The Need For Automated Pharmaceutical Label Inspection Systems
Much attention has been given to the recent final ruling1 by the Food and Drug Administration (FDA) amending the current Good Manufacturing Practice (cGMP) for drug product labeling control. The changes are intended to reduce the frequency of drug product mislabeling and associated drug product recalls. Suppliers of packaging and labeling machinery are endeavoring to assist pharmaceutical packagers to comply with the newly revised regulations by providing, among other things, automated inspection using bar code readers and machine vision systems. These inspection systems typically read bar, matrix or date & lot codes to ensure that the correct label is being applied to the correct container and that the correct container and insert are placed into the correct carton. These simple inspection devices do not, however, ensure that all the information printed on the label, insert and carton are correct and complete.
By the time labeling material reaches the packaging line, it must have already been carefully scrutinized to ensure that each and every label is printed properly and that all the printed copy on every label is present and legible. To date, the process of visually inspecting pharmaceutical labels has been performed by human operators. Unfortunately, human inspection is labor-intensive, tedious and prone to errors. This white paper describes PharmaVision, an automated machine vision system that enables high speed, 100% verification of all of the printed information on every label prior to its use on a packaging line.
Table of Contents
The Need for 100% Print Label Inspection
The newly revised cGMP for labeling control is intended to minimize the likelihood of a labeling mix-up. It is imperative that the correct label be applied to the appropriate drug product. It is equally important, however, that all of the printed information on every label be complete and legible. Of particular importance is the legibility of the list of ingredients, directions for use, and dosage information.
Occasionally, the printing process will create print defects such as broken or missing characters, smudges, and ink splashes. These print defects can obscure or obliterate critically important textual information on the product label. For example, a portion of a drug product label may contain a serious print defect in the dosage information, such as a missing decimal point. This would result in a 2.5 ml dose being misread as a 25 ml dose.
The Missing Decimal Point - A Critical Print Defect
This type of print defect can cause a drug product to be unintentionally misused and the consequences may be hazardous, even fatal. The regulations for cGMP require that, "Labeling materials issued for a batch shall be carefully examined for identity and conformity to the labeling specified in the master or batch production records."2 This requirement is not diminished by the recent FDA ruling. In order to ensure that every label is without flaws in the printed information, 100% full visual verification of all the printed information on every label is required.
Focus Automation's WebScan 2000
The Manual Method of Print Verification
Today, both pharmaceutical label printers and drug product packagers perform manual visual inspection at one or more stages throughout the label production process. However, both printers and packagers rely on human inspectors to visually inspect every label to ensure that they conform to the master label. At the label printer's shop, manual visual inspection may be performed at various stages throughout the label production process. While printing, the press operator periodically observes the printed web to ensure that the press is operating correctly.
The press operator may be aided by the use of a strobe light or a video web viewer to freeze an image of the continuously moving web. At the slitter/rewinder used to slit the printed web into individual rolls, the machine operator may also perform a partial visual inspection of the labels using a strobe light. Before shipping the finished labels to the customer, each roll of labels is given a final manual inspection using a dedicated inspection rewinder, however none of these inspection methods can guarantee that every label is entirely perfect.
Pharmaceutical packagers often visually inspect all incoming roll labels. Each roll is unwound using an inspection rewinder equipped with sensors to count labels, check for missing or torn labels and, optionally, verify each bar code. Unfortunately, none of these sensors are able to inspect all of the printed copy on every label, so the rewinders must be equipped with a strobe light to enable a human operator to try to visually verify that the printed information on every label is correct. Obviously, this is a very difficult task for a human inspector to perform at high rewinder speeds.
Limitations of Manual Print Verification
There are several problems associated with manual inspection of pharmaceutical labels. Human operators are severely limited in their ability to perform visual inspection at any appreciable speed. A typical inspection rewinder can move labels past the operator's visual inspection station at speeds up to 850 feet per minute (170 inches per second). This means that, for a typical pharmaceutical label that is 1 to 2 inches long, the operator must visually inspect all of the printed information at upwards of 150 labels per second (the operator sees each label for less than 10 milliseconds). The human eye can not discern more than 30 different images per second, and certainly can not give careful examination to every minute detail of the printed information on every label.
At this high rate of label presentation, the inspection operator is only able to detect gross print errors that are repeated over many labels. Small but critical print errors and errors that occur on only a few labels can not be reliably detected using manual visual inspection. In order to maximize the effectiveness of manual visual inspection, it must be performed at low speeds, which means that inspection takes more time and is therefore more expensive. Also, even at web speeds as low as 25 feet per minute, the task of manually inspecting printed labels is very tedious and the inspection operator is subject to rapid fatigue, which further reduces the effectiveness of inspection. Compounding this problem, drug product manufacturers are including more and more information on product labels.
In order to incorporate all the required information on a drug product label, smaller and smaller type must be used. The combined effect of more information printed in smaller type is that the print verification task is becoming increasingly more difficult for human visual inspectors.
Benefits of Fully Automated Print Inspection
The task of label print verification can greatly benefit from the application of machine vision technology. An automated 100% print verification system overcomes many of the problems associated with manual visual inspection and provides the following benefits:
- increased security by performing 100% vigilant inspection of all print on every label
- higher productivity due to faster inspection speeds
- improved quality through finer inspection resolution detecting subtle defects
- consistent inspection that is not degraded over time by fatigue
The WebScan in operation
In order to perform 100% fully automated print verification, PharmaVision performs the following tasks:
- acquires high resolution images of every label on a fast, continuously moving web
- examines every label and compares it to a "golden" standard
- produces inspection results in realtime
- presents defects to the inspection operator for removal
- re-inspects defect area to confirm error-correction
- adapts easily to a wide variety of label sizes, label stock and product styles
PharmaVision performs all of the above with an industry tested, user-friendly graphical interface, award winning documentation, and a sales-support team committed to customer satisfaction.
References
1 Federal Register, vol. 58, no. 147, Tuesday August 3, 1993.
2 21 CFR Part 211 section 125 paragraph (b), Office of the Federal Register, National Archives and Records Administration, U.S. Government Printing Office, Washington, DC, 1994.
For more information: Mandy Weeber, Focus Automation Systems, Inc., 101 Randall Dr., Waterloo, Ontario, Canada N2V 1C5. Tel: 519-746-1100. Fax: 519-746-1170.