Dosage versus Dose

The U.S. FDA published a draft guidance on the dosage and administration labeling section for certain medicinal products. The guidance is one of several FDA guidance documents addressing labeling for human prescription drugs. Other available guidelines provide, for example, recommendations for container labels and carton labeling design or for labeling medical products packaged in multiple-dose, single-dose, and single-patient-use containers. For additional drug labeling guidance documents, see the FDA’s Labeling Resources for Human Prescription Drugs website. The webpage includes searchable labeling and product databases and explains how "current" labeling that is submitted by companies to the FDA may differ from the last FDA-approved labeling. 

Clarification of Terms

According to the document, applicants should use the term dose to refer to a specific amount of drug taken at one time, and the term dosage to refer to a specific amount of drug administered at a specific frequency (and over a certain duration). The appropriate term (dosage / dose) should be used throughout the labeling depending on the information being discussed.

In addition, the sequence of dosage- and administration-related information should be based on its relative clinical importance. The most clinically relevant information should generally appear first (e.g., the recommended dosage, the route of administration, instructions on how and when to administer the drug relative to the ingestion of food). Other types of dosage- and administration-related information (e.g., dosage modifications, instructions on how to reconstitute) should generally appear later in the section.

Information that is not specific to the drug and is considered general medical knowledge (e.g., information such as “use the optimal dosage” or statements such as “individual patients will experience a variable time to onset and degree of symptom improvement”) should generally not be included in the dosage and administration section.

Parenteral Drug Products

For parenteral products, the dosage and administration section must include the following verbatim statement:

• “Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.” If a parenteral product needs to be filtered before administration, this section should identify the appropriate filter(s) and filter pore size (e.g., low-protein binding, 0.2 micron, in-line filter).

Storage Instructions for Reconstituted or Diluted Products

Typically, storage instructions for the reconstituted or diluted product are included with the preparation instructions in the same subsection in the dosage and administration section. The respective section should contain the following information:

• Storage conditions needed to maintain the stability and sterility of the reconstituted or diluted product,
• Duration for which the reconstituted or diluted product can be safely used under these storage conditions, and an appropriate discard statement.

More detailed information is available in FDA´s draft guideline Dosage and Administration Section of Labeling for Human Prescription Drug and Biological Products — Content and Format.