Exploring new dimensions in texture analysis

The way a tablet feels in the mouth is important in ensuring patient compliance. Thus, textural analysis is seen as a way to improve product quality and gain market share

For decades, drug manufacturers have attempted to understand why certain products are more easily accepted than others.Working with universities and commercial research departments, pharmaceutical companies are increasingly looking at ways of measuring certain product characteristics that impact on quality and can affect the efficacy, safety and customer acceptance of a product.

Drug administration, interactions and side-effects are well established areas of research, but texture is another aspect that has proven critical to overall performance of pharmaceutical products. Today's ever-changing market climate is dominated by stringent legislative and consumer demands, as well as increasing involvement from patients in areas such as self-prescribing.

watching and listening

Constant testing, re-evaluation and new product developments are demanded to meet the trends. As a result, new dimensions of texture analysis are being explored to further improve product quality, gain competitive advantage and increase market share.

Two recent developments in this field are the analysis of acoustic emissions from solid products during deformation, and the video recording of the test during texture measurements to supplement traditional force-distance -time information. The following article explores these areas in more depth, explaining how they can be used to gain maximum commercial benefit.

Analysing the sounds emitted from products can provide vital information on actual and perceived product quality. When solid pharmaceutical products, such as chewable vitamins, painkillers and indigestion tablets, are crushed through mastication or mechanical testing, unique sounds are emitted by the fracture event(s). These noises play a major role in determining the consumer's perception and acceptance of a product.

Every product has its own particular acoustic characteristics and the level or type of noise produced can determine the consumerÕs acceptance or rejection of it, as well as giving an indication of its behaviour under compression.

Acoustic analysis can therefore help manufacturers identify and analyse the sounds emitted from products and the results used to improve texture, change formulations etc.

Until recently, there have been few developments in instrumentation designed specifically to analyse acoustic emissions. Manufacturers have traditionally used mainly force- distance-time data, or relied on makeshift methods and tools that are inaccurate or incompatible with existing texture analysis equipment.

acoustic advantages

Today, however, significant advances have been made to enable the measurement of acoustic emissions alongside traditional force-distance-time data - so providing accurate and realistic results. This technology can be used in conjunction with existing analysis equipment and offers many advantages:

• Unwanted background noise can be omitted. Sophisticated equipment will discriminate between the sounds emitted from the product and mechanically-generated noise, so only the relevant acoustic emissions are recorded.

• Force and sound profiles from individual tests can be synchronised, so the resulting curves are analysed simultaneously. The relationship between acoustic and force events can then be easily identified.

• The tests themselves and sound acquisition can be handled automatically by software incorporated into sophisticated texture analysis machinery. This saves time, facilitates use and increases accuracy.

• Data can be saved in smaller files to aid the interpretation of test results - previous means of acoustic data collection that have not used fully integrated or compatible equipment have often produced unmanageable files, sometimes of several megabytes.

One of the most recent developments in acoustic measurement is the Acoustic Envelope Detector from Stable Micro Systems. Attached to the company's existing TA.XTPlus texture analyser, the new equipment enables manufacturers to record and analyse acoustic data simultaneously with other information. This is facilitated by the instrument's advanced software, Texture Exponent, which synchronises the collection of data during an experiment. The result is a more synergistic and detailed analysis of a productÕs structure and consistency.

accurate analysis

While the measurement of acoustic data is emerging as a test method in its own right, improvements are also being made to help manufacturers collect and interpret other test data. One of the most recent innovations in this field is instrumentation that synchronises video recordings with the corresponding force-distance-time data, so a more detailed and accurate sample analysis can be achieved.

Capturing texture analysis on video offers genuine benefits to manufacturers. Crucial visual elements of an experiment can be easily missed by the human eye, due to the rapid speed of the test or to the complex breaking pattern of the sample; brittle products, for example, break very quickly. Video recordings allow manufacturers to replay a test at their own speed at a later date if required. Supplemented by force-distance-time data captured in the same test, a more in-depth product analysis could be achieved.

new technology

However, interpreting visual and graphical information after an experiment has taken place can prove difficult if the data are not synchronised.

Correlating the peaks and troughs of a force-distance-time graph, for example, to specific moments in the test can be tricky, even if the experiment has also been captured on video.

This is particularly true for products that have uneven textures or that break quickly in a complicated manner. Certain tablets or capsules, for instance, consist of a range of textures and each component produces its own event on a graph when broken during an experiment. With new technology, manufacturers can play back each frame of a video recording with the corresponding point on the force-distance-time graph, so a more accurate interpretation of the test can be achieved.

Testing the product at a later date to iron out these inconsistencies is often unfeasible due to the sample not being available or to time limitations. Using synchronised visual and graphical data, irregularities in test results can be more easily identified without the need for re-evaluation, so any misleading information could be eliminated from findings.

Currently, Stable Micro Systems' Video Playback Indicator is the only simple device on the market that enables manufacturers to replay visual recordings frame by frame, simultaneously with the corresponding force-distance-time graph.

Data collected through the machine is processed by the Texture Exponent software supplied with the analyser. As the instrument begins collecting data, a signal is relayed to the video playback indicator that prompts an LED light source. The display of this light is captured on the video that is already recording the test.

When replayed later, this light indicates the beginning of the data capture, enabling the frame at this point to be matched to the beginning of the force-time curve. Thus video frames can be synchronised with the matching points on the force-time graph, facilitating the interpretation of test data.

accurate and objective

In recent years, technological developments in the field of texture analysis have helped pharmaceutical manufacturers improve product quality and performance. In order to keep pace with the changing needs of todayÕs rapidly evolving market, manufacturers must continue to seek innovative ways to improve their products.

The emergence of advanced acoustic analysis and video playback instrumentation is enabling manufacturers to investigate new dimensions in texture analysis. Using this ground-breaking equipment, they can achieve more accurate and objective test results that facilitate improvements and boost commercial success.