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Ambulatory Care Article Medication Safety

Addressing Discrepancies in Prescription Billing Units and Dispensing

Problem: Determining the correct medication billing units can be a challenging process for outpatient, specialty, and ambulatory care pharmacies. Billing units and the appropriate billing quantity are key elements of prescription dispensing and pricing. As a required characteristic of pharmacy prescription coverage, the amount to dispense and the unit itself must be consistent with what the payor requires to properly process a prescription claim. The assigned billing unit within pharmacy dispensing software, which is obtained from their drug information compendia provider, may not align with the packaging configuration used by the manufacturer for a medication product, creating confusion regarding the appropriate billing quantity to use in claims submissions. This is a concern for a variety of products, including those available as injectables which may be sold in a carton of multiple syringes together with other items used for administration, but are billed as “1 each (kit)” instead of milliliters of drug or the number of syringes. Pharmacy staff may interpret the dispense quantity as number of cartons instead of milliliters or syringes, or vice versa, resulting in a greater or less than intended amount of syringes being dispensed.

Medication Errors Reported to ISMP

Case 1: A patient was prescribed a 30-day supply of icatibant 30 mg/3 mL syringes, for a total dispense quantity of 9 syringes. The label for the prescription printed with a listed quantity of 9, which the specialty pharmacy staff interpreted as 9 boxes of icatibant. Each carton (National Drug Code [NDC] 63323-574-93) contains 3 syringes, so the pharmacy dispensed a total of 27 syringes to the patient. A pharmacist identified the error while processing the refill, noticing the discrepancy in the dispensed number of boxes between the current month and previous month. [Note: Given an average wholesale price of as much as $4,000 per mL, this error in the dispensed quantity of icatibant could have placed significant financial strain on the pharmacy and patient.]

Case 2: A prescriber ordered a kit (NDC 72606-025-02) containing two ZYMFENTRA (infliximab-dyyb) prefilled pen devices and alcohol pads for a patient. The selected NDC was for a carton of 2 pens, and the billing unit set for this product was “1 each KIT.” The same billing unit of “1 each KIT” is used for another Zymfentra NDC that contains only 1 pen per carton (NDC 72606-025-01). During order entry, specialty pharmacy staff interpreted “1 each KIT” to mean each carton contained only a single pen. Instead of entering the dispense quantity as 1 carton for the 2-pen kit, they entered a dispense quantity of 2 cartons of what they thought was a 1-pen kit. As a result, a total of 4 pens would have been dispensed instead of the prescribed quantity of 2 pens. Pharmacy staff identified the error when 2 labels printed instead of 1 for the prescription. Moving forward, the pharmacy decided to stock only the carton size containing 2 pens and specify the number of pens per carton in the prescriber comments.

Case 3: A specialty pharmacy reported multiple errors with the dispensing of SIMLANDI (adalimumab-ryvk). The pharmacy carries two Simlandi 40 mg NDCs which contain either 1 (NDC 51759-402-17) or 2 (NDC 51759-402-02) autoinjectors per carton. Wrong quantity errors have occurred in which the 1-device carton was selected instead of the 2-device carton, resulting in the patient not receiving the full prescribed quantity. Although the correct billing unit for these products is “each,” as each carton contains alcohol swabs and are considered kits, the pharmacy decided to standardize the billing units from “each” to “pen” to reduce staff confusion. However, these types of changes can have downstream effects including risk of improper billing. In fact, this pharmacy received feedback from an insurer that they required the billing unit to be “each” for claim approval.

Confusion with Billing Units and Product Descriptions

Practitioners have reported confusion and perceived inconsistency with assigned billing units among similar formulations. This includes confusion at the time of prescribing, dispensing, and during insurance audits after dispensing the medication to the patient. Some medications are packaged as combination products, in which the drug or biologic is packaged with a certain non-drug product, such as an alcohol swab. One example is HUMIRA (adalimumab), which is available as either autoinjectors or prefilled syringes, and is co-packaged with alcohol swabs. The device and alcohol swab are dispensed together and billed as a kit in the pharmacy dispensing software. A snapshot of how one pharmacy’s dispensing software has been built to display Humira as a kit is shown in Figure 1. However, some manufacturers of other autoinjectors, including some adalimumab biosimilar products, have decided not to co-package the autoinjectors with alcohol swabs and, therefore, must be billed in milliliters (mL) (Figure 2).

Figure 1. A Humira carton containing 2 syringes is billed as 1 each (kit) in the pharmacy dispensing software of a specialty pharmacy. The kit, in the “Pack (Package size)” column, refers to one package of 2 syringes and alcohol swabs.

Figure 2. A HYRIMOZ (adalimumab-adaz) carton is billed in mL for the volume of the solution contained in the autoinjector within the carton. Unlike Humira, Hyrimoz is not packaged with an alcohol swab and is not billed as a kit.

Pharmacies may not be aware of the existence of standards for billing unit designation. As a result, each pharmacy and healthcare organization may adopt a different billing unit practice than what is provided by the drug compendia, which can create discrepancies as seen in Case 3 on page 1. Insurance providers may be expecting a product to be billed as a kit, but it is coded by the organization to be billed in mL or vice versa. This discrepancy may prevent the medication from being dispensed until the correct billing unit is identified and applied, requiring the claim to be re-adjudicated. If the medication is billed incorrectly and the payor’s audit detects the error, the pharmacy may face financial consequences. Also, the incorrect amount of product may be dispensed.

Often, it is not readily apparent when a self-injection device must be billed in mL or as a kit, as the package labeling does not always specify, or may conflict. The US Food and Drug Administration (FDA) does not currently have a standard or guidance to help ensure product description wording used in labeling aligns with the National Council for Prescription Drug Programs (NCPDP) Billing Unit Standard© (BUS).1 For example, the FDA-approved prescribing information for an injectable product may describe it as being available as a “kit,” but the NCPDP BUS may assign the billing unit of mL rather than each (i.e., a kit).

Progress Toward Standardizing Billing Practice

NCPDP is a not-for-profit, multi-stakeholder forum, that is American National Standards Institute (ANSI)-accredited. NCPDP develops standards to improve the exchange of healthcare information. Through multidisciplinary collaboration with pharmacy staff, manufacturers, computer system vendors, electronic prescribing networks, health plans, pharmacy benefit managers, and other stakeholders, NCPDP maintains the BUS.1 This standard, which was originally developed in 1993, for assigning billing units and billing quantities to pharmaceutical products aims to ensure consistent and accurate billing practices in the outpatient setting. The BUS considers several factors for each medication being classified, including how it will be prescribed, the packaging and package labeling, and how it will affect claims adjudication. Manufacturers may submit a Quantity Unit Information Communication (QUIC) Form to NCPDP to request clarification of the billing unit and the billing quantity prior to finalizing their package labeling.2 Completed QUIC Forms are available on the NCPDP website and may serve as a valuable resource to better understand the billing unit and billing quantity designation for previously reviewed products.

NCPDP categorizes each medication into three billing unit types:1

  • “Each” (EA) refers to products dispensed as discrete units and are not measured by volume or weight. Examples include:
    • Tablets
    • Capsules
    • Transdermal patches
    • Powder-filled vials for injection
    • Devices
    • Kits (Note: NCPDP defines kits as products containing two or more distinct items with different billing units such as products (e.g., medications) packaged with swabs, wipes, or cotton balls; or meters (e.g., glucometers) packaged with test strips. Additionally, if a kit contains separate, distinct trays within the kit, the billing unit is “each,” but the quantity is the number of trays rather than “1.”)
  • “Milliliter” (ML) refers to products measured by liquid volume regardless of its state (liquid or frozen). Examples include:
    • Vials (those containing solutions or suspensions)
    • Ampules
    • Syringes containing solutions or suspensions for injection
    • Liquid non-injectable products of at least 1 mL
    • Inhalers when labeled as 1 mL or greater on the package
  • “Gram” (GM) refers to products measured by weight. Examples include:
    • Creams/ointments of at least 1 gram
    • Inhalers when labeled as 1 gram or greater on the package

It is important to note that the Centers for Medicare and Medicaid Services (CMS) utilizes different standards for medical billing, and the NCPDP BUS may not be consistent with CMS billing procedures or other organizations’ standards. NCPDP and CMS both acknowledge and understand that these differences exist.

Safe Practice Recommendations: Although NCPDP has achieved great progress toward standardizing billing units for prescription billing, many healthcare practitioners are not familiar with NCPDP’s role in billing unit determination or the NCPDP BUS. The lack of awareness of the BUS and how to distinguish between product-specific billing units limits the effectiveness of the standard, resulting in continued risk for billing unit discrepancies and dispensing errors. Consider the following recommendations for reducing medication errors associated with billing units:

Work with electronic health record (EHR) vendors. Healthcare organizations and medical offices should evaluate how medication quantities appear on electronic prescriptions. Collaborate with the EHR vendor, and drug information compendia as necessary, to ensure that electronic prescriptions include the units (e.g., mL vs. syringe vs. kit) consistent with the NCPDP BUS unit to minimize pharmacy staff confusion.

Engage pharmacy informatics  and dispensing software analysts. Evaluate NCPDP standards to identify discrepancies between their recommendations and the prospective or currently built billing units in the pharmacy dispensing software. Review completed QUIC Forms for past NCPDP decisions. In health systems with community pharmacies, medical offices, and inpatient services on an integrated EHR, engage inpatient, ambulatory care, and community/specialty pharmacy team members involved in the build process for newly added drugs.

Educate practitioners. Make the NCPDP BUS known to pharmacists and pharmacy technicians who are routinely involved with claim adjudication. Provide pharmacy staff with the NCPDP BUS Fact Sheet and ensure they are familiar with NCPDP definitions, including kits, and billing categories. 
Clearly communicate intended dispense quantity. Pharmacies may consider using dispensing software notes to alert the team to the correct package size for specific products (e.g., quantity 1 = 2 syringes). When a prescription label is generated, ensure the intended quantity to dispense is clear to pharmacy staff. Configure the computer system to print the correct number of labels based on the number of packages needed for the prescription.

Conduct proactive risk assessments. When new products are added to the community/specialty pharmacy inventory or organization’s formulary, use a proactive risk assessment process to identify potential medication error risks when using the medication. This should include evaluating the package size and billing unit prior to dispensing the new medication.

Standardize language in prescribing information. The FDA should provide guidance on standardizing the language used in official prescribing information to align with the NCPDP BUS. Manufacturers should collaborate with NCPDP prior to product approval to determine the proper billing unit and the associated language used to describe their product in prescribing information.

Report errors. Encourage staff to report close calls and errors related to billing units both internally and externally to ISMP for shared learning.

References

  1. National Council for Prescription Drug Programs (NCPDP). NCPDP billing unit standard fact sheet. NCPDP; 2025. https://standards.ncpdp.org/Standards/media/pdf/BUS_fact_sheet.pdf. Accessed October 15, 2026.
  2. National Council for Prescription Drug Programs (NCPDP). Billing unit requests. NCPDP; 2026. https://standards.ncpdp.org/Billing-Unit-Request. Accessed October 15, 2026.