FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION [See section 10]
EMPTY CAPSULE SHELLS WITH IMPROVED SURFACE QUALITY AND METHOD OF PRODUCING THE SAME;
SCITECH CENTRE, A COMPANY INCORPORATED UNDER SECTION 25 OF THE COMPANIES ACT, 1956, WHOSE ADDRESS IS 7, PRABHAT NAGAR, JOGESHWARI (WEST), MUMBAI - 400 102, MAHARASHTRA, INDIA.


THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.


TITLE
Empty capsule shells with improved surface quality and method of producing the
same
FIELD OF INVENTION:
The present invention relates to the field of capsules which are used as soluble
containers to carry materials such as pharmaceuticals, nutraceuticals,
cosmeceuticals and agrochemicals.
BACKGROUND ART:
Capsules are elegant, easy to use, portable and tasteless shells for drugs. They are produced in a wide range of colours and they generally provide ready availability of the contained drug, since minimal excipient and little pressure are required to compact the material as is necessary in tabletting.
Conventionally, tablets are preferred choice for coating compared to capsules. Coating on a solid dosage form is carried out to mask the taste, odour or colour of the drug. Coating is also done to provide physical and chemical protection for the drug, or to control the release of the drug from the tablet, or to protect the drug from the gastric environment of the stomach with an acid resistant enteric coating or to incorporate another drug or formula adjuvant in the coating to avoid chemical incompatibilities or to provide sequential drug release.
To achieve a good coating , good adhesion between a polymer and the surface of a solid is a major prerequisite for the film coating of pharmaceutical dosage forms. Loss of adhesion may lead to an accumulation of moisture at the film tablet interface, significantly affecting the stability of hygroscopic drugs. Loss of adhesion may also compromise the mechanical protection that the film coating provides to the solid substrate.

Many difficulties have been reported in the film coating of hard gelatin capsule and have been attributed to the physical properties of the gelatin and the dosage form .(Ref:K. Thoma, K. Bechtold, Enteric coated hard gelatin capsules, Cap-sugel Technical Bulletin, 1986 ). In addition to the capsule shell softening and becoming sticky during the coating process due to solubilization of the gelatin, poor adhesion of the polymer to the walls of the hard gelatin capsule may occur, insufficient adhesion may resuit in splintering of the film coating.
The capsule shell is relatively smooth and generally provides less surface area for interfacial contact between the polymer and the surface of the gelatin than tablet compacts .(Ref: 1.K. Thoma, R. Oschmann, Investigations of the permeability of enteric coatings, Part 5: Pharmaceutical-technological and analytical studies of enteric-coated preparations, Pharmazie 46 (1991) 278-282. 2. H.P. Osterwald, Experience with coating of gelatin capsules with Driacoater and WSG apparatus, especially rotor WSG, Acta Pharm. Technol. 28 (1982) 329-337.
The addition of polyethylene glycol 400 (PEG 400) and polyethylene glycol6000 (PEG 6000) to the coating formulation has been used to improve adhesion of polymeric films to the gelatin shell.(Ref: K. Thoma, K. Bechtold, Enteric coated hard gelatin capsules, Cap-sugel Technical Bulletin, 1986.). An aqueous-alcoholic solution has also been shown to enhance polymer adhesion to the capsule shell. In 1996, Felton et al. conducted diametrical compression experiments on film-coated soft gelatin capsules and found that adhesion of the aqueous-based acrylic polymer was dependent on the fill liquid of the capsule in conjunction with the plasticizer used in the coating formulation.

SUMMARY OF THE INVENTION
The present invention provides an empty capsule shell with improved surface quality comprising gelatin, dicalcium phosphate and triethyl citrate characterized in that the external surface of the capsule shell has a rough or matt finish. The rough or the matt finish of the empty capsule shell enhances the adhesion of the polymeric film to the surface of the capsule. The empty capsule shell is a hard gelatin capsule wherein gelatin is in the range of 10 to 40% w/w, dicalcium phosphate is in the range of 0.1 to 10% w/w, and triethyl citrate is in the range of 0.05 to 5% v/w.
Further, the present invention provides a method for producing the empty capsule shell
with improved surface quality comprising the steps of:
Preparing a gelatin solution;
Heating (Deaerating) the gelatin solution on a water bath at a predetermined
temperature;
Preparing a slurry of Dicalcium phosphate;
Mixing gelatin solution and slurry of dicalcium phosphate;
Adding a plasticizer to the above mixture;
Deaerating the mixture to remove air bubbles;
Dipping and molding the capsule.

DETAILED DESCRIPTION OF THE INVENTION:
The present invention provides an empty capsule shell with improved surface quality wherein the external surface of the hard gelatin capsule has been modified and given a "rough" or "Matt" finish. The rough surface provides greater interfacial contact between the polymer film and the surface of the capsule, thus resulting in stronger polymer adhesion.
The process for preparing rough surface capsule is given below with the help of non-limiting examples. Example 1
Gelatin solution (33% w/w) 100 g.
Dicalcium Phosphate 5 g.
Water 25 ml
Gelatin solution 33% w/w is prepared according to a conventional process. The prepared gelatin solution is kept on water bath at 52 deg.C. Dicalcium phosphate is added to 25 ml water and stirred well to make a slurry. This slurry is added to gelatin solution and stirred well till it is mixed homogeneously. The solution is deaerate to remove the air bubbles. This solution taken to dip bath for molding capsules by dip molding method.
Example 2
Gelatin solution (33% w/w) 100 g.
Dicalcium Phosphate 1 g.
Water 25 ml
Gelatin solution 33% w/w is prepared according to a conventional process. The
prepared gelatin solution is kept on water bath at 52 deg.C. Dicalcium phosphate
is added to 25 ml water and stirred well to make a slurry. This slurry is added to

gelatin solution and stirred well till it is mixed homogeneously. The solution is deaerate to remove the air bubbles. This solution taken to dip bath for molding capsules by dip molding method.
Example 3
Gelatin solution (33% w/w)100 g.
Dicalcium Phosphate(#60) 1 g.
Water 25 ml
Triethyl citrate 0.5 ml
Gelatin solution 33% w/w is prepared according to a conventional process. The
prepared gelatin solution is kept on water bath at 52 deg.C. Dicalcium phosphate
is added to 25 ml water and stirred well to make a slurry. This slurry is added to
gelatin solution and stirred well till it is mixed homogeneously. Triethyl citrate is
added to the solution and the solution is deaerated to remove the air bubbles.
This solution is taken to dip bath for molding capsules by dip molding method.
Example 4
Gelatin solution (33% w/w) 100 g.
Dicalcium Phosphate(#80) 1 g.
Water 25 ml
Triethyl citrate 0.5 ml
Gelatin solution 33% w/w is prepared according to a conventional process. The
prepared gelatin solution is kept on water bath at 52 deg. C. Dicalcium
>
phosphate is added to 25 ml water and stirred well to make a slurry. This slurry is added to gelatin solution and stirred well till it is mixed homogeneously. Triethyl citrate is added to the solution and the solution is deaerated to remove the air

WE CLAIM:
1. An empty capsule shell comprising gelatin in the range of 10 to 40% w/w,
dicalcium phosphate in the range of 0.1 to 10%w/w, and triethyl citrate in the
range of 0.05 to 5%v/w,
wherein, an external surface of the capsule shell has a rough or matt finish thereby enhancing the adherence of the polymer to the capsule shell.
2. An empty capsule shell as claimed in claim 1, wherein the capsule is a hard gelatin capsule.
3. A method for preparing empty capsule shell comprising the steps of: preparing a gelatin solution;
deaerating the gelatin solution on a water bath at a predetermined temperature;
preparing a slurry of dicalcium phosphate;
mixing gelatin solution and slurry of dicalcium phosphate;
adding a plasticizer to the above mixture;
deaerating the mixture to remove air bubbles;
dipping and molding the capsule;
wherein the dicalcium phosphate is in range of 0.1 to 10% w/w of gelatin solution.
4. A method as claimed in claim 3, wherein the gelatin solution is deaerated by heating at a temperature of 52°C.
5. A method as claimed in claim 3 or 4, wherein the gelatin solution is in the range of 10 to 40% w/w.
6. A method as claimed in claim 3 or 5, wherein the gelatin solution is in the range of 15 to 35% w/w.
7. A method as claimed in any one of the preceding claims 3 to 6, wherein the slurry of dicalcium phosphate is prepared with water.