Quality Is in the Eye of the Inspection System

Nov 12, 2008

Final bulk inspection helps ensure the high quality of solid-dose pharmaceuticals. Until recently, automated inspection of solid-dose pharmaceuticals was crude, expensive, slow, and difficult to change over. But technological advances have ushered in a new class of vision-inspection systems that is more effective and more commercially viable than older systems.

Single-file optical-inspection systems
For the past 20 years, the best technology for automated inspection has been single-file (or single-stream) optical-inspection systems. These systems are highly effective in detecting and ejecting defective products and foreign matter based on differences in size, shape, and color. Single-file inspection systems carry solid-dose products individually past cameras placed above them and alongside them. The system then turns products over to inspect their bottom surface.

Despite its efficacy, this technology has not been widely adopted because of its limited commercial viability. The drawbacks of single-file optical-inspection systems include high capital costs, low throughput (often around 50,000 doses per hour), the need for many expensive change parts, and changeovers that take as long as eight hours. These systems are implemented only when the need to ensure the highest product quality outweighs other commercial considerations.

Bulk optical-inspection systems
Although the first bulk optical-inspection system for pharmaceuticals was introduced recently, similar technology has been successfully adopted in a majority of the food-processing industry for more than 20 years. Similar to single-file optical-inspection systems, bulk optical-inspection systems effectively detect and remove defects and foreign matter based on differences in size, shape, and color, but they don’t require products to be oriented in a particular way before inspection.

Bulk inspection systems feature excellent, high-resolution color cameras that detect subtle differences between tablets. The systems cost roughly one-third the price of single-file systems. Bulk optical-inspection systems also are more efficient than single-file systems. The former achieve throughputs as high as 1 million tablets or capsules per hour and can be cleared and cleaned in less than five minutes.

The benefits of bulk optical-inspection systems
A bulk optical-inspection system’s high-performance color cameras perform objective and consistent in-line inspection, thereby ensuring high final-product quality and maximizing production throughput. The system also provides many benefits unrelated to product quality such as reduced labor costs, faster changeovers, greater yield, reduced capital costs, and simplified operation. In addition, the system can be integrated with continuous size-grading, polishing, and packaging technology to provide a complete, continuous-processing solution.

As tablet and softgel dosage manufacturers automate their production lines, they are replacing batch processes with continuous processes because the latter reduce labor and work-in-process inventory. Bulk optical-inspection systems enable the shift to continuous processing and, when combined with other continuous components, achieve fully automated, high-throughput finishing lines.

In addition, modern bulk optical-inspection systems may potentially be part of a company’s efforts to incorporate manufacturing based on the US Food and Drug Administration’s process analytical technology initiative. Because the systems continuously capture real-time data about products on the line, they allow manufacturers to improve upstream operations.

Selecting an optical-inspection system
To achieve the operational advantages described above, manufacturers must consider various criteria when selecting an optical-inspection system. A system must be validated to meet FDA requirements, including 21 CFR 11, and comply with good automated manufacturing practice guidelines.

A system that offers ultrahigh resolution (i.e., 0.18 mm2 pixels) can detect and remove foreign capsules and those with small color and shape defects (e.g., air bubbles, stains, and deformities). A system with four cameras, located both above and below the product stream, views the product from all sides and provides excellent inspection. Such systems can examine as many as 1 million tablets per hour.

Bear in mind that the system’s effectiveness relies not only on its hardware, but also on its software. Algorithms that define acceptable and unacceptable product greatly influence system performance.

Equipment vendors should also be evaluated. Vendors’ experience and success with optical-inspection systems and the pharmaceutical industry indicate their ability to deliver systems that achieve optimal performance. Vendors should be able to help develop and execute the required qualification protocols. Manufacturers should also consider vendors’ services, including engineering, validation, and support.

Modern bulk vision-inspection systems designed specifically for solid-dose pharmaceuticals will likely assist the industry by enabling continuous processing. Because these systems ensure final-product quality and are commercially viable, both in terms of production throughput and capital costs, they appeal to product manufacturers and contract packagers that seek to deliver consistently high product quality and reduce operational expenses.

Jon Donovan is a product manager at Symetix, 150 Avery St., Walla Walla, WA 99362, tel. 509.394.3321, fax 509.394.3219, jdonovan@symetix.com.