Potency & Purity Testing for Compounding Pharmacies

Renew Lab Group provides compounding pharmacy potency testing: independent HPLC and LC-MS testing of preparations. We measure potency against the labeled strength, confirm identity and check purity, then report the results on a certificate of analysis. 503A pharmacies and 503B outsourcing facilities use our Houston, Texas lab to verify batches, support beyond-use dates and document quality for inspectors and prescribers.

Why compounding pharmacies test potency

Compounded preparations are made in small batches from bulk ingredients, so each batch depends on accurate weighing, complete mixing and a stable formulation. When FDA sampled 29 compounded products ordered online, 34% failed one or more standard quality tests. Every product that failed potency was subpotent, ranging from 59% to 89% of the expected strength (FDA survey report). FDA noted the survey was small. Even so, the findings show why independent verification is worth doing.

Testing also supports your own quality program. It documents that your process produces what the label says, gives data behind your beyond-use dates and backs up your answers when prescribers or inspectors ask how you verify quality. Testing requirements vary by state and by 503A or 503B status. Check with your state board of pharmacy and FDA guidance for the rules that apply to you.

Tests we offer for compounded preparations

Microbiology, endotoxin and other tests

The same lab also runs the non-chromatography tests pharmacies often need: endotoxin testing (LAL), microbiological testing (sterility, TAMC/TYMC, bioburden and specified organisms), heavy metals and elemental impurities by ICP-MS, total organic carbon (TOC), and container closure and extractables/leachables testing. Controlled work is done in our ISO 5/ISO 7 cleanroom. See the full menu on our HPLC Lab Testing Services page.

Dosage forms

Send us your formulation details (dosage form, active ingredient, strength, and base or excipients) before you ship, because excipients affect method selection. We’ll confirm whether we can test the preparation and which method we’ll use.

How our compounding testing program works

1. Set up your account. Call 936-379-5515. We review your formulary and the tests you need.
2. Method confirmation. We confirm methods and reference standards for your preparations. If a new formulation needs extra method work, we tell you the cost and timing up front.
3. Submit batches. Drop off samples at our lab at 6001 Central Crest, Houston, TX 77092, or ship them using the sample requirements we send with your quote.
4. Results. You receive a certificate of analysis for each sample. We confirm turnaround when we quote.
5. Recurring testing. Set a schedule (per batch, monthly, quarterly) for your highest-risk or highest-volume preparations. Ask us about pricing for recurring testing.

Choosing a testing lab: what to ask

• Is the method validated or verified for this preparation and base?
• Is the result reported against a qualified reference standard?
• Will the report include the chromatogram and the specification you’re testing against?
• What happens if a result is out of specification? Is there a retest policy?
• What is the real turnaround, including shipping?

We’re happy to answer each of these for your preparations before you send a sample. For documentation tips, see our existing guide to compounding pharmacy COA requirements.

Key terms for compounding quality testing

• Label claim: the strength stated on the label. Potency is reported as a percentage of it.
• Assay: the test that measures the amount of active ingredient. In practice it’s the same thing as a potency test.
• Specification: the acceptable range for a result, for example a percentage window around label claim. Your quality program or the applicable standard sets it.
• Out of specification (OOS): a result outside the acceptable range, which should trigger an investigation.
• Beyond-use date (BUD): the date after which a compounded preparation should not be used. Stability data can support extended BUDs.
• Stability-indicating method: a method that can tell the intact active ingredient apart from its degradation products.

HPLC or LC-MS for your preparation?

Potency testing is almost always HPLC. LC-MS earns its place when identity must be confirmed by mass, an unexpected peak needs investigating, or an impurity must be measured at trace levels. Our HPLC vs LC-MS guide explains the difference in plain language.