FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
" ORAL COMPOSITION OF CALCIUM "
2. APPLICANT NAME :
VAVIA PRADEEP RATILAL
(Last Name/Surname) (First Name) (Father's Name/Middle Name)
NATIONALITY: INDIAN
ADDRESS : DEPARTMENT OF PHARMACEUTICAL SCIENCES
AND TECHNOLOGY
INSTITUTE OF CHEMICAL TECHNOLOGY (DEEMED UNIVERSITY), NATHALAL PARIKH MARG, MATUNGA (EAST) MUMBAI 400 019 INDIA
3. The following specification particularly describes the invention and the manner in which it is to be performed.

4. DESCRIPTION
FIELD OF THE INVENTION
The present invention discloses the calcium composition for oral delivery. The said oral calcium composition comprises calcium or its salt from oyster shells (up to 95% w/w) but not limited to and may be prepared with calcium or its salt form other natural or semi-synthetic origin. Calcium or its salt in the said composition has mean particle size below 1000 nm. The said composition also comprises at least one stabilizer (0.5 to 20% w/w) from natural or semi-synthetic or synthetic origin. The said composition also comprises at least one carrier solvent as dispersing or wetting media in 5 to 85% w/w of total composition. The invention also discloses method for preparing the same.
BACKGROUND OF THE INVENTION
The benefits of calcium supplements to bone strength and health are thought to derive from both the increased availability of serum calcium for bone deposition. The uptake of various calcium supplements, including calcium carbonate, calcium citrate, calcium phosphate, calcium gluconate, calcium lactate, tricalcium phosphate, calcium gluconolactate, calcium citrate malate, and tricalcium phosphate/ calcium lactate were investigated before (Shires and Kessler 1990; Reginster et. al, 1993).
Among them, calcium carbonate prepared from oyster shell is the most common one on the market (Gregory 2000). Oyster shell powder contains over 25 organic salts and 10 amino acids, providing a rich source of organic calcium, selenium, zinc, and other trace metal elements which improve the immune system. Worldwide marketed formulations of oyster shell calcium are still suffering from incomplete absorption and poor bioavailability. The particle size of oyster shell calcium is an influential factor for calcium bioavailability in humans.
Recommendations for daily dietary calcium intake that range from 400 to 1200 mg per day depending on age and gender have been issued by governmental and nongovernmental organizations in many countries (Levenson and Bockman, 1994; Report, 2001). Because many modern diets do not provide the recommended levels of calcium, dietary calcium supplements have been recommended for prevention of osteoporosis as well as for other conditions including hypertension, hypercholesterolemia, and cancer (Porter, 2003).
US patent 4,509,987 concentrated dispersions of calcium carbonate ground to particle size such that at least 87% by weight of the particles are less than 2 micron and have tendency to gel on standing. The said calcium composition also comprises 5 to 75% by weight of copolymer as dispersing agent. The invention is primarily focused on the synthesis of copolymer for stabilization of calcium particles.

US patent 4,159,312 discloses method of producing calcium carbonate powder by bottom up approach. The invention uses pre-synthesized calcium from precipitation method of size range 100-300 nm as nuclei for further surface treatment to generate calcium carbonate powder having particle size below 300 nm. Considering the high process variability in chemical precipitation methods, the invention fails in industrial scalability and thereby loses potential to reach patients.
US patent 4,732,748 discloses finely divided, wet-ground, dispersant-free calcium carbonate filler or pigment compositions are disclosed in which the particles of calcium carbonate are distributed in particular amounts in a particular fashion-broadly stated: in fine particle size distribution. Such compositions are useful in aqueous slurry or dry form as opacifying fillers for paper. As per the embodiments in the invention at least about 98 weight percent of the particles present are less than about 8 µm in equivalent spherical diameter.
US patent 6,294,143 discloses process for the preparation of discrete precipitated calcium carbonate particles that result from preparing an aqueous calcium carbonate slurry containing carbohydrates, carbonating the aqueous calcium carbonate slurry while maintaining the selected starting carbonation temperature. The product of the present invention is discrete particles of calcium carbonate which are especially useful in paints, plastics, paper coating, paper filling, and because of the purity level of the calcium carbonate particle may be used in cosmetics, pharmaceuticals and food applications.
US patent 4,559,214 discloses a dry particulate calcium carbonate composition, having a particle size in the range of 0.01 urn to 50 µm and having pores within the range of 0.5 nm to 200 nm, which comprises calcium carbonate, and 0.1 to 10% by weight, based on the weight of calcium carbonate, of polymaleic acid or a water-soluble salt thereof, wherein the calcium carbonate is formed by precipitating in the presence of said polymaleic acid or a water-soluble salt thereof.
Korean patent application 10-2006-0091675 discloses method of preparing nano meter sized oyster shell calcium carbonate particles by dry grinding method in multiple steps. However the said composition of calcium suffers from impurities like Fe2O3, AI2O3, MgO, SiO2, Pb, As, Mg etc. The method disclosed requires long time and presence of toxic impurities which may be fatal to patients.
World patent application WO 2009/011520 A2 discloses nano particles containing calcium and method of preparing the same. The said composition in the invention comprises of calcium form variable resources with at least one polysaccharide compound as complexing agent. The said composition is prepared by nanoprecipitation of calcium form organic solvent in aqueous stabilizer solution.

It was clearly evident from the prior art that, majority of the inventions disclose preparation of calcium micro or nano particles by dissolving the calcium source in suitable organic solvent followed by precipitation in aqueous media. However natural sources of calcium comprise of many additional nutritional actives like amino acids and essential element in abundance which get lost during the nanoprecipitation process. The said process also suffers from poor industrial compliance which restricts their path to reach consumer. Dry grinding process is further critical in case of naturally hard and abrasive material like calcium carbonate as it leads to abrasion of instrument linings and become potential source of impurities.
Considering the significant limitations of prior art methodologies for nanonized formulation of calcium or its salts, the present invention discloses oral composition of calcium comprising stable nanoparticulate oyster shell calcium carbonate stabilized with at least one surface stabilizer for enhancement in permeation and thereby bioavailability of calcium. The calcium source in the composition disclosed in the present invention can be altered with obvious modifications in process and excipients.
OBJECTS OF THE INVENTION
An object of the present invention is, therefore, to develop stable nanoparticulate calcium composition with average particle size below 1000 nm for oral drug delivery.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: Particle size distribution of oyster shell calcium carbonate Figure 2: Media milling of oyster shell calcium carbonate Figure 3: X-Ray Diffraction (XRD) studies
SUMMARY OF THE INVENTION
The pharmaceutical composition according to the present inventions comprises oral calcium composition having average particle size equal to or below 1000 nm. The calcium or its salt in the said invention is from natural or semi-synthetic origin, more preferably oyster shell calcium carbonate
The said composition comprises at least one stabilizer from natural or semisynthetic or synthetic or combination thereof in 0.5 to 20% w/w concentration. The said composition of calcium or its salt as described in invention is prepared by wet milling of calcium or its salt in presence of at least one stabilizer and at least one carrier solvent as dispersing or wetting media with comparatively few processing stages as required for compositions mentioned in prior art. These and other advantages of the present invention will become apparent from the

subsequent detailed description of the preferred embodiments of the invention and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
The pharmaceutical composition according to the present inventions comprises,
1. Calcium or salts thereof
2. at (east one stabilizer
3. at least one carrier solvent as dispersing or wetting media
In accordance with this invention, calcium or salts thereof refers to calcium carbonate from natural or semi-synthetic origin, more preferably from natural origin or even more preferably oyster shell calcium carbonate or combination thereof.
In accordance with this invention, at least one stabilizer refers to ionic or nonionic or amphiphilc or hydrophilic compound or combination thereof and may be from natural and/or semi-synthetic and/or synthetic origin. Some of the representative category of compounds which can be used as stabilizers for the said composition are but not limited to celluloses or their derivatives, carbohydrates from natural and/or semi-synthetic and/or synthetic origin like xanthan gum, gellan gum, gum acacia, gaur gum, glycol derivatives, hydrophilic polymers or copolymers, surfactants like sodium lauryl sulphate, tocopheryl polyethylene glycol succenate, tween 80, poloxamers etc.
In accordance with this invention, at least one carrier solvent as dispersing or wetting media refers to solvent used for wet milling of said composition. Carrier solvent further refers to water or hydro-alcoholic mixture or glycol derivatives or fixed oils or medium chain triglycerides from natural or semi-synthetic or synthetic origin or their ester forms or rational combinations thereof. However water is most preferred wetting media used in pharmaceutical compositions.
In accordance with this invention, the concentration of calcium or salts in said composition is up to 95% w/w, more preferably 75% or even more preferably up to 55% w/w of total composition. Concentration of stabilizer to be used is from 0.5 to 20% w/w, more preferably 0.5 to 10% w/w or even more preferably 0.5 to 5% w/w of total composition. Concentration of carrier solvent as dispersing or wetting media to be used is from 5 to 85% w/w, more preferably 15 to 65% w/w or even more preferably 25 to 45% w/w of total composition.
In accordance with this invention, the steps involved in preparation of oral composition of calcium are;

1. Preparation of homogenous dispersion of said calcium or its salt in carrier solvent as dispersing or wetting media containing dissolved or dispersed stabilizer using conventional mixing techniques.
2. Stable nanoparticulate dispersion formation by nanonization of said dispersion in step 1 with suitable nano comminution /milling technique like media milling or planetary ball milling or microfluidization or high pressure homogenization or combination thereof.
3. Formulated nanoparticulate calcium composition is used as if or concentrated or dried with thin film drying and /or spray drying and /or freeze drying and /or vacuum drying or combinations thereof.
4. The nanoparticulate calcium composition can be further formulated as nanosuspension, tablets, capsules, granules, composites, pellets, powder, powder for reconstitution or other suitable dosage forms to be given by oral route or other suitable route.
In accordance with this invention, there is no specific limitation of temperature conditions to be used for the preparation of said composition. However, processing at room temperature (25°C±5 °C) is preferred to avoid evaporation of carrier solvent or degradation of stabilizer used. Elevated temperatures can be used depending upon the thermal behavior of carrier solvent or stabilizer used.
In accordance with the present invention, processing time required for effective nanonization of said calcium composition may vary depending upon the processing method used for nanonization. However wet media milling with zirconium or polystyrene beads is found to be more efficient method for rapid and homogeneous nanonization in comparison with nano comminution techniques like microfluidization or high pressure homogenization or combination thereof.
In accordance with the present invention, the average particle size of said calcium composition is <1000nm, preferably <800nm, even more preferably < 700nm.
Final dosage form of said nanoparticulate calcium composition may also include pharmaceutically acceptable excipients which are routinely incorporated into solid or liquid oral dosage forms.
Characterization of said nanoparticulate oral calcium composition for particle size distribution using laser diffraction analysis, crystalinity studies using X-ray Diffraction (XRD) analysis and in-vitro intestinal permeation studies through rat (Wistar) intestine by averted rat sac method are well depicted in subsequent example of this invention.

Examples:
Example 1:
Preparation of oral nanoparticulate calcium composition:
Hydroxy propyl methyl cellulose (HPMC 5cps, 5%w/w) is dissolved in deionised water (55%w/w) using laboratory stirrer at 300 rpm. Oyster shell calcium powder (40%w/w) is uniformly dispersed in above solution using laboratory stirrer at 600 rpm. The prepared dispersion is nanonized at room temperature using media mill for successive 7 cycles (media composition: zirconium beads of 0.5mm diameter). The resultant nanonized calcium composition is appropriately diluted and spray dried to get free flowing powder which is further filled in capsules.
Coarse oyster shell calcium carbonate powder was initially evaluated for particle size by laser diffractometry (Malvern Mastersizer 2000, Malvern Instruments, U.K.). Particle size of formulated calcium composition is evaluated by laser diffractometry (Malvern Mastersizer 2000, Malvern Instruments, U.K.). % crystalinity of formulated calcium composition was evaluated with X-ray diffractometry methods and compared with coarse oyster shell calcium carbonate powder. Samples of developed formulation were assayed for calcium content per unit dosage form (500mg) using atomic absorption spectrophotometer at 422 nm. In-vitro intestinal permeability studies through Wistar rat intestine were done using averted rat sac method.
Characterization of amorphous ternary nanocomposites:
Initial particle size of oyster shell calcium carbonate was observed to be 64 micron. Average particle size of nanoparticulate calcium composition was 890 ± 62nm (Fig 1). It was observed that 7 cycles of media milling were sufficient for particle size reduction below 1000nm (Fig.2). XRD studies of developed formulation reveled that % crystalinity of nanonized calcium was reduced as compared to initial value (Fig. 3). The percent content of calcium per unit dosage form was found to be 100.15%. In-vitro intestinal permeability studies through Wistar rat intestine were done using averted rat sac method confirmed that permeation of calcium is a particle size dependent phenomenon. Nanosized calcium composition exhibited maximum permeation through intestinal membrane in comparison to coarse calcium grades as shown in table 1.

Table 1.
Sample Particle Size(microns) Conc.(10m g/ml) Length of Intestine %RSD Abs. Replicates Cone, of Ca inppm
Blank 0 0 0 HIGH 0 0 0 0 0
sample 1 25.5 40ml 12 cm 4.% 0.0847 0.0894 0.0834 0.0813 2.886
sample 2 18.8 40ml 12 cm 4.62 0.0887 0.0898 0.0871 0.0894 3.024
sample 3 <1.0 40ml 12 cm 5.68 0.3934 0.3924 0.3942 0.3938 9.384

5. CLAIMS
We claim
1. Oral composition of calcium, wherein the calcium is in the form of
nanocrystals having average particle size below 1000nm; wherein the said
composition further comprises of;
a. Calcium or salts thereof
b. at least one stabilizer
c. at least one carrier solvent as dispersing or wetting media
2. A pharmaceutical composition according to claim 1 wherein the calcium or salts thereof refers to calcium or its salts from natural or semi-synthetic origin or combination thereof.
3. A pharmaceutical composition according to claim 1 wherein the concentration of calcium or salts in said composition is up to 95% w/w, more preferably 75% or even more preferably up to 55% w/w of total composition.
4. A pharmaceutical composition according to claim 1 wherein the concentration of stabilizer to be used is from 0.1 to 20% w/w, more preferably 0.5 to 10% w/w or even more preferably 0.5 to 5% w/w of total composition.
5. A pharmaceutical composition according to claim 1 wherein the concentration of carrier solvent as dispersing or wetting media to be used is from 5 to 85% w/w, more preferably 15 to,65% w/w or even more preferably 25 to 45% w/w of total composition.
6. A pharmaceutical composition according to claim 1 wherein the average particle size of calcium or its salt is below or equal to 1000 nm, more preferably below 800 nm or even more preferably below 700 nm.
7. A pharmaceutical composition according to claim 1 wherein at least one stabilizer refers to ionic or nonionic or amphiphilc or hydrophilic compound or combination thereof and may be from natural and/or semisynthetic and/or synthetic origin.
8. A pharmaceutical composition according to claim 1 wherein the carrier solvent used for wet milling refers to water or hydro-alcoholic mixture or glycol derivatives or fixed oils or medium chain triglycerides from natural or semi-synthetic or synthetic origin or their ester forms or rational combinations thereof.
9. A pharmaceutical composition according to claim I wherein the method of preparation of said pharmaceutical composition is but not limited to wet milling, even more specifically medial milling or planetary ball milling high pressure homogenization or microfluidization or combination thereof.

10. A pharmaceutical composition according to claim I is used as if or concentrated or dried with thin film drying and /or spray drying and /or freeze drying and /or vacuum drying or combinations thereof.
11. A pharmaceutical composition according to claim 1 - 8 wherein the said composition of calcium can be converted to oral solid or liquid or semisolid dosage forms or combination thereof.