Maltodextrin and Its Amylose Is a Linear Polymer with D- of Various Lengths

Aes appeayred in Te ablets & Capsules October 2011, Copyright CSC Publishing www.tabletscapsules.com eoxn cipients

Carrie Shipley Grain Processing Corp.

In this edition of the column, Carrie an acid and an enzyme reaction. The Cor n starch consists of two major Shipley discusses the basic carbohy - basic hydrolytic reaction cleaves the polymers, amylose and amylopectin. starch molecules into smaller chains drate chemistry of maltodextrin and its Amylose is a linear polymer with D- of various lengths. The slurry is then glucose alpha (1-4) bonds, while use in tablet and capsule formulations. (usually) refined and concentrated amylopectin is a highly branched before the moisture is removed in a polymer with alpha (1-6) linkages. Maltodextrins have become popu - spray dryer. Sometimes the product Figure 1 shows the content and struc - lar excipients in the pharmaceutical will also undergo agglomeration. tures of the glucose, amylose, and industry because of their multifunc - Maltodextrins can be prepared amylopectin of corn starch. Waxy tionality and cost-effectiveness. from most grains and other sources of corn starch comprises almost all amy - Manu facturers use them in a variety starch, including corn, potatoes, rice, lo pectin, while yellow dent corn is of applications, including as binders tapioca, and wheat. The source of the about 76 percent amylopectin. This and as components in aqueous film maltodextrin can impart slightly differ - variation makes a difference in the coatings. They are also available in a ent characteristics to it. The discussion final maltodextrin product, especially range of particle sizes and dextrose below focuses on starch from corn, at a DE of less than 10. Maltodextrins equivalences (DEs). and in particular, yellow dent corn. made from waxy starch have a slightly What is a maltodextrin? According to USP, maltodextrin is a Figure 1 “non-sweet, nutritive saccharide mix - Content of corn starch ture of polymers with a dextrose equivalent of less than 20.” Malto - dextrins are produced from the hydro - Glucose (dextrose) lysis of starch, and the DE is a quanti - tative measurement of the de gree of starch-polymer hydrolysis. The DE also can be defined as the measurement Amylose of the reducing power of the mal to - dextrin polymer when compared to a dextrose standard of 100. The higher the maltodextrin’s DE, the greater the extent of starch hydrolysis [1]. Basic starch hydrolysis starts with Amylopectin a starch slurry, which then is reacted with an amylase enzyme—such as glucoamylase, beta amylase, alpha amylase, or isoamylase—and/or an acid. Some manufacturers use both higher solubility and increased solu - face area, which promotes flow. The because they all have wet binding abil - tion clarity in the lower DE range. agglomerated forms also generate ities. The lower the DE, however, the That’s because they lack the linear less dust than spray-dried powders. greater the wet-binding strength that molecules that can re-associate in Chewable tablets or orally disinte - the maltodextrin provides. Malto - waxy starch as compared to the grating tablets (ODTs) are another dextrins are soluble in cold water; they starch of yellow dent corn [2]. area where maltodextrins are used. need no heat. In addition, the solubil - They have bland flavors, and the ity is high, eliminating the need to Direct-compression tabletting higher-DE products are only very keep the solution agitated while Direct compression is the fastest, mildly sweet. Thus, they can hide pumping it. See Figure 2. A normal simplest, and least expensive way to bitter flavors and improve mouth-feel binding solution contains 10 to 20 make tablets, and maltodextrins serve by smoothing out grittiness. percent maltodextrin in water. Figure 3 as binders in direct-compression shows th e viscosity of a maltodextrin tablets. Although all DE ranges of Wet, dry granulations solution derived from dent corn. The maltodextrins have some dry-binding Maltodextrins also serve as bind ers DE ranges of 5 to 19 percent are rep - capability, the higher the DE, the bet - in wet granulations, and any DE can resented. With in the range of 10 to ter the dry binding. When determin - be used for binding wet granulations 20 percent, the graph shows that vis - ing the correct DE to use in a direct- compression tablet, also consider its tackiness since as the maltodextrin’s Figure 2 DE increases, so does its hygroscopic - ity. Too high a DE (17 to 19.9) in the Apparent solubility (measured by clarity) maltodextrin can cause tablet sticki - ness and die-wall friction. Therefore, it is important during pro duct devel - opment to consider how much mal - todextrin your formulation requires ) n o and what the DE of the maltodextrin i t a r

should be to achieve good binding. u t a s

Maltodextrins can also add bulk to t a ( a tablet. Since they are easily com pres - s d i l

sible, are inexpensive, and can con - o s

tribute to overall binding, maltodex - % trins are attractive to manufacturers, who may choose a low-DE maltodex - trin instead of more expensive fillers. Much like microcrystalline cellu - lose (MCC), maltodextrin used in direct-compression tablets increases tablet hardness, reduces friability, and Figure 3 alleviates capping. MCC also helps Solution viscosity [2] decrease disintegration, while mal - todextrin neither increases nor de - creases disintegration time. Many manufacturers use a 50-50 blend of MCC and maltodextrin. This combi - nation helps cut costs but still pro - duces a strong tablet that disintegrates e s quickly. i o p i

Maltodextrins come in a range of t n e

particle sizes and bulk densities, C including spray-dried powders and agglomerated forms. Specialty prod - ucts with fine particle sizes or very low bulk densities are also available, and those products can be used as diluents or carriers in direct-compres - sion formulas. Agglomerated prod - % solids (w/w) ucts are porous and have a large sur - cosity is less than 100 centipoise, maltodextrin as a secondary film-for - which means that the solution will be mer. Maltodextrins not only extend extremely thin, even on the higher the film-forming properties of the end of the recommended amount of main polymer, but add gloss and binder usage. This quality allows it to enhance the color while simultane - be pumped easily into a fluid-bed or ously increasing the solids content of conventional high-shear granulator. the formula. Increasing the solids in a Some manufacturers prefer to gran - formula enables manufacturers to ulate with water only, foregoing a obtain the desired weight gain more binding solution. In that case, they quickly, thereby reducing production add maltodextrins with the dry pow - time and cost. They can achieve all ders, and the wetting process activates these benefits with little if any varia - binding. Binding strength is lower in tion in the solution’s viscosity. this type of granulation compared to granulations that in clude a maltodex - Other uses trin solution, but the method is quick Maltodextrins have a large pres - and can achieve sufficient binding. ence in medical nutrition because Maltodextrins can also be used as they are a readily digestible carbohy - binders in roller compaction. Their drate source that can provide energy compressibility is advantageous in this and rehydration at body osmolality. type of granulation but, as mentioned Their ability to inhibit crystal above, maltodextrins do not increase growth as well as regulate sweetness or decrease disintegration time. and viscosity allows manufacturers to use maltodextrins for liquid pharma - Capsules ceuticals as well as for lozenges. Most two-piece capsules are filled Agglomerated and lower-bulk den - using modern high-speed capsule fill - sity maltodextrins find a place in ing equipment, and reliable flow is reconstituted dry blends. They act as very important to keep the process bulking agents as well as carriers that moving smoothly. As discussed above, dissolve quickly in water. most maltodextrin manufacturers pro - duce not only spray-dried powders Conclusion but agglomerated forms as well. The pharmaceutical industry uses Capsule manufacturing uses agglom - maltodextrins in many ways. Their erated maltodextrins as fillers or in varied particle sizes, bulk densities, forming slugs due to their fast and and DEs make them a cost-effective even flow, as well as their dry-binding choice for many pharmaceutical abilities. Maltodextrins are also used manufacturers. T&C as adhesive agents in the shell layer of soft non-gelatin capsules [1]. References 1. Grain Processing Corp. techni - Aqueous film coatings cal literature. Maltrin Maltodextrin As with many starches, maltodex - and Corn Syrup Solids. 2010. trins are good film-formers, allowing 2. Kuntz, Lynn A. Making the them to be used as coatings for tablets most of maltodextrins. Food Product and granules. Manufacturers can use Design. August 1997. maltodextrins as the main film-forming polymer, but maltodextrin films alone Carrie Shipley is an applications scientist at are not as strong as many of the other Grain Processing Corp., 1600 Oregon Street, film-forming polymers that are avail - Muscatine, IA 52761. Tel. 563 264 4265. able. They can also be quite tacky, so E-mail: [email protected]. most manufacturers use them either as a secondary polymer or add them to in - crease the solids of a coating solution. Many of the strong film-forming polymers used in tablet coating for - mulations are expensive. To keep coating costs down, formulators add