Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-02-10
2002-07-16
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C424S078310, C424S078310
Reexamination Certificate
active
06420473
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of aqueous enteric film coating of pharmaceutical tablets and the like for preventing release of the ingredients of the coated tablet in the gastric juices of the stomach and for releasing the ingredients of the tablet in the intestines, and more particularly concerns providing a fully-formulated, non-toxic, edible, enteric, film-coating, dry powder composition based on an acrylic resin for use in making an aqueous enteric coating suspension that may be used in coating pharmaceuticals with an intestinally soluble coating that is insoluble in gastric juices of the stomach.
2. Description of the Prior Art
Several aqueous enteric film-coating systems are known. These include the AQUATERIC system, based on cellulose acetate phthalate, the SURETERIC system, based on polyvinylacetate phthalate (PVAP), and the EUDRAGIT L system, based on copolymers of acrylic acid esters and methacrylic acid. Both the AQUATERIC and EUDRAGIT L systems require at least three processing steps to form the enteric coating suspension. With the AQUATERIC system, the AQUATERIC powder is dispersed in water followed by stepwise addition of plasticizer Tween 80 and optional pigments to form the AQUATERIC suspension. The EUDRAGIT L system is available as a powder (L100-55) or as an aqueous dispersion (L30-D). The “EUDRAGIT L Technical Application Pamphlet (Info LD-13/e)” published by Rohm Pharma GmbH specifies a step-wise procedure to prepare an aqueous enteric dispersion which includes: 1) addition of the EUDRAGIT L100-55 powder to water; 2) dropwise addition of a pre-calculated amount of aqueous sodium hydroxide solution; 3) stirring of the dispersion for 30 minutes using a simple stirrer running at a medium and controllable speed; 4) filtration of the suspension; 5) subsequent addition of an aqueous solution of plasticizer (at a recommended use level of 10% by weight with respect to the EUDRAGIT L100-55 powder), “separating agent”, and anti-foam to the filtered suspension; 6) further stirring; and 7) final filtration. Special precautions noted in this pamphlet include the warning that coagulation of the EUDRAGIT L aqueous dispersion may occur as a result of the presence of electrolytes, foam formation, exposure to heat and frost, the presence of finely divided pigments and exposure to high shear gradients when using fast-running stirrers and mills. Special attention is also drawn to the requirement to observe the specified formulation ratios, as a deviation could result in the formation of coagulum, which as set out in the pamphlet is “impossible” to redisperse rendering the entire aqueous dispersion “unusable.”
The EUDRAGIT L30-D suspension is a dispersion of ethyl acrylate/methacrylic acid copolymer, 30% by weight in water. The “EUDRAGIT L Technical Application Pamphlet (Info LD-11 /e)” published by Rohm Pharma GmbH specifies a multi-step process for forming a complete aqueous dispersion system based on EUDRAGIT L30-D suspension that includes: 1) addition of plasticizer; 2) addition of a “separating agent”; 3) addition of an anti-foam; 4) optional addition of pigments; 5)stirring; and 6) final filtration. Special precautions, identical to those described for EUDRAGIT L100-55 powder, are also indicated in the EUDRAGIT L30-D suspension pamphlet.
The SURETERIC composition, which is described in Colorcon U.S. Pat. No. 5,733,575, which is incorporated herein by reference, advanced the art in the field by teaching the complete formulation of an enteric film coating pre-mix, which may be dispersed readily in water along with an anti-foam in two steps. The SURETERIC system requires the addition of a viscosity modifier to prevent settling of the suspended solids in the resulting aqueous dispersion during coating.
Lehmann et al. U.S. Pat. No. 4,520,172, which is incorporated herein by reference, discloses a binary mixture of EUDRAGIT L copolymer and a suitable alkalizing agent or “salt-forming agent.” However, there are no known enteric film-coating systems based on the copolymer of ethyl acrylate and methyacrylic acid of the EUDRAGIT L system that are analogous to the SURETERIC system. Further, given the precautions cited in the Rohm Pharma literature and the chemical differences between PVAP and the methacrylic acid/ethyl acrylate copolymers, it would be surprising and unexpected if the Lehmann et al. binary system could be expanded into a fully-formulated solid composition which could then be dispersed readily in water for use in providing an enteric film coating.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a fully-formulated, enteric film coating composition based on EUDRAGIT L copolymers that may be readily dispersed in water and applied to pharmaceutical tablets and the like.
Another object of this invention is to provide a fully formulated, enteric film coating composition based on EUDRAGIT L copolymers which does not cake upon preparation.
Another object of this invention is to provide a fully formulated, enteric film coating composition based on EUDRAGIT L copolymers which does not form agglomerates upon storage at elevated temperature and humidity.
Another object of this invention is to provide a fully-formulated, enteric film coating composition based on EUDRAGIT L copolymers which may be dispersed readily into water to form a coating dispersion that when applied to pharmaceutical tablets produces a tack-free coating.
Another object of this invention is to provide a fully formulated, enteric film coating composition, containing lake pigment and neutralizing agent, said lake pigment being stable upon dispersion in water.
Another object of this invention is to provide a fully-formulated, enteric film coating composition based on EUDRAGIT L copolymers which may be dispersed readily into water to form a coating dispersion that when applied to pharmaceutical tablets produces a film coating having an exceptional degree of film strength. This exceptional film strength is manifested by excellent performance in a “stressed disintegration test.”
Another object of this invention is to provide a fully formulated, enteric film coating composition based on EUDRAGIT L copolymers that disperses in water without the formation of coagulum.
Another object of this invention is to reduce the number of steps in the preparation of aqueous film coating dispersions based on EUDRAGIT L copolymers from six (6) or more to two (2), thereby achieving the beneficial result of reducing the overall preparation time for preparing aqueous film coating dispersions from about 90 minutes to about 20 minutes.
These and other objects of the invention are accomplished by our invention, which is described below.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the invention, our non-toxic, edible, enteric film coating, dry powder composition for use in making an aqueous enteric suspension which may be used in coating pharmaceutical tablets comprises an acrylic resin (e.g., EUDRAGIT L copolymers), an alkalizing agent, and a detackifier. Optionally but advantageously, our dry powder composition may also include one or more of the following additives: a plasticizer; a pigment; a flow aid; a surfactant; an anti-agglomerating agent; a secondary film former; and a secondary detackifier. In a particularly preferred embodiment of this invention, the inventive dry powder composition contains an acrylic resin, an alkalizing agent, a detackifier, a plasticizer, a pigment, a flow aid, a surfactant, an anti-agglomerating agent, a secondary film-former and a secondary detackifier.
A method of making the inventive dry powder composition comprises the steps of mixing an acrylic resin with an alkalizing agent, detackifier, and optionally with one or more of the following additives: a plasticizer; a pigment; a flow aid; a surfactant; an anti-agglomerating agent; a secondary film former; and a secondary detackifier. The resulting enteric film coating dry powder composition and a separately-added anti-foam is readily dispersed in water, prefera
Chittamuru Ramireddy
Farrell Thomas P.
Lehmann Klaus
Mehra Dev K.
Petereit Hans-Ulrich
BPSI Holdings, Inc.
Michl Paul R.
Roberts & Mercanti LLP
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