If your clinic works with compounded GLP-1 medications, you have seen the beyond-use date (BUD) on every vial. But do you know how that date is actually determined? Understanding the calculation methodology behind BUDs is not just useful for compliance conversations — it directly affects how you order, store, and administer compounded preparations.

This post walks through the exact framework compounding pharmacies use to assign BUDs under USP <797>, what factors influence the final date, and what your clinic should be asking its pharmacy partners.

The United States Pharmacopeia (USP) General Chapter <797> is the primary standard governing sterile compounding in the United States. It establishes the maximum BUD limits that compounding pharmacies may assign to sterile preparations.

The 2023 revision to USP <797> introduced a two-category system that replaced the older low/medium/high risk framework. Understanding which category applies to your compounded GLP-1 preparations is the first step in understanding how the BUD was calculated.

Under USP <797> (2023), all compounded sterile preparations (CSPs) fall into one of two categories:

Category 1 CSPs are preparations that:

• Are not tested for sterility before release, OR
• Do not meet the conditions required for Category 2

Default BUD limits for Category 1:

• 12 hours at controlled room temperature (CRT, 20–25°C)
• 24 hours refrigerated (2–8°C)

Category 2 CSPs are preparations that meet more stringent requirements, including:

• Sterility testing performed on each lot before release
• Environmental monitoring program in place
• Personnel training and competency assessments documented
• Appropriate beyond-use date studies or stability data

Default BUD limits for Category 2 (aqueous preparations, refrigerated):

• Up to 45 days refrigerated for aqueous preparations
• Up to 30 days at CRT for aqueous preparations
• Longer BUDs are possible with supporting stability data

Most compounded GLP-1 preparations dispensed by 503A pharmacies fall under Category 1 unless the pharmacy has implemented the full Category 2 program. 503B outsourcing facilities, which operate under cGMP standards, are more likely to produce Category 2 preparations with longer BUDs.

A pharmacy that wants to assign a BUD longer than the USP defaults must conduct stability testing using validated analytical methods. This is not a simple process — it requires:

The pharmacy must design a study that tests the preparation under the intended storage conditions over time. For a compounded semaglutide preparation intended to be stored refrigerated for 45 days, the pharmacy would test samples at multiple time points (e.g., day 0, day 7, day 14, day 30, day 45) and analyze them for:

• Potency: Is the active ingredient still present at labeled concentration?
• Purity: Have degradation products formed?
• pH: Has the pH shifted outside acceptable limits?
• Particulate matter: Are there visible or sub-visible particles?
• Sterility: Is the preparation still sterile?
• Container integrity: Is the container-closure system maintaining sterility?

The testing must use validated analytical methods. High-performance liquid chromatography (HPLC) is the standard method for potency and purity testing of peptide-based preparations like semaglutide and tirzepatide. The method must be validated to demonstrate it accurately measures the specific compound being tested.

The preparation must meet pre-defined acceptance criteria at each time point. Typically, potency must remain within 90–110% of labeled concentration, and degradation products must remain below specified limits.

All stability data must be documented and retained. If a regulatory authority or accreditation body requests evidence supporting the assigned BUD, the pharmacy must be able to produce it.

Several factors affect how long a compounded GLP-1 preparation can maintain its quality:

The specific formulation — including the concentration of active ingredient, the choice of solvent or diluent, the pH, and the presence of preservatives or stabilizers — significantly affects stability. A well-designed formulation can extend BUD; a poorly designed one can shorten it.

The vial, stopper, and seal used to package the preparation affect stability. Glass vials are generally preferred for sterile injectables. The stopper material must be compatible with the preparation and must maintain a seal over the intended BUD period.

Temperature is the most critical storage variable. Most compounded GLP-1 preparations are designed for refrigerated storage (2–8°C). Freezing or exposure to elevated temperatures can accelerate degradation and invalidate the assigned BUD.

Light exposure is also a factor for some preparations. Amber vials or light-protective packaging may be used to extend BUD for light-sensitive compounds.

The cleanliness and sterility of the compounding environment affects the microbial quality of the preparation. Category 2 preparations require compounding in ISO 5 conditions (Class 100 cleanroom) with ongoing environmental monitoring.

503B outsourcing facilities are registered with the FDA and must comply with cGMP standards. This has direct implications for BUD calculation:

• Formal stability programs: 503B facilities are required to have formal stability programs that support the BUDs they assign. This is not optional — it is a cGMP requirement.
• Lot release testing: Each lot of product must pass sterility and potency testing before release. This supports Category 2 classification and longer BUDs.
• FDA inspection: 503B facilities are subject to FDA inspection, which includes review of stability data and BUD assignment methodology.
• Consistency: Because 503B facilities produce larger batches under controlled conditions, there is less batch-to-batch variability than in small-scale 503A compounding.

For clinics that need longer BUDs to support their patient volume and ordering patterns, sourcing from a 503B facility is often the most practical solution.

When evaluating a compounding pharmacy for GLP-1 supply, ask these specific questions about BUD:

1. What BUD do you assign to your compounded semaglutide/tirzepatide preparations?
2. Is that BUD based on USP default limits or extended stability testing?
3. If extended stability testing, can you provide a summary of the data?
4. Are your preparations Category 1 or Category 2 under USP <797> (2023)?
5. Do you conduct sterility testing on each lot before release?
6. What are your storage and shipping conditions, and how do they affect the BUD?

A pharmacy that cannot answer these questions clearly is a pharmacy that may not have a rigorous BUD assignment process. That is a compliance risk for your clinic.

Once a compounded preparation arrives at your clinic, the BUD clock is running. Your clinic's responsibilities include:

• Logging receipt date and BUD for every preparation received
• Verifying storage conditions are maintained (refrigerator temperature logs)
• Discarding preparations that have reached their BUD
• Never using a preparation that has been stored outside labeled conditions, even if the BUD has not passed
• Training staff on BUD compliance and proper storage procedures

1. United States Pharmacopeia. USP General Chapter <797> Pharmaceutical Compounding — Sterile Preparations. 2023 Revision.
2. U.S. Food and Drug Administration. Current Good Manufacturing Practice (CGMP) Regulations. 21 CFR Parts 210 and 211.
3. U.S. Food and Drug Administration. Guidance for Industry: Drug Product Stability Testing. FDA, 2003.
4. Allen LV Jr. Stability and Beyond-Use Dating of Compounded Preparations. International Journal of Pharmaceutical Compounding. 2019;23(4):272–278.
5. U.S. Food and Drug Administration. Outsourcing Facilities Under Section 503B of the Federal Food, Drug, and Cosmetic Act. FDA, updated 2024.

MedClinic Partners connects licensed clinics and 503A pharmacies with vetted 503B supply and USA-made cGMP RUO peptides. Questions about BUD compliance or supply? Use the Get Connected form to reach our team.