The invention relates to a delivery system based on polymeric materials to be used in the formulation of food supplements, the process for the manufacture thereof and the use thereof in the nutraceutical field.

Polymeric materials, albeit potentially usable from the regulatory point of view, are currently little explored in the nutraceutical field. Depending on the mode with which such materials are combined and formulated, it is possible to modify their release performance and properties, as well as optimize the solubility/stability profile of one or more active components of the formulation, optimizing their oral absorption.

Changing the release performance in a delayed release system consists in releasing an active ingredient with a pre-programmed delay or as a result of pH changes. In order to achieve an efficient control of the release rate, the active ingredient is generally incorporated in a pharmaceutical form coated with natural, semi-synthetic or synthetic polymers.

Widely used polymers among the synthetic coating polymers are methacrylic acid derivatives, or in general polymers containing carboxyl groups, which at acidic pH (stomach) are undissociated and confer insolubility to the coating, while at a more alkaline pH (bowels) solubilize allowing the release of the active ingredient dose contained in the core. Among the natural polymers, plant polysaccharides are rarely used in the pharmaceutical/nutraceutical field for such application, due to poor reproducibility of the properties (molecular weight, polydispersity index), which do not guarantee a satisfactory release performance. The most used are semi-synthetic pH-sensitive cellulose derivatives. Zein is a plant protein (approximately 35 kDa) belonging to the prolamine class, which is water insoluble due to the presence of a large number of hydrophobic amino acids. Thanks to its hydrophobic nature, zein has been proposed as a coating material and recently as a drug carrier in the form of films, fibres and particles of different sizes.

Patel et al., Current Opinion in Colloid & Interface Science, Vol. 19, No. 5, October 2014, p. 450-458, describe zein micro- and nano-structures and their application as functional materials.

Vann Leeuwev et al, Food Chemistry, Vol. 155, July 2014, p. 161-166, describe a zein colloidal dispersion for ferric ion encapsulation and the use of this system as a functional fortified food.

US patent 5,356,467 discloses stable aqueous dispersions of zein that can be used as coatings for the controlled release of pharmaceutical, veterinary, health or food products in an environment free of inorganic solvents, and methods for the preparation of the above mentioned dispersions.

However, as can be seen from the diagrams illustrated in the figures of US Patent 5,356,467, the release systems based on colloidal dispersions of zein have the drawback of excessively slowing down the release of the active ingredient. Cyclodextrins (CD) are cyclic oligosaccharides obtained by hydrolysis and enzymatic cyclization of starch and are made up of glucopyranose units linked by alpha- 1,4 bonds. Based on the number of units, they are classified into alpha-cyclodextrins, consisting of six monosaccharide units, beta-cyclodextrins with seven units, and gamma-cyclodextrins with eight. Cyclodextrins have the ability to form inclusion complexes (the so-called "host-guest complexes") with non-polar substances, or portions thereof, by means of a molecular complexation mechanism. In these complexes the guest molecules arrange themselves into the lipophilic cavity of the cyclodextrin, forming a complex characterised by a complexation constant, which is a function of the affinity of the CD for the guest. Thanks to this property of theirs, CDs are able to increase the apparent water solubility of an active principle, its dissolution rate, stability and bioavailability.

Cyclodextrins are able to interact with hydrophobic amino acids, forming supramolecular complexes capable of modifying the structure of proteins in the solid state.

Cyclodextrins have been proposed for improving the stability of proteins in solution and in the solid state and promoting water-solubilisation of active substances.

For example, patent CN 103756360 B describes a method for the preparation of a micro- powder of a water-insoluble yellow corn pigment, which constitutes the core of the micro- powder particles, which is coated with a coating consisting of maltose, β-cyclodextrin, modified starch, zein and an emulsifying agent.

US patent 20040109920 Al describes a formulation of a carotenoid that is sparingly soluble in water, complexed with cyclodextrins, and coated with a natural or synthetic oil or polymer. However, there is no description of controlled release properties for the systems described in CN 103756360 B and US 20040109920 Al .

Moreover, in the production process disclosed in US 20040109920 Al, the cyclodextrin and carotenoid complex is a dispersion, which is coated by a suitable coating agent. This limits the probability of forming nanometer-sized particles and limits the usefulness of the coating only for increasing the stability of the particles formed by the carotenoid/cyclodextrin inclusion complex.

In order to overcome these and other drawbacks of the prior art, the present invention provides a liquid pharmaceutical composition comprising a stable hydroalcoholic colloidal dispersion (also referred to as "pseudolatex") comprising polymeric particles of zein and β- cyclodextrin in suspension in a hydroalcoholic continuous phase, the particles having a mean diameter less than 1 μηι, preferably comprised within the range of from 100 nm to less than 1 μιη, more preferably comprised within the range of from 500 nm to less than 1 μιη, the pharmaceutical composition including at least one active ingredient incorporated in the particles. The active ingredient incorporated in the particles is a hydrophiiic or lipophilic pharmaceutical or nutraceutieal active ingredient, preferably a nutraceutical active ingredient selected from, the group consisting of iron bisglycinate or other iron salts, coenzyme Q 10. lycopene. β-carotene, lutein, zeaxanthin, tocopherol, boswellic acids, colecalciferol, ergocalciferol, N-palmitoylethanolamide. retinol, resveratroi, curcurain, cr- lipoic acid, gingerols, silymarin, qitercetin, melatonin, acetyl carnitine, caniiiine. ilavonoids. diosmin. hesperidin, rutin, citieohne, glutathione and combinations thereof.

Table i below lists the most interesting active ingredients and the related logP.

Fable 1

The liquid pharmaceutical composition of the present invention is advantageously suitable for use in the preparation of systems for the controlled release of active ingredients, in particular controlled-release solid gastro-resistant pharmaceutical forms, such as granulates, tablets or capsules, which form a further aspect of the invention.

These controlled-release solid gastro-resistant pharmaceutical forms consist of or comprise a micro-powder obtained by spray-drying the liquid pharmaceutical composition of the invention.

The method of preparing the liquid pharmaceutical composition of the invention is described hereinafter and forms a further aspect of the present invention, as well as the method of preparing the solid gastro-resistant pharmaceutical form starting from the liquid composition.

The method of preparing the liquid pharmaceutical composition of the invention comprises the steps of:

(i) preparing a hydroalcoholic solution (preferably ethyl alcohol/water in a ratio of 8:2 v/v) containing zein and the lipophilic active ingredient, if provided in the final composition; (ii) preparing an aqueous solution of β-cyclodextrin (βCD) and the hydrophilic active ingredient, if provided in the final composition;

(iii) mixing the hydroalcoholic solution and the aqueous solution (hydroalcoholic solutiomaqueous solution volume ratio of 1 :1 to 1 :5), with consequent formation of a colloidal dispersion containing submicron particles of zein and β-cyclodextrin in suspension in a hydroalcoholic continuous phase and including the lipophilic or hydrophilic active ingredient incorporated in the particles.

As indicated previously, the liquid composition of the invention is used for preparing solid gastro-resistant pharmaceutical forms consisting of a micro-powder or comprising a micro- powder. The micro-powder is obtained by spray-drying the liquid pharmaceutical composition prepared as described above.

The method of preparing the liquid pharmaceutical composition of the invention has some important advantages with respect to the prior art. For example, the method described in CN 103756360 B requires homogenizing the dispersion of the carotenoid and the two coating phases, with considerable expenditure of energy. In the method of the present invention, instead, the active ingredient is in an aqueous solution or in the hydroalcoholic solution and is trapped in the polymer matrix by mixing the two solutions, with consequent precipitation of zein. In this way, there is no requirement for high amounts of energy and it is possible to obtain submicron-sized particles, which are not necessarily obtainable with the method of CN 103756360 B. In addition, the submicron particles obtained with the method of the present invention, besides being stable in the continuous phase without generating agglomeration, allow, once dried into the micro-powder, a higher bioavailability of the carried active ingredient, its protection from the acidic environment of the stomach and a sustained release, which can be useful for active principles characterised by a short half-life.

Typically, in the method of the present invention, the mixing of the hydroalcoholic solution with the aqueous solution is carried out at room temperature, under continuous and moderate stirring for less than 5 hours.

The weight ratio of β-cyclodextrin in the aqueous solution is comprised within the range of from 0.1 to 5% w/v, preferably from 0.1 to 2% w/v, more preferably approximately 1%.

The concentration of zein in the hydroalcoholic solution is comprised within the range of from 1% to 10% w/v, preferably from 2% to 6% w/v, still more preferably approximately 4% w/v. As described, the water-soluble active agents are directly added to the aqueous β- cyclodextrin solution. The liposoluble active agents can be added in advance to the hydroalcoholic zein solution or may be dissolved in the organic solvent used for zein and added to the zein/ -cyclodextrin colloidal dispersion.

According to the present invention, the term "active ingredient" is intended to mean both pharmacologically active compounds and compounds that have beneficial/health properties on the body, such as nutraceutical compounds. Similarly, the terms "pharmaceutical composition" and "solid pharmaceutical form" refer to compositions or solid dosage forms including pharmaceutical active ingredients or compounds having beneficial/health properties on the body, such as nutraceutical compounds.

As indicated above, the formation of submicron-sized particles in suspension (pseudolatex) occurs as a result of the mixing of the hydroalcoholic zein solution with the aqueous β- cyclodextrin solution. The pseudolatex particles exhibit a mean diameter less than 1 μm, preferably comprised within the range of from 100 nm to less than 1 μm, even more preferably from 500 nm to less than 1 μιη.

Zein and β-cyclodextrin form a complex during the formation of the pseudolatex and approximately 60% of β-cyclodextrin interacts with zein. The remaining 40% of β- cyclodextrin remains solubilized in the continuous phase of the pseudolatex.

For the preparation of a gastro-resistant micro-powder, the pseudolatex is subjected to spray- drying, selecting as the operating parameter an inlet temperature preferably of about 1 15°C.

The production yield of the powder is very high and equal to 90% of the theoretical quantity of solid components used in the preparation of the pseudolatex. It can be noted that the production yield is duplicated with respect to that obtainable by using zein as such (i.e. without β-cyclodextrin), demonstrating that the presence of β-cyclodextrin in the formation of the pseudolatex improves the process of production of the micro-powder by spray-drying.

The micro-powder obtained by spray-drying has been characterised and showed a mean diameter of between 2 and 8 microns, generally of approximately 5 μηι, and a tapped density ranging from 0.12 to 0.35 g/cm ³ , generally of approximately 0.255 g/cm ³ .

A SEM analysis of the zein/β-cyclodextrin microparticles was also performed, showing a partially spherical and collapsed morphology typical of powders prepared by spray-drying.

The addition of a hydrophilic or lipophilic active principle to the pseudolatex does not significantly change the characteristics of the micro-powder prepared by spray-drying and mentioned above.

The peculiar characteristic of a zein and β-cyclodextrin (β-CD) micro-powder of releasing an active ingredient as a function of the pH and time was evaluated by way of example with the hydrophilic active ingredient iron bisglycinate (mass ratio 1 :40 with respect to zein). It should be noted that, in the case of iron bisglycinate, without the aid of β-CD it is not even possible to obtain a stable pseudolatex which can then be spray-dried.

The release of iron bisglycinate was performed in media simulating the biological environment (gastric fluid, intestinal fluid with enzymes) and prepared as indicated in the 12th edition of the Official Pharmacopoeia (also set forth in the 8th edition of the European Pharmacopoeia). The micro-powder containing iron bisglycinate obtained by spray-drying showed a remarkable gastroresistance, as can be seen in Table 2 below, which shows the percentages of iron bisglycinate released by the micro-powder in artificial gastric juice at pH = 1.2 with pepsin. In an intestinal medium at pH 6.8 with pancreatin, instead, a progressive increase in the percentage of released iron is observed, demonstrating an efficient control of the release rate (Table 3).

From the results obtained, it is clear that the zein/βCD/iron bisglycinate micro-powder has properties of gastroresistance and sustained release at the intestinal level. Table 2. Percentage of iron bisglycinate released over time in simulated gastric fluid with pepsin; pH 1.2 (stomach).

Table 3. Percentage of iron bisglycinate released over time in simulated intestinal fluid with pancreatin; pH 6.8 (intestine).

As indicated, the zein/βCD combination allows the processing and incorporation of iron bisglycinate, which can not be included in the formulation in the absence of βCD.

In addition to being essential for obtaining powders containing different active ingredients, β-cyclodextrin also plays a central role in the preparation of thin films, which can be placed as a gastro-resistant coating on solid pharmaceutical forms including various types of active ingredients, so as to obtain solid gastro-resistant pharmaceutical forms including a core and a gastro-resistant coating.

Therefore, another aspect of the present invention is a controlled-release solid gastro- resistant pharmaceutical form consisting of a core, such as for example a granulate or a tablet, containing an active ingredient, the core being coated with a thin film obtained by drying a hydroalcoholic solution of zein and β-cyclodextrin optionally containing at least one plasticizer.

A method for obtaining these solid gastro-resistant pharmaceutical forms comprises the steps of:

(i) preparing a hydroalcoholic solution of zein, β-cyclodextrin and at least one plasticizer, wherein the zein concentration is comprised within the range of from 2% to 20% w/v and the β-cyclodextrin concentration is comprised within the range of from 0.2% to 2.5% w/v;

(ii) pouring the solution containing zein, βCD and the plasticizer on a plastic support (e.g. polyethylene, polyethylene terephthalate), preferably at a density between 30 and 150 g/m ³ , more preferably 60 g/m ³ , and drying at temperatures comprised between 25 and 80°C, preferably at room temperature, to obtain a thin film; and

(iii) placing said thin film as a gastro-resistant coating on a core including an active agent.

The plasticizer is preferably selected from polyethylene glycol, polyols, fatty acids; more preferably, it is polyethylene glycol 400 (0.5-12% w/v).

As an alternative to the method described above, the hydroalcoholic solution of zein, β- cyclodextrin and at least one plasticizer is nebulized onto the core containing the active ingredient (for example a granulate or a tablet) in a heated gas flow at temperatures preferably between 25 and 80°C, to form a coating.

The method according to the present invention allows the achievement of thin films having a thickness of 0.1-2 mm, which are endowed with high flexibility. To highlight the effect of β-cyclodextrin in films obtained with the method described above, its amount in the film was modulated while keeping the zein/plasticizer (PEG 400) ratio fixed. The thickness of the films was directly dependent on the amount of β-cyclodextrin ^CD) therein. Furthermore, it has been shown that increasing the amount of β-cyclodextrin increases the flexibility of the films obtained. For these reasons, β-cyclodextrin acts as a plasticizer and the modulation of the amount of cyclodextrin is fundamental to ensure the formation of coatings which meet the expected requirements. A further property given to films by β-cyclodextrin is that of ensuring gastroresistance compared to control films consisting of zein alone. This property was assessed by treating zein/βCD films and control films consisting of zein alone with media simulating the biological environment as described previously and evaluating the flexibility of the films.

In artificial gastric juice in the absence/presence of pepsin, films containing zein/βCD showed no change in their morphological characteristics and flexibility, unlike what happens to control films consisting of zein alone, which stiffen and tend to break. This substantial difference indicates that β-cyclodextrin plays a fundamental role in bringing about the formation of gastro-resistant coatings, which remain unchanged while passing through the gastric tract.

When films containing zein/βCD and respective zein-only control films are treated with simulated intestinal fluid, in the absence/presence of pancreatin, they lose their morphological and plastic characteristics, indicating that the coating is gastro-resistant only in the presence of β-cyclodextrin and degrades as the pH increases.

In this respect, solid gastro-resistant pharmaceutical forms including zein and β-cyclodextrin films/coatings according to the present invention, as well as the micro-powder described above, also show a remarkable gastroresistance attributable to the use of the combination of zein and β-cyclodextrin.

The examples that follow are provided for illustration purposes only and should not be construed as limiting the scope of the invention as defined in the appended claims.

Examples

Example 1

Powder containing zein βCD iron bisglvcinate 50 mL of a hydroalcoholic solution (ethyl alcohol/water in a ratio of 8:2 v/v) containing 2 g of zein (4% w/v zein) were prepared.

50 mL of an aqueous solution containing 500 mg of βCD and 50 mg of iron bisglycinate were prepared.

The hydroalcoholic zein solution was diluted with the aqueous βCD/iron bisglycinate solution (volume ratio 1 :1) causing the formation of submicron-sized particles in suspension. The mixing is carried out at room temperature, under continuous and moderate stirring for less than 5 hours.

The obtained pseudolatex was dried by spray drying to obtain a micro-powder containing iron bisglycinate.

Example 2

Zein βCD curcumin powder 50 mL of a hydroalcoholic solution (ethyl alcohol/water in a ratio of 8:2 v/v) containing 2 g of zein (4% w/v zein) and 50 mg of curcumin were prepared.

50 mL of an aqueous solution containing 500 mg of βCD were prepared. The hydroalcoholic zein/curcumin solution was diluted with the aqueous βCD solution (volume ratio 1 :1) causing the formation of submicron-sized particles in suspension.

The mixing is carried out at room temperature, under continuous and moderate stirring for less than 5 hours.

The obtained pseudolatex was dried by spray drying to obtain a micro-powder containing curcumin. Example 3

Zein/βCD film 1 mL of a hydroalcoholic solution (ethyl alcohol/water in a ratio of 8:2 v/v) containing 100 mg of zein and 4.2 mg of βCD was prepared, with 60 mg of polyethylene glycol 400 added.

The mixture containing zein, βCD and the plasticiser was poured on 7-cm diameter Teflon capsules. The drying was carried out at room temperature. 0.1 -mm thick films are obtained.