More than simply fizzy

Published: 10-May-2018

Technologies to tablet effervescent products

Tableting effervescent products is a complex process. Yet, with the right technology, these tablets can be produced just as rapidly and safely as regular oral solid dosage forms. Romaco Kilian has the perfect solution for compressing effervescent formulations with maximum efficiency.

The Kilian KTP 590X single-sided rotary press is equipped with three separate compression stations

The Kilian KTP 590X single-sided rotary press is equipped with three separate compression stations

Children are particularly fond of effervescent products because, quite simply, they’re fizzy. As such, the beverage and confectionery sectors offer an enormous variety of products … as does the pharmaceutical industry, such as pain relievers, cough syrups or medications for the gastrointestinal tract.

A broad array of nutraceuticals is also available, often in several different flavours. The administration of water-soluble drugs is particularly recommended for children, the elderly or patients with swallowing difficulties or a sensitive stomach.

Tablets with complex demands

Effervescent tablets offer many consumer benefits; but, manufacturing and processing these hygroscopic products inevitably presents a number of complicated hurdles to overcome. By their very nature, effervescent tablets react extremely vigorously with air, light and moisture.

In addition, many of the active pharmaceutical ingredients (APIs) and vitamins processed in effervescent formulations are readily affected by heat. Furthermore, effervescent tablets tend to be friable and susceptible to breakage. All these factors must be considered when tableting effervescent powders. The Romaco Kilian KTP 590X tablet press is tailor made for these kinds of applications.

Gentle compression

Effervescent tablets are naturally prone to unwanted air pockets and capping, which is why the tableting process takes place in three steps. The Kilian KTP 590X single-sided rotary press is consequently equipped with three separate compression stations. The first compression roller simply tamps the powder. Next, the tablets are precompressed; in the third step, they are converted into finished products in the main compression unit. The use of Kilian 28/41 tooling simultaneously extends the dwell time, meaning that harder tablets can be made because there is more overall time for deaeration. This stops the tablets from bursting during subsequent processing steps.

Smoother than ever

Effervescent powders are hygroscopic and demonstrate poor flow properties. As such, the fill shoes and paddles of the tablet press must be designed to accommodate efficient filling and uniform distribution within the die. The powder can also be lubricated with magnesium stearate to prevent the product from sticking to the tooling. An external lubricant supply system sprays the punch tips and the die walls during the production process. This has the advantage that the lubricant no longer has to be mixed into the product beforehand. Much less material is required for external lubrication and harder tablets can be achieved as a result, which improves the overall quality of the end product. What’s more, external lubrication protects both the product and the machine by reducing the tablet ejection force. Effervescent tablets that are lubricated using an external system have a smoother surface, contain less magnesium stearate and dissolve in water without leaving a greasy film, much to the delight of the consumer.

Cool machines

Extremely low temperatures are essential to process temperature-sensitive medications. The process temperature of the tablet presses in Romaco Kilian’s KTP X series is therefore kept at a constant level — below 30 °C. To reduce heat input, the compression rollers are fitted with smooth-running bearings and the fill shoe gear is mounted externally. A special cooling ring, situated underneath the die table, acts as a thermal barrier. Additionally, the low temperature in the service area is maintained by the torque drive’s efficient cooling system. The brake magnets also play a crucial role here by eliminating frictional heat and protecting the material. Thus, there’s no need to install an additional cooling unit when tableting temperature-sensitive products.

Fast off the mark

If effervescent tablets are to be manufactured efficiently, it is vital to optimise the retooling and cleaning times. The number of product-contact parts in the tablet presses has been systematically reduced by Kilian for this very purpose. Furthermore, the die-table, tablet chute and fill shoe can be swung right out for easy access to all components.

Format changes can be completed without any additional tools. At the same time, the start-up dosing control based on the filling parameters shortens the run-in times and avoids material loss. The OEE (overall equipment effectiveness) of the tablet press can be significantly improved under these conditions.

Depending on the formulation, the Kilian KTP 590X achieves an output of up to 290,000 effervescent tablets an hour with mono or bilayer formats; the single-sided rotary press manages a maximum hourly output of 511,200 tablets.

Clean performance

Manufacturing effervescent tablets is an extremely dusty affair. Hygienic design is all the more important to keep unwanted dust formation in check. The compaction, retooling and service areas of the KTP 590X are strictly separated for precisely this reason. This prevents tablet dust from entering the machine compartment or, in the opposite direction, machine oil from contaminating the product. A patented punch bellows surrounds the upper and lower punches and protects the tablets from impairments in the form of black spots.

The closed system, made from an elastic synthetic material, is ventilated by means of holes in the die table. The press’s fill shoe and tablet chute are fully washable and easy to clean. The concentration of particles in the production environment is greatly reduced by the dust-tight tablet chute. In short, Kilian’s hygiene concept ensures reliable processing and reduces the risk of cross-contamination to a minimum.

Kilian’s hygiene concept ensures reliable processing and reduces the risk of cross-contamination to a minimum

Kilian’s hygiene concept ensures reliable processing and reduces the risk of cross-contamination to a minimum

Safe processing

Once the effervescent tablets have been compressed, they must be further processed according to the specific application. Owing to their chemical and physical properties, effervescents are not stored in a buffer container but transferred directly to downstream packaging machines. A special transfer station developed by Romaco conveys the fragile tablets from the press to the primary packaging unit.

The tablets are fed from the press scraper directly to a high-speed Kilian conveyor belt. Tailbacks of tablets at the press discharge area are prevented by acceleration, so that the products are removed and separated gently. This enables selective sampling before the tablets are distributed by a rotary table to the primary packaging machine’s conveyor belt.

On their way to this machine, they pass via two more stations for dust aspiration and breakage elimination. Effervescent tablets are normally packed in strips or tubes. The Romaco Siebler brand includes both heat-sealing machines and tube fillers. Together with Kilian presses, these two product lines form a functional unit to manufacture and package effervescent tablets. Romaco’s effervescent portfolio is optimally complemented by Promatic cartoners and case packers.

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