FDA backs tablet imaging tech

In the study, published recently in the Journal of Pharmaceutical Sciences, the FDA aimed to determine whether coating thickness of delayed-release tablets, such as Procter & Gamble's ulcerative colitis and Crohn's disease drug Asacol (mesalamine), accounted for the tablets dissolution behaviour.

The agency used TeraView's Terahertz pulsed imaging (TPI) technology and concluded: "The speed and ease of TPI mapping may make it an attractive replacement for wet dissolution testing both in product development and eventually for process analysis."

TeraView chief scientific officer Professor Sir Michael Pepper said in a statement: "This study demonstrates that Terahertz technology has a potential role to play alongside dissolution in the optimisation of therapeutic effectiveness of dosage forms during product development and stability assessment, as well as routine assessment of production quality to ensure uniformity between production lots."

The study focussed on Asacol delayed-release tablets which use a special coating designed to breakdown and release the drug in the lower intestinal tract, but the tablets were found to dissolve erratically during conventional wet dissolution measurements.

TPI technology was therefore used to map the coating thickness and the researchers found the mean dissolution times, or drug release, correlated with the average coating thickness.

"Additional studies are required to demonstrate and understand to what extent Terahertz can be used alongside dissolution in other contexts.

However, the evidence here suggests that our Terahertz products have the capacity to reduce drug development times and help ensure in-spec performance of product, thereby minimising the risk of regulatory non-compliance for the industry and more rapidly providing consumers with improved pharmaceutical products," TeraView chief executive Dr Don Arnone said in a statement.

TPI technology works by mapping the three-dimensional variations in the thickness of the tablet coating by using a pulse of terahertz radiation, which is reflected by the internal layers of the tablet.

The time-delays of the reflected pulses build up a picture of the internal structure of the tablet.

The terahertz radiation falls between the infrared and microwave regions of the spectrum but does not generate the power to destroy the tablet - unlike wet dissolution testing.

Dissolution technology is commonly used by the pharmaceutical industry to check the performance of the tablet, but has its limitations such as the inability to check all tablets particularly during manufacture.

In the past, near infrared (NIR) and Raman spectroscopy have been used to study tablet coatings, tablet dissolution and batch uniformity, the FDA study said.

While TPI provides similar information to NIR and Raman spectroscopy, TPI has the ability to map the thickness of the entire tablet surface, as well as the tablet core.

"The FDA's view that Terahertz could be used as a tool to ensure in-spec and safe controlled release products, has crucial significance for safety and quality.

It is a green light for Terahertz imaging . . .

and heralds the wider adoption of Terahertz imaging by the industry," the company said in a statement.

The company was happy to work with EU regulators if they wished to investigate applications of the technology, a TeraView spokeswoman told in-PharmaTechnologist.com.

The technology is already used by GlaxoSmithKline, Pfizer, AstraZeneca and Takeda.

The development and use of delayed and controlled release oral formulations is expected to increase from 15 per cent in 2003 to 25 per cent by 2010.