The Evolution of Imprint Identification

Pharmacy Times
Volume 0

The ability to quickly identify a tablet ingested by a patient can potentially mean life or death. Personnel at poison control centers and hospitals, medical professionals, and others previously had a difficult, if not impossible, time identifying drug products. The reason was that drug product identification-data submissions by companies involved in the manufacturing or distribution of drugs were not mandatory. As a result, a comprehensive list of products and their respective imprint information was not collected and therefore not available to members of the public and the medical community.

In 1986, the FDA began gathering limited imprint information from voluntary submissions by drug manufacturers and distributors. The Division of Drug Information organized and stored the imprint data. In order to retrieve imprint codes and respond to imprint queries, pharmacists had to search manually. The system was inefficient and time-consuming.

History of Imprint-Code Regulations

Prior to 1995, there were no federal regulations addressing imprint data on solid oral-dosage forms of prescription drug products. Approximately 23 states had existing state laws requiring the imprinting of prescription drugs. There also were no requirements addressing imprinting of OTC drug products. Professional organizations such as the National Association of Pharmaceutical Manufacturers, the Consumer Healthcare Products Association, and the American Medical Association petitioned the agency to mandate a requirement for a coding system for solid medication forms.1

Federal regulations implemented in 1995 required imprinting of solid oral-dosage forms for most prescription, OTC, biologic, and homeopathic drug products.2 Exemptions to the regulations are summarized in Table 1. The rule requirements alsostated that an oral-dosage-form drug product would not be "introduced or delivered into interstate commerce" unless it had an imprint code recorded, along with its size, shape, and color. This information would allow unique identification of the drug product and its manufacturer or distributor. A drug product not exempt from the regulation or not able to meet the imprint requirements could be considered adulterated, misbranded, or an unapproved drug.2 In light of these directives, the FDA's Center for Drug Evaluation and Research (CDER) created an imprint database to process the large increase in the number of imprint-data submissions, as well as the increasing number of requests for such information from health care professionals, caregivers, and patients.

Since 1986, CDER's database has grown to include >30,000 imprint records.3 Maintained by CDER's Division of Drug Information, the database has become the focal point for product-imprint information. The division provides prompt and reliable service to health care practitioners, consumers, and other customers across the country.

Imprint Codes

The federal regulations allow a drug firm to use its own system to convey enough information about the drug to allow for identification. Products marketed in multiple strengths are required to be distinguishable from each other. An imprint code may consist of any single letter or number or any combination of letters, numbers, marks, or symbols. The imprint code may include words, the company name, all or part of the National Drug Code, or a monogram. Firms that use product logos or symbols are encouraged, but not required, to include some of these elements. Homeopathic drug products are required only to bear identification of the manufacturer and the homeopathic nature of the product.2

Principal Functions of Imprint Codes

Imprint codes serve multiple public health functions for health care professionals, law enforcement officers, regulatory authorities, and the lay public. Identification of oral-dosage forms can do the following:

  • Lead to quick determination in cases of overdose
  • Enable differentiation between unknown drug products
  • Empower patients to be able to ascertain whether the correct medications have been dispensed

Table 2 summarizes functions of imprint codes.

Exemptions to Imprint Code Regulations

As mentioned earlier, there are exemptions to the imprint code outlined in the federal regulations.2 Examples of exemptions are as follows:

  • When the physical characteristics of the drug product make it impossible to imprint
  • When the medication is dispensed in a controlled health care setting (eg, in a physician's office)
  • When the drug is not dispensed to patients for self-administration

These exemptions are reviewed on a case-by-case basis when the manufacturer or distributor of the drug product provides evidence supporting the exemption to the FDA. There also are entire classes of drugs that have been exempted by the rule (Table 1).

Data Collection and Retrieval

The FDA does not evaluate or approve imprint codes. At this time, there is no standard government form to collect imprint code data. The FDA requires drug firms only to provide their imprint information, along with their listing forms, to the agency's Drug Listing Team, where it is entered into a database. The data captured include identifiers such as shape, size, color, imprint code, scoring, and coating. The database also incorporates imprint graphics, which describe a logo that does not consist of conventional characters (eg, mortar and pestle, hourglass). Figure 1 illustrates the data-entry fields for imprint information. The implementation of the automated database helps one conduct a timelier and more comprehensive search.

Imprint-Code Requests

The Division of Drug Information currently responds to >200 requests for product identification per month from across the United States.3 Calls are received from other government agencies, hospitals, pharmacies, drug information centers, poison control centers, pharmaceutical firms, quality assurance departments, and crime laboratories. Calls from poison control centers account for the majority of requests (29%). Other calls are from health care professionals (23%), drug information centers (22%), police crime laboratories (12%), pharmaceutical firms (8%), and others (6%; Figure 2).

The number of calls has increased by ~10% per year since the implementation of the regulation. This yearly increase is partly due to the limited resources and budget constraints among many poison control centers. Some poison control centers have adopted a policy of no longer answering drug identification requests, referring the requesters directly to the FDA.

One study concluded that variability in drug-identification practices and inadequate training of poison control center personnel to provide the service to consumers may pose problems such as liability risk and inability to preserve patient confidentiality. The majority of inquiries are for the identity of generic drug products (Figure 3).3 The reason may be the greater familiarity with the logo of brand name products or the fact that most generic products are not published in the available proprietary compendia and private databases.

CDER's Drug-Identification Service

The FDA has become known as the most comprehensive collector of imprint information. Ninety-six percent of the products for which identification is requested are positively identified.3 The inability to identify a product may be due to one of the following situations:

  • Incorrect or limited information from the caller
  • A partially worn imprint on the product
  • Lack of industry compliance with the regulations

In addition, dietary supplements are not required to have imprint information.

The FDA recognizes that the Division of Drug Information's database can be, and is in many cases, a lifesaving tool for the medical community. The evolution of imprinting?from a voluntary, unregulated, paper system in the mid 1980s to a state-of-the-art, comprehensive and accessible database today?is the result of a collaborative mission among government, advocacy groups, and industry.

The Division of Drug Information staff can identify oral-dosage drugs based on physical appearance and markings. This service offered by the FDA is free to the American public. Drug-identification inquiries can be sent to the Division of Drug Information via telephone at 888-INFOFDA (888-463-6332), via fax (301-827-4577), or via e-mail (

Dr. Kiliany, team leader, and Dr. Kremzner, deputy director, are both with the FDA Center for Drug Evaluation and Research, Division of Drug Information. Dr. Nelson now is a manager of medical communications for a major pharmaceutical company.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Stahl, Pharmacy Times, 241 Forsgate Drive, Jamesburg, NJ 08831; or send an e-mail request to:

This document is not covered by copyright. It may be copied or reprinted without permission. Inquiries and comments should be sent to FDA-CDER, Division of Drug Information, HFD-240, 5600 Fishers Lane, Rockville, MD 20857.

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