Bespoke solutions

Ron Garwood of Electro-mec looks at how increasingly sophisticated tablet manufacturing processes are leading to a proliferation of bespoke handling systems

Blisterpack filling has always been a critical part of the tablet and capsule manufacturing process. With the high cost of product development, plus the risk that after all this work the drug might not gain final regulatory approval, the importance of maximising throughput and efficiencies once a drug is in production remains paramount. Shorter production runs, necessitating more frequent pack changeovers, are another result of commercial pressures.

Advances in manufacturing techniques can also influence handling and filling requirements. Tablets and capsules vary from standard round bi-convex tablets to flat or elliptical and multi-faceted shapes in a huge range of sizes.

precise tolerances

In many instances the manufacturing tolerances are so precise that avoiding even minor damage to the tablet or capsule during filling is critical. And even the most basic products are prone to chipping or breaking if not handled correctly.

Blisterpack layouts contribute to the challenge as well. While there has never been a standard format, since it is the flexibility of the blister that is its greatest asset, designs such as the chevron layout, which increases the number of tablets that can be included in the blister, or a 'looped' cycle format, where the first dose is isolated from the rest of the pack, need special handling. Packs that contain two or more different tablets for combination dosage are also increasingly common.

For filling equipment suppliers the major requirement has been to combine high packing speeds with pinpoint accuracy and careful handling. This in turn has resulted in a marked increase in the development of bespoke systems.

Typical requirements include the simultaneous feeding of different products into one blisterpack - achieved by separate control of each tablet, dedicated change part tooling and the positioning of multiple feeders over a single blister forming machine or creating split hoppers to allow multi-product feeding from a single feeder.

Individual feed systems, where tablets are handled literally one by one during the filling of each blister form, help to tackle the problems of chipping and shingling. Dust extraction units remove dust that accumulates on the blister form during the filling operation, which can affect the sealing process.

accurate placement

However, in addition to feeding product into thermoformed packs, more recently there has been an increase in secondary packaging requirements.

The card wallet presentation is well established, particularly for clinical trial studies, but novel marketing solutions to give increased integrity or heightened consumer presentation have generated the requirement for special feeding and handling systems that incorporate bulk segregation and pick and place with robotic motions.

A recent example from Reading-based Electro-mec is where its ability to ensure accurate placement of tablets into blister forms has been adapted to prepare a particular tablet for further processing. In this instance, Electro-mec created a special handling system to place individual tablets accurately into a plate with a clearance of just 0.1mm per tablet in readiness for a secondary process. The requirement was to take tablets supplied in bulk and position them for a special coating.

Accurate placement onto the special slave plate was of paramount importance but so too was the need to maintain throughput speeds. The system also had to handle gently different tablet and capsule shapes and different patterns on the plates.

pick and place

The solution involved utilising and combining proven handling and filling methods such as brush box and pick-and-place technology.

Tablets are initially fed in bulk through a brush box system, which guides them into a preset pattern on a holding plate. From here a pick-and-place system using vacuum suction transfers the tablets to the dedicated slave plate, positioning them to within 0.1mm, a level of accuracy essential for the subsequent processing to be achieved successfully. Stepper motor control ensures consistent and reliable operation.

A total of 460 tablets are positioned in each 17-second cycle, thereby allowing 95,000 tablets an hour to be processed.

In another application, blisterpacks were required to be inserted into a sealed sachet. The packs are orientated through vibratory bowls, positioned into a drop chute and gated into the sachet on demand.

A unique stepper motor driven rotating turret with vacuum modules is used to transfer the packs from stop and release gates. The system is twin lane with each lane feeding above 80 packs per minute.

A separate development has been the adoption of blister filling methods for other pack formats. Recently, for example, Electro-mec used its existing counting technology as the basis to devise a bespoke system, with dedicated software and infra-red scanning, to control a filling operation and guarantee the correct number of items in pharmaceutical bottles for the Japanese market.

What these examples demonstrate is how the need for accurate tablet filling has now widened into a more general requirement for efficient handling throughout what are becoming more technically involved manufacturing and packing processes. At the same time, essential elements such as accuracy, speed, gentle handling and flexibility remain as vital as ever.