FILM COATING OF PHARMACEUTICAL. FOOD AND

CONFECTIONERY PRODUCTS

TECHNICAL FIELD This invention is in the field of aqueous film coating of pharmaceutical, food and confectionery pro¬ ducts, and is more specifically concerned with providing such coatings based on polydextrose.

BACKGROUND OF THE INVENTION Cellulose polymers such as hydroxypropyl methyl- cellulose have long been recognized in the art as being suitable for the aqueous film coating of pharmaceutical tablets and the like.

While it is normally possible to produce excellent film coatings with such cellulosic materials, diffi¬ culties can sometimes arise with respect to the ability of the resultant film coatings to adhere satisfactorily to the surface to which they are applied. This is especially true when considering tablet substrates such as waxy matrix sustained release products and multi- vitamin products (with which the phenomenon of "bridging" of the coating across debossed legends can be a sub¬ stantial problem).

It is also desirable to be able to produce film coatings for food and confectionery products which are able to replace the currently used sugar coatings, in order to meet the requirements for low calorie, non- cariogenic (that is, not harmful to teeth) coatings for such products.

While cellulosic polymers can meet these require¬ ments, they tend to produce coatings that have undesirable taste and -mouth-feel (that is, they are somewhat bitter and slimy in texture; both undesirable features especially for confectionery products) .

SUMMARY OF THE INVENTION Aqueous film coatings based on the polymer poly¬ dextrose provide the solution to both the pharmaceutical, and the food and confectionery problems described. Used alone, or in combination with otlier polymers, polydextrose produces pharmaceutical film coatings that exhibit ex¬ cellent adhesive qualities, while when used in food and confectionery applications, it can produce coatings with good organoleptic properties that are low calorie and non-cariogenic in nature.

One characteristic of polydextrose, however, is that it has an extremely low average molecular weight value (for example, peak molecular weight, Mp, is approximately 1230) . It is well known that low molecular weight polymers produce extremely weak films. ^' Rowe ("Molecular Weight Studies on Kydroxypropyl Methyl- cellulose Phthalate" Acta-Pharm. Technologica 28 (2) , p.129 1982) has stated that for the purposes of film coating, there exists a CRITICAL MOLECULAR WEIGHT value for polymers such as hydroxypropyl methylcellulose

(H.P.M.C.), below which there is a great risk of the coating cracking. For H.P.M.C., he stated that the Mp value, which is indicative of the molecular weight of the main component, is approximately 8.0 x 10^. There is significantly greater than the Mp value for polydextrose, which would thus not be expected to produce satisfactory film coatings.

Additionally, Osterwald ("Properties of Film- Formers and Their Use in Aqueous Systems", Phar . Res., 1985, p.15) has stated that for film coating, polymers producing solutions (containing 2% w/w of the polymer in water) having viscosities in the range of 3-15 Pas (miHi Pascal seconds) (same as centipoise numerically)

ought to be used, and that below this range, the polymer chains shorten to such an extent that the stability of the film is affected (i.e. film strength decreases too much) . Two percent aqueous solutions of polydextrose have a viscosity of less .than 2 mPas (in fact the value is too low to be differentiated from that of plain water) ,

Consequently, to those skilled in the art, poly¬ dextrose would be considered to produce film coatings that are entirely unsuitable for modern film coating processes; yet we have found it can produce excellent film coatings that in some cases have superior properities to thoseobtained from more traditional polymers.

Finally, polydextrose can be formulated into a dry-edible film coating composition, shipped to the user and mixed easily into water to form an aqueous coating suspension.

The aqueous coating suspension comprises an effective amount of polydextrose, plasticizer, detackifier and a secondary film former, mixed into water to form an aqueous coating suspension which may be applied to the forms to be coated, as by spraying. Optionally, a colorant may be added to the aqueous coating suspension before the coating step. Also, a cellulosic polymer, such as hydroxypropyl methylcellulose, may be substituted for the secondary film former, and the resulting formula is particularly adapted for coating waxy matrix tablets, which are particularly difficult to coat.

The film former of the coating is polydextrose, or a mixture of polydextrose and a cellulosic polymer film former. Also, it may be advantageous to coat with a layer of polydextrose aqueous coating suspension, and then overcoat with a layer of cellulosic film polymer coating suspension.

The cellulosic film polymer may be hydroxypropyl methylcellulose or hydroxypropyl cellulose.

The plasticizer may be polyethylene glycol, triacetin, propylene glycol, or acetyltriethyl citrate. The colorants may be FD&C lakes, D&C lakes, titanium dioxide, or dyes approved for ingestion by the U.S. Federal Drug Administration. Examples of such pig¬ ments are listed in Colorcon U.S. Patent 4,543,370 issued September 24, 1985, and incorporated herein by reference.

The detackifier may be lecithin or mineral oil. The secondary film former may be sodium alginate or propylene glycol alginate.

The polydextrose coating is especially effective in coating tablets and the like having debossed or in¬ taglio logos, trademarks, designs or words thereon since it adheres to the tablet surfaces without bridging and obscuring the debossed or intaglio printing.

DETAILED DESCRIPTION We now turn to the examples of the invention, all of which disclose formulations which may be mixed into water to form an aqueous coating suspension that may be effective to coat pharmaceuticals, food, and confectioneries. This invention is concerned with coating pharma¬ ceutical, confectionery and food forms including medici¬ nal tablets, vitamin tablets, aspirin tablets, capsules, chewing gum balls, chocolates, pieces of candy, almonds, breakfast cereal, and the like. EXAMPLES

The following examples illustrate the invention. All units and percentages used herein are by weight. Example 1

A clear coating suspension is made for coating chocolates by mixing the following ingredients into

water to form an aqueous coating solution.

% Grams

Polydextrose 81.42 2050 Soda Ash 0.72 18.2 Kelgin LV 4.96 125

Alcolec F-100 2.98 75 Triacetin 4.96 125

PEG 8000 4.96 125

Polydextrose is made by Pfizer, Inc., Kelgin LV is sodium alginate made by the-Kelco division of Merck and is used as a secondary film former, Alcolec F-100 is water miscible lecithin made by the American Lecithin Co. and is used as a detackifier in the formula, triacetin is triethyl citrate by Pfizer and is used as a plasticizer and PEG 8000 is polyethylene glycol 8000 and is used in the formula as a plasticizer.

The mixing procedure is to mix 300 grams of the dry ingredie into about 1700 milliliters of water to make an aqueous coating. The chocolates to be coated are placed in a 24 inch Accela Cota coating pan with 4 anti-skid bars, and the aqueous coating suspension is sprayed onto the choco¬ lates. During the coating procedure, the inlet air is 45°C, the outlet air is 30°C, the atomizing air is 3 bar, the pan speed is 12 rpm, the feed rate is 18 grams/minute, and the coating time is 90 minutes. The procedure pro¬ duced a very nice coating on the chocolates with no tack, and with no slimy taste. Example 2 in order to coat vitamin tablets, a formula having the following ingredients is dry mixed together and then mixed into water to form an aqueous coating suspension which is sprayed onto the vitamin tablets:

Ά Grams

Polydextrose 68.38 492.3

Kelgin LV 4.18 30.1

Alcolec F- 100 2.51 18.1

Triacetin 2.09 15.0

PEG 8000 6.27 45.1

R-40 lake 12.50 90.0

Ti0 ₂ 4.00 28.8 720.0

H ₂ 0 4080.0

4800.0

The R-40 lake is FD&C Red number 40 aluminum lake made by Colorcon, Inc., West Point, Pennsylvania.

The mixing procedure is to blend all dry ingredi¬ ents into a blender for about 5 minutes, and add tri¬ acetin and blend for an additional 5 minutes. Then the formula is mixed into 4080 milliliters of distilled water to form an aqueous coating solution.

A 24 inch Accela Cota coating pan is loaded with 11 kilograms of vitamin tablets which have a debossed or intaglio logo on them. The spray coating parameters are inlet air 85°C, outlet air 50°C, atomizing air 3 bar, pan speed 12 rpm, feed rate 60 grams/minute, and coating time 80.minutes. The vitamin tablets receive a very nice coating with a good logo with no bridging, and no tack. Example 3

It is desired to color gumballs and for this purpose the following formula is dry mixed together and is mixed into water to make an aqueous coating suspen¬ sion which is sprayed onto the gumballs.

% Grams

Polydextrose 70.0 210.0 PEG 400 2.5 7.5

Sodium Alginate MV 5.0 15.0

Ά Grams

Ti0 ₂ 10.0 30.0

Alcolec F-100 2.5 7.5

Y-5 HT lake 10.0 30.0 The Y-5 HT lake is FD&C Yellow number 5 aluminum lake made by Colorcon, Inc., West Point, Pennsylvania. The solids of this aqueous coating suspension amount to 300 grams and the water amounts to 1700 grams, so the suspension is about 15% solids. In spray coating the gumballs, the inlet air is 66°C, the outlet air is 35°C, the atomizing air is 3 bar, the feed rate is 30 grams/ minute, the pan speed is 18 rpm, and the coating time is 45 minutes. Example 4 Instead of coating the gumballs with a lake formula as in Example 3, it is desired to coat the gum¬ balls with a dye formula, and the following formula is mixed into water to form an aqueous coating suspension which is sprayed onto the gumballs. % Grams

Polydextrose 79.5 238.5

PEG 400 2.5 7.5

Sodium Alginate MV 5.0 15.0 τio ₂ 10.0 30.0

Alcolec F-100 2.5 7.5

Y-5 Dye 0.5 1.5

The Y-5 dye is FD&C Yellow number 5 dye approved by the U.S. Federal Drug Administration for ingestion, the solids content amounts 300 grams, and the water content of the aqueous coating suspension is 1700 grams, the sus¬ pension being about 15% solids. The air, feed rate, and pan speed parameters of the spraying are the same as in Example 3 except the coating time is 50 minutes.

Example 5

It is desired to coat almonds with a cherry color, and the following formula is mixed together and into an aqueous suspension and sprayed onto the almonds.

Ά Grams

Polydextrose 68.47 ^" 1711.75

Sodium Alginate (Kelgin LV) 4.18 104.50

Alcolec F-100 2.51 62.75

Triacetin 4.18 104.50

PEG 8000 4.18 104.50

R-40 HT lake 13.39 334.75

Y-6 HT lake 3.11 77.75

The sodium alginate is a secondary film former that gives the resulting coating a glossy appearance. The R-40 HT lake is FD&C Red number 40 aluminum lake, and the Y-6 HT lake is FD&C Yellow number 6 aluminum lake, both made and sold by Colorcon, Inc., West Point, Pennsylvania. The formula, 240 grams, is mixed into 960 imUliliters of water, and the resulting aqueous coating suspension is spray coated onto the almonds in a coating pan. The almonds may have previously been given a subcoat of the clear polydextrose formula of Example 1, by spraying the Example 1 aqueous coating suspension onto the almonds with inlet air 73°C, outlet air 48°C, atomizing air

45 psi, pan speed 12 rpm, feed rate 34 grams/minute, and coating time 35 minutes.

To apply the cherry color to the almonds, the almonds are placed in a coating pan and the cherry color aqueous coating suspension is sprayed onto the almonds as they are being rotated in the pan, with the inlet air being 73°C, the outlet air being 48°C, the atomizing air being 45 psi. the pan speed being 12 rpm, and the feed rate being 40 grams/minute, and the coating time being 30 minutes.

Example 6

It is desired to coat KIX breakfast cereal with polydextrose, and the following formula is mixed into an aqueous suspension which is sprayed onto the KIX cereal puffs in a fluidized bed coater, such as made by Aeromatic.

1 Grams

Polydextrose 71.00 16.05

PEG 400 2.26 0.51

Kelgin LV 4.52 1.02

Alcolec F-100 2.26 0.51

Ti0 ₂ 10.00 2.26

Y-5 HT lake 10.00 2.26 22.60

H ₂ 0 277 _* 5

The procedure is to partly fill the bed coater cone with KIX cereal puffs, and turn on the coater to support the puffs in the air, and spray the puffs with the aqueous suspension. The inlet temperature is 80°C, the outlet temperature is 38°C, the feed rate is 10 grams/minute, and the air is 1 bar. Example 7

Polydextrose may be combined with a cellulosic polymer, such as Methocel E5, to obtain the superior adhesiveness of the polydextrose and the superior moisture barrier of the cellulosic polymer in coating vitamin tablets. An example of a formula is as follows ^,

" 1 Grams

Polydextrose 34.24 246.5

Methocel E5 34.24 246.5

Kelgin LV 4.18 30.1

Alcolec F-100 2.51 18.1

Triacetin 2.09 15.0

PEG 8000 6.27 45.1

Y-5 HT lake 12.50 90.0

Ti0 4.00 28.8

The Y-5 HT lake is FD&C Yellow number 5 lake made by Colorcon, Inc., West Point, Pennsylvania. The formula contains 720 grams of solids and is mixed into 4080 milliliters of water to give a total weight of the aqueous coating suspension of 4800 grams. Methocel E-5 is hydroxypropyl methyl cellulose made by Dow Chemical Co. The aqueous coating suspension is sprayed onto tablets in a coating pan with inlet air at 85°C, outlet air at 50°C, atomizing air 3 bar, pan speed 12 rpm, feed rate 53 grams/minute, and coating time 90 minutes. Example 8

Another example of a formula particularly adapted for applying a coating to vitamin tablets with intaglio logos without bridges comprises a 75% to 25% ratio of polydextrose to Methocel E-5, instead of the 50% to 50% ratio shown in Example 7, and is listed below.

1 Grams

Polydextrose 51.36 369.8

Methocel E-5 . 17.12 123.3

Kelgin LV 4.18 30.1

Alcolec F-100 2.51 18.1

Triacetin 2.09 15.0

PEG 8000 6.27 45.1

Y-6 HT lake 12.50 90.0

Ti0 _£ 4.00 28.8

Example 9

Another example of a formula containing a mixture of polydextrose and a cellulosic polymer for coating vitamin tablets is: to Grams

Polydextrose 51.36 369.8

Klucel EF 17.12 123.3

Kelgin LV 4.18 30.1

Alcolec F-100 2.51 18.1

Triacetin 2.09 15.0

1 Grams

PEG 8000 6.27 45.1

Y-6 HT lake 12.50 90.0

Ti0 ₉ 4.00 28.8 Klucel EF is hydroxypropyl cellulose by Hercules, Inc. Example 10

Another example of a formula containing both polydextrose and a cellulosic polymer is as follows.

Grams

Polydextrose 61.60 443.50

Klucel EF 6.80 48.96

Kelgin LV 4.18 30.10

Alcolec F-100 2.51 18.10

Triacetin 2.09 15.00

PEG 8000 6.26 45.10

R-40 HT lake 6.25 45.00

Y-6 HT lake 6.25 45.00

Ti0 ₂ 4.06 29.23

Example 11

Another formula containing a mixture of polydex¬ trose and hydroxypropyl methyl cellulose is as follows.

Ά Grams

Polydextrose 36.86 921.5

Methocel E-5 36.86 921.5

Kelgin LV 4.50 112.5

Alcolec F-100 2.70 67.5

Triacetin 2.25 56.3

PEG 8000 6.75 168.8

Ti0 ₂ 9.32 233.0

B-l lake 0.76 19.0

The B-l lake is FD&C Blue number 1 aluminum lake. This formula is especially advantageous if it is desired to coat waxy matrix tablets, such as Dimetaps by A. H. Robbins, which are very hard to coat because it is

difficult to get anything to adhere to their waxy sur¬ face.

The formula ingredients are mixed into sufficient water to make a 15% solids suspension, and the suspen- sion is sprayed onto waxy matrix tablets at 45°C inlet air, 30°C outlet air, 3 bar atomizing air, 44 grams/ minute feed rate, and 12 rpm pan speed. Example 12

The outer surface of gumballs may be very rough with a large number of holes, and it may be desirable to apply a subcoat and fill in the holes before applying the thin coating of polydextrose as in Example 1, for example. A suitable subcoat may be made from the follow¬ ing formula into an aqueous coating suspension and sprayed onto the gumballs.

% Grams Polydextrose 52.2 208.8 PEG 400 1.8 7.2

Sodium Alginate 7.0 28.0 Titanium Dioxide 7.0 28.0

Alcolec F-100 2.1 8.4

Avicel 105 30.0 120.0

_^ πricrpcrystalline cellulose , , , _ΛΛ PEG 40CT is polyethylene glycol 400.

Example 13 Another formula for coating chocolates, an orange color, is as follows.

/o Grams

Polydextrose 68.81 206.4

Kelgin LV 4.18 12.5

Alcolec F-100 2.15 6.5

Triacetin 4.18 12.5

PEG 8000 4.18 12.5

Red 40 lake 13.39 40.2

Y-6 lake 3.11 9.3

Example 14

Vitamin tablets are spray coated in a coating pan with an aqueous coating suspension of Example 1 with the inlet air 85°C, outlet air 50°C, atomizing air 3 bar, pan speed 12 rpm, feed rate 60 grams/minute, and coating time 80 minutes.

Then the polydextrose coated vitamin tablets are spray coated with an OPADRY coating suspension made in accordance with the disclosure in Colorcon, Inc. U.S. Patent 4,543,370 which issued September 24, 1985, which is incorporated herein by reference.

ADVANTAGES The polydextrose coatings of the invention have the advantage of adhering to surfaces that are difficult to coat, such as the waxy matrix surfaces of some pharma¬ ceutical tablets, such as Dimetaps. The coatings also have the further advantage of adhering to the debossed or intaglio surfaces of logos or words on tablets with¬ out obscuring those logos or words. This is very impor¬ tant when a manufacturer debosses his trademark, which may be a design or words, on his product. Previously, coatings made of cellulosic polymer film formers would bridge the grooves formed by the debossed word or design on the tablet, and would obscure it so that it could not be read.

In addition to coating waxy matrix tablets, the polydextrose coating of the invention is particularly adapted to coat sugarless chewing gum pieces which are very difficult to coat in an aqueous system. The coating suspension of Example 3 is particularly effective in coating sorbitol gum pieces.