Replacing the lubricants stearic acid or magnesium stearate with lubricants based on natural ingredients.

The following data shows a comparison between conventional lubricants (stearic acid / magnesium stearate) and natural based lubricants (rice extract) or excipient premixes (cellulose/rice extract/oil/wax). By working with natural ingredients it would be possible to label your product cleaner than other chemical-sounding words.

The natural lubricant which was used for trials is a vegetable rice extract from RIBUS, a manufacturer of specialty ingredients. Nu-RICE® is a patented hypoallergenic extract from rice bran. This natural processing aid helps hydrate, lubricate and emulsify ingredients to create easier and faster processing.

Rice extract has light lubricant properties, additional ingredients can be used to increase the efficiency of the lubricant. Therefore an excipient premix of cellulose, oil, wax and vegetable rice extract (Nu-RICE®) from BIOGRUND was used for the trials. CompactCel® LUB combines the properties of a dry binder and lubricant. It’s a homogeneous dry milled powder compound.

All trials were performed on Romaco Kilian’s tableting robot STYL’ONE Evolution. It is predestined for a broad array of R&D applications and for producing
very small batch sizes. With a maximum output of 1200 tablets per hour, this single-stroke press processes mono-layer, multilayer or core tablets (tab in tab).

Styl'One Evolution by Romaco Kilian

STYL’ONE Evolution by Romaco Kilian

To measure the lubricant effect, the preparation of the tablet mass were performed as follow:

Tablet mass basis mixture:
– 49,5% Microcrystalline cellulose
– 30,0% Lactose
– 20,0% Dicalcium phosphate

Trial 1: without lubrication
Trial 2: Rice extract 0,5%
Trial 3: Compact Cel® 490.01 LUB 0,5% and 1%
Trial 4: Compact Cel® 290.02 LUB 0,5% and 1%
Trial 5: Stearic acid 0,5%

Before the tableting process started all tablet mass mixtures were mixed for 15 minutes.

Only 49% microcrystalline cellulose were used in the tablet mass mixtures for the 1% CompactCel® formulations in trial 3 and 4.

Comparison of the different lubricants

Comparison of the different lubricants


The most interesting data in this study is the ejection force. Starting on a scale from 0 N (for best lubrication effect) up to over 2500 N (for worst lubrication effect).

Best lubrication results were achieved by using only stearic acid as a lubricant. The measured ejection forces of the performed trials show that CompactCel® LUB premixes, based on natural ingredients, show comparable results when they are used as an alternative lubricant to stearic acid.

Beside this study another comparison was done were magnesium stearate instead of stearic acid was compared with the alternative natural lubricants. The results achieved comparable effects as shown in the figure above.

More information:
CompactCel® LUB premixes by BIOGRUND
Nu-RICE® rice extract by Ribus
Tableting Machine by Romaco

What excipients do I need in my tablet formulation? And how can I optimize them?

The pharmaceutical, food and cosmetics industries are just a few examples of the many areas in which powders are used or produced on a daily basis. In the pharmaceutical and dietary supplement industries, these powders are used to manufacture tablets, among other things. More than 50% of medicines are administered in the form of tablets because they are easier to dose and cheaper to produce.

In the manufacture of tablets, excipients are often added to the active ingredient to be processed. These excipients act as fillers, binders, stricter agents (disintegrants) or lubricants and thus simplify the processing (tableting) of the tableting mass or improve the properties of the finished tablet (disintegration, hardness, release of active ingredient).

Fillers (e.g. cellulose) are added during the manufacture of a tablet, so that even when a small amount of active ingredient is used, a sufficient tablet size and mass is achieved and thus the intake is simplified. – MCC & Lactose

Binders (e.g. polyvinylpyrrolidone (PVP)) are added to the tableting mass to increase tablet strength. This is usually necessary for active ingredients that are difficult to compress or when a high proportion of active ingredients (e.g. extracts) is used. CC & CC Sil

Disintegrants (e.g. sodium carboxymethyl cellulose (Na-CMC)) are added to the tablet mass so that the tablet disintegrates as quickly as possible at the desired place of application and the active ingredient is released. – NaCMC

Lubricants serve to reduce the sliding and static friction between the tableting tool and the tableting mass and to increase the flowability of the tableting mass. Lubricants are divided into three subgroups: 1. Lubricants (e.g. magnesium stearates), which are intended to reduce friction between the tableting mass and the tableting tool. 2. (mould) release agents (e.g. talc) which are intended to prevent the tablet from sticking to the tablet die. 3. superplasticizers (e.g. highly dispersed silicon dioxide) improve the flowability of the tablet mass and loosen it. – CC FLO

Good flow properties of a tableting mass are important in the production of tablets using the direct tableting process. Here, the active ingredient is homogeneously mixed with the excipients in advance. In a continuous process, the tableting mass is then filled into the die without further processing through a filling funnel and compacted by pressure with an upper and lower punch. Poor flow properties of the tableting mass can lead to delays in the powder flow or blockage of the filling shoe. This would lead to insufficient and non-reproducible filling of the die and thus to an inaccurate dosage (and possibly incorrect dosage of the active ingredient). Furthermore, clogging of the hopper can lead to a delay or disruption in the process and thus to economic damage for the producing company. Poorly flowing tablet masses may not always be produced using the direct tableting process. In this case, conventional granulation/wet granulation must be used. However, these manufacturing processes are usually more complex and cost-intensive. Tablet manufacturers therefore prefer the simpler process of direct tableting.

In order to still be able to process poorly flowing tablet masses in direct tableting, the producer can add a flow promoter (CompactCel® FLO) to the tablet mixture.

What can BIOGRUND’s flow agent CompactCel® FLO do?

See illustration: Pure MCC in the formulation leads to poor flow behavior of the powder mixture. CompactCel® FLO provides a remedy here. It reduces the Angle of repose and thus flows better than pure MCC. In addition, the use of SiO2 can be dispensed with.

Click here for product information about our CompactCel (Tableting) products.

CompactCel® FLO
Flow aid, glidant, free of silicon dioxide
A separating agent which loosens up powder mixtures and improves their flowability. It replaces synthetic ingredients like silicon dioxide – for a consumer-friendly label. CompactCel® FLO provides a clean funnel flow of the powder mass to be processed during both tableting process and capsule filling. A formation of bridge during flow from hopper can be avoided.

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Spalling of the film – possible cracking of the coating

Possible Reason:

– Tablet is swelling
– Plasticizer content in coating suspension is too low
– Tablet is too wet
– Tablet hardness is too low
– Tablet is outgassing


– Using a subcoat
– Increasing the plasticizer content
– Spraying with drier conditions
– Increasing the film forming polymer

Contact our experts for further tips.


Viscosity describes the viscosity of substances and gases (fluids). The higher the viscosity, the thicker (less flowable) the fluid; the lower the viscosity, the thinner (more flowable) it is.

Example: Water low, honey high.


The role of viscosity in film coating for solid dosage forms

How viscous should my coating suspension be? What happens if it is high or low viscous? What should I watch out for?

Too high a viscosity causes problems for the pump that sucks the suspension in for the coating process. If the product is too viscous, it cannot be processed.

When processing highly viscous polymers in suspensions, only small amounts of solids (e.g. 10 %) can be dissolved in the water. This has the consequence that the process time of the spraying process is extended, since only a small amount of solid material is applied to the end product (tablet, granulate, pellet).

If, on the other hand, low-viscosity polymers are used, a higher solids content of up to 20 % is achieved when suspending the coating solution, which also results in comparatively shorter process times. Because a lot of solid matter is applied to the tablet surface through the nozzle in a short time.
Coating suspensions with a viscosity of 200 – 700 mPa*s are easy to spray and apply to tablets. For polymer suspensions with a viscosity of more than 700 mPa*s, the spraying process is critical because pump problems can occur. While under 200 mPa*s insoluble components sediment in the suspension.

Examples of polymers with…

… low viscosity: polyvinyl alcohol-polyethylene glycol copolymer.
… high viscosity: hypromellose (HPMC)

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Individual tablets have heterogeneous colors

Possible reason:

– Application rate is to low
– API interacts with the coating material
– Low opacity
– Active ingredients diffuse from the core
– Over humidification


– Increasing the weight gain
– Adapting the formula or changing the pigments
– Increasing the coverage properties of the film coating formulation
– Using a sub coat
– Increasing the tablet bed temperature

Contact our experts for further tips.


Batch has heterogeneous colour

Possible reason:

– Coverage properties of the coating are insufficient
– Solid content of the suspension is too high
– Weight gain level is too low
– Batch quantity is too low


Increasing the coverage properties of the coating (more pigments)
Reducing the solid content
Increasing the weight gain level

Contact our experts for further tips.