WATER INSOLUBLE POLYMER: STARCH-BASED FILM COATINGS FOR COLON TARGETING
A controlled release delivery dosage form for controlled release of an active ingredient, includes an active ingredient coated in a polymeric mixture of: at least a water insoluble polymer and a starch composition including at least one component selected from the group consisting of a starch having an amylose content of between 20 and 45%, a modified starch having an amylose content of between 50 and 80% and a legume starch. The present invention also relates to the use and method for making the same.
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The present invention relates to a dosage form for the controlled delivery of active ingredient(s). The present invention also relates to the use and method for making the same.
BACKGROUND OF THE INVENTIONColon targeting can be very helpful for many pharmaco-therapies, including the treatment of inflammatory bowel diseases, such as Crohn's Disease (CD) and Ulcerative Colitis (UC).
If a locally acting drug is orally administered using a conventional pharmaceutical dosage form, the latter rapidly dissolves in the contents of the stomach, the drug is released and likely to be absorbed into the blood stream. This leads to elevated systemic drug concentrations and, thus, an increased risk of undesired side effects and at the same time to low drug concentrations at the site of action in the colon, resulting in poor therapeutic efficiency. These restrictions can be overcome if drug release is suppressed in the stomach and small intestine and time-controlled in the colon. This type of site-specific drug delivery to the colon might also offer an interesting opportunity for protein and peptide drugs to get absorbed into the systemic circulation upon oral administration.
To allow for colon targeting, the drug can for instance be embedded within a polymeric matrix former, or can be drug-loaded tablets or pellets such as spherical beads, approximately 0.5-1 mm in diameter; or can be coated with a polymeric film. In the upper gastro intestinal tract (GIT), the permeability of the polymeric networks for the drug should be low, whereas the macromolecular barriers must become permeable once the colon is reached. This increase in drug permeability of the polymeric networks at the site of action might be induced by: (i) a change in the pH of the contents of the GIT, (ii) a change in the quality and/or quantity of enzymes along the GIT, or (iii) significant structural changes within the dosage form occurring after a pre-determined lag-time (e.g. crack formation in poorly permeable film coatings providing pulsatile drug release patterns).’38 Alternatively, drug release might already start in the stomach and continue throughout the GIT, at a rate that is sufficiently low to assure that drug is still inside the dosage form once the colon is reached.
An attempt to solve the problem of colon targeting is disclosed in US2005220861A that relates to a controlled release formulation for delivery of prednisolone sodium metasulphobenzoate. The formulation comprises prednisolone sodium metasulphobenzoate surrounded by a coating comprising glassy amylose, ethyl cellulose and dibutyl sebacate, wherein the ratio of amylose to ethyl cellulose is from (1:3.5) to (1:4.5) and wherein the amylose is corn or maize amylose. In contrast to the American patent application number US2005220861, the system described in the present invention is adapted to the disease state of patients. This is a very crucial aspect, because to allow for colon targeting the dosage form must become more permeable for the drug once the colon is reached. This can for instance be assured by a preferential degradation of a compound that hinders rapid drug release in the upper gastro intestinal tract. This site-specific degradation can be based on significant differences in the quality and quantity of enzymes present in the upper gastro intestinal tract versus the colon. The compound should not be degraded in the upper gastro intestinal tract (and hinder drug release), but should be degraded in the colon (and, thus, allow for drug release). The performance of this type of advanced drug delivery systems is fundamentally depending on the environmental conditions in the colon of the patients, in particular on the types and concentrations of the enzymes present in the colon. It is well known and has been well documented in the literature that the disease state can significantly affect the quality and quantity of the enzyme secreting microflora in the gastro intestinal tract. This is particularly true for the microflora in the colon of patients suffering from inflammatory bowel diseases: the quality and quantity of the enzymes present in the colon of a patient can, thus, significantly vary from those in a healthy subject. Consequently, the performance of this type of drug delivery systems can significantly be affected by the disease state. Systems that are based on the preferential degradation by enzymes which are not present in sufficient concentrations in the disease sate in the colon of the patient fail. The present invention reports for the first time on dosage forms allowing for controlled delivery of active ingredient under pathophysiological conditions: in feces of patients suffering from inflammatory bowel diseases. Thus, the performance of these dosage forms is assured under the given pathophysiological conditions in vivo. This is decisive for the success and safety of the treatment.
U.S. Pat. No. 6,534,549 relates to a method for producing a controlled release composition comprising a mixture of a substantially water-insoluble film-forming polymer and amylose in a solvent system comprising (1) water and (2) a water-miscible organic solvent which on its own is capable of dissolving the film-forming polymer is contacted with an active material and the resulting composition dried. The composition is particularly suitable for delivering therapeutic agents to the colon. In contrast to the present invention that disclosure addresses drug delivery systems prepared using an organic solvent. This is not the case in the present invention. The use of organic solvents implies several concerns, including toxicity and environmental concerns as well as explosion hazards. Furthermore, the use of amylose implies the extraction of this polymer and its stabilization. Amylose is extracted from starch after an hydrolysis and a purification step. This process is complex and difficulty usable at an industrial level. This formulation doesn't take into account the drug release kinetics for patients suffering from inflammatory bowel diseases. It has to be pointed out that the types and amounts of bacteria present in the colon of inflammatory bowel disease patients can significantly differ from those in healthy subjects. Thus, the types and amounts of enzymes secreted by these bacteria and being in contact with the drug delivery system can significantly differ. Consequently, the performance of the drug delivery system can significantly differ.
SUMMARY OF THE INVENTIONAn object of the present invention is to provide a delivery dosage form to control the rate and extent of delivery of an active ingredient, for example, without limitation, an active pharmaceutical ingredient, biological, chemical, nutraceutical, agricultural or nutritional active ingredients.
Another object of the present invention is to provide new polymeric film coatings that allow for site-specific drug targeting to the colon and that may be used for patients suffering from inflammatory bowel diseases as well as for patients with a healthy colon.
A further object of the present invention is to provide new polymeric film coatings having a sufficient mechanical stability to withstand the shear stress they are exposed to in the upper GIT (due to the gastro intestinal motility) and to withstand the potentially significant hydrostatic pressure developed within the dosage forms due to water penetration into the systems upon contact with aqueous media. Indeed, with known polymer coatings, the problem of accidental crack formation can result in premature drug release through water-filled channels.
A further object of the present invention is to provide new polymeric film coatings adjustable to the specific needs of a particular type of drug treatment e.g, osmotic activity of the drug and administered dose.
The present invention provides a controlled release delivery dosage form for controlled release of an active ingredient, comprising an active ingredient coated in a polymeric mixture of:
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- at least a water insoluble polymer and
- a starch composition comprising at least one component selected from the group consisting of a starch having an amylose content of between 20 and 45%, preferably of between 25 and 44%, and more preferably still of between 30 and 40%, a modified starch having an amylose content of between 50 and 80% and a legume starch.
Preferentially the controlled release dosage form is an oral formulation and has a gastric resistance. In a preferred embodiment, the controlled release pharmaceutical dosage form is in a solid, liquid or semi-liquid form. Advantageously the controlled release pharmaceutical dosage form is a solid dispersion. According to the invention, the polymeric mixture is an intimate mix of the water insoluble polymer and the starch composition, said starch does not form particulates in the water insoluble polymer.
In an embodiment of the present invention, the polymeric mixture of the controlled release delivery dosage form is a coating mixture, the controlled release delivery dosage form comprising a core, the active ingredient being dispersed or dissolved in the core and/or in the coating mixture.
In a further embodiment of the present invention, the starch composition:water insoluble polymer ratio in the controlled release delivery dosage form is between 1:2 and 1:8, preferentially 1:3 to 1:6, and more preferentially 1:4 to 1:5.
Preferably, the starch composition has a starch content of at least 50%, preferably of between 70 to 100% more preferably 70 to 100%, still more preferably between 90 to 100%.
Typically, the starch composition exhibits an amylose content of between 20 and 45%, preferentially an amylose content of between 25 and 44%, more preferentially of between 32 and 40%, this percentage being expressed in dry weight with respect to the dry weight of starch present in said composition.
In a further embodiment of the invention, the starch composition comprises at least one legume or cereal starch.
Preferably, the legume is selected from the group consisting of pea, bean, broad bean and horse bean.
According to another advantageous alternative form, the legume is a plant, for example a variety of pea or of horse bean, giving seeds comprising at least 25%, preferably at least 40%, by weight of starch (dry/dry). Preferably, the legume starch is a granular legume starch.
Advantageously, the legume is pea. Pea starch granules have two particularities. The first one is large granule diameter, larger than for example corn starch granules, improving the granule's surface area and thus contacts with water and micro flora enzymes in the colon. In addition, pea starch granules have a high swollen ability improving their surface area thus granules granules digestibility and consequently the active ingredient release in the colon.
According to another advantageous alternative the legume starch is a native legume starch.
Advantageously, this starch content of the starch composition is greater than 90% (dry/dry). It can in particular be greater than 95%, preferentially greater than 98%.
According to the invention, the modified starch is preferably stabilized. Indeed, according to a preferred embodiment of the invention, the chemical treatments, which are particularly well suited to the preparation of a film-forming composition, are the “stabilizing” treatments. Common stabilization modifications may be accomplished by esterifying or etherifying some of the hydroxyl groups along the starch chain. Preferentially, said modified starch is hydroxypropylated and/or acetylated; it being possible for these treatments optionally to be supplemented by a fluidification that is a chemical or enzymatic hydrolysis treatment. Preferably, said modified starch is fluidification-treated, for example by acid treatment. The starch composition according to the invention thus advantageously comprises at least one stabilized starch and preferably a hydroxypropylated starch exhibiting a degree of substitution (DS) of at most 0.2. The term “DS” is understood to mean, in the present invention, the mean number of hydroxypropyl groups per 10 anhydroglucose units. This mean number is determined by the standard analytical methods well known to a person skilled in the art.
In a further embodiment of the invention, the starch composition may additionally comprise at least one indigestible polysaccharide selected from the group consisting of xylooligosaccharides, inulin, oligofructoses, fructo-oligosacharides (FOS), lactulose, galactomannan and suitable hydrolysates thereof, indigestible polydextrose, indigestible dextrin and partial hydrolysates thereof, trans-galacto-oligosaccharides (GOS), xylo-oligosaccharides (XOS), acemannan, lentinan or beta-glucan and partial hydrolysates thereof, polysaccharides-K (PSK), and indigestible maltodextrin and partial hydrolysates thereof, preferably an indigestible dextrin or an indigestible maltodextrin.
According to the invention, an indigestible maltodextrin or indigestible dextrin having between 15 and 35% of 1->6 glucoside linkages, a reducing sugar content of less than 20%, a polymolecularity index of less than 5 and a number-average molecular mass Mn at most equal to 4500 g/mol.
According to a variant, all or some of the said indigestible maltodextrins are hydrogenated.
According to a variant, the core has a coating level of 5% to 30%, preferably of 10% to 20%.
In a further embodiment, the polymeric mixture comprises a plasticizer. Preferably the plasticizer content is between 25% to 30% w/w referred to the water insoluble polymer content.
Preferably, the water insoluble polymer is selected from the group consisting of ethyl cellulose, cellulose derivatives, acrylic and/or methacrylic ester polymers, polymers or copolymers of acrylate or methacrylate polyvinyl esters, starch derivatives, polyvinyl acetates, polyacrylic acid esters, butadiene styrene copolymers methacrylate ester copolymers, cellulose acetate phtalate, polyvinyl acetate phtalate, shellac, methacrylic acid copolymers, cellulose acetate trimellitate, hydroxypropyl methylcellulose phtalate, zein, starch acetate.
According to a further embodiment the plasticizer is a water soluble plasticizer. Preferably the water soluble plasticizer is selected from the group consisting of polyols (glycerin, propylene glycol, polyethylene glycols), organic esters (phtalate esters, dibutyl sebacate, citrate esters, triacetin), oils/glycerides (castor oil, acetylated monoglycerides, fractionated coconut oil), soya lecithin alone or as a mixture with one another.
In a preferred embodiment, the controlled release delivery dosage form is a multiparticulate dosage form.
The present invention also provides a method for preparing a controlled release delivery dosage form for controlled release of an active ingredient in the colon of patients having a colonic microflora imbalance or in the colon of healthy subjects, as claimed in claims 1 to 12, said method comprising:
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- forming a polymeric mixture of:
- at least one water insoluble polymer and
- a starch composition comprising at least one component selected from the group consisting of a starch having an amylose content of between 20 and 45%, preferably of between 25 and 44%, and more preferably still of between 30 and 40%, modified starches, a modified starch having an amylose content of between 50 and 80% and a legume starch.
- coating said active ingredient in the polymeric mixture.
- forming a polymeric mixture of:
In a further embodiment, the step of coating the active ingredient is a coating step of a core, the active ingredient being dispersed or dissolved in the core and/or the step of coating the active ingredient is a step of dispersing or dissolving the active ingredient in the polymeric mixture.
The conditions in the gastro intestinal tract of patients suffering from inflammatory bowel diseases (e.g. Crohn's Diseases and Ulcerative Colitis) can significantly differ from those in a healthy subject. The intra- and inter-individual variability can be substantial with respect to the pH of the GIT contents, types and concentrations of enzyme-secreting bacteria as well as to the transit times within the various GIT segments. For instance, considerable amounts of bifidobacteria are generally present in the colon of healthy subjects and are able to degrade complex polysaccharides due to multiple extracellular glycosidases. However, in the disease state their concentration can be significantly reduced.’ For example, it was shown that the fecal glycosidase activity (especially that of β-D-galactosidase) is decreased in patients suffering from Crohn's Disease and that the metabolic activity of the colonic flora is strongly disturbed in the active disease state.’ Thus, the impact of the pathophysiology can be crucial and can lead to the failure of the pharmaco-treatment.
To avoid treatment failures for patients suffering from inflammatory bowel diseases, the site-specific drug delivery system must be adapted to the conditions given in the patients' colon. For instance, polymeric film coatings might be used that are degraded by enzymes, which are present in the feces of Crohn's Disease and Ulcerative Colitis patients in sufficient amounts. However, yet it is unclear which type(s) of polymers fulfills these pre-requisites.
Table 1: Concentrations of bacteria [log CFU/g] in the investigated fecal samples of healthy subjects and inflammatory bowel disease patients.
Table 2: Effects of the type of polysaccharide blended with ethylcellulose and of the polysaccharide: ethylcellulose blend ratio on the mechanical properties of thin films in the dry state at room temperature.
Table 3: Dissolution media used to simulate the gradual increase in pH along the GIT.
DETAILED DESCRIPTION OF THE INVENTIONIn describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out herein.
As used herein, the term “active ingredient”, “drug” or “pharmacologically active ingredient” or any other similar term means any chemical or biological material or compound suitable for administration by the methods previously known in the art and/or by the methods taught in the present invention, that induces a desired biological or pharmacological effect, which may include but is not limited to (1) having a prophylactic effect on the organism and preventing an undesired biological effect such as preventing an infection, (2) alleviating a condition caused by a disease, for example, alleviating pain or inflammation caused as a result of disease, and/or (3) either alleviating, reducing, or completely eliminating the disease from the organism. The effect may be local, such as providing for a local anaesthetic effect, or it may be systemic.
As used herein, the expression “Colonic microflora imbalance” also called Dysbiosis or dysbacteriosis is intended to mean, in the present invention, microbial imbalances as in quality and in quantity in the gastrointestinal tract. This phenomenon is reflected by the quality and quantity of the enzymes present in the colon. Particularly, this altered microflora is observed in the colon of patients suffering from inflammatory bowel diseases, such as Crohn's Disease (CD) and Ulcerative Colitis (UC).
As used herein, the term “controlled release delivery” or “controlled release” means that the release of the active ingredient out of the dosage form is controlled with respect to time or with respect to the site of delivery.
The expression “modified starch” should be understood broadly, this expression refers for instance to reticulated or acetylated or hydroxypropylated, or more generally to esterification or etherification starch.
The term “coat” is used herein to encompass coatings for solid supports and also capsules enclosing fluids and/or solids and the term “coated” is used similarly.
The expression “water insoluble polymer” should be understood broadly, this expression refers to polymers that do not completely dissolve in water, such as for example ethyl cellulose, certain starch derivatives or acrylic acid/methacrylic acid derivatives.
The term “indigestible polysaccharides” as used in the present invention refers to saccharides which are not or only partially digested in the intestine by the action of acids or digestive enzymes present in the human upper digestive tract (small intestine and stomach) but which are at least partially fermented by the human intestinal flora. Indigestible water-soluble polysaccharides that may be employed in preferred embodiments of the invention are xylooligosaccharides, inulin, oligofructoses, fructo-oligosacharides (FOS), lactulose, galactomannan and suitable hydrolysates thereof, indigestible polydextrose, indigestible dextrins and partial hydrolysates thereof, trans-galacto-oligosaccharides (GOS), xylo-oligosaccharides (XOS), acemannans, lentinans or beta-glucans and partial hydrolysates thereof, polysaccharides-K (PSK), and indigestible maltodextrins and partial hydrolysates thereof.
Polysaccharide-K is also known as polysaccharide-Krestin (PSK) in Japan, and as polysaccharide-peptide (PS—P) in China. Both have the same chemical and structural characteristics. PSK is a proteoglycan found in the polypore fungus Trametes versicolor and contains approximately 35% carbohydrate (91% beta-glucan), 35% protein and the remainders are free residues such as sugars, amino acids and moisture. PSK is a mixture of polysaccharides covalently linked to various peptides with an average molecular weight of 100 kilodaltons. The polysaccharide component is in a class of beta-glucans which comprise of glucopyranose units. Structural analysis showed that PSK has a 1, 4-glucan configuration as the main glucoside portion with branches at positions 3 and 6 at a frequency of one branch per several residual groups of 1-4 bonds.
As used herein, the term “cereal” is intended to mean, in the present invention, any plant belonging to the Gramineae, preferably wheat, rice, rye, oats, barley, corn, sorghum and millets.
The term “legume” is intended to mean, in the present invention, any plant belonging to the Caesalpinaceae, Mimosaceae or Papilionaceae families and in particular any plant belonging to the Papilionaceae family, such as, for example, pea, bean, broad bean, horse bean, lentil, alfalfa, clover or lupin.
The expression “starch derivative” means a starch that has been enzymatically or chemically treated.
The “coating level” means the difference in weight between uncoated and coated cores that is the weight gain in percentage.
This definition includes in particular all the plants described in any one of the tables present in the paper by R. Hoover et al. entitled “Composition, Structure, Functionality and Chemical Modification of Legume Starches: A Review”.
The term “pea” in this instance is considered in its broadest sense and includes in particular:
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- all the wild varieties of smooth pea and
- all the mutant varieties of smooth pea and of wrinkled pea, this being the case whatever the uses for which said varieties are generally intended (food for man, animal nutrition and/or other uses).
Said mutant varieties are in particular those referred to as “mutants r”, “mutants rb”, “mutants rug 3”, mutants rug 4″, “mutants rug 5” and “mutants lam” as described in the paper by C-L Heydley et al. entitled “Developing Novel Pea Starches”, Proceedings of the Symposium of the Industrial Biochemistry and Biotechnology Group of the Biochemical Society, 1996, pp. 77-87.
The term “legume starch” is understood to mean any composition extracted, this being the case in whatever way, from a legume as defined hereinabove and having a starch content of greater than 40%, preferably of greater than 50% and more preferably still of greater than 75%, these percentages being expressed in dry weight with respect to the dry weight of said composition.
Furthermore, it is possible to use starches naturally exhibiting an amylose content within the range selected according to the invention. In particular, the starch resulting from legumes may be suitable. In accordance with the present invention, this legume starch exhibits an amylose content of less than 45%, more specifically of between 20 20 and 45%, preferably of between 25 and 44%, and more preferably still of between 32 and 40%.
For the purpose of the invention, the term “ingestible maltodextrin” means maltodextrin containing indigestible glucosidic linkages conferring on those maltodextrins additional properties identical to dietetic fibers such as “branched maltodextrins”. As used herein, the term “branched maltodextrins” is intended to mean the ingestible maltodextrins described in patent EP 1 006 128, of which the applicant company is the proprietor.
According to a preferred variant, said branched maltodextrins have a reducing sugar content of between 2% and 5%, and a number-average molecular mass Mn of between 2000 and 3000 g/mol.
The branched maltodextrins have a total fiber content of greater than or equal to 50% on a dry basis, determined according to AOAC method No. 2001-03 (2001).
The invention provides novel polymeric film coatings for colon targeting which are adapted to the disease state of the patients suffering from inflammatory bowel diseases.
Novel polymeric films according to the invention serve as substrates for colonic bacteria for healthy patients as for patients suffering from inflammatory bowel diseases and are likely to exhibit beneficial effects on the ecosystem of the GIT of the patients. The polymeric film is specially adapted to the conditions at the target site, also in the disease state and able to deliver pharmacologically active ingredients specifically to the colon.
In the following, the invention will be illustrated by means of the following examples as well as the figures.
Example 1A. Materials and Methods
A.1. Materials
Branched maltodextrin (BMD) [a branched maltodextrin with non digestible glycoside linkages: α-1,2 and α-1,3, NUTRIOSE® FB 06 Roquette Fréres], Peas starch (granular pea starch N-735) (35% amylose), a pregelatinized hydroxypropyl pea starch (PS HP-PG)(LYCOAT® RS 780), a maltodextrin (MD)(GLUCIDEX® 1, Roquette Freres), EURYLON® 7 A-PG (an acetylated and pregelatinized high amylose maize starch (70% amylose) (Roquette Freres, Lestrem, France), EURYLON® 6 A-PG (an acetylated and pregelatinized high amylose maize starch) (60% amylose) (Roquette Freres, Lestrem, France) and EURYLON® 6 HP-PG (a hydroxypropylated and pregelatinized high amylose maize starch (60% amylose) (Roquette Freres, Lestrem, France); aqueous ethylcellulose dispersion (Aquacoat® ECD 30; FMC Biopolymer, Philadelphia, USA); triethylcitrate (TEC; Morflex®, Greensboro, USA); pancreatin (from mammalian pancreas=mixture containing amylase, protease and lipase; Fisher Bioblock, Illkirch, France); extract from rat intestine (rat intestinal powder, containing amylase, sucrase, isomaltase and glucosidase; Sigma-Aldrich, Isle d'Abeau Chesnes, France); Columbia blood agar, extracts from beef and yeast as well as tryptone (=pancreatic digest of casein) (Becton Dickinson, Sparks, USA); L-cysteine hydrochloride hydrate (Acros Organics, Geel, Belgium); McConkey agar (BioMerieux, Balme-les-Grottes, France); cysteinated Ringer solution (Merck, Darmstadt, Germany).
A.2. Film Preparation
Thin polymeric films were prepared by casting blends of different types of aqueous polysaccharides and aqueous ethylcellulose dispersion into Teflon moulds and subsequent drying for 1 d at 60° C. The water soluble polysaccharide was dissolved in purified water (5% w/w) and blended with plasticized ethylcellulose dispersion (25% TEC, overnight stirring; 15% w/w polymer content) at a ratio of 1:3 (polymer:polymer w:w). The mixture was stirred for 6 h prior to casting.
A.3. Film Characterization
The thickness of the films was measured using a thickness gauge (Minitest 600; Erichsen, Hemer, Germany). The mean thickness of all films was in the range of 300-340 μm. The water uptake and dry mass loss kinetics were measured gravimetrically upon exposure to:
(i) simulated gastric fluid (0.1 M HCl)
(ii) simulated intestinal fluid [phosphate buffer pH 6.8 (USP 30) with or without 1% pancreatin or 0.75% extract from rat intestine]
(iii) culture medium inoculated with feces from healthy subjects
(iv) culture medium inoculated with feces from inflammatory bowel disease patients
(v) culture medium free of feces for reasons of comparison.
Culture medium was prepared by dissolving 1.5 g beef extract, 3 g yeast extract, 5 g tryptone, 2.5 g NaCl and 0.3 g L-cysteine hydrochloride hydrate in 1 L distilled water (pH 7.0±0.2) and subsequent sterilization in an autoclave. Feces of patients with Crohn's Disease or Ulcerative Colitis as well as feces of healthy subjects were diluted 1:200 with cysteinated Ringer solution; 2.5 mL of this suspension was diluted with culture medium to 100 mL. Film pieces of 1.5×5 cm were placed into 120 mL glass containers filled with 100 mL pre-heated medium, followed by horizontal shaking at 37° C. (GFL 3033, Gesellschaft für Labortechnik, Burgwedel, Germany). The incubation with fecal samples was performed under anaerobic conditions (5% CO2, 10% H2, 85% N2). At predetermined time points samples were withdrawn, excess water removed, the films accurately weighed (wet mass) and dried to constant weight at 60° C. (dry mass). The water content (%) and dry film mass (%) at time t were calculated as follows:
A.4. Bacteriological Analysis
For the bacteriological analysis of fecal samples, the latter were diluted 1:10 with cysteinated Ringer solution. Eight further tenfold dilutions in cysteinated Ringer solution were prepared and 0.1 mL of each dilution was plated onto non-selective, modified Columbia blood agar (for total cultivable counts) and on McConkey agar (being selective for enterobacteria). Columbia blood agar plates were incubated during 1 week at 37° C. under anaerobic conditions (5% CO2, 10% H2, 85% N2). Colonies were outnumbered; predominant colonies subcultured and identified based on phenotypic identification criteria. 25 McConkey agar plates were incubated during 48 h at 37° C. in air. The colonies were outnumbered and identified using the API 20E system (BioMerieux, Balme-les-Grottes, France). Counts were expressed as log CFU/g (Colony Forming Units per gram) of fresh feces.
For the bacteriological analysis of the microflora developed upon film incubation with fecal samples, photomicrographs were taken after Gram-staining with an Axiostar plus microscope (Carl Zeiss, Jena, Germany), equipped with a camera (Unit DS-L2, DS camera Head DS-Fi 1; Nikon, Tokyo, Japan). Incubation was performed in a glucides-free culture medium containing only small amounts of polypeptides (thus, favoring the use of the investigated polysaccharides as substrates) under anaerobic conditions.
B. Results and Discussion
B.1. Film properties in the upper GIT
The permeability of a polymeric system for a drug strongly depends on its water content and dry mass, which determine the density and mobility of the macromolecules. For instance, in dry hydroxypropyl methylcellulose (HPMC)-based matrix tablets the apparent diffusion coefficient of a drug approaches zero, whereas in a completely hydrated HPMC gel diffusivities can be reached, which are in the same order of magnitude as in aqueous solutions. With increasing water content the macromolecular mobility significantly increases and, thus, the free volume available for diffusion. In some systems, the polymer undergoes a glassy-to-rubbery phase transition as soon as a critical water content is reached. This leads to a significant, stepwise increase in polymer and drug mobility. Thus, the water content of a polymeric film coating can give important insight into the macromolecular mobility and, hence, permeability for a drug.
In addition to the water uptake kinetics also the dry mass loss behaviour of thin polymeric films serves as an indicator for the coatings' permeability for the drug, and, hence, potential to suppress premature release within the upper GIT. If the films loose significant amounts of dry mass upon exposure to the release media, the coatings can be expected to become permeable for many drugs, in particular those with a low molecular weight such as 5-aminosalicylic acid (5-ASA, 153.1 Da).
It has to be pointed out that the results shown in
B.2. Film Properties in the Colon
Once the colon is reached, the polymeric film coatings should become permeable for the drug. This can for instance be induced by (partial) enzymatic degradation. Importantly, the concentrations of certain enzymes are much higher in the colon than in the upper GIT. This includes enzymes, which are produced by the natural microflora of the colon (this part of the GIT contains much more bacteria than the stomach and small intestine). However, great caution must be paid when using this type of colon targeting approach, because the microflora of patients suffering from inflammatory bowel diseases can be significantly different from the microflora of healthy subjects. Thus, the drug delivery system must be adapted to the disease state of the patient. Table 1 shows for instance the concentrations of the bacteria determined in the fecal samples of the healthy subjects as well as of the Crohn's Disease and Ulcerative Colitis patients included in this study. Importantly, there were significant differences, in particular with respect to the concentrations of Bifidobacterium (being able to degrade complex polysaccharides due to multiple extracellular glycosidases) and Escherichia coli, which where present at much higher concentrations in the feces of healthy subjects compared to the feces of the inflammatory bowel disease patients. In contrast, the fecal samples of the Crohn's Disease and Ulcerative Colitis patients contained lactose negative E. coli, Citrobacter freundii, Klebsiella pneumoniae, Klebsiella oxytoca and Enterobacter cloacae, which were not detected in healthy subjects. Thus, there are fundamental differences in the quality and quantity of the microflora, which must be taken into account: Polymeric film coatings, which allow for colon targeting under physiological conditions in a healthy volunteer, might fail under the pathophysiological conditions in the disease state of a patient. To address this very crucial point, which is very often neglected, the water uptake and dry mass loss of thin films consisting of various types of polysaccharide: polysaccharide ethylcellulose blends were determined upon exposure to fecal samples from Crohn's Disease and Ulcerative Colitis patients as well as to the feces of healthy subjects and to pure culture medium for reasons of comparison (
The fact that the investigated polymeric films serve as substrates for the bacteria in feces from inflammatory bowel disease patients could be further confirmed by the analysis of the microflora developed upon film exposure to fecal samples under anaerobic conditions at 37° C. (
The novel polymeric film coatings identified for colon targeting are composed of water insoluble polymer: polysaccharide particularly ethylcellulose: BMD, ethylcellulose: pea starch, ethylcellulose: MD, ethylcellulose: EURYLON® 6 A-PG, ethylcellulose: EURYLON® 6 HP-PG and ethylcellulose: EURYLON® 7 A-PG blends, which are adapted to the disease state of the patients. Importantly, low water uptake and dry mass loss rates and extents in media simulating the contents of the upper GIT can be combined with elevated water uptake and dry weight loss upon contact with feces from inflammatory bowel disease patients. Changes in the composition of the flora in the colon of patients indicate that these polysaccharides serve as substrates for colonic bacteria in the disease state and are likely to exhibit beneficial effects on the ecosystem of the GIT of the patients. The obtained new knowledge, thus, provides the basis for the development of novel polymeric film coatings able to deliver drugs specifically to the colon. Importantly, these polymeric barriers are adapted to the conditions at the target site in the disease state.
Example 2A. Materials and Methods
A.1. Materials
Pregelatinized hydroxypropyl pea starch (PS HP-PG) (LYCOAT® RS 780, Roquette Freres), EURYLON® 7 A-PG (an acetylated and pregelatinized high amylose maize starch (70% amylose)) (Roquette Freres, Lestrem, France), EURYLON® 6 A-PG (an acetylated and pregelatinized high amylose maize starch (60% amylose)) (Roquette Freres, Lestrem, France) and EURYLON® 6 HP-PG (a hydroxypropylated and pregelatinized high amylose maize starch (60% amylose)) (Roquette Freres, Lestrem, France); aqueous ethylcellulose dispersion (Aquacoat ECD 30; FMC Biopolymer, Philadelphia, USA); triethylcitrate (TEC; Morflex, Greensboro, USA).
A.2. Preparation of thin, polymeric films
Thin polymeric films were prepared by casting blends of different types of polysaccharides and aqueous ethylcellulose dispersion into Teflon moulds and subsequent drying for 1 d at 60° C. The water soluble polysaccharide was dissolved in purified water (5% w/w, in the case of EURYLON® 7 A-PG, EURYLON® 6 A-PG and EURYLON® 6 HP-PG in hot water), blended with plasticized aqueous ethylcellulose dispersion (25.0, 27.5 or 30.0% w/w TEC, referred to the ethylcellulose contentovernight stirring; 15% w/w polymer content) at a ratio of 1:2, 1:3, 1:4, 1:5 (polymer:polymer w:w), as indicated. The mixtures were stirred for 6 h prior to casting.
A.3. Film Characterization
The thickness of the films was measured using a thickness gauge (Minitest 600; Erichsen, Hemer, Germany). The mean thickness of all films was in the range of 300-340 μm. The water uptake and dry mass loss kinetics of the films were measured gravimetrically upon exposure to 0.1 M HCl and phosphate buffer pH 6.8 (USP 30) as follows: Pieces of 1.5×5 cm were placed into 120 mL plastic containers filled with 100 mL pre-heated medium, followed by horizontal shaking at 37° C. (80 rpm, GFL 3033; Gesellschaft fuer Labortechnik, Burgwedel, Germany). At predetermined time points samples were withdrawn, excess water removed, the films accurately weighed (wet mass) and dried to constant weight at 60° C. (dry mass). The water content (%) and dry film mass (%) at time t were calculated as follows:
A.4. Mechanical Properties of Thin Films
The mechanical properties of the films in the dry and wet state were determined with a texture analyzer (TAXT.Plus, Winopal Forschungsbedarf, Ahnsbeck, Germany) and the puncture test. Film specimens were mounted on a film holder (n=6). The puncture probe (spherical end: 5 mm diameter) was fixed on the load cell (5 kg), and driven downward with a cross-head speed of 0.1 mm/s to the center of the film holder's hole. Load versus displacement curves were recorded until rupture of the film and used to determine the mechanical properties as follows:
Where F is the load required to puncture the film and A the cross-sectional area of the edge of the film located in the path.
Here, R denotes the radius of the film exposed in the cylindrical hole of the holder and D the displacement.
Where AUC is the area under the load versus displacement curve and V the volume of the film located in the die cavity of the film holder.
B. Results and Discussion
B.1. PS HP-PG: Ethylcellulose Blends
B.2. EURYLON® 7 A-PG: Ethylcellulose Blends
The water uptake and dry mass loss kinetics of thin films consisting of 1:2 to 0:1 EURYLON® 7 A-PG: ethylcellulose blends in 0.1 M HCl and phosphate buffer pH 6.8 are shown in
B.3. EURYLON® 6 A-PG: Ethylcellulose and EURYLON® 6 HP-PG: Ethylcellulose Blends
EURYLON® 6 A-PG is an acetylated and pregelatinized high amylose maize starch (60% amylose) (Roquette Freres, Lestrem, France), and EURYLON® 6 HP-PG a hydroxypropylated and pregelatinized high amylose maize starch (60% amylose) (Roquette Freres, Lestrem, France). Interestingly, the dry mass loss of thin films consisting of EURYLON® 6 A-PG: ethylcellulose and EURYLON® 6 HP-PG: ethylcellulose blends was much less pronounced than that of the other investigated polymer blends upon exposure to 0.1 M HCl and phosphate buffer pH 6.8, respectively (
The key properties of thin polymeric films consisting of polysaccharide: water insoluble polymer blends exhibiting an interesting potential to provide site specific drug delivery to the colon (and being adapted to the pathophysiology of inflammatory bowel disease patients) can effectively be adjusted by varying the polymer blend ratio and type of polysaccharide. This includes the water uptake and dry mass loss kinetics as well as the mechanical properties of the films before and upon exposure to aqueous media simulating the contents of the upper GIT. Thus, broad ranges of film coating properties can easily be provided, being adapted to the needs of the respective drug treatment (e.g., osmotic activity of the core formulation and administered dose)
Example 3A. Materials and methods
A.1. Materials
Peas starch N-735 (peas starch; Roquette Freres, Lestrem, France); Aquacoat ECD 30 (aqueous ethylcellulose dispersion; FMC Biopolymer, Brussels, Belgium); triethylcitrat (TEC; Morflex, Greensboro, N.C., USA); 5-aminosalicylic acid (5-ASA; Sigma-Aldrich, Isle d'Abeau Chesnes, France); microcrystalline cellulose (Avicel PH 101; FMC Biopolymer); bentonite and polyvinylpyrrolidone (PVP, Povidone K 30) (Coopertation Pharmaceutique Francaise, Melun, France); pancreatin (from mammalian pancreas=mixture of amylase, protease and lipase) and pepsin (Fisher Bioblock, Illkirch, France); extracts from beef and yeast as well as tryptone (=pancreatic digest of casein) (Becton, Dickinson and Company, Franklin Lakes, N.J., USA); L-cysteine hydrochloride hydrate (Acros Organics, Geel, Belgium); cysteinated Ringer solution (Merck, Darmstadt, Germany).
A.2. Preparation of Free Films
Thin, free films were prepared by casting blends of peas starch and aqueous ethylcellulose dispersion (plasticized with 25% TEC) onto Teflon moulds and subsequent controlled drying (1 d at 60° C.). Peas starch was dispersed in purified water at 65-75° C. (5% w/w). Aqueous ethylcellulose dispersion (15% w/w solids content) was plasticized for 24 h with 25% TEC (w/w, referred to the solids content of the dispersion). The peas starch and ethylcellulose dispersions were blended at room temperature at the following ratios: 1:2, 1:3, 1:4 and 1:5 (polymer:polymer, w:w). The mixtures were stirred for 6 h prior to casting.
A.3. Characterization of Free Films
The thickness of the films was measured using a thickness gauge (Minitest 600; Erichsen, Hemer, Germany). The mean thickness of all films was in the range of 300-340 μm.
The water uptake and dry mass loss kinetics of the films were measured gravimetrically upon exposure to: (i) simulated gastric fluid (0.1 M HCl), and (ii) simulated intestinal fluid [phosphate buffer pH 6.8 (USP 32)] at 37° C. as follows: Pieces of 1.5 cm×5 cm were placed into 120 mL plastic containers filled with 100 mL pre-heated medium, followed by horizontal shaking at 37° C. (80 rpm, GFL 3033; Gesellschaft fuer Labortechnik, Burgwedel, Germany). At predetermined time points samples were withdrawn, excess water removed, the films accurately weighed (wet mass) and dried to constant weight at 60° C. (dry mass). The water content (%) and dry film mass (%) at time t were calculated as follows:
The mechanical properties of the films were determined using a texture analyzer (TAXT.Plus; Winopal Forschungsbedarf, Ahnsbeck, Germany) and the puncture test in the dry state and upon exposure to 0.1 M HCl and phosphate buffer pH 6.8 (in the wet state). Film specimens were mounted on a film holder (n=6). The puncture probe (spherical end: 5 mm diameter) was fixed on the load cell (5 kg), and driven downward with a cross-head speed of 0.1 mm/s to the center of the film holder's hole. Load versus displacement curves were recorded until rupture of the film and used to determine the mechanical properties as follows:
where F is the load required to puncture the film and A the cross-sectional area of the edge of the film located in the path.
Here, R denotes the radius of the film exposed in the cylindrical hole of the holder and D the displacement.
Where AUC is the area under the load versus displacement curve and V the volume of the film located in the die cavity of the film holder.
A.4. Preparation of Coated Pellets
Drug (5-amino salicylic acid, 5-ASA) loaded pellet starter cores (diameter: 0.7-1.0 mm; 60% 5-ASA, 32% microcrystalline cellulose, 4% bentonite, 4% PVP) were prepared by extrusion and subsequent spheronisation as follows: The respective powders were blended in a high speed granulator (Gral 10; Collette, Antwerp, Belgium) and purified water was added until a homogeneous mass was obtained (41 g of water for 100 g of powder blend). The wetted mixture was passed through a cylinder extruder (SK M/R, holes: 1 mm diameter, 3 mm thickness, rotation speed: 96 rpm; Alexanderwerk, Remscheid, Germany). The extrudates were subsequently spheronised at 520 rpm for 2 min (Spheroniser Model 15; Calveva, Dorset, UK) and dried in a fluidized bed (ST 15; Aeromatic, Muttenz, Switzerland) at 40° C. for 30 min. The size fraction 0.7-1.0 mm was obtained by sieving. These drug loaded starter cores were then coated in a fluidized bed coater, equipped with a Wurster insert (Strea 1; Aeromatic-Fielder, Bubendorf, Switzerland) with different peas starch: ethylcellulose blends until a weight gain of 5, 10, 15 or 20% (w/w) was achieved. The coating formulations were prepared in the same way as the dispersions used for film casting (as described in section 2.2. Preparation of free films). The process parameters were as follows: inlet temperature=39±2° C., product temperature=40±2° C., spray rat=1.5-3 g/min, atomization pressure=1.2 bar, nozzle diameter=1.2 mm. Afterwards, the pellets were further fluidized for 10 min and subsequently cured in an oven for 24 h at 60° C.
A.5. Drug Release from Coated Pellets
Drug release from coated pellets was measured in media simulating the conditions in the:
Upper gastro intestinal tract: Pellets were placed into 120 mL plastic containers, filled with 100 mL dissolution medium: 0.1 M HCl (optionally containing 0.32% pepsin) during the first 2 h, and phosphate buffer pH 6.8 (USP 32) (optionally containing 1% pancreatin) during the subsequent 9 h. The flasks were agitated in a horizontal shaker (80 rpm; GFL 3033). At pre-determined time points, 3 mL samples were withdrawn and analyzed UV-spectrophotometrically for their drug content (A=302.6 nm in 0.1 M HCl; λ=330.6 nm in phosphate buffer pH 6.8) (UV-1650; Shimadzu, Champs sur Marne, France). In the presence of enzymes, the samples were centrifuged for 15 min at 11000 rpm and subsequently filtered (0.2 μm) prior to UV-measurements. Each experiment was conducted in triplicate.
Entire gastro intestinal tract: Pellets were exposed to 0.1 M HCl for 2 h and subsequently to phosphate buffer pH 6.8 (USP 32) for 9 h in a USP Apparatus 3 (Bio-Dis; Varian, Paris, France) (dipping speed=10 dpm). Afterwards, the pellets were transferred into 120 mL flasks filled with: (i) 100 mL culture medium inoculated with feces from inflammatory bowel disease patients, (ii) culture medium inoculated with Bifidobacterium, or (iii) culture medium free of feces and bacteria for reasons of comparison. The samples were agitated (50 rpm) at 37° C. under anaerobic conditions (5% CO2, 10% H2, 85% N2). Culture medium was prepared by dissolving 1.5 g beef extract, 3 g yeast extract, 5 g tryptone, 2.5 g NaCl and 0.3 g L-cysteine hydrochloride hydrate in 1 L distilled water (pH 7.0±0.2) and subsequent sterilization in an autoclave. Feces of patients suffering from Crohn's disease or ulcerative colitis were diluted 1:200 with cysteinated Ringer solution; 2.5 mL of this suspension was diluted with culture medium to 100 mL. At pre-determined time points, 2 mL samples were withdrawn, centrifuged at 13000 rpm for 5 min, filtered (0.22 μm) and analyzed by HPLC for their drug content (ProStar 230; Varian). The mobile phase consisted of 10% methanol and 90% of an aqueous acetic acid solution (1% w/v) (Siew et al., 2000a). Samples were injected into a Pursuit C18 column (150×4.6 mm; 5 μm), the flow rate was 1.5 mL/min. The drug was detected UV-spectrophotometrically at λ=300 nm.
Drug release was measured from freshly prepared pellets (if not otherwise stated), as well as from pellets stored for 1 year at room temperature (23±2° C.) and ambient relative humidity (55±5%) in open glass vials.
B. Results and Discussion
B.1. Water Uptake and Dry Mass Loss of Thin Films
Ideally, a polymeric film coating allowing for site specific drug delivery to the colon should effectively suppress drug release in the upper part of the gastro intestinal tract: the stomach and the small intestine. Thus, the film coating (which surrounds the drug reservoir) should be poorly permeable for the drug upon exposure to media simulating the contents of these organs (in order to avoid premature drug release and subsequent absorption into the blood stream). If a polymeric film coating takes up significant amounts of water or looses considerable amounts of dry mass upon exposure to a bulk fluid, its permeability for drug molecules can be expected to remarkably increase [ ]. For this reason, the water uptake and dry mass loss kinetics of thin peas starch: ethylcellulose films were monitored upon exposure to: (a) 0.1 M HCl (simulating the contents of the stomach) for 2 h, and (b) phosphate buffer pH 6.8 (simulating the contents of the small intestine) for 8 h.
Thus, the observed water uptake and dry mass loss kinetics of peas starch: ethylcellulose films are very promising with respect to the potential use of these films as barrier membranes hindering drug release in stomach and small intestine. If required, the film thickness and/or ethylcellulose contents might be increased. However, care should be taken that sufficient amounts of peas starch are present in the coatings, because this compound is intended to induce the onset of drug release in the colon (being degraded by enzymes secreted from colonic bacteria.
B.2. Mechanical Properties of Thin Films
In addition to limited water uptake and dry mass loss, polymeric film coatings aiming at site specific drug delivery to the colon should provide a sufficient mechanical stability: Due to the physiological motility of the stomach and small intestine, mechanical stress is exerted onto the coated dosage forms. If the film coatings are fragile, crack formation occurs and the drug is rapidly released through water-filled channels. To evaluate the mechanical stability of the investigated peas starch: ethylcellulose blends, a texture analyzer and the puncture test were used.
However, it has to be pointed out that the results shown in
B.3. Drug Release in the Upper Gastro Intestinal Tract
Ideally, no or very little drug should be released from the dosage form in the stomach and small intestine. The solid curves in
However, it has to be pointed out that the presence of enzymes within the gastro intestinal tract in vivo might significantly affect the film coating properties, e.g. due to partial polymer degradation. For this reason, drug release from the coated pellets was also measured in: (i) 0.1 M HCl containing 0.32% pepsin (for 2 h), followed by (ii) phosphate buffer pH 6.8 containing 1% pancreatin (for 9 h). The respective results are indicated by the dotted curves in
As an increase in the relative ethylcellulose contents of the films resulted in decreased water uptake and dry mass loss rates and extents (
Based on the obtained results (
B.4. Drug Release in the Entire Gastro Intestinal Tract
Once the dosage form reaches the colon, the film coating should become permeable for the drug and release the latter in a time-controlled manner.
As the regular supply of fresh fecal samples from inflammatory bowel disease patients is difficult to assure (and since the samples cannot be deep-frozen or freeze-dried without significant damage of the microflora), it is highly desirable to provide an alternative type of release medium, simulating the conditions in the colon of a patient. For drug delivery systems that are sensitive to the presence of bacterial enzymes, caution has to be paid that the bulk fluid contains the crucial types and amounts of bacteria. In this study, culture medium inoculated with Bifidobacterium has been tested as potential alternative to culture medium inoculated with fresh fecal samples.
Similar results were obtained using dibutyl sebacate as plasticizer (data no shown) confirming that the efficiency of pea starch in controlled released delivery is not plasticizer dependent.
B.5. Storage Stability
A very important aspect from a practical point of view is the long term stability of a controlled drug delivery system. Dosage forms should ideally be stable during at least 3 years. In case of polymer coated delivery systems the resulting drug release rate might eventually increase with increasing storage time, e.g. due to drug migration into the film coating.
C. Conclusions
Peas starch: ethylcellulose-based film coatings have been proposed with a highly promising potential for site specific drug delivery to the colon: Drug release from coated pellets can effectively be suppressed in media simulating the contents of the stomach and small intestine. But once the devices come into contact with fecal samples, drug release sets on and is time-controlled, due to the partial degradation of the peas starch by enzymes secreted from bacteria present in the colon of inflammatory bowel disease patients. Thus, this type of advanced delivery systems allows avoiding premature drug release in the upper gastro intestinal tract (and subsequent absorption into the blood stream), whiling assuring that the drug is released at the site of action. Consequently, undesired side effects in the rest of the human body can be expected to be minimized, while the therapeutic effects of the drug are likely to be optimized.
Example 4A. Materials and Methods
A.1 Materials
2,4,6-Trinitrobenzene sulfonic acid (TNBS) (Sigma-Aldrich, Isle d'Abeau Chesnes, France); cysteinated Ringer solution (Merck, Darmstadt, Germany); BMD (NUTRIOSE® FB 06; Roquette Freres, Lestrem, France); Peas starch N-735 (peas starch; Roquette Freres, Lestrem, France); aqueous ethylcellulose dispersion (Aquacoat ECD 30; FMC Biopolymer, Philadelphia, USA); triethylcitrate (TEC; Morflex, Greensboro, USA); 5-aminosalicylic acid (5-ASA; Sigma-Aldrich, Isle d'Abeau Chesnes, France); microcrystalline cellulose (Avicel PH 101; FMC Biopolymer, Brussels, Belgium); polyvinylpyrrolidone (PVP, Povidone K 30) (Cooperation Pharmaceutique Francaise, Melun, France); Pentasa® (coated pellets, Ferring, batch number: JX 155), Asacol® (coated granules, Meduna, batch number: TX 143).
A.2 Preparation of Bmd: Ethylcellulose and Peas Starch: Ethylcellulose Coated Pellets
5-Amino salicylic acid (5-ASA) loaded pellet starter cores (diameter: 0.7-1.0 mm; 60% 5-ASA, 32% microcrystalline cellulose, 4% bentonite, 4% PVP) were prepared by extrusion and subsequent spheronisation as follows: The respective powders were blended in a high speed granulator (Gral 10; Collette, Antwerp, Belgium) and purified water was added until a homogeneous mass was obtained (41 g of water for 100 g of powder blend). The wetted mixture was passed through a cylinder extruder (SK M/R, holes: 1 mm diameter, 3 mm thickness, rotation speed: 96 rpm; Alexanderwerk, Remscheid, Germany). The extrudates were subsequently spheronised at 520 rpm for 2 min (Spheroniser Model 15; Calveva, Dorset, UK) and dried in a fluidized bed (ST 15; Aeromatic, Muttenz, Switzerland) at 40° C. for 30 min. The size fraction 0.7-1.0 mm was obtained by sieving.
The obtained drug loaded starter cores were subsequently coated in a fluidized bed coater, equipped with a Wurster insert (Strea 1; Aeromatic-Fielder, Bubendorf, Switzerland) with BMD:ethylcellulose 1:4 blends (BMD:EC coated pellets) or with peas starch: ethylcellulose 1:2 blends (peas starch:EC coated pellets) until a weight gain of 15% (w/w) (BMD:EC coated pellets) or 20% (w/w) (peas starch: EC coated pellets) was achieved.
BMD was dissolved in purified water (5% w/w), blended with plasticized aqueous ethylcellulose dispersion (25% TEC, overnight stirring; 15% w/w polymer content) at a ratio of 1:4 (w/w, based on the non-plasticized polymer dry mass) and stirred for 6 h prior to coating. The drug-loaded pellet cores were coated in a fluidized bed coater equipped with a Wurster insert (Strea 1; Aeromatic-Fielder, Bubendorf, Switzerland) until a weight gain of 15% (w/w) was achieved. The process parameters were as follows: inlet temperature=39±2° C., product temperature=40±2° C., spray rate=1.5−3 g/min, atomization pressure=1.2 bar, nozzle diameter=1.2 mm. After coating, the beads were further fluidized for 10 min and subsequently cured in an oven for 24 h at 60° C.
Peas starch was dispersed in purified water at 65-75° C. (5% w/w). Aqueous ethylcellulose dispersion (15% w/w solids content) was plasticized for 24 h with 25% TEC (w/w, referred to the solids content of the dispersion). The peas starch and ethylcellulose dispersions were blended at room temperature at the following ratio: 1:2 (polymer:polymer, w:w). The mixture was stirred for 6 h prior to coating. The drug-loaded pellet cores were coated in a fluidized bed coater equipped with a Wurster insert (Strea 1; Aeromatic-Fielder, Bubendorf, Switzerland) until a weight gain of 20% (w/w) was achieved. The process parameters were as follows: inlet temperature=39±2° C., product temperature=40±2° C., spray rat=1.5−3 g/min, atomization pressure=1.2 bar, nozzle diameter=1.2 mm. Afterwards, the pellets were further fluidized for 10 min and subsequently cured in an oven for 24 h at 60° C.
A.3 Induction of Colitis and Study Design
Male Wistar rats (250 g) were used for the in vivo study, which was conducted in accredited establishment at the Institut Pasteur de Lille (A 35009), according to governmental guidelines (86/609/CEE). Four animals were housed per cage, all rats had free access to tap water.
At the beginning of the experiment (day 0), the rats were divided in six groups (5-8 animals/group). Two groups received standard chow (negative and positive control groups). The other groups received food with either Pentasa® pellets (n=8), Asacol® pellets (n=8), BMD: ethylcellulose coated pellets (n=8) or peas starch: ethylcellulose coated pellets (n=8). These four different chows were prepared using the “food admix” technique. All systems were added to obtain a dose of 5-ASA of 150 mg/kg/day.
At day 3, colitis was induced as follows: The rats were anesthetized for 90-120 min using pentobarbital (40 mg/kg) and received an intrarectal administration of TNBS (250 μl, 20 mg/rat) dissolved in a 1:1 mixture of an aqueous 0.9% NaCl solution with 100% ethanol. Control rats (negative control) received an intrarectal administration of the vehicle only (1:1 mixture of an aqueous 0.9% NaCl solution with 100% ethanol). Animals were sacrificed 3 days after intrarectal TNBS or vehicle administration (day 6).
A.4 Macroscopic and Histological Assessment of Colitis
Macroscopic and histological indications of colitis were evaluated blindly by two investigators. A colon specimen located precisely 4 cm above the anal canal was used for histological evaluation according to the Ameho criteria. This grading on a scale from 0 to takes into account the degree of inflammation infiltrate, the presence of erosion, ulceration, or necrosis, and the depth and surface extension of lesions.
A.5 Statistics
All comparisons were analyzed using the nonparametric test (Mann-Whitney) test. Differences were judged statistically significant if the P value was <0.05.
B Results and Discussion
TNBS-induced colitis is improved by the treatment with BMD: ethylcellulose coated pellets and peas starch: ethylcellulose coated pellets.
The development of colitis in animals subjected to intrarectal TNBS administration was characterized. Control rats (negative control group), sacrificed 3 days after intrarectal administration of the vehicle only (a 1:1 mixture of an aqueous 0.9% NaCl solution with 100% ethanol), had no macroscopic lesions in the colon (
These results clearly prove the efficacy of the proposed novel film coatings for colon targeting in vivo.
Claims
1. A controlled release delivery dosage form for controlled release of an active ingredient, comprising an active ingredient coated in a polymeric mixture of:
- at least a water insoluble polymer and
- a starch composition comprising one component selected from the group consisting of a starch having an amylose content of between 25 and 45%, a modified starch having an amylose content of between 50 and 80% and a legume starch.
2. The controlled release delivery dosage form according to claim 1, comprising a core, the active ingredient being dispersed or dissolved in the core.
3. The controlled release delivery dosage form according to claim 1, wherein the starch composition: water insoluble polymer ratio is between 1:2 and 1:8.
4. The controlled release delivery dosage form according to claim 1, wherein the starch composition exhibits an amylose content of between 25 and 45%, this percentage being expressed by dry weight with respect to the dry weight of starch present in said composition.
5. The controlled release delivery dosage form according to claim 1, wherein the starch composition comprises at least one legume or cereal starch.
6. The controlled release delivery dosage form according to claim 1, wherein the starch composition comprises at least one modified starch, said modified starch being stabilized.
7. The controlled release delivery dosage form according to claim 2, wherein the core has a coating level of 5% to 30%.
8. The controlled release delivery dosage form according to claim 7, wherein the core has a coating level of 10% to 20%.
9. The controlled release delivery dosage form according to claim 1, wherein the polymeric mixture comprises a plasticizer, preferably in a content between 25% to 30% w/w referred to the water insoluble polymer content.
10. The controlled release delivery dosage form according to claim 1, wherein the water insoluble polymer is selected from the group consisting of acrylic and/or methacrylic ester polymers, polymers or copolymers of acrylate or methacrylate polyvinyl esters, polyvinyl acetates, polyacrylic acid esters, and butadiene styrene copolymers methacrylate ester copolymers, ethyl cellulose, cellulose acetate phtalate, polyvinyl acetate phtalate, shellac, methacrylic acid copolymers, cellulose acetate trimellitate, hydroxypropyl methylcellulose phtalate, zein, starch acetate.
11. The controlled release delivery dosage form according to claim 9, wherein the plasticizer is a water soluble plasticizer, the plasticizer being preferably selected from the group consisting of polyols, organic esters, oils or glycerides, soya lecithin, alone or as a mixture with one another.
12. The controlled release delivery dosage form according to, wherein said controlled release delivery dosage form is a multiparticulate dosage form.
13. A method for preparing a controlled release delivery dosage form for controlled release of an active ingredient in the colon of patients having a colonic microflora imbalance or in the colon of healthy subjects, as claimed in claim 1, said method comprising:
- forming a polymeric mixture of: at least one water insoluble polymer and a starch composition comprising at least one component selected from the group consisting of a starch having an amylose content of between 25 and 45%, a modified starch having an amylose content of between 50 and 80% and a legume starch,
- coating said active ingredient in the polymeric mixture.
Type: Application
Filed: Oct 27, 2009
Publication Date: Aug 18, 2011
Applicant: Roquette Freres (Lestrem)
Inventors: Olaf Haeusler (Fletre), Daniel Wils (Morbecque), Juergen Siepmann (Phalempin), Youness Karrout (Lille)
Application Number: 13/126,212
International Classification: A61K 9/14 (20060101); A61K 9/00 (20060101); A61K 47/26 (20060101); A61K 47/32 (20060101); A61P 1/00 (20060101); B05D 5/00 (20060101); B05D 7/24 (20060101);