MICROENCAPSULATION: ADVANCEMENTS IN TECHNOLOGY AND ITS PATENTS

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The technology to be applied will depend on the way the particles are considering before the encapsulation process. Two possibilities are there;
Individualization of the particles before encapsulation
Blending of the matrix and the substrate to be protected before separation (Tarun et al, 2011).

Solvent exchange method (A novel microencapsulation technique)
A solvent exchange method is employed to provide microencapsulated compositions, such as microcapsules of pharmaceutical preparations. The method is based on an exchange of water and a hydrophilic organic solvent, whereby a decline in solvent quality for the organic solvent causes a polymer dissolved therein to be deposited onto an aqueous core. Optimal results are rationalized in terms of a balance of water solubility and surface tension for the organic solvent. In a preferred embodiment, microcapsules of selected drugs are formed by contacting microdroplets of an aqueous solution containing the drug with the organic solvent containing a polymer dissolved therein(Yoon Yeo et al. 2003).

This technique could address traditional difficulties that have been encountered during the microencapsulation of protein drugs. Reservoir-type microcapsules were produced using a dual microdispenser system or a coaxial ultrasonic atomizer, based on midair collision between component materials followed by interfacial phase separation of a polymeric membrane. It was found that the reported process had no negative effect on functional integrity of the encapsulated model protein, lysozyme. Furthermore, the microcapsules released the encapsulated lysozyme at near zero-order for an extended period when tested without drying. The reported example demonstrated a complete release of intact lysozyme over 50 days. It is believed that these results are additive effects of following features of the new microencapsulation method. First, the method minimizes the exposure of encapsulated proteins to a large water/organic solvent interfacial area, in which the proteins can easily accumulate and be denatured. Second, the method utilizes only a minimal energy for producing microdrops and does not generate damagingly strong mechanical stresses. Third, the contact between the encapsulated drugs and the hydrophobic polymer and their degradation products is minimal in the reservoir-type microcapsules, which could otherwise cause extensive denaturation of the encapsulated proteins. The new method provides a simple and efficient way of making protein-loaded microcapsules, which will lead to commercially viable products in the near future. (Yoon Yeo 2003)

Table No. 4: Patents Granted for Solvent Exchange Microencapsulation Technique

Patent NO.

Name of Method

Discussion

Reference

US/ Patent 6599627 (July 29 2003)

Microencapsulation of drugs by solvent exchange

A solvent exchange method is employed to provide microencapsulated compositions, such as microcapsules of pharmaceutical preparations. The method is based on an exchange of water and a hydrophilic organic solvent, whereby a decline in solvent quality for the organic solvent causes a polymer dissolved therein to be deposited onto an aqueous core. Optimal results are rationalized in terms of a balance of water solubility and surface tension for the organic solvent. In a preferred embodiment, microcapsules of selected drugs are formed by contacting microdroplets of an aqueous solution containing the drug with the organic solvent containing a polymer dissolved therein. A preferred method employs biodegradable poly(lactic acid-co-glycolic acid) (PLGA) dissolved in acetic acid, ethyl acetate, methyl acetate, or ethyl formate, to form a PLGA membrane around an aqueous drug core. The method is particularly attractive for encapsulating protein-based drugs without substantial denaturation.

(freepatentsonline.com/ 6599627.html)

US/ Patent 7442439 (Oct 28 2010)

Microencapsulated heat delivery vehicles

Microencapsulated delivery vehicles comprising an active agent are disclosed. In one embodiment, the microencapsulated delivery vehicles are heat delivery vehicles capable of generating heat upon activation. The microencapsulated heat delivery vehicles may be introduced into wet wipes such that, upon activation, the wet wipe solution is warmed resulting in a warm sensation on a user's skin. Any number of other active ingredients, such as cooling agents and biocides, can also be incorporated into a microencapsulated delivery vehicle

(freepatentsonline.com/ 7442439.html)

US/ Patent 8192841 (June 05 2006)

Microencapsulated delivery vehicle having an aqueous core

Microencapsulated delivery vehicles comprising an active agent are disclosed. The microencapsulated delivery vehicles may be introduced into products such that, upon activation, the product provides a functional benefit to a substrate, such as a user's skin.

(freepatentsonline.com/ 8192841.html)

US/ Patent Application 20020160109 (Oct 31 2002)

Microencapsulation of drugs by solvent exchange

A solvent exchange method is employed to provide microencapsulated compositions, such as microcapsules of pharmaceutical preparations. The method is based on an exchange of water and a hydrophilic organic solvent, whereby a decline in solvent quality for the organic solvent causes a polymer dissolved therein to be deposited onto an aqueous core. Optimal results are rationalized in terms of a balance of water solubility and surface tension for the organic solvent. In a preferred embodiment, microcapsules of selected drugs are formed by contacting microdroplets of an aqueous solution containing the drug with the organic solvent containing a polymer dissolved therein. A preferred method employs biodegradable poly(lactic acid-co-glycolic acid) (PLGA) dissolved in acetic acid, ethyl acetate, methyl acetate, or ethyl formate, to form a PLGA membrane around an aqueous drug core. The method is particularly attractive for encapsulating protein-based drugs without substantial denaturation.

(freepatentsonline.com/y2002/0160109.html)

References
1.Microencapsulation Available at <en.wikipedia.org/wiki/Micro-encapsulation> [Accessed 28 feb. 2012].
2.Pachuau et al (2008) “Formulation and evaluation of matrix microspheres for simultaneous delivery of salbutamol sulphate and theophylline” Tropical Journal of Pharmaceutical Research, June 2008; 7 (2): P. No. 995-1002.
3.Swarbrick James (2007) “ Encyclopedia of Pharmaceutical Technology” Third Edition VOL. 1 PharmaceuTech, Inc. Pinehurst, North Carolinia, USA P.No. 2315-2328.
4.Tarun et al “Patented Microencapsulation Techniques And Its Application” Journal of Pharmacy Research Vol.4, Issue 7, July 2011 P.No. 2097-2102.
5.Encyclopedia of controlled drug delivery system Vol.I &I Edition mathiowitz brown university published by John Wiley & sons inc printed in U.S.A 356, 493-543
6.Leon lachman; Herbert A. Lieberman; Joseph L.Kanig; “The Theory And Practice Of Industrial Pharmacy”III Edition (1991) Varghese Publishing House Dadar Bombay 412-428
7.Howard c. Ansel; Loyd V.; Allen Jr.; Nicholas g. Popvich “Ansel’s pharmaceutical dosage form & drug delivery system” viii edition, reprinted 2005 Lippincott Williams & Wilkins 265
8.M.E.Aulton “Pharmaceutics The Science Of Dosage Form Design’’II edition Churchill Livingstone 82-83
9.Jackson L.S. Lee k. (1991-01-01).”Micro encapsulation and the food industry” (htm).Lebensmittel-Wissenchaft technologies. cat.inist.fr/?aModele=affichen&cpsidt=5014466.retrived on 1991-02-02.
10. gate2tech.com/article.php3?id_article=2
11. gate2tech.com/article.php3?id_article=25
12. gate2tech.com/article.php3?id_article=6
13.Christine McInnis “Microencapsulation:It’s What’s Outside That Counts” Blackwell Lab UW-Madison, Department of Chemistry January 24, 2008.
14.Yoon Yeo et al 2003 “Microencapsulation of drugs by solvent exchange” (June 29 2003) (google.com/patents/US6599627).
15.Yoon Yeo 2003 “The solvent exchange method: A novel microencapsulation technique” (docs.lib.purdue.edu/dissertations/AAI3124244/).
16.United States Patent 6022525 “Preparation of diagnostic agents” (Feb 8 2000) Sutton et al. (freepatentsonline.com/6022525.html)
17.United States Patent 8192841 “Microencapsulated delivery vehicle having an aqueous core” (June 5 2012) Amundson et al. (freepatentsonline.com/8192841.html).
18.United States Patent 4749575 " Microencapsulated medicament in sweet matrix” (June 7 1988) Rotman (freepatentsonline.com/4749575.html)
19.United States Patent 4925674 “Amoxicillin microencapsulated granules” (May 15 1990) Giannini et al. (freepatentsonline.com/4925674.html).
20.United States Patent 4808408 “Microcapsules prepared by coacervation” (Feb 28 1989) Baker et al. (freepatentsonline.com/4808408.html).
21.United States Patent 5540927 “Microencapsulation process by coacervation” (July 30 1996) Jason et al. (freepatentsonline.com/5540927.html)
22.United States Patent Application 20090253165 “METHOD FOR PREPARING MICROCAPSULES BY COACERVATION” (OCT 08 2009) Dardelle et al. (freepatentsonline.com/y2009/0253165.html).
23.United States Patent 3872024 “ENCAPSULATION PROCESS BY SIMPLE COACERVATION USING INORGANIC POLYMERS” (March 18 1975) horger (freepatentsonline.com/3872024.html) .
24.United States Patent 3878121 “Method of encapsulation by coacervation, and the substances obtained” (April 15 1975) Roche et al. (freepatentsonline.com/3878121.html).
25.United States Patent Application 20080089927 “Methods for Coacervation Induced Liposomal Encapsulation and Formulations Thereof” (April 17 2008) Malinin et al. (freepatentsonline.com/y2008/0089927.html).
26.United States Patent 3639256 “ENCAPSULATION PROCESS BY COMPLEX COACERVATION USING INORGANIC POLYMERS” (Feb 1 1972) horger (freepatentsonline.com/3639256.pdf).
27.United States Patent Application 20090189304 “Encapsulation of oils by coacervation” (July 30 2009) Friedmann et al. (freepatentsonline.com/y2009/0189304.html)
28.United States Patent Application 20070048385 “Microcapsules by coacervation containing a pharmaceutical incorporated in the coating polymer” (March 01 2007) Golzi et al. (freepatentsonline.com/y2007/0048385.html).
29.United States Patent Application 20090263480 “TASTE-MASKED PHARMACEUTICAL COMPOSITIONS PREPARED BY COACERVATION” (Oct 22 2009) Lai et al. (freepatentsonline.com/y2009/0263480.html).
30.United States Patent 4963364 “Microencapsulated antitumor agent” (Oct 16 1990) Fox et al. (freepatentsonline.com/4963364.html)
31.United States Patent 4948506 “Physicochemically functional ultrathin films by interfacial polymerization” (Aug 14 1990) Lonsdale et al. (freepatentsonline.com/4948506.html).
32.United States Patent 6080412 “Pharmaceutical microencapsulation” (June 27 200) Jordan et al. (freepatentsonline.com/6080412.html)
33.European Patent EP0342685 “Microencapsulating composition and kit; and process for producing microcapsules” (April 13 1994) Yoshimoto et al (freepatentsonline.com/EP0342685B1.html)
34.United States Patent 4766012 “Microencapsulation of a medicament” (Aug 23 1988) Valenti et al. (freepatentsonline.com/4766012.html).
35.United States Patent 4518547 “Microencapsulation process” (May 21 1985) Cuff et al. (freepatentsonline.com/4518547.html).
36.United States Patent 6599627 “Microencapsulation of drugs by solvent exchange” (July 29 2003) Yeo et al. (freepatentsonline.com/6599627.html).
37.United States Patent 7442439 “Microencapsulated heat delivery vehicles” (Oct 28 2010) Joseph et al. (freepatentsonline.com/7442439.html)
38.United States Patent 8192841 “Microencapsulated delivery vehicle having an aqueous core” (June 05 2006) Amundson et al. (freepatentsonline.com/8192841.html).
39. United States Patent Application 20020160109 “Microencapsulation of drugs by solvent exchange” (Oct 31 2002) Yeo et al. (freepatentsonline.com/y2002/0160109.html).

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