>> LYCOAT^® coating suits your plant extract tablets so well

Nutraceutical tablets are very popular as consumers are looking for natural and traditional medicines. According to the database GNPD Mintel review (Global New Products database), herbal/botanical claims represent 27% of the VDS (Vitamins and Dietary Supplements) product launches in 2007. This reflects the consumer’s consciousness of the medicinal properties attributed to plants and their extracts. Among the plants used, green tea and ginseng are the most favoured followed by ginkgo, echinacea and garlic.

Herbal extracts are usually very difficult to formulate, for the following reasons:

• Generally with very poor organoleptic properties that need to be masked
• Very hygroscopic
• Usually waxy products
• Poorly compressible, difficult to bind and poor flowability
• Used often in high doses, making the formulation even more difficult.

Film coating of herbal tablets is a common practice as it makes it possible to mask unpleasant taste, odour and colour often associated with plant extracts. Because of food regulatory restrictions, no synthetic polymers such as PVA or PEG can be used. As a consequence, only few polymers are suitable. In addition, some plant extracts can be incompatible with natural origin film coating polymer.

LYCOAT^® a natural origin coating polymer reveals total inertness and full compatibility with plant extract, as illustrated by a case study with green tea extract. LYCOAT^® has food (E1440) and pharmaceutical regulatory status.

Benefits and performances of LYCOAT^® for film-coating

LYCOAT^® is ROQUETTE’s modified pea starch film coating polymer developed for a quicker quality coating.

Besides the quick coating time, LYCOAT^® has a number of other benefits to offer:

• Simple preparation: no problem with lump or foam formation
• Complete aqueous dissolution at room temperature with traditional mixing equipment
• Neutral suspensions
• Low viscosity for substantial cost savings
• Reduction of process time thanks to quick coating

In addition, LYCOAT^® exhibits excellent coating performances and gives a glossy and high quality film:

• pH-independent disintegration time
• brilliant appearance
• film robustness means tablet strength

Inertness of LYCOAT^® in connection with plant extract: green tea extract

The inertness of LYCOAT^® coating versus HPMC types was demonstrated through trials carried out on green tea tablets containing 40% of green tea extract (80% polyphenol content). Tablets were coated using ready-to-use film-coating products based either on LYCOAT^® (ReadiLYCOAT^TM) or on HPMC. The appropriate coating conditions for ready-to-use film coating systems containing LYCOAT^® or HPMC were applied using conventional coating equipment. A target of 3.2% weight gain was applied.

Friability, hardness, disintegration time and dissolution profile (polyphenol content) of coated tablets versus uncoated ones were evaluated using standard EP/USP methods and equipment. The resulting data are shown in table 1 and figure 1 respectively.

	Friability	Hardness (N)	Disintegration time (min)
Uncoated tablets	None	108	26 min 50 sec
LYCOAT® Formulation coating	None	117	28 min 53 sec
HPMC Formulation coating	None	137	67 min 46 sec

Table 1: Influence of coating on tablet characteristics

Figure 1: Influence of coating LYCOAT® vs HPMC on dissolution profile of green tea extract tablets (as measured by polyphenol content)

As demonstrated by the above results, the HPMC film-coating of green tea extract tablets increases significantly the tablet hardness and disintegration time, whereas a negligible non-significant increase is observed with the LYCOAT^® film-coating. This difference between HPMC and LYCOAT^® is further confirmed by the dissolution profile data (figure 1) that shows a marked increase in dissolution time for the HPMC coated green tea extract tablets whereas the LYCOAT^® coating does not have any impact on the dissolution rate. The LYCOAT^® coated green tea extract tablets display a dissolution profile matching that of the uncoated tablets.

These results observed can be explained by a physicochemical interaction between the green tea extract and the HPMC which hinders the polyphenol dissolution. A gel like mixture is formed when the HPMC and the green tea extract are mixed together whereas no interaction occurs between the LYCOAT^® and the green tea extract (figure 2). 

Figure 2: LYCOAT® does not interact with green tea extract, contrary to HPMC

 
The above case study is one illustration of the inertness of LYCOAT^® in connection with plant extracts which can be used in vitamins and dietary supplements. This inertness on top of its other benefits and performances will make LYCOAT^® one of the reference film coating and an ideal polymer for nutraceutical film-coatings.