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Getting ready for testing and pre-clinical trials
At this point, I’ve basically gotten everything formulated except for the buffer system for my facial serum. I found some good prices on a 50 person Human Repeat Insult Patch Test (HRIPT) and will try to get a dermatologist and pediatrician signature so we can claim “dermotologist approved” and “pediatrician approved”.
I’m a bit worried about the 5 microorganism challenge test because our only preservative is caprylyl glycol EHG. We’ll do an initial screening that allows up to 3 different formulations to be tested. Then we can choose either the USP<51> or ISO 11930 test. I’m leaning towards the latter because it allows us to be pump bottle certified (to use a non-technical term) if the product fails the challenge test that I was told simulates dipping your fingers into a bottle.
We’re also doing to a skin penetration test at a pre-clinical testing laboratory since our product is supposed to have deep penetration. There’s a Static SPF test on a 10 person panel we’re considering later if we decide to go into the European market and use some chemical sunscreens that are not approved in the US (not because they’re unsafe, but because US regulations are slow).
Any other tests you think we’re missing for a facial serum to be sold primarily in the US market? I’m also happy to share links to companies who offer these tests at a reasonable price, and in turn check out any resources that you all recommend.
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8 Replies
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That’s a poor presrvative system. Neither USP nor ISO simulates anything in use - they’re just tests that show some efficacy conventionallypresumed to justify marketing.. The latter has more demanding “pass” criteria (hopefully you satisfy A). Don’t know what pump certification means but “fail” means you fix the preservative system - not hide it in a pump paclage..
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What are your thoughts on this article on Caprylyl Glycol and EHG? https://www.thaiscience.info/journals/Article/JHRE/10893376.pdf
I’d have no problem using parabens, phenoxyethanol, or quats, but they’re reported in multiple studies to be incompatible with non-ionic surfactants, especially at the concentrations I’m using. I considered citric acid, but it’s more likely to promote bacterial growth at pH 5. I tried hexylene glycol at 10% but it caused issues with the formula. I prefer not to use DMDMH due to regulatory concerns. I’m almost certainly going to do a cheaper antimicrobial screening before I pay for the full test, and penetration testing can be done for relatively cheap with the base formula. I’ll do the RIPT test only after everything is sorted out.
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Fyi, I can screen 4 formulations for just $600. The plan as of right now is to try:
1) 1.5% caprylyl glycol EHG
2) 1.5% 1,2-hexanediol + caprylyl glycol
3) 1.5% caprylyl glycol + 1% phenoxyethanol (just to try it out)
4) 1.5% caprylyl glycol EHG + 3% hexylene glycol (if my formula can take it)
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To the aticle, only profoundly obscure journal publishing without useful review routine preservative testing data (probably old) from a contract lab reagrding one simplified formula. This is less than most sales borchures offer for Leucidal et al.
Please design a system that should be effective (Gram neg and pos bacteria and fungi) and confirm efficacy. Simply passing a USP 51 with whatever means little - virtually every recalled formlua passed the test. Look at competitve prodhuct
Gram neg - glycols are ok but you need more - phenoxy/EHG* is much better - esp.. with chelator EDTA. Gram +’s and fungi are not so bothered by glycols - phenox helps some for Gram +’s. Parabens could work vs. both but you try orgnaic acids if pH permits. IPBC (for fungi) ,Chlorphenesin might work.
What’s fornula and packaged.
*EHG is a booster esp. with phenoxy - useless alone
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Thanks Phil, the packaging is airless pump bottle, and while the formula is proprietary, I’ll say that it’s 25% oil phase, 14% non-ionic surfactant, and the remainder water phase. It’s not a typical product, so don’t be alarmed by the high surfactant concentration. No foaming, rubs in quickly, and feels very good on skin according to myself and a dozen other friends, family, and colleagues.
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what’s the pH and surfactant? maybe an orgnaic acid could fit in
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pH is right at 5.5 and the non-ionic surfactant is primarily polysorbate 80.
I did a bunch more digging to see if I might have missed some preservatives that could work with high levels of this surfactant, understanding that no negative interactions could simply mean not studied. I also found 1,2-Hexanediol and Sodium Dehydroacetate. I can’t find a good source of IPBC for testing that doesn’t come in a bucket.
It’d be nice to find an organic acid that won’t act as a nice carbon source for microorganisms. Maybe an aromatic?
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Polysorbate complicates - at that level you may be neutralizing preservatives Don’t worry about carbon source - you’ve enough already and the relevant bugs can grow in disitilled water.
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