WO2008138571A1

WO2008138571A1 - Probiotic bacteria containing oral dosage form

Info

Publication number: WO2008138571A1
Application number: PCT/EP2008/003777
Authority: WO
Inventors: Guy Vergnault
Original assignee: Jagotec Ag
Priority date: 2007-05-11
Filing date: 2008-05-09
Publication date: 2008-11-20
Also published as: EP2155218A1; GB0709162D0

Abstract

A nicotine-containing orally administered dosage form useful in smoking cessation therapy wherein said chewing gum comprises probiotic bacteria.

Description

PROBIOTIC BACTERIA CONTAINING ORAL DOSAGE FORM

The present invention is concerned with orally administrable dosage forms for use in smoking cessation therapy.

One of the approaches currently employed in smoking cessation therapy using nicotine is that of a nicotine-containing chewing gum. A particular example of such is the chewing gum sold under the trade name NICORETTE. The gum contains nicotine on a resin carrier that is incorporated into a gum material.

The release of nicotine from a chewing gum can be quite variable and depends on the duration and vigour of chewing. However, it is generally accepted that substantially all of the nicotine contained in a gum base will be released within about 20 minutes and a gum would have to be held in the oral cavity during this time to ensure adequate buccal absorption. Furthermore, given the fact that nicotine has a very short half life, such therapy will require frequent administration of gum in order to maintain effective plasma concentrations and thus curb the urge of smoking.

However, it is known that smoking can promote the formation of dental plaque and that dental plaque is particularly susceptible to fix nicotine and be discoloured by it. Unfortunately, chewing nicotine-containing gum for prolonged periods and at regular intervals as is required for smoking cessation therapy, can lead to unsightly staining of the teeth.

There is a need for improved nicotine-containing orally administrable dosage forms, in particular chewing gums, which exhibit a reduced tendency towards the discolouration of teeth.

The present invention provides an orally administrable dosage form, e.g. a chewing gum, that overcomes the problems of the prior art, by means of an additive introduced to the dosage form, which additive acts to reduce existing dental plaque or the formation of new plaque.

In a first aspect the invention provides a nicotine-containing orally administrable dosage form, e.g. a chewing gum, useful in smoking cessation therapy, wherein said dosage form comprises probiotic bacteria. Any suitable orally administrable dosage form is contemplated by the present invention, such as for example chewable dosage forms such as chewing gums, lozenges and the like, however, for brevity the remainder of this specification illustrates the invention with reference to chewing gums, which are preferred dosage forms.

It is generally known that introducing live microorganisms into a host in sufficient amounts can confer healthy effects on the host. Live microorganisms used in this fashion are often referred to as probiotic bacteria or probiotics. Probiotics introduced prophylactically or into an affected area can restore the balance of pathogens and beneficial bacteria, and thereby treat or prevent disease states. The term "probiotic" as generally used in the art, and as used in the present invention refers to non-pathogenic and non-toxigenic organisms capable of colonizing an affected area of a host and exerting a beneficial effect therein. It has been proposed in the art to use probiotic materials to treat conditions or disease states or conditions of the buccal cavity.

An interesting class of probiotics are the lactic acid bacteria. Recently, the antimicrobial activity of lactic acid bacteria has been studied (see J. Applied Microbiology 2001 , 90, 172-179), and it has been suggested that these bacteria may inhibit oral pathogens. However, to-date, applicant is not aware of formulations of probiotics in convenient and desirable oral dosage forms for local treatment of the oral cavity.

An important requirement for a dosage form intended for use in the oral cavity is that it must be palatable. It must have both a pleasant taste and a pleasant mouth feel, since an unpalatable dosage form stands a greater chance of being rejected by a patient, or not being retained in the oral cavity for a sufficient period of time for the bacteria to establish themselves and to exert a beneficial effect.

Apart from sensorial considerations, a dosage form must be sufficiently robust such that a sufficient number of viable probiotic bacteria survive manufacturing conditions and storage, in order to exert a beneficial effect when in use. This problem is compounded by the fact that it is particularly important to have a high viable microbial count in a unit dosage form intended to treat conditions in the oral cavity, because a high proportion of the probiotic bacteria can be expected to be lost to the oral cavity because of ingestion by the patient. Accordingly, in a preferred embodiment of the present invention a chewing gum is suitable for establishing or maintaining a healthy flora in the oral cavity and contains at least one strain of a probiotic bacteria and wherein the gum contains a viable probiotic bacterial count of at least 10⁴.

The present invention also provides in another of its aspects a method of smoking cessation and of establishing or maintaining a healthy flora in the oral cavity of a subject, the method comprising the step of administering to a subject a chewing gum contaim^'ng nicotine and probiotic bacteria, more particularly at least one strain of probiotic bacteria, in an amount such that there is a viable probiotic bacterial count of at least 10⁴.

The chewing gum of the present invention provides a source of probiotic bacteria, which can attach efficiently to sites in the oral cavity for a period of time during which they compete for nutrients with potentially pathogenic bacteria such as Streptococcus oralis, Actinobacillus actinomycetemcomitans, Escherichia coli, Streptococcus faecalis, Lysteria monocytogenes and Staphylococcus aureus, one or more of which can cause disease states of the oral cavity. As such, in addition as a treatment for smoking cessation the chewing gums of the present invention can provide a means of treatment or prophylaxis, control or prevention of certain disease states of the mouth.

The count of viable probiotic bacteria obtained can be determined by standard laboratory dilution methods generally known in the art, such as plating a quantified dilution of bacteria onto Lactobacilli MRS agar plates (Difco n. 288130) containing 0,05% cysteine - HCl , incubation at 37⁰C for 48 hours in anaerobic cabinet (Forma Scientific, Mod 24 ), and then performing a colony count. Removal of the nutrient media may be conveniently carried out using Beckman centrifuge at 10,000 rpm and a temperature of 4 ⁰C. Pellets so formed may then be suspended in a sterile suspending fluid containing Skimmed milk (Difco) 5%, lactose 3%, Yeast extract (Difco) 0.5%, cysteine-HCl 0,02%, pH 7.0-7.2. The bacteria may be rapidly frozen at -80°C and lyophilized in a known manner using, for example an Edwards Module YO Instrument.

The number of viable bacteria in each dosage form is preferably in the range of about 10⁴- 10⁶ or greater, more preferably in the range of 10⁵ to 10⁶ per unit dosage form. A typical dosage form will contain about 5.0 to 1000 mg, more particularly 10 to 500 mg of probiotic bacteria.

Preferred probiotic bacteria may be selected from the group consisting of strains of L. curvatus, L. casei, L. delbrueki, L. acidophilus, L.reuteri, L. plantarum, L. gasseri, L. lactis sp. Lactis, L.lactis sp. cremoris, L. heviticus, L. salivarius, L. brevis, S. thermophilics, B. breve, L. crispatus, S.

Lactis, B Dentium, B. Longum, B.bifidum, and B infantis. Particular strains include L. acidophilus M252, MB425, M253, M254, MB358, MB359, MB422, MB423, MB424, MB442, MB443, ATCC4356 and DSM20052; L. reuteri DSM20016 and DSM20053; L. delbruekii, L. delbrueckii subsp. delbruekii DSM20074, DSM20076 and ATCC9469; L. curvatus MB67, MB68, ; L. cassei MB459, ATCCl 1741, ATCC393, ATCC7469, DSM20011, DSM20024, and MB50; L. planterum MB396, ATCC8014, NCDOl 193; L. gasseri MB335; L. lactis sp. lactis MB445, DSM20481, MB447; L. lactis sp. cremoris DSM4645, DSM20069, MB446; 5. thermophilus MB418, MB417, MB419, MB420, MB421, MB426; B. breve MB202; L. crispatus ATCC33197; L. salivarius ATCCl 1741, ATCCl 1742; L. helveticus S36.2, S40.8; L. brevis ATCC4006, MB64, MB65; S. lactis MB405, MB406, MB407, MB408; B. dentium ATCC423; Bifido SP MB200; B. longum MB201; B. bifidium MB254, MB225; and B. infantis MB257.

Most preferred probiotic lactic acid bacteria are selected from the group consisting of L. plantarum, L. casei and L. delbruekii, in particular the strains L. plantarum MB67, L. casei MB459, and L. delbrueckii subsp. delbruekii DSM20074

In a preferred embodiment of the present invention a chewing gum may additionally comprise a prebiotic material. A prebiotic material is a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or the activity of the probiotic in the oral cavity. Prebiotics are typically thought of as carbohydrates of relatively short chain length.

Nondigestible oligosaccharides that exert the best prebiotic effects are inulin, resistant starch, fructosans, xylooligosaccharides, galactooligosaccharides and fructooligosaccharides. In a particularly preferred embodiment, the prebiotic is raftilose. In addition to its properties as a prebiotic, applicant has surprisingly found that it has the additional desirable property of creating a desirable mouth-feel, and may enhance the sensorial impression experienced by a patient. Still further, raftilose adds a certain adhesive quality to the dosage form as it is broken down in the mouth, and may assist in adhesion of the probiotic bacteria to sites in the oral cavity, thereby maintaining a high concentration of bacteria in the oral cavity for an extended period of time.

Prebiotic materials may be employed in amounts of about 10 to 90% by weight of formulations according to the invention. A single chewing gum may contain between 100 and lOOOmg of prebiotic material.

The nicotine can be provided in any pharmaceutically acceptable salt, hydrate or derivative. Typically it is provided as its bitartrate dihydrate. The amount of nicotine contained in a chewing gum is usually between 2 to 4 mg based on nicotine base, more particularly 2mg or 4mg.

Nicotine may be mixed directly into the chewing gum formulation although more typically it is provided on a carrier material and it is the nicotine-containing carrier that is incorporated into a chewing gum formulation. A convenient carrier is a carboxylic cation- exchange resin prepared from methacrylic acid and divinylbenzene. A particular example of such a carrier material is sold under the trade name POLACRILEX ™. POLACRILEX ™ may be added to a chewing gum formulation to provide nicotine (free base) at a level of 2 to 4mg per chewing gum. POLACRILEX ™ USP is commercially available at 10, 20 or 25% nicotine base content.

The chewing gums according to the present invention comprise one or more food or pharmaceutically acceptable excipients. Preferably excipients are chosen that do not inhibit growth of the probiotics. Apart from the foregoing consideration, the excipients are chosen according to the properties desired of the chewing gums. Suitable excipients include for example, diluents, binders, lubricants, disintegrants, colours, flavours and sweeteners.

Suitable diluents for use in the present invention include, but are not limited to, dicalcium phosphate, calcium sulphate, lactose, skimmed milk, sorbitol, microcrystalline cellulose, kaolin, mannitol, sodium chloride, dry starch, powdered sugar and sugar spheres. Suitable binders for use in the present invention include, but are not limited to synthetic gums such as hydroxypropyl methylcellulose ("HPMC"), povidone, carboxymethylcellulose, ethylcellulose and methylcellulose, starch, pregelatinized starch, gelatin, sugars (e.g., molasses) and natural gums (e.g., acacia gum, sodium alginate, parnar gum).

Disintegrants which can be utilized in the present invention include, but are not limited to, methylcellulose, cellulose, carboxymethylcellulose, croscarmellose sodium, magnesium aluminum silicate, povidone, starch, sodium starch glycolate, pregelatinized starch, alginic acid and guar gum.

The food or pharmaceutically acceptable excipients may be employed in amounts of from 20 to 90 %, more particularly 40 to 75 % by weight of the dosage form.

A chewing gum formulation may comprise one or more of known synthetic elastomers, natural elastomers, plasticizers, fillers, softeners/emulsifiers, and other standard excipients such as colourants, sweeteners and flavourants.

Synthetic elastomers may include, but are not limited to, polyisobutylene with GPC weight average molecular weight of about 10,000 to about 95,000, isobutylene-isoprene copolymer (butyl elastomer), styrene-butadiene copolymers having styrene-butadiene ratios of about 1:3 to about 3:1, polyvinyl acetate having GPC weight average molecular weight of about 2,000 to about 90,000, polyisoprene, polyethylene, vinyl acetate-vinyl laurate copolymer having vinyl laurate content of about 5 to about 50 percent by weight of the copolymer, and combinations thereof.

Preferred ranges are, for polyisobutylene, 50,000 to 80,000 GPC weight average molecular weight, for styrene-butadiene, 1:1 to 1:3 bound styrene-butadiene, for polyvinyl acetate, 10,000 to 65,000 GPC weight average molecular weight with the higher molecular weight polyvinyl acetates typically used in chewing gum base, and for vinyl acetate-vinyl laurate, vinyl laurate content of 10-45 percent.

Natural elastomers may include natural rubber such as smoked or liquid latex and guayule as well as natural gums such as lechi caspi, perillo, sorva, massaranduba balata, massaranduba chocolate, nispero, rosindinha, chicle, gutta hang kang, and combinations thereof. The preferred natural elastomers are jelutong, chicle, sorva and massaranduba balata.

Elastomer plasticizers may include, but are not limited to, natural rosin esters such as glycerol esters of partially hydrogenated rosin, glycerol esters polymerized rosin, glycerol 5 esters of partially dimerized rosin, glycerol esters of rosin, pentaerythritol esters of partially hydrogenated rosin, methyl and partially hydrogenated methyl esters of rosin, pentaerythritol esters of rosin; synthetics such as terpene resins derived from alpha-pinene, beta-pinene, and/or d-limonene; and any suitable combinations of the foregoing. The preferred elastomer plasticizers will also vary depending on the specific application, and

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Fillers/texturizers may include magnesium and calcium carbonate, ground limestone, silicate types such as magnesium and aluminum silicate, clay, alumina, talc, titanium oxide, mono-, di- and tri-calcium phosphate, cellulose polymers, such as wood, and combinations thereof.

15 Softeners/emulsifiers may include tallow, hydrogenated tallow, hydrogenated and partially hydrogenated vegetable oils, cocoa butter, glycerol monostearate, glycerol triacetate, lecithin, mono-, di- and triglycerides, acetylated monoglycerides, fatty acids (e.g. stearic, palmitic, oleic and linoleic acids), and combinations thereof. Hydrogenated vegetable oils and lecithin are generally preferred, either alone or in combination with other softeners. 0 Colorants and whiteners may include FD&C-type dyes and lakes, fruit and vegetable extracts, titanium dioxide, and combinations thereof.

A sweetener can also be used to enhance to taste of the chewing gum. Sweeteners include natural sugars and artificial sugar substitutes. Non-limiting examples of sweeteners that can be used in accordance with this invention include aspartame, acesulfame potassium, 5 alitame, sucralose, saccharin, trehalose, xylitol, sorbitol, mannitol, dextrose, sucrose, and fructose. Optionally, a color agent may be added to aid in tablet identification and to enhance the visual appearance of the tablet. The color agent may be any that is well known to those in the tablet-making art in view of the present disclosure, and could be used in any amount to impart the desired colour. Soluble colour agents can also be used in chewing gums as a tracer of drug release in vivo. Selecting an appropriate dose of colour agent one can follow drug release as a function of a decrease in the intensity of the colour and one is able to determine when substantially all of a drug is released independently of chewing frequency or chewing intensity. The relationship of drug and dye release is a function of their solubility in aqueous media.

In order to facilitate the preparation of a unit dosage form according to this invention there is provided, in a further aspect of the present invention, a process for the preparation of a chewing gum according to the present invention.

The probiotic bacteria may be obtained from commercial sources, or they may be obtained from laboratory strains. The bacteria can be grown to log phase in a nutrient media according to techniques known in the art. Suitable media include MRS lactobacilli agar (Difco), or any other enriched media suitable for the cultivation of such media. The bacteria can be recovered from the culture medium in the form of a pellet by using centrifuge and filtration techniques generally known in the art. The pellet of bacteria thus formed is thereafter dried by lyophilisation.

Lyophilised bacteria pellets may be reduced to the required particle size prior to formulation. Suitable size reduction techniques include grinding and sieving according a process generally known to those skilled in the art.

It is preferred if the bacteria mass is employed with a particle size in the range of 60 to 800 microns.

Considering that the probiotic bacteria are formed from highly hygroscopic lyophilized material, and considering also that microbial growth is triggered by the presence of humidity, in order to keep the bacteria in a stable and quiescent state they must be maintained in a dry state at all times in the manufacturing process.

Manufacturing methods for chewing gum are generally known in the art.

Chewing gum may be made by sequentially adding the various chewing gum ingredients to a softened or melted gum base. Softening or melting may be carried out at temperatures of between 50 and 70⁰C in any commercially available kettle mixer with blades known in the art. After the ingredients have been thoroughly mixed, the chewing gum mixture may be discharged from the mixer then cooled and shaped into the desired form such as by rolling into sheets and cutting into sticks, extruding into chunks, or casting into pellets.

The foregoing method relies on heating the gum to workable temperatures. Any process involving elevated temperatures may reduce the viable count of microbial species and so it is preferred to produce chewing gums using compression methods. A preferred method of manufacturing chewing gum according to the present invention is the preparation of a mixture containing the gum base in granular form, sequentially adding the various chewing gum ingredients to any commercially available mixer known in the art. After the ingredients have been thoroughly mixed, the mixture is discharged from the mixer and the powder can be compressed into tablets shaped into the desired form depending on the size and design of the punches and dies employed.

Following is a description by way of example only of embodiments of the present invention.

Example 1

Preparation of a dosage form :

Lactic acid bacteria are cultivated anaerobically in Lactobacilli MRS broth (DIFCO) for 16 hours at 37⁰C. To obtain a microbial biomass, cells are cultivated in a fermentor for 24 hours at 37⁰C. The culture obtained is centrifuged at 6000 rpm for 30 minutes to produce a pellet containing the cells. The pellet is then suspended in a suspending fluid (10% skimmed milk, 0.5% lactose, 0.5% yeast extract), freeze dried and used for tablet preparation, after grinding and sieving through a suitable screen to obtain granulates of the desired particle size in the range of 60 to 800 microns.

Preparation of three-layer chewing gum tablet containing Nicotine POL ACRILEX to give 4mg nicotine in the middle layer.

1-a Preparation of mixture used for the outer layers.

Each outer layer has the following unit composition: Xylitol (Xylisorb) 100.00 mg Maltodextrin 100.00 mg Talc (C. Erba) 5.00 mg

Magnesium stearate (C. Erba) 5.00 mg

Colloidal silicon dioxide (Syloid 244-Gτace) 2.00 mg

Mint flavouring (Peppermint) 5.00 mg

Xylitol + maltodextrin are mixed for 10 minutes. The remaining components are then added, and mixing continues for a further 20 minutes, to produce a homogeneous mixture.

1-b Preparation of mixture constituting the middle layer.

The inner layer has the following unit composition:

Freeze-dried Probiotic lOOmg Nicotine POLACRILEX USP 20% 20mg (4 mg nicotine base)

Powdered Gum Base (Flarer-PG Mondo TA) 500.00 mg

TaIc (C. Erba) 10.00 mg

Magnesium stearate (C. Erba) 10.00 mg

Colloidal silicon dioxide (Syloid 244-Grace) 5.00 mg Mint flavouring (Peppermint) 5. 00 mg

Aspartame 4.00 mg

The Nicotine POLACRILEX, probiotic and gum base are mixed with flavouring, aspartame and talc, and mixing continues for 10 minutes. The other excipients are then added, and mixing continues for a further 20 minutes, to produce a homogenous, flowable mixture.

1-c Preparation of three-layer chewing gum by compression.

The mixture of powders obtained as described in paragraphs 1-a and 1-b, and in accordance with well-known manufacturing processes, is loaded into the three loading hoppers of a rotary tablet press suitable to make three-layer tablets (e. g. Manesty Layer- Press, Liverpool, UK). In particular the mixture described in paragraph 1-a is loaded into the first and third hoppers, and the mixture described in paragraph 1-b is loaded into the second hopper. The tablet press is equipped with flat circular punches with a diameter of 13.0 mm. Due to the presence of the outer layers, which minimise the contact area between the gum layer and the mechanical parts of the tablet press, the compression process proceeds without difficulty, with a high output, and no adherence to the punches.

Example 2

Preparation of a dosage form:

Lactic acid bacteria are cultivated anaerobically in Lactobacilli MRS broth (DIFCO) for 16 hours at 37⁰C. To obtain a microbial biomass, cells are cultivated in a fermentor for 24 hours at 37⁰C. The culture obtained is centrifuged at 6000 rpm for 30 minutes to produce a pellet containing the cells. The pellet is then suspended in a suspending fluid (10% skimmed milk, 0.5% laciose, 0.5% yeasl exiraci), freeze dried and used for tablet preparation, after grinding and sieving through a suitable screen to obtain granulates of the desired particle size in the range of 60 to 800 microns.

2-a Preparation of mixture used for the outer layers.

Each outer layer has the following unit composition:

Freeze dried probiotics 100 mg prebiotic (Raftilose) 500 mg

Talc (C. Erba) 5.00 mg

Magnesium stearate (C. Erba) 5.00 mg Colloidal silicon dioxide (Syloid 244-Grace) 2.00 mg

Mint flavouring (Peppermint) 5.00 mg

Sweetener 1.00 mg

Probiotic and Raftilose are mixed for 10 minutes. The remaining components are then added, and mixing continues for a further 20 minutes, to produce a homogeneous mixture.

2-b Preparation of mixture constituting the middle layer.

The inner layer has the following unit composition:

Nicotine POLACRILEX USP 20% 20 mg (equivalent 4 mg Nicotine base) Powdered Gum Base (Flarer-PG Mondo TA) 500.00 mg TaIc (C. Erba) 10.00 mg Magnesium stearate (C. Erba) 10.00 mg Colloidal silicon dioxide (Syloid 244-Gτace) 5.00 mg Mint flavouring (Peppermint) 5. 00 mg Aspartame 4.00 mg

1-c Preparation of three-laver chewing gum by compression.

The mixture of powders obtained as described in paragraphs 2-a and 2-b, and in accordance with well-known manufacturing processes, is loaded into the three loading hoppers of a rotary tablet press suitable to make three-layer tablets (e. g. Elizabeth Hata Layer-Press, Pittsburg , USA). In particular the mixture described in paragraph 2-a is loaded into the first and third hoppers, and the mixture described in paragraph 2-b is loaded into the second hopper. The tablet press is equipped with flat circular punches with a diameter of 16.0 mm. Due to the presence of the outer layers, which minimise the contact area between the gum layer and the mechanical parts of the tablet press, the compression process proceeds without difficulty, with a high output, and no adherence to the punches.

Example 3

To assess the viability and stability of probiotics in the tablets formed according to Example 2, the microbial counts of a tablet are carried out at room temperature and 4⁰C for a period of 8 months during the following time intervals: T= 0, 15 days, 1 month, 3 months, 6 months and 8 months. The Serial Dilution Method is employed by plating in duplicate onto Lactobacilli MRS Agar.

T₀= Microbial count at zero time T₂=Microbial count after 2 months T₄=Microbial count after 4 months T₆=Microbial count after 6 months

Microbial counts are expressed as number of colonies in each tablet.

Effect of Lactic acid bacteria strains on oral pathogens.

To evaluate the activity of the probiotic bacteria against oral pathogens the Halo-Foiming method was employed. Probiotic bacteria were grown in Lactobacilli MRS broth (Difco) at 37⁰C for 24 h. The supematents were neutralized with NaOH (pH 6.5-7,0), centrifuged at 10,000 r.p.m. for 10 minutes and filtered with sterile filters (pore si∑e of 0.45 um). Cell pellets and 50 ul of the supermatents were spotted onto antibiotic test discs (diameter 9.0 mm, Schleicher and Schull, Dassel, Germany) on the agar surface containing the • appropriate medium seeded with the test organisms. After 34 days of incubation in aerobic or anaerobic conditions, depending by the oxygen requirement of each strain, the diameter of title clear inhibition zone around the disc was measured.

For the microorganism L_* delbruekii DSM20074, when the cells were spotted directly onto an antibiotic test disc containing Streptococcus Oralis a halo inhibition diameter of between 2 and 5 cm was observed. A similar result was achieved when the disc contained Actinobacillus actinomycetemcomitans.

For the microorganism L. plantarum MB67 an inhibition diameter of between 2 and 5cm was observed on discs containing Streptococcus oralis and Actinobacillus actinomycetemcomitaπs.

The test shows that probiotics contained in chewing gums of the present invention are able to compete with oral pathogens that are causal factors m the formation of dental plaque and therefore reduce its formatiorL

Claims

Claims:

1. A nicotine-containing orally administered dosage form useful in smoking cessation therapy wherein said chewing gum comprises probiotic bacteria.

2. A nicotine-containing chewing gum useful in smoking cessation therapy, wherein said chewing gum comprises probiotic bacteria.

3. A dosage form according to claim 1 or claim 2 comprising at least one strain of a probiotic bacteria, and wherein the dosage form contains a viable probiotic bacterial count of at least 10⁵.

4. A dosage form according to any preceding claim, wherein the probiotic bacteria are selected from the group consisting of L. curvatus, L. casei, L. delbruecki, L. acidophilus, L.reuteri, L. plantarum, L. gasseri, L. lactis sp. Lactis, L.lactis sp. cremoris, L. heviticus, L. salivarius, L. brevis, S. thermophilus, B. breve, L. crispatus, S. Lactis, B Dentium, B. Longum, B.bifidum, B infantis, and mixtures thereof.

5. A dosage form according to any preceding claim, wherein the probiotic bacteria are selected from the group consisting of L. acidophilus M252, MB425, M253, M254, MB358, MB359, MB422, MB423, MB424, MB442, MB443, ATCC4356 and DSM20052; L. reuteri DSM20016 and DSM20053; L. delbrueckii, L. delbrueckii subsp. delbruekii DSM20074, DSM20076 and ATCC9469; L plantarum MB67, MB68, ; L. cassei MB459, ATCCl 1741, ATCC393, ATCC7469, DSM20011, DSM20024, and MB50; L. planterum MB396, ATCC8014, NCDOl 193; L. gasseri MB335; L lactis sp. lactis MB445, DSM20481, MB447; L. lactis sp. cremoris DSM4645, DSM20069, MB446; S. thermophilus MB418, MB417, MB419, MB420, MB421, MB426; B. breve MB202; L. crispatus ATCC33197; L. salivarius ATCCl 1741, ATCCl 1742; L. helveticus S36.2, S40.8; L. brevis ATCC4006, MB64, MB65; S. lactis MB405, MB406, MB407, MB408; B. dentium ATCC423; Bifido SP MB200; B. longum MB201; B. bifidium MB254, MB225; B. infantis MB257, and mixtures thereof.

6. A dosage form according to any of the preceding claims additionally comprising a prebiotic material.

7. A dosage form according to claim 6, wherein the prebiotic material is selected from the group consisting of inulin, resistant starch, fructosans, xylooligosaccharides, galactooligosaccharides, fructooligosaccharides, and mixtures thereof.

8. A dosage form according to claim 6 or 7, wherein the prebiotic material is raftilose.

9. A dosage form according to any of the preceding claims, wherein the nicotine is present in a concentration of between 2 and 4mg.

10. A dosage form according to any of the preceding claims, wherein the nicotine is provided on a carrier.

11. A dosage form according to claim 10, wherein the carrier is a cationic exchange resin prepared from methacrylic acid and divinylbenzene.

12. A method of reducing discolouration of teeth as a result of smoking cessation therapy using a nicotine-containing orally administered dosage form by including in said gum a probiotic material.

13. A method according to claim 12, wherein the probiotic material contains at least one strain of probiotic bacteria, in a dosage form containing a viable probiotic bacterial count of at least 10⁵.

14. A nicotine-containing orally administered dosage form useful in smoking cessation therapy as claimed in claim 1 and substantially hereinbefore described in the Examples.

15. Use of probiotic bacteria in the manufacture of a nicotine-containing orally administered dosage form for use in smoking cessation therapy.