Package Inserts: A Medical Writer’s Primer


    Medical writers can find vast amounts of information about prescription drugs and biologics from a variety of resources, such as scientific publications, electronic databases, and free online content from sites such as

    A challenge for medical writing professionals is sorting through these resources to find information that is accurate and acceptable to use as a reference source when writing content that will ultimately go through medical‑legal review. 

    The most useful and accurate information source that medical writers have access to is the drug’s label, also known as the prescribing information or the package insert (PI). The US Food and Drug Administration (FDA) requires PIs to be included with packages of prescription drugs and biologic products. All of the information included in the PI is supported by substantial evidence and data from clinical trials, which manufacturers provide to the FDA as part of the New Drug Application (NDA) or Biologics Licensure Application (BLA). Data are included in the PI only after they have been reviewed and approved by the FDA. Typically, regulatory writers do not develop PIs, but they may support a team of regulatory and safety experts who lead content development.

    PIs contain critical information that helps practitioners and patients understand the usage, risk, and safety of a drug. The current PI format contains two main components: the highlights of prescribing information (HPI) and the full prescribing information (FPI). The HPI appears on the first page of the drug label and briefly summarizes important information about the drug, including boxed warnings, the strongest warning issued by the FDA. A boxed warning alerts prescribers and patients to an increased risk of any serious adverse reactions associated with the use of the drug that could lead to death or serious injury. The information in the HPI is cross‑referenced to the corresponding information within the FPI. 

    The FPI contains 17 sections:

    1. Indications and Usage
    2. Dosage and Administration
    3. Dosage Forms and Strengths
    4. Contraindications 
    5. Warnings and Precautions
    6. Adverse Reactions
    7. Drug Interactions
    8. Use in Specific Populations
    9. Drug Abuse and Dependence
    10. Overdosage
    11. Description
    12. Clinical Pharmacology
    13. Nonclinical Toxicity
    14. Clinical Studies
    15. References
    16. How Supplied/Storage and Handling
    17. Patient Counseling Information

    Medical writers should become familiar with the structure and contents of the PI. Each section contains important information about FDA‑approved drugs and biologics that medical writers can use. Let’s take a high‑level look at four of these sections.

    Indications and Usage

    The Indications and Usage section of the PI answers the following questions:

    • What is the drug used for? The insert explains how the drug is used for the treatment, cure, or prevention of a “recognized disease or condition.”
    • Who is the drug intended for? The population and age group.
    • What are the other parameters for the population taking the drug? For example, is the drug a concomitant therapy for another medication?

    Some PIs also have a "Limitations of Use" statement that describes circumstances in which the drug should not be used because evidence suggests that use of the drug would be unsafe or ineffective. 

    Dosage and Administration

    The Dosage and Administration section of the PI answers these questions:

    • What is the recommended dosage of the drug for each indication, population, and age group?
    • What is the recommended interval between doses?
    • What is the usual length of treatment when treatment duration should be limited?
    • What dose adjustments should be made if the drug is to be taken with other medications?

    Adverse Reactions 

    The Adverse Reactions section describes common adverse reactions, including serious adverse events, seen among clinical trial participants, and, if applicable, adverse reactions reported after the drug came to market. An adverse reaction is an undesirable effect reasonably associated with the use of a drug.

     Medical writers should always reference the PI when writing about adverse events associated with a particular drug.

    Clinical Studies

    Not every study that was part of a product’s clinical development program makes it into the PI. This section of the PI includes only the studies that best represent how the drug is used properly and effectively and that provide evidence to support the labeled indications. The Clinical Studies section contains 3 important subsections:

    1. Study Design. This subsection provides the number of patients taking the drug and the placebo, and the type of study.
    2. Population. This subsection describes the characteristics of patients who participated in the study, including age, sex, and ethnicity.
    3. Endpoints and Results. This subsection describes the parameters that were tested to determine the effectiveness of the drug and the results, which are presented in tables. 

    Next Steps

    Once the PI has been written, the document is submitted and finalized through discussions with the FDA during the NDA/BLA review of all the clinical data before a drug is approved for marketing. 

    Even after a prescription drug is approved by the FDA, the PI may need to be revised from time to time. In some cases, this means adding new data, new formulations, new indications, and new medical findings. 

    After all that, patients and practitioners get to read the fine print.


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    February 7, 2022 at 9:15 AM

    American Medical Writers Association

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