Formulating a cleansing product means solving an age-old problem: the surfactants that clean and foam best are often the ones that irritate skin most. But the real problem isn’t the trade-off itself. It’s the lack of data to optimise it. Here’s what we’ve learned from testing, and what it means for your formulation.
The Testing Gap
Standard regulatory methods like OECD Test Guideline 439 are designed for hazard classification: Is this irritating or non-irritating? Once a formulation is confirmed, all formulations look identical to the test. But they’re not. If you have three candidate blends, which one is actually mildest? The regulatory tests only determine hazard or not and don’t allow for optimisiation to generate the mildest of the mild.
Validating Your Predictions
As an example, we tested four commercially available final formulations, each with different SLES:CAPB ratios to determine which was the most mild. Their ET50 values (the time taken to reduce tissue viability to 50%) ranged from 3.60 to 9.97 hours. They were ranked in order of mildness based upon these ET50 values, with the highest ET50 value equalling the most mild blend. The in vitro formulation ranking matched the order of mildness of the SLES:CAPB blends and also the rank order of mildness demonstrated in parallel volunteer patch testing, performed by our project partners: CuTest. This matters because it means when you adjust your surfactant ratios, you can predict how that will affect mildness before you move to real-world testing.
De-Risking Your Development Stage
We used this approach to screen four developmental baby shampoo formulations before they went into human trials. ET50 values ranged from 4.50 to 14.02 hours. The mildest formulation was identified in vitro first. You don’t move questionable blends to clinical testing. You screen them, refine them, and only progress candidates you know will perform.
Getting It Right
If you’re optimising a formulation and need data that goes beyond pass/fail regulatory classification, sensitive mildness testing reveals which candidate is actually gentlest. You can benchmark against market leaders. You can identify your mildest formulation before human trials. You can substantiate competitive claims with actual data.
XtraMild is our current test of the month and is being offered at a discounted rate for orders placed throughout July.
If you’re screening formulations and need this kind of data, get in touch. We can design a screening protocol tailored to your development challenge.
Email info@x-cellr8.com or call +44 (0)1925 607 134.
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Email info@x-cellr8.com
Call +44 (0)1925 607 134.
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