Edible functional coatings and hybrid polymer-based coatings for pharmacy and food

Abstract

A composition contains silicic acid polycondensate modified with organic groups, as a coating for medicines and foodstuffs or as a component in such a coating. The organic groups are partially or wholly biodegradeable. A method for producing a product coated with the composition and a coated product are further described.

Claims

1. A method for preparation of a coated edible product selected from the group consisting of coated medicines and coated foods, which comprises the steps of: (i) applying a coating composition, which contains an organo-modified silicic acid polycondensate, to a drug or food substrate; and (ii) drying and/or curing the coating composition.

2. The method according to claim 1, which comprises prior to the step (i) or after the step (ii) an additional step (iii) in which the drug or food substrate is at least partially coated with a metal oxide layer.

3. The method according to claim 1, wherein the coating composition contains silicic acid polycondensate modified with organic groups.

4. The method according to claim 1, wherein the coating composition is present in a diluent and/or solvent.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 includes two diagrams showing determined values; and

(2) FIGS. 2 and 3 are diagrams showing the in vitro cytotoxicity of some PCL-T materials.

DESCRIPTION OF THE INVENTION

(3) The attached FIG. 1 shows the determined values. The “prior art ORMOCER®” herein means a lacquer made of a hybrid material according to the above-described comparative example. The coating referred to as “45% by weight of PCL-T content” is approximately equivalent to Example 3-PCL-T-1/3 above, except that a slightly larger proportion of GLYMO was replaced with PCL-T such that the content of PCL-T was increased from 41 to 45 wt.-%. The coating referred to as “15% by weight of PCL-T” corresponds approximately to Example 1 above -PCL-T-1/3, i. e. the reference lacquer, but with slightly less GLYMO replaced with PCL-T so that its content is only 15% by weight.

(4) A flawless look is necessary for use as a tablet or food coating. The optics of two developed coatings on a polyethylene terephthalate-based (PET) substrate were investigated. The developed biopolymer-containing layers had either 30% by weight of chitosan or 45% by weight of PCL-T on a PET substrate. In both produced PCL-T or chitosan-containing coatings, a transparent, smooth, homogeneous surface was obtained which showed no defects. Regardless of the chosen biopolymer content, the layers exhibited the same good optical quality with excellent adhesion to the substrate.

(5) Biodegradable Layers with Good Barrier Properties

(6) Tablet coatings, in particular, require extremely good barrier properties against odors, water vapor and oxygen, when oxygen or water-vapor-sensitive agents are involved. By matching the network density and polarity of the hybrid polymeric coating material, it is possible in combination with inorganic oxide layers, such as SiO.sub.x (1.5<x<1.8) to achieve very good barrier values [Amberg-Schwab, S.: Handbook of Sol-Gel Science and Technology, Vol. 3, Ed.: S. Sakka, Kluwer Academic Publishers, Norwell, Chap. 21 (2004), p. 455]. The applied hybrid polymer layer reduces micro- and nanoporosity.

(7) The combination with an inorganic oxide layer may constitute a functional coating. The material used according to the invention can be present in a layer composite with one or more other, preferably inorganic, layers. The layer composite is edible.

(8) Exemplary of the invention, the oxygen permeability and the water vapor permeability, each with and without hybrid polymer barrier coating, were examined. The investigation of the oxygen permeability was carried out according to DIN 53 380 (23° C., 50% rh, relative humidity), the investigation of the water vapor permeability was carried out according to DIN 53 122 (23° C., 85% rh, relative humidity). The substrate showed an oxygen permeability of 160 cm.sup.3/m.sup.2×d×bar, for the substrate coated with hybrid polymer an oxygen permeability of 10 cm.sup.3/m.sup.2×d×bar. For the water vapor permeability, the biodegradable model substrate had a value of 140 g/m.sup.2×d, and for the hybrid polymer-coated biodegradable model substrate a value of 30 g/m.sup.2×d.

(9) FIG. 1 shows the oxygen (OTR, at 50% RH and 23° C.) and water vapor transmission rate (WVTR, at 90% RH and 38° C.) of the developed chitosan and PCL-T containing coatings in a layer system of PET film and SiO.sub.x layer. The mark at 0.10 cm.sup.3/m.sup.2×d×bar at the oxygen permeability and the mark at 0.10 g/m.sup.2×d at the water vapor permeability represent the barrier requirement for food packaging.

(10) Cytotoxicity Studies

(11) FIGS. 2 and 3 show the in vitro cytotoxicity of some PCL-T materials.

(12) FIG. 2: In vitro cytotoxicity of glass slides coated with the lacquer usable according to the invention.

(13) Cells of the murine fibroblast cell line (L929) grew for 24 hon three glass plates coated with various organically modified silicic acid polycondensates. After the tetrazolium-containing reagent WST-1 was added, the optical density (OD.sub.450) of the cell culture was measured. 3 shows the result for the glass plate with reference varnish, 4 shows the result for the glass plate with 2-PCL-T-1/3, and 3 shows the result for the glass plate with 1-PCL-T-1/3.

(14) In the figure: a)=cells were grown on well bottoms (in the vessel, without glass substrate) b) *=cells were grown on the glass plates ***=cells were grown on well bottoms and treated toxically with 1% SDS (i. e. targeted killed to mimic a toxic substrate) (SDS=sodium dodecyl sulfate)

(15) Since the L929 viability is proportional to the value of the optical density of the cell culture, the cytotoxicity can be determined from OD.sub.450: A sample is considered non-cytotoxic if OD.sub.450 is ≥80% of the blank Nc2 value (the black line indicates this area).

(16) FIG. 3: In vitro cytotoxicity of glass slides coated with the lacquer which can be used according to the invention.

(17) Silicic acid polycondensate extracts were obtained by shaking the sterile with the silicic acid polycondensate coated glass plates for 24 h in a cell culture medium (DMEM—Dulbecco's Modified Eagle Medium) under physiological and aseptic conditions. Subsequently, the subconfluent cell cultures (L929) were incubated in undiluted extraction solutions for 24 h and prepared analogously to the previous film to determine OD.sub.450. “Ormocer” refers to the reference lacquer.

(18) In the figure: a)=cells were grown on well bottoms (in the jar, without glass substrate) **=cells were grown in the medium, which was incubated like the extracts for 24 hours b) *>=cells were grown on well bottoms and toxically treated with 1% SDS (i. e. targeted killed to mimic a toxic substrate) (SDS=sodium dodecyl sulfate)

(19) The figures show that the two coating materials which can be used according to the invention are not cytotoxic to mammalian cells since they reach the minimum value. Therefore, these compositions can be used as coatings for medicines and foods.

(20) Extract from contact with organically modified silicic acid polycondensate without biodegradable groups is weakly cytotoxic. Due to a biodegradable, harmless coating on the tablets, which have excellent barrier properties, it is possible to replace PVDC and aluminum with alternative packaging materials that do not have any outstanding barrier effect, but are deep-drawable. In addition, alternative, simpler packaging concepts are conceivable, for example, a waiver of the separation in blister packs.

(21) The properties of the highly functional coating materials can be adjusted, combined and customized in addition to the barrier effects. As explained above, the coatings are, for example, stable in an acidic environment, but can also be adjusted so that they dissolve already in the stomach. The composition of the coating can be chosen so that it behaves harmlessly in the body.

(22) Due to the excellent barrier properties of the newly developed coating, it will be possible to save on the packaging materials chlorine-containing films and aluminum foils in future. Alternative, cheaper packaging concepts are conceivable. The barrier coating also improves the shelf life of pharmaceutical products and food. In addition, the use according to the invention makes it possible to produce products which are edible coatings and have the following properties: No toxic, allergenic and non-digestible substances Prevent structural stability and mechanical damage during transport, handling and sales Good adhesion to the food surface and uniform coating Semipermeable: For some products a controlled gas or water migration into and out of the product to be protected is desirable. Examples are the fruit and vegetable transport, as the products are often subject to a maturing process during transport to the trade (aerobic and anaerobic respiration). Preventing the uptake or release of components which stabilize the flavor, the taste, nutrients and organoleptic properties; without changing the taste or the visual appearance Ensuring biochemical and microbial stability while protecting against contamination, pest infestation, microbial proliferation and other types of disintegration Maintaining or improving the aesthetic and sensory attributes (appearance, taste, etc.) of the food Use as a carrier for desired additives such as: taste, smell, color, nutrients and vitamins. Incorporation of antioxidants and antimicrobial agents. Simple and inexpensive production