-soluble or in water rapidly disintegrating,

wherein the layers II and III and the optional layer IV may appear in repeated sequences (in this order) and each set of layers (II + III) gives an additional single pulse of the drug. The dosage form is finally covered by an outer enteric coating layer (V).

Thus, a three-pulsed delayed release pellet or tablet could be constructed as having the following sequence of layers I+ II + III + II + III + an optional layer IV, and the prescribed outer enteric coating layer (V).

According to an alternative aspect of the invention, the multiple dose layered pellets or tablets may also be constructed with the following parts: -a core material (I), optionally layered on a seed/sphere, the core material comprises the drug optionally together with pharmaceutically acceptable excipients, and the core material is being free from acidic compounds, and thereupon the following sequence of layers: -a surrounding layer (II) comprising a water swellable substance, followed by -a surrounding lag time controlling layer (III) and -a layer (IV) comprising the drug optionally together with pharmaceutically acceptable excipients; the layer is being free from acidic compounds, and -optionally a separating layer (V) which is water-soluble or in water rapidly disintegrating, wherein the layers II, III, IV and the optional layer V may appear in repeated sequences (in this order) and each set of layers (II + III+ IV) gives an additional single pulse of the drug.

The dosage form is covered by an outer enteric coating layer (VI).

Thus, a three-pulsed pellet or tablet could be constructed as having the following sequence of layers I+ II + III + IV+ II + III + IV + an optional layer V, and the prescribed outer enteric coating layer (VI).

The core material comprising the active drug can be prepared either by coating layering the drug onto a seed, such as for instance sugar spheres, or by extrusion

/spheronization of a mixture comprising the drug and pharmaceutical acceptable excipients.

It is also possible to prepare the core material by using tablet technology, i. e. compression of drug granules and optionally pharmaceutically acceptable excipients into a tablet core.

For pellets of the two types, i. e. single or multiple dose pellets, which have the drug deposited onto a seed/sphere by layering, it is also possible to have an optional layer comprising a water swellable substance beneath the drug containing layer in the core material.

The prepared core material is used for further processing. Different techniques to prepare the core material for pellets or tablets are described below.

Core material The core material for the individual pellets or tablets can be constituted according to different principles. A seed/sphere layered with active substance, the active substance is optionally mixed with a water swellable substance and/or a pharmaceutically acceptable excipient, can be used as core material for the further processing. The core material is free from acidic compound except that the active substance as such might be slightly acidic.

The micro environment around the acid susceptible H K-ATPase inhibitor should preferable be not less than pH=7, and more preferably not less than pH=8 when water is absorbed to the core material mixture or when water is added in small amount to the mixture.

The seeds/spheres can be water insoluble and comprise different oxides, celluloses, organic polymers and other materials, alone or in mixtures, or be water soluble and comprise different inorganic salts, sugars and other materials, alone or in mixtures. Further, the seeds/spheres may comprise active substance in the form of crystals, agglomerates, compacts etc. The size of the seeds may vary between approximately 0.1 and 2 mm. The

seeds layered with active substance are produced either by powder or solution/suspension layering using for instance granulating or spray coating/layering equipment.

Before the seeds are layered, the active substance may be mixed with further components to obtain preferred handling and processing properties and a suitable concentration of the active substance in the final mixture.

Such components can be binders, surfactants, fillers, disintegrating agents, alkaline additives or other pharmaceutically acceptable ingredients, alone or in mixtures. The binders are for example celluloses such as hydroxypropyl methylcellulose, methylcellulose, hydroxypropyl cellulose and carboxymethyl-cellulose sodium, polyvinyl pyrrolidone, gelatine, sugars, starches and other pharmaceutically acceptable substances with cohesive properties. Suitable surfactants are found in the groups of pharmaceutically acceptable non-ionic surfactants, such as polysorbate 80, or ionic surfactants such as for instance sodium lauryl sulfate.

Optionally an osmotic agent is placed in the core material. Such an osmotic agent is water soluble and will provide an osmotic pressure in the tablet. Examples of osmotic agents are magnesium sulfate, sodium chloride, lithium chloride, potassium chloride, potassium sulfate, sodium carbonate, lithium sulfate, calcium bicarbonate, sodium sulfate, calcium lactate, urea, magnesium succinate, sucrose or mixtures thereof.

Alternatively, the active substance optionally mixed with any of the components defined above can be formulated into a core material. Said core material may be produced by extrusion/spheronization, balling or compression utilizing different process equipments.

For extrusion/spheronization processes incorpaoration of a microcrystalline cellulose and a low-substituted hydroxypropylcellulose in the core material is preferred. The size of the formulated core materials is approximately between 0.1 and 4 mm, preferably between 0.1 and 2 mm for a pellet preparation, and between 2 and 10 mm, preferably between 3 and 7 mm for a tablet preparation.

Suitable alkaline additives can be chosen among, but are not restricted to, substances such as the sodium, potassium, calcium, magnesium and aluminium salts of phosphoric acid, carbonic acid, citric acid or other suitable weak inorganic or organic acids; aluminium hydroxide/sodium bicarbonate coprecipitate; substances normally used in antacid preparations such as aluminium, calcium and magnesium hydroxides; magnesium oxide or composite substances, such as A1203.6MgO. CO2.12H2O, (Mg6Al2 (OH) 16CO3. 4H2O), MgO. Al203.2Si02. nH20 or similar compounds; organic pH-buffering substances such as trihydroxymethylaminomethane, basic amino acids such as arginine, and their salts or other similar, pharmaceutically acceptable pH-buffering substances.

Alternatively, the aforementioned core material for a pellet preparation can be prepared by using spray drying or congealing techniques.

Swelling layer.

The applied swelling layer comprises one or more water swellable substances, a suitable binder, and optionally pharmaceutically acceptable excipient (s). Suitable swellable substances, binders, as well as pharmaceutically acceptable excipients are described below.

The swelling layer expands when exposed for an aqueous solution such as intestinal fluid.

Alternatively, one of the additional drug containing layers applied onto the core material may be a combined drug swelling layer.

Water swellable substances.

Water swellable substances suitable for the dosage forms according to the present invention are compound which are able to expand when they are exposed to an aqueous solution, such as intestinal fluid.

One or more water swellable substances may be present in the core material together with the active substance and optionally pharmaceutically acceptable excipient (s). Alternatively, one or more water swellable substances are included in a swelling layer applied onto the core material. As a further alternative, swellable substances (s) they may also be present in an optional swelling layer situated beneath the drug containing layer, if a layered seed or sphere is used as the core material.

The amount and art of water swellable substance (s) in the swelling layer or in the core material is chosen in such a way that the core material or the swelling layer in contact with an aqueous solution, such as intestinal fluid, will expand to such a degree that the surrounding lag-time controlling membrane ruptures. A water swellable substance may also be included in the drug comprising layer of the multiple layered pellets or tablets to increase dissolution rate of the drug fraction.

Suitable substances which can be used as water swellable substances are for instance, low- substituted hydroxypropyl cellulose, e. g. L-HPC; cross-linked polyvinyl pyrrolidone (PVP- <BR> <BR> <BR> TU T. M<BR> <BR> <BR> XL), e. g. Kollidon CL and Polyplasdone XL; cross-linked sodium TM TM carboxymethylcellulose, e. g. Ac-di-sol, Primellose; sodium starch glycolate, e. g.

TM TM Primojel; sodium carboxymethylcellulose, e. g. Nymcel ZSB 10; sodium TM TM TM carboxymethyl starch, e. g. Explotab; ion-exchange resins, e. g. Dowex or Amberlite ; microcrystalline cellulose, e. g. Avicel; starches and pregelatinized starch, e. g. Starch TM TM TM 1500, Sepistab ST200; and formalin-casein, e. g. Plas-Vita. One of these substances can be used or any combinations or mixtures thereof, taking into consideration that the use of any acidic compound not is suitable.

Lag time controlling layer.

The lag time controlling layer is a semipermeable membrane comprising a water resistant polymer that is semipermeable for an aqueous solution, such as intestinal fluid. Suitable polymers are cellulose acetate, ethylcellulose, polyvinyl acetate, cellulose acetate butyrate, TAM cellulose acetate propionate, acrylic acid copolymers, such as Eudragit RS or RL. The polymer may optionally comprise pore forming agents, such as a water soluble substance, eg. sucrose, salt; or a water soluble polymer eg. polyethylene glycol. Also pharmaceutically acceptable excipients such as fillers and membrane strength influencing agents such as talc, aerosil, or sodium aluminium silicate may be included.

There is at least one lag time controlling layer present in the dosage forms according to the invention. The lag time controlling layer positioned nearest the inner core material is constructed in the form of a semipermeable membrane that will disrupt after a desired time after ingestion.

A desired lag time may be adjusted by the composition and thickness of the layer. The amount of substances forming such a disrupting semipermeable membrane, i. e. a lag time controlling layer, is usually in the range from 0.5 to 25 % counted on the weight of the core material including swelling substances or a swelling layer. Preferably the amount of such a lag time controlling layer, i. e. a disrupting semipermeable membrane, is between 2 to 20 % by weight.

A preferred disrupting semipermeable membrane, i. e. lag time controlling layer, is composed of a mixture of ethylcellulose and talc. The mixture contains most preferably 10 to 80 % w/w of talc.

Optionally, any additional lag time controlling layer may be constructed as a disrupting semipermeable membrane.

Enteric coating layer (s) and separating layer (s).

Before applying an enteric coating layer onto the layered pellets or tablets, they may optionally be covered with one or more separating layers comprising pharmaceutical excipients optionally including alkaline compounds such as for instance pH-buffering compounds. This separating layer separates the composition of the layered pellets or tablets from the outer enteric coating layer.

The separating layer as well as the other type of layers, such as the swelling and lag time controlling layers, can be applied by coating or layering procedures in suitable equipments such as coating pan, coating granulator, centrifugal granulator or in a fluidized bed apparatus (including Wurster type) using water and/or organic solvents for the coating process. As an alternative the layer (s) can be applied by using powder coating or press- coating techniques.

Suitable materials for the optional separating layer are pharmaceutically acceptable compounds such as, for instance, sugar, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetate, hydroxypropyl cellulose, methylcellulose, ethylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose sodium and others, used alone or in mixtures. Additives such as plasticizers, colorants, pigments, fillers, anti- tacking and anti-static agents, such as for instance magnesium stearate, titanium dioxide, talc, pH-buffering substances and other additives may also be included into the separating layer.

When the optional separating layer is applied to the layered pellets or tablets it may constitute a variable thickness. The maximum thickness of the optional separating layer is normally only limited by processing conditions. The separating layer may serve as a diffusion barrier and may act as a pH-buffering zone. The optional separating layer may improve the chemical stability of the active substance and/or the physical properties of the dosage form.

Finally the layered pellets or tablets are covered by one or more enteric coating layers by using a suitable coating technique. The enteric coating layer material may be dispersed or

dissolved in either water or in suitable organic solvents. As enteric coating layer polymers one or more, separately or in combination, of the following can be used; e. g. solutions or dispersions of methacrylic acid copolymers, cellulose acetate phthalate, hydroxypropyl methylcellulose phthalate, hydroxypropyl methylcellulose acetate succinate, polyvinyl acetate phthalate, cellulose acetate trimellitate, carboxymethyl ethylcellulose, shellac or other suitable enteric coating layer polymer (s).

Additives such as dispersants, colorants, pigments, additional polymers e. g. poly (ethylacrylat, methylmethacrylat), anti-tacking and anti-foaming agents may also be included into the enteric coating layer. Other compounds may be added to increase film thickness and to decrease diffusion of acidic gastric juices into the acid susceptible material. The enteric coating layer (s) constitutes a thickness of approximately at least 10 ) lu, preferably more than 20)-un. The maximum thickness of the applied enteric coating layer (s) is normally only limited by processing conditions.

Any of the applied polymer containing layers, and specially the enteric coating layers may also contain pharmaceutically acceptable plasticizers to obtain desired mechanical properties. Such plasticizers are for instance, but not restricted to, triacetin, citric acid es- ters, phthalic acid esters, dibutyl sebacate, cetyl alcool, polyethylene glycols, glycerol monoesters, polysorbates or other plasticizers. The amount of plasticizer is preferably optimized for each formula, in relation to the selected polymer (s), selected plasticizer (s) and the applied amount of said polymer (s).

Final dosage form The prepared layered pellets, optionally mixed with tablet excipients are filled into a capsule, or compressed into a multiple unit tableted dosage form. Alternatively, the dosage form is a multiple layered tablet. Prepared tablets are optionally covered with filmforming agent (s) to obtain a smooth surface of the tablet and further enhance the stability of the tablet during packaging and transport. Such a tablet coating layer may further comprise

additives like anti-tacking agents, colorants and pigments or other additives to obtain a tablet of good appearance.

The dosage forms according to the invention are suitable for oral administration. The dose will depend on the nature and severity of the disease to be treated. The dose may also vary according to the age, body weight, and response of the individual 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. In the treatment of other conditions higher doses than average will be used.

Preferably, a dosage form of the proton pump inhibitor, for instance 1-500 mg is administered once a day. Suitable doses comprise for instance about 5-100 mg of the substance, and more preferably 10-80 mg. The dosage form may be administered together with other suitable drugs, such as antibacterial compound (s), NSAID (s), motility stimulating agents, and/or antacida.

Examples The following examples describe the invention more in detail without restricting it.

Example 1.

Pulsed single dose delayed release layered pellets comprising magnesium salt of S- omeprazole (pellet strength approx. 44 mg/g).

Preparation of core material (spheres layered with drug).

A drug containing suspension was made according to the composition below; S-omeprazole Mg-salt 100g HPMC, 6 cps 15 g

Polysorbate 80 2 g Purified water 323 g HPMC was dissolved in water during stirring with subsequent addition of Polysorbate 80 and the drug. The suspension was sprayed onto 290 g of sugar spheres (Non-pareil) in a fluidized bed. The weight of the obtained product was 395 g.

Application of a swelling layer A (water free) suspension containing in water swellable substances was prepared according to the following composition; Low-substituted hydroxypropylcellulose (L-HPC) 162 g Hydroxypropylcellulose LF (HPC-LF) 74 g Talc 354 g EtOH (99.5%) 3100 g HPC-LF was dissolved in ethanol during stirring, then talc and swelling agent L-HPC was added. The suspension was sprayed onto 175 g of the core material from above in a Wurster equipped fluidized bed. The weight of the obtained product was 711 g.

Application of lag time controlling layer (semipermeable membrane).

A coating suspension was made according to the following formula; Ethylcellulose, 10 cps 10 g Talc 23 g EtOH (99.5%) 1000 g The ethylcellulose was dissolved in the ethanol during stirring, then talc was added.

Spraying of the suspension onto 150 g of swelling layered pellets from above (0.61- 0.71

mm obtained by sieving) was done in a Wurster equipped fluidized bed. The weight of the obtained pellets was 176 g.

Pellets (corresponding to approx. 10 mg active substance) were analyzed using USP dissolution apparatus No. 2 (paddle), and operated at 100 rpm, 37°C and with a phosphate buffer pH 6.8. The dissolution of active substance was followed by registration of the absorbance at 292 nm in a buffer solution, using a 0.5 cm flow-through compact cell. The dissolution profile measured at 292 nm is shown in Figure 1.

Example 2.

Pulsed single dose delayed release layered pellets comprising magnesium salt of S- omeprazole (pellet strength approx. 43 mg/g).

Preparation of core material (spheres layered with drug) A drug containing suspension was made according to the composition below; S-omeprazole Mg-salt 100g HPMC, 6 cps 15 g Polysorbate 80 2 g Purified water 323 g HPMC was dissolved in water during stirring with subsequent addition of Polysorbate 80 and the substance. The suspension was sprayed onto 290 g of sugar spheres (Non-pareil) in a fluidized bed. After coating the weight of the obtained product was 395 g.

Application of swelling layer A water free suspension containing in water swellable substances was prepared according to the following composition;

Low-substituted hydroxypropylcellulose (L-HPC) 162 g Hydroxypropylcellulose LF (HPC-LF) 74 g Talc 354 g EtOH (99.5%) 3100 g HPC-LF was dissolved in ethanol during stirring, then talc and swelling agent L-HPC was added. The suspension was sprayed onto 175 g pellets from above in a Wurster equipped fluidized bed. The weight of the obtained product was 711 g.

Application of lag time controlling layer (semipermeable membrane).

100 g of the swelling layered pellets obtained above were coated to obtain a lag-time controlling layer with the suspension below; Ethylcellulose, 10 cps 8 g Talc 9 g Mg-Stearate 2 g EtOH (99.5%) 620 g The suspension was prepared by dissolving the ethylcellulose in the ethanol during stirring, then the other compounds were added. Spraying of the suspension onto the pellets was done in a Wurster equipped fluidized bed. The weight of the obtained pellets was 116 g.

The pellets were analyzed as is described in Example 1. The dissolution profile is shown in Figure 2.

Example 3.

Single dose layered pellets, i. e. enteric coated pulsed single dose delayed release pellets comprising magnesium salt of S-omeprazole (pellet strength approx. 37 mg/g).

Application of enteric coating layer.

Pellets from Example 1 were enteric coated in a fluidized bed with a coating dispersion according to below; Eudragit L30 D-55 (30 % w/w dispersion) 73.3g Triethylcitrate (TEC) 6.6 g Glycerole monostearate (GMS) 0.3 g Polysorbate 80 0.03 g Purified water 40.4 g A homogenous coating dispersion was prepared by dispersing polysorbate 80 and glycerol monostearate in water. Triethylcitrate was dissolved in the Eudragit dispersion and thereafter the two dispersions were mixed to obtain the coating dispersion.

The coating dispersion was applied onto 120 g pellets from Example 1, using a Wurster equipped fluidized bed. The weight of the layered pellets was 140 g.

Pellets (corresponding to approx. 10 mg active substance) were analyzed using USP dissolution apparatus No. 2 (paddle) and operated at 100 rpm and 37°C. First the pellets were immersed n 0.1M HCl for 2 hours (pH 1.2), thereafter phosphate buffer components were added to obtain pH 6.8. The dissolution profile was registered as described in example 1, and is shown in Figure 3. The pellets were examined with respect to acid resistance. After exposure to 0.1 M HCl during two hours, 96 % of the active substance remained intact.

Example 4.

Single dose layered pellets, i. e. enteric coated pulsed single dose delayed release pellets comprising magnesium salt of omeprazole (pellet strength approx. 35 mg/g.).

Preparation of core material (spheres layered with drug).

A drug containing suspension was made according to the composition below; Omeprazole Mg-salt 100 g HPMC, 6 cps 15 g Polysorbate 80 2 g Purified water 323 g HPMC was dissolved in the water during stirring with subsequent addition of Polysorbate 80 and the drug. The suspension was sprayed onto 290 g of sugar spheres (Non-pareil) in a fluidized bed. After the coating the weight of the obtained product was 395 g.

Application of swelling layer A (water free) suspension containing in water swellable substances was prepared according to the following composition; Low-substituted hydroxypropylcellulose (L-HPC) 162 g Hydroxypropylcellulose LF (HPC-LF) 74 g Talc 354 g EtOH (99.5%) 3100 g HPC-LF was dissolved in ethanol during stirring, then the talc and the swelling agent L- HPC was added. The suspension was sprayed onto 175 g of core material from above in a Wurster equipped fluidized bed. The weight of the obtained product was 711 g.

Application of lag time controlling layer (semipermeable membrane).

120 grams of the swelling layered pellets (the fraction 0.61 mm-0.71 mm obtained by sieving) obtained above were coated with the suspension below; Ethylcellulose, 10 cps 8 g

Talc 18 g EtOH (99.5%) 810 g The suspension was prepared by dissolving ethylcellulose in ethanol during stirring, then talc was added. The suspension was sprayed onto the pellets in a Wurster equipped fluidized bed. The weight of the obtained product was 137 g.

Application of enteric coating layer.

120 grams of the pellets from the previous step above were coated with an enteric coating solution according to below; HPMCP (HP-55) 33 g Cetanol 2.4 g Acetone 353 g EtOH (99.5%) 151 g The coating solution was prepared by dissolving HPMCP and cetanol in a mixture of the solvents during stirring. The coating solution was applied in a Wurster equipped fluidized bed. The weight of the layered pellets was 149 g.

The layered pellets were examined with respect to acid resistance in 0.1 M HC1. The acid resistance was 97 %.

Example 5.

Single dose layered tablets, i. e. enteric coated pulsed single dose delayed release tablets comprising magnesium salt of S-omeprazole (Tablet strength approx. 16 mg).

Granules Granules for homogeonous tablet cores were made according to the following composition;

S-omeprazole Mg-salt 229 g Microcrystalline cellulose, Avicel pH 101 151 g Microcrystalline cellulose, Avicel PH 102 sp. coarse grade 400 g L-HPC 256 g PVP-XL 302 g Sodium laurylsulphate (SLS) 30 g Water purified 1060 g A granulating solution was prepared by dissolving the SLS in 460 g of purified water.

The powders above were mixed in a mixer after which the solution was added in an even stream. Thereafter approx. 600 g water was added during continued mixing, to give satisfactory consistency to the mass.

The mass was dried in a drying oven at 50°C over night.

Preparation of tablet cores After milling through a 1.0 mm screen the obtained granules were mixed with tablet lubricant, sodium chloride, and an additional amount of swellable substance, according to the following composition; Granules for tablet core 400 g Sodium chloride (passing 0.3mm) 80 g Sodium stearyl fumarate (PruvO) 8 g Polyvinyl pyrrolidone cross-linked (PVP-XL) 20 g The mixing was performed to homogeneity in a Kenwood mixer.

The mixture was compressed to 6 mm in diameter tablets having an average weight of 126 mg, on a single punch tableting machine (Diaf).

Application of lag time controlling layer (semipermeable membrane).

The tablets from previous step were coated in a Wurster equipped fluidized bed coating apparatus with a coating suspension of the following composition; EtOH 99.5% (w/v) 291 parts by weight Ethyl cellulose N-10 11 parts by weight Talc, micronized 7 parts by weight Sum: 309 parts.

200 grams of tablets were processed and the coating was continued until the average tablet weight was 134 mg.

Application of enteric coating layer The tablets obtained in the previous step were coated with an enteric coating layer in the same equipment as for the preceding coating step. The coating solution had the following composition; Hydroxypropyl methylcellulose phtalate (HP-550) 16 parts by weight Cetanol 1 Acetone 151-"- Ethanol (95% w/v) 65-"- Sum: 233 parts 100 grams of the tablets were processed and the coating was continued until the average tablet weight was 148 mg.

Individual tablets were analyzed using USP dissolution apparatus No. 2 (paddle) equipped with stationary baskets and operated at 100 rpm and 37°C. First the tablets were pre-

exposed for 0.1 M HCl for two hours (pH 1.2), whereafter the dissolution medium was changed to phosphate buffer pH 6.8.

The dissolution profile obtained was registered as described in example 1, and can be seen in Figure 4.

Example 6.

Multiple dose layered tablets, i. e. enteric coated dual pulsed multiple release tablets. (tablet strength approx. 2 x 15 mg).

Granules Granules for tablet cores were made according to the following composition; S-omeprazoleMg-salt 229 g Microcrystalline cellulose, Avicel PH 101 151 g Microcrystalline cellulose, Avicel PH 102 sp. Coarse grade 400 g L-HPC 256 g PVP-XL 302 g Sodium laurylsulphate (SLS) 30 g Water purified 1060 g A granulating solution was prepared by dissolving the SLS in 460 g of purified water.

The powders above were mixed in a mixer after which the solution was added in an even stream. Thereafter approx. 600 g water was added during continued mixing, to give satisfactory consistency to the mass.

The mass was dried in a drying oven at 50°C over night.

Preparation of tablet cores After milling through a 1.0 mm screen the obtained granules were mixed with tablet lubricant, sodium chloride, and an additional amount of swellable substance, according to the following composition; Granules for homogenous tablet core 400 Sodium chloride (passing 0.3mm) 80 Sodium stearyl fumarate (PruvO) 8 Polyvinyl pyrrolidone cross-linked (PVP-XL) 20 The mixing was performed to homogeneity in a Kenwood mixer.

The mixture was compressed to 6 mm in diameter tablets having an average weight of 126 mg, on a single punch tableting machine (Diaf).

Application of lag time controlling layer (semipermeable membrane).

The tablets from previous step were coated in a Wurster equipped fluidized bed coating apparatus with a coating suspension of the following composition; EtOH 99.5% (w/v) 291 parts by weight Ethyl cellulose N-10 11 parts by weight Talc, micronized 7 parts by weight Sum: 309 parts.

200 grams of tablets were processed and the coating was continued until average tablet weight was 134 mg.

Application of a drug comprising layer The tablets obtained in previous step were coated in the same equipment as above with a coating suspension of the following composition;

S-omeprazole Mg-salt 20 parts by weight Hydroxypropyl methylcellulose 6 cps 13 parts by weight Ethanol 99% 128 parts by weight Water purified 128 parts by weight Sum: 289 parts.

99 grams of tablets were processed and the coating was continued until the average tablet weight was 162 mg.

Application of enteric coating layer The tablets obtained in previous step were coated with an enteric coating layer in the same equipment as for the preceding coating step. The coating solution had the following composition; Hydroxypropyl methylcellulose phtalate (HP-55) 16 parts by weight Cetanol 1-"- Acetone 153-"- Ethanol (95% w/v) 65-"- Sum: 235 parts 119 grams of the tablets were processed and the coating was continued until the average tablet weight was 173 mg.

Individual tablets were analyzed using USP dissolution apparatus No. 2 (paddle) equipped with stationary baskets and operated at 100 rpm and 37°C. First the tablets were pre- exposed for 0.1 M HCl for two hours, whereafter the dissolution medium was changed to phosphate buffer pH 6.8.

The dissolution profile obtained was registered as described in example 1, and can be seen in Figure 5. The acid resistance of the tablets were examined and the result was 98 %.

Example 7 Multiple dose capsule formulation comprising (2 x 20) mg of omeprazole in the form of enteric coated pellets, mixed with an enteric coated tablet with delayed release.

Suspension layering Magnesium omeprazole 5 kg Sugar spheres cores (0.25-0.355 mm diam.) 10 kg Hydroxypropylmethylcellulose 0.8 kg Water purified 20 kg Separating layer Drug containing cores (acc. to above) 14.6 kg Hydroxypropyl cellulose 1.5 kg Talc 2.5 kg Magnesium Stearate 0.2 kg Water purified 29 kg Enteric coating Pellets (acc. to above) 9 kg Methacrylic acid copolymer (30% suspension) 15 kg Triethyl citrate 1.4 kg Mono-and diglycerides (NF) 0.2 kg Polysorbate 80 0.02 kg Water purified 9 kg Over-coating Enteric coated pellets 9 kg

Hydroxypropyl methylcellulose 0.2 kg Mg-Stearate 0.005 kg Water purified 3.6 kg Suspension layering was performed in a fluid bed apparatus. Magnesium omeprazole was sprayed onto inert sugar sphere cores from a water suspension containing the dissolved binder.

The prepared core material was sub-coated in a fluid bed apparatus with a hydroxypropyl cellulose solution containing talc and magnesium stearate.

The enteric coating consisting of methacrylic acid copolymer, mono-and diglycerides, triethylcitrate and polysorbate was sprayed onto the sub-coated pellets in a fluid bed apparatus. In the same type of apparatus the enteric coated pellets were coated with hydroxypropyl methylcellulose/Mg-Stearate suspension. The over-coated pellets were classified by sieving, to pass 0.71 mm The product was analyzed and found to contain 209 mg/g Mg-omeprazole.

Single dose layered tablets, i. e. enteric coated delayed release tablets comprising magnesium salt of omeprazole. (Tablet strength approx. 16 mg.)

Granules Granules for tablet cores were made according to the following composition (parts by weight); Omeprazole Mg-salt 229 g Microcrystalline cellulose, Avicel PH 101 145 g Microcrystalline cellulose, Avicel PH 102 sp. coarse grade 400 g L-HPC 251 g PVP-XL 302 g Hydroxy methylcellulose 6 cps 11 g Sodium laurylsulphate (SLS) 30 g Water purified 960 g A granulating solution was prepared by dissolving the SLS in 460 g of purified water.

The powders above were mixed in a mixer after which the solution was added in an even stream. Thereafter approx. 500 g water was added during continued mixing, to give satisfactory consistency to the mass.

The mass was dried in a drying oven at 50°C over night.

Preparation of tablet cores After milling through a 1.0 mm screen the obtained granules were mixed with tablet lubricant, sodium chloride and an additional amount of swellable substance, according to the following composition; Granules for tablet core 400 g Sodium chloride (passing 0.3mm) 80 g Sodium stearyl fumarate (PruvO) 8 g Polyvinyl pyrrolidone cross-linked (PVP-XL) 20 g

The mixing was performed to homogeneity in a Kenwood mixer.

The mixture was compressed to 6 mm in diameter tablets having an average weight of 126 mg, on a single punch tableting machine (Diaf).

Application of lag time regulating layer (semipermeable membrane).

The tablets from previous step were coated in a Wurster equipped fluidized bed coating apparatus with a coating suspension of the following composition; EtOH 99.5% (w/v) 291 parts by weight Ethyl cellulose N-10 11 parts by weight Talc, micronized 7 parts by weight Sum: 309 parts.

200 grams of tablets were processed and the coating was continued until the average tablet weight was 134 mg.

Application of enteric coating layer The tablets obtained in previous step were coated with an enteric coating layer in the same equipment as for the preceding coating step. The coating solution had the following composition; Hydroxypropyl methylcellulose phtalate (HP-550) 16 parts by weight Cetanol 1-"- Acetone 151-"- Ethanol (95% w/v) 65-"- Sum: 233 parts

100 grams of the tablets were processed and the coating was continued until the average tablet weight was 148 mg.

Filling of capsule 0.10 g of the pellets prepared above and one of the layered tablets obtained above were filled in a hard gelatine capsule size 1.

The best mode to practice the invention is according to the description given in Example 6.