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X-ray inspection of tablets and blister packages
Q: How can X-ray inspection ensure the integrity of tablets and their blister packages?
One broken tablet in a blister package of prescription or over-the-counter (OTC) medication can immediately cause concern, calling into question not only the efficacy of that tablet but also the manufacturer's quality standards. The same is true when even one cavity in a blister pack is empty.
Pharmaceutical companies recognize this and invest in inspection systems to ensure the integrity of their drug products and their packaging. These systems guarantee consumer safety, safeguard the manufacturer's brand reputation, and ensure compliance with governmental regulations.
One of the most effective of these tools is the X-ray inspection system, which is the only type of system that can simultaneously inspect both the drug products and the packaging at high production-line speeds after cartoning (photo).
X-ray inspection systems detect dense foreign bodies that can contaminate drug products, including metal, glass, calcified bone, mineral stone, and high-density plastic and rubber. They can also detect broken or missing tablets and improper or incomplete seals in packaging.
The system rejects nonconforming tablets and packages and removes them from the line to prevent them from reaching the marketplace. If not detected, these defects can result in losses from costly recalls, lawsuits, and damage to a brand's image that can take great effort to restore.
These inspections give manufacturers verifiable assurance that only properly filled packages of uncontaminated and unbroken tablets reach the consumer.
A tablet package usually contains several formed plastic sleeves of tablets, sealed with foil film. The X-ray system's beam uses a variable voltage to penetrate the outer packaging and sleeve and variable amperage to inspect the tablets for integrity and for potential contamination by metal or other materials.
The most advanced systems can be trained during setup using a sample package to automatically adjust the beam's voltage and amperage.
After the operator trains the system, it inspects packages accurately at high speed, rejecting those containing contaminated or missing tablets or faulty packaging and diverting the rejected packages into a lockable bin. This bin ensures that only qualified personnel handle the packages, which must be quarantined for quality auditing, and that packages cannot be inadvertently returned to the line.
Systems also often include reject verification. In the event of a package rejection, the system stops the machine and sounds an alarm if the reject-verification sensor doesn't detect a rejected product. This allows the quality team to review the issue and remove any nonconforming package from the production stream if necessary. In addition, the system's pressure-monitoring sensor will stop the machine and trigger an alarm if inadequate air pressure is available to remove defective products from the production stream. These verification features are essential to positively confirm that the system is operating as designed.
Data transfer and image capture allow the X-ray system to store time-stamped images of all rejected products. The quality team can then further investigate recurring issues within the upstream packaging process, where equipment may be misplacing tablets or damaging them during handling. By quickly detecting errors without destroying packaging, X-ray systems give quality teams the ability to diagnose challenges with greater precision.
In addition to inspecting the dosage forms, an X-ray system simultaneously inspects the packaging for proper forming, sealing, and filling of both individual sleeves and cartons. For example, the X-ray system can inspect a package of multiple stacked sleeves within a carton and detect a missing tablet or tablets in the third layer or a tablet broken or trapped in the seal of one of the sleeves. It can also detect whether each sleeve or the outer carton is completely sealed.
The system also records and stores all inspection data, including visual images of each inspection, both passed and rejected. This provides detailed information for continuous improvement programs or retrieval in the event of a recall or FDA inspection.
Some manufacturers have expressed concerns that radiation from X-ray inspection might damage or affect the safety of the drug products being inspected. However, scientific studies have revealed that exposure to X-rays has no effect on the pharmaceutical quality of inspected drug products.
For example, scientists at the Department of Drug Delivery and Nano Pharmaceutics at the Graduate School of Pharmaceutical Sciences at Nagoya City University in Nagoya, Japan, have conducted a study to investigate the effect of X-rays on the pharmaceutical quality of drug tablets .
The researchers exposed acetaminophen, loxoprofen, and mefenamic-acid tablets to X-ray doses ranging from 0.34 milligray (three times the typical dose of an X-ray inspection) to 300 grays (approximately 1 million times the typical dose of an X-ray inspection). Following exposure, the researchers evaluated the samples using formulation tests and found that exposure to X-rays didn't affect the pharmaceutical quality of the drug content.
Aaron Rossi is sales director, pharma, at Mettler Toledo Product Inspection, Lutz, FL. The company is a division of Mettler-Toledo and includes Safeline, Hi-Speed CI-Vision, and PCE. The division supplies metal detectors, X-ray inspection systems, in-line checkweighers, machine vision systems, and serialization and track-and-trace solutions.
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