Automation the buzz word

"The challenge before manufacturers of tablet machines and tools is to satisfy consumer demands and develop technology to support the same" - Mahendra Mehta Director and CEO Parle Global Technologies

Among solid dosage forms, tablets are the most preferred form of medication as they ensure a high level of patient compliance, a certain degree of manufacturing efficiency and high-precision dosing. Injectables are associated with pain and inhalation devices require a certain amount of expertise and practice.

Though the basics of tablet technology have not changed much in the past decades, modern machines have higher levels of automation. Therefore, the instrumentation is more and the machines look more sophisticated. In such a scenario, what are the trends driving developments in the tablets segment?

As with most industries, consumer behavior patterns have driven technology changes in this sector as well. According to Mahendra Mehta, Director and CEO, Parle Global Technologies, "Tabletting has undergone rapid changes due to ever changing market demands. Today the patient needs dosages in various forms and strengths." For instance, a patient might prefer to have a single tablet of 500 mg instead of two 250 mg. Conversely, in some cases, you would like the tablets to break equally into two or four parts allowing the patient to use a single tablet in a day, three-four times a day.

Giving further examples, Mehta points out that we now see the trend of two-layered, three-layered tablets where two or more ingredients can be compressed in a single tablet. Also consumer pattern and liking are varied and you will find tablets in various shapes like heart shape, triangle, tablet with a hole etc to satisfy the consumer demand. Therefore, the challenge before manufacturers of tablet machines and tools is to satisfy these demands and develop technology to support the same.

In response to these demands, Mehta says that tablet presses of today are versatile and geared up to offer flexibility through double/triple rotary presses, tooling with special design, multi-tips for making pellets through tabletting etc.

A general survey of industry professionals reveals that the increased automation, driven by the necessity of cutting labor costs and upgrading to the standards required by exports, has been the dominant trend. Conventional planetary mixers have been replaced by Rapid Mixer Granulator (RMGs), which have capacities of more than 500 kg. Fluidised bed driers (FBDs) having a single loading capacity of 200 kg has enabled manufacturers to increase their manufacturing capacities many times over.

Increased batch size and fully automated systems have reduced product/batch changeover times. Octagonal blenders having a capacity of more than 500 kg is very useful for lubrication purposes are opted by most manufacturers. Compression machines have become all the more sophisticated. The seventies and eighties had 16-station, 35-station, 45-station machines which have been replaced by 61-station Rota presses giving outputs of more than 4600 tablets per minute. Modern rotary machines give production rates greater that a million tablets per hour, which can be boosted, using multiple tools per die, to tens of million tablets per hour.

So also, conventional 36-inch coating pans have been replaced by 48/72 inch coating pans which have considerably increase coating capacity. Packaging machines have become all the more sophisticated. Emphasis is being applied to blister packaging machines though certain products continue to be strip-packed. Modern strip-packing machines have six tracks, giving more than 150 strips per minute. Blister packing machines have also moved towards more sophistication. Today they are fully automated with integrated blister-cartoning operations, colour cameras and pharma-code detection systems for on-line inspection and high levels of GMP compliance.

Future trends include enhancing tableting technology with ultrasound during tableting to give better compactability and a novel centrifugally fed tablet machine. Another technology is the electrostatic deposition of the drug substance onto a film substrate. Here, dosing is controlled by applying an electrostatic charge to spots on the film so that a cloud of oppositely charged drug particles deposits the target dose at point-of-charge neutralisation. The drug-loaded film is laminated to seal the deposited doses, which can then be punched out and encapsulated or embedded in a tablet.

Regulatory push

Changes in tablet technologies are also in response to the regulatory pushes like the US FDA drive to reduce manufacturing inefficiencies. Under the PAT initiative, the FDA is encou-raging innovation and improvement in all manufacturing processes across the industry.

PAT is a general term covering the application to drug manufacturing of process analytical chemistry tools, feedback process controls, information management, and product/process optimisation. The implementation of these technologies involves the online measurement of quality and performance together with multivariate statistical and pattern recognition methods.

As per the conventional approach of testing, quality is tested after each stage of manufacture. Only after it passes muster, can it go to the next stage. This means that tablets could spend more time awaiting test results and subsequent release than it takes to actually make them. The PAT initiative attempts to drive intrinsic quality using nonparametric release, which is a challenge for the tablet making process, as most test methods involve the destruction of the test sample. Therefore, these test methods, ie disintegration, dissolution, and hardness) do not lend themselves to on-line testing.

The PAT method uses nondestructive testing methods, like testing tablet hardness using near infrared (NIR) spectroscopy. PAT may pose challenges to some tableting processes, however, if the insight gained is not matched by commensurate process control. Closer scrutiny could reveal variations in existing products missed by current sampling and testing.

Tablet machines of the 21st century

What will the tablet machines of the 21st century look like? Mehta hazards a guess. Tablet presses of the fifties were a mechanical assembly of parts to do the function of the compression of the powder to a tablet form. It was highly man dependent for the quality control and productivity.

Mehta says that as of today and in the future, what we see is a sophisticated servo driven and electronically controlled man less operation, where data of the operation is controlled over LAN/WAN by a central production console. "The rejection monitoring and productivity will be programmable and once loaded will run by itself. With the accessories of automatic powder loaders, metal detectors, transfer conveyors etc the tablet machine of the 21st century will be no less than an electronic gadget with mechanical components amounting to not more than 30 percent of the total equipment," predicts Mehta.