Composition of Medicated Chewing Gum

Medicated Chewing Gum (MCG) is a novel drug delivery system containing masticatory gum base with pharmacologically active ingredient(s) and intended to use for local treatment of mouth diseases or systemic absorption through oral mucosa. MCG provides additional patient benefits and compliance, offering several advantages over tablets or liquid formulations in that, the therapeutic system is not be swallowed and this increases patient compliance, especially for geriatrics and pediatrics with swallowing disorders; moreover, the product can be taken anywhere and at any time as it does not require liquids to aid swallowing.

Read more on the advantages of medicated chewing gum

Medicated chewing gums are formulated with suitable excipients to enhance chewability, palatability, and efficient delivery of the medicament. In addition to the active pharmaceutical ingredient(s), medicated chewing gums contain:

1. Gum base

This is the nonnutritive part of medicated chewing gum which does not dissolve while chewing. Usually, the gum base forms about 40% but can be up to 65%, and includes a complex mixture, insoluble in saliva, comprising mainly of elastomer, plasticizers, waxes, lipids, and emulsifiers.

Typical formulation of gum base

2. Elastomers

These are polymers with high elongation properties and elasticity. They provide elasticity and controls gummy texture. Examples include natural rubbers like latex or natural gums such as Jelutong, Lechi-caspi, Perillo, Chile gum, Niger gutta, Nispero, etc.

Artificial elastomers such as polyisobutylene, isobutylene, isoprene copolymer, styrene-butadiene copolymer, polyvinyl acetate, etc. have also been used.

3. Plasticizers

Plasticizers are used to regulate the cohesiveness of the product. It promotes gum texture by applying plasticity and reducing brittleness. It also softens the elastomers.

Plasticizers of both natural and synthetic origin have been used in the manufacture of chewing gum.  Examples include natural rosin esters like glycerol esters of partially dimerized rosin, glycerol esters of partially hydrogenated rosin, glycerol esters of polymerized esters, and pentaerythritol esters of rosin.

Synthetic materials which are used as plasticizers include terpene resins derived from α-pinene and/or d-limonene.

4. Texture agents/ fillers

These include talc, calcium and magnesium carbonate, ground limestone, aluminum and magnesium silicate, alumina, clay, titanium oxide, and mono/ di/ tri-calcium phosphate. They provide texture, improve chewing ability, and provide reasonable size of the gum lump with low dose drug. They also facilitate blending and other processing stages.

5. Lipid and Wax

The lipid and the waxes melt in the mouth to provide a cooling, lubricating feeling. The base may be wax free.

6. Softeners and Emulsifiers.

These are added to MCG in order to optimize the chewability and mouth feel of the gum. Softeners used in the manufacture of medicated chewing gum include tallow, hydrogenated tallow, glycerine, lecithin, mono/ di/ triglycerides, fatty acids like oleic acid, stearic acid, linoleic acid, and palmitic acid.

7. Antioxidants

Antioxidants such as ascorbic acid, tocopherol, butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate and mixtures thereof, may be added to inhibit oxidation.

8. Flavoring agents

These are used to improve flavor in medicated chewing gums. Examples include essential oils, such as citrus oil, fruit essences, spearmint oil, mint oil, peppermint oil, clove oil, anise oil, and oil of Wintergreen. Synthetic flavors can also be used.

9. Sweeteners

Sweeteners provide the desired sweetness of the product. Water-soluble sweetening agents e.g., sorbitol, hydrogenated starch, corn syrups, help to retain moisture and freshness of the finished product. They also act as a plasticizer or softening and binding agents.

High-intensity synthetic sweeteners can also be added to provide longer lasting sweetness and flavour perception. They produce lower calorie due to the partial absorbance in the intestine. Examples include sucralose, aspartame, alitame, saccharin, glycyrrhizin, dihydrochalcones etc.

10. Coloring agents

Colorants are added to improve the color of the formulation. Examples include FD & C type dyes and lakes, fruit and vegetable extracts, titanium dioxide.

11. Anti-tack agents

These are included in MCG to prevent self-adhesiveness also known as blocking in materials which have a tendency to stick together (e.g., rubbers). It also reduces fragmentation of the gum and prevents it from attaching to the teeth during mastication. Examples include α-cellulose and vegetable proteins.

12. Anti-caking agents

Anti-caking agents (e.g., precipitated silicon dioxide, solid carbon dioxide) are used to prevent caking and lump formation. These materials improve flow properties and rehydration and help for good packaging. They also help extend shelf life and detract dispersibility.

A typical chewing gum formulation is shown in the table below.

Example of chewing gum formulation

Reference

• Aslani, A. and Rostami, F. (2015). Medicated Chewing Gum, A Novel Drug Delivery System. Journal of Research in Medical Sciences, 20(4): 403-411.
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• Gad, S. (2008). Pharmaceutical Manufacturing Handbook: Production and Processes. New Jersey: John Wiley & Sons, Inc.
• http://www.dissolutiontech.com/DTresour/201008Articles/DT201008_A02.pdf
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• Rathbone, J., Hadgraft, J. Roberts, M. and Lane, M. (2008). Modified-Release Drug Delivery Technology (2^nd). New York: Informa Healthcare USA, Inc.
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