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Antimicrobial Effectiveness Testing
USP ⟨51⟩ antimicrobial effectiveness (preservative) testing for multi-dose products.
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Compendial standard this method is validated to.
Business days from sample receipt to report.
Compounded formulations supported to date.
WHY YOU NEED IT
Why Antimicrobial Effectiveness Testing Matters
Prove the antimicrobial preservative works
USP ⟨51⟩ challenges the product with microorganisms to confirm the preservative (e.g. benzyl alcohol) actually suppresses growth over the in-use period (28 days).
Essential for multiple-dose vials
Every needle entry is a contamination opportunity — preservative effectiveness is what protects later doses.
Substantiate in-use dating under USP ⟨797⟩
USP ⟨797⟩ requires aqueous multiple-dose CSPs to pass AET, and those results are what support using the vial for up to 28 days after first entry.
OUR PROCESS
How we run this test for you
Method Suitability
Proving the method first
Before the study runs, we confirm the neutralizer recovers every challenge organism from your product — otherwise the preservative masks growth in the test itself.
3 vials
Support for Multi-Dose Containers
Releasing every batch
For aqueous multiple-dose containers, USP ⟨797⟩ requires AET for both Category 2 and 3 compounded sterile preparations — it's a one-time test for each formulation and container.
Stability Studies
Across your stability timeline
Run at Day 0 and Day 90 alongside the rest of your stability panel, AET shows that the preservative works — and that it still works when the beyond-use date expires.
6 vials
TECHNOLOGY
Challenge the product, then count survivors.
01
Qualify the method
Method suitability confirms the ability of the assay to measure microbial growth.
02
Challenge and incubate
The product is inoculated with the five compendial organisms and held under controlled conditions.
03
Count over 28 days
Survivors are enumerated at Day 0, 7, 14, and 28, and log reduction is compared to the USP ⟨51⟩ category criteria.
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TALK TO A SCIENTIST
Tell us what you need tested
Whether you need testing guidance, a quote, or just have questions — we’re here. A scientist will follow up within one business day.
USP-compliant, validated methods
Response within one business day
No obligation — guidance and quotes welcome
For service requests, quotes, or technical questions, email our support team.
info@saphobio.com
Phone
Available Monday to Friday, 9:00 AM – 6:00 PM (Pacific Time).
Text us: +1 (929) 437-6148
Site Visit
Visits by appointment only. Please contact us to schedule.
1068 Washington St. STE B, San Carlos, CA 94070
1068 Washington St Ste B, San Carlos, CA 94070
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