India Herbs

Publication: Express Pharma

Date: December 8th 2006

Herbal medicines are known to human race since the man gained any knowledge about diseases and their treatment. Man discovered that nature has provided him several medicinal plants which have therapeutic value that can cure him from many diseases. Therefore, men in every time period have put enough efforts to identify and isolate such herbal products which have medicinal value. In the modern ages (during 20th and 21st century) scientists tried to identify the active principal in such medicinal plants which is actually responsible for any particular therapeutic activity and then tried to produce those active principals in large quantities by various chemical processes for the benefit of much larger population. Still, many herbal medicines find place in different dispensaries. There are several established methods of medical practice like Ayurveda, Unani and Chinese medication which are based on the usage of natural medicines derived mainly from various plants.

It has been discovered that many times it is only a part of the plant which is medically effective indicating that the active principal is available only in that part of the plant. Medical experts have identified these parts and then formulated them in suitable dosage forms like powders (churanas), tablets (batti, gutika or pills), solutions (quaths and decoctions), syrups, tinctures. As far as tablets are concerned mainly two forms of materials are used—the powdered crude herb or the extract (aqueous or alcoholic) from the crude herbs. Till nearly 50 years ago, majority of these medicines formulated as tablets were marketed as compressed tablets (uncoated tablets) and some of them were sugar coated (as the sugar coating is a very time consuming process and require highly skilled operators, there were few sugar coated products in the market).

Such compressed tablets presented certain specific problems to the manufacturer, retailers, dispensing pharmacist as well as to the patients. As the tablets are exposed to high temperature during film coating, the difference in these values create serious problems in retaining the tablet surface smoothness during coating. If the difference in these values is very high, the core tablet may expand so much to rapture the film coating.

Tablet breakage: Most of the herbal tablets are not very strong due to the poor compressibility of active ingredients (either powdered crude herb or the herbal extract). Hence, these tablets tend to break during packaging operation within the factory as well as during transportation and handling by retailer or patient.

Moisture pick-up: Most of the active herbal ingredients are hygroscopic in nature and tend to pick moisture from atmosphere when exposed to high humidity. Such moisture pickup detoriates the product in the following ways:

The tablet may become soft making it unacceptable to patient.

The active ingredient may undergo chemical degradation.

As most of the herbal active ingredients are dark in colour, such moisture uptake generally changes the colour of the finish product, giving an impression that the product is no longer suitable for consumption.

Due to moisture pickup, there is a possibility of bacterial/fungal growth as many of the herbal ingredients support the bacterial growth in presence of moisture.

Poor physical appearance: The physical appearance of most of the herbal ingredients does not remain constant as well as uniform and varies depending on the various environmental factors like when the herb has been collected, from where it has been collected, what was the age of the plant from which the herb has been collected etc. Such changes are very prominent when the crude and grounded herb is used in the finish product, but also varies even when the herbal extract is used in the tablet formulation. Such variations in the active ingredients make the physical appearance of the finish product non-uniform, giving an impression that the manufacturers’ quality systems are not up to the standards and many times the QC department also finds it difficult to release the manufactured batch for sales.

As described earlier that herbal ingredients have poor compressibility and compressed tablets are generally not very strong, such tablets tend to generate lots of powder during initial stages of film coating, making the tablet surface very rough. All the above mentioned problems can be solved by film coating the compressed tablets before sending to the market place. By applying the film coating, the tablets become strong enough to withstand the handling / transportation stress and also become less sensitive to the atmospheric variations like exposure to oxygen, light etc. The tablets can also become impermeable to the atmospheric humidity when these are coated with Insta Moistshield film coating systems (coating systems manufactured by m/s Ideal Cures. As these film coating systems come ready made with the desired colour shades which is very stable and remain uniform through out its shelf life, the appearance of the final coated tablets always remain same batch after batch.

The film coating technology is now well established process for general allopathic tablets but the same technology when applied to herbal tablets, cause several problems like:

As described earlier that herbal ingredients have poor compressibility and compressed tablets are generally not very strong, such tablets tend to generate lots of powder during initial stages of film coating, making the tablet surface very rough. Most of the times this powder re-settles on the tablet surface and gets further coated making the finish product appearance unacceptable. Another problem under such circumstances is that this powder interferes with the colour of the film coating, giving it a different colour shade then the desired one. As the amount of such powder will differ from batch to batch, every batch may then have different colour shade.

In large size tablets, poor compressibility makes the tablets more fragile. If lots of tablet break during the film coating process, the process yield and the production economics gets adversely affected.

The thermal expansion of the herbal ingredients is very different then the values for other excipients used for tablet manufacturing. As the tablets are exposed to high temperature during film coating, the difference in these values create serious problems in retaining the tablet surface smoothness during coating. If the difference in these values is very high, the core tablet may expand so much to rapture the film coating.
In case the coating is not protective enough, the active ingredients tend to pick up moisture from atmosphere. If the exposure to high humidity is significant, the core tablet may swell so much to burst open the film coating. Such moisture uptake then destroys the product.

As described earlier, the colour of the herbal ingredients varies significantly due to various reasons, the colour of the core tablet also changes as the lot of herbal ingredient changes. If the film coating system is not properly formulated, this variation in core colour is not completely masked by coating and one can see batch to batch colour variation.

Thus the film coating of herbal tablets is quite a challenging task. One needs to scientifically understand the reasons for various problems and modify the process and coating formulation accordingly.

Ideal Cures has developed an entire range of such film coating systems which are optimally formulated to suit these requirements and has helped many herbal manufacturers (within India and abroad) to successfully film coat the herbal tablets with long shelf-life.

The company is also providing the necessary technical expertise to validate the whole film coating process either using conventional coating set-up or auto coaters.

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