PhilGeis
Forum Replies Created
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Concentration and formula dependent.
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Irritation effect ? Is this from experience or heresay? Glycols help but that still at minimum leaves a fungal gap. IPBC is any option - some use PHMB.
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Please work off water activity of the product, not percentage of any ingredient. As a stand-alone agent of preservation, water activity should be less than 0.7. As shown in the attached, you’ll need much greater levels for the polyols in aq. solution - e.g. >60% propanediol. As pharma said, lesser levels may contribute but please measure water activity of the product as the control element not their %. per se. and be aware - lowering Aw will inhibit but not necessarilly kill - and may not contribute in challenge test.
https://hal.archives-ouvertes.fr/hal-00301063/docuent
and
https://www.researchgate.net/publication/266083369_Optimization_of_cosmetic_preservation_Water_activity_reduction#fullTextFileContent -
count yes - but “recognized pathogens” is not enough. An y Gram negative bacteria?
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Formaldehyde releaser, organic acid if pH works. Is context rinse off or leave on? Hot process? How clean is your otameal nd what is package design?
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I’d not expect much from triethyl citrate and wonder at phenethyl if 9010.
Look at similar, marketed products, esp. those from major companies. Think adding a more water soluble preservative and something for fungi will help. Are you budgeted to do range finding PET testing? -
It is a project - prob end up with a complex system.
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Be aware - some preservatives can affect voscosity and color. So you may need to recycle ln some development matters.
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The bugs don’t need much to contaminate. Oatmeal certainly works for them as pharma said and also redcues preservative efficacy.
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Me too - Merry Christmas!!
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What is the product? Rinse-off or leave on?
DMDM H and Phenoxy are used to target bacteria - esp. Gram negative. I’d combine with parabens or, if the pH works or a surfactant product, an organic acid salt like Na benzoate. If rinse off - consider CMIT.
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In my exprience, longer chain glycols exert an antimicrobial effect beyond any modification of product Aw.
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Paracelsus the father of toxicology - The dose makes the poison (“All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison.” Latin- sola dosis facit venenum ‘only the dose makes the poison’)
Maybe add route of administration - but you get the idea.
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ngarayeva001 said:@PhilGeis Dr. Geis, it always fascinated me how some bacteria manage to multiply in steam distilled water.
Yes! Even more bizarre - raw materials: fungal (Penicillim spores) contamination citric acid, ZPT suspension for antidandruff shampoo with P. aeruginosa, concentrated disinfectant quat active raw material with P. aeruginosa, B. cepacia in 70% ethanol (not mine - in literature).
products: colonies of Kurthia sp. isolate in/on soap bar (with milk), Bacillus sp. isolate in pH 9 built hard surface cleaner, Halomonas in high pH liquid laundry
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and they don’t even need much “food” as bugs (esp. Gram negatives like cepacia) can contaminated purified water systems.
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Agree re. secondary preservatives of capylyl whatever, but would not go with lesser amounts than recommended for any primary preservative (e.g. formaldehyde releasers). Please do not titirate down based on preservative testing - they are not validated to cosmetic endpoints. Please establish a system within the estabished efficacy and safety parameters for each preservative used and confrm with challenge testing. There is no advantage to lesser levels.
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Yes - please use the appropriate recommended concentrations.
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Think fFormaldehyde releasers - such as Germall, Suttocide, Glydant - would be preferable to formalin.
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Appreciate you challenge. Assumje you’ve ruled out formaldehyde releasers (?).
pH 6 isn’t great for sorbic acid, and benzoate might be a better choice if you can ,lower the pH. Is 6 cast in stone?
Suggest you start testing and see what breaks through. -
Wonder at efficacy of sorbic acid in your app. pKa of benzoic acid with some surfactants is reportedly “effectively” increased. You’ll see it (as Na benzoate) in many shampoos at pH 6 and 7.
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Preservation of products with “colloidal oatmeal” is an experiment that requires preservative testing your confident. and prob a round or 2 including aged product before your coonfident. Llook at the similar products on the shelvees now. You’ve phenoxyethyl alcohol - why add less effective phenethyl - unless its for rose odor? Additions should be the more water soluble. Check micro content of you oarmeal.
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Mark - because you want preservative and efficacy in the water that invades the product. I’d not be confident your suggestions would effectively accomplish that.
In any case, please don’t consider just adding any preservative will simply “be done with it” . If you’re preserving vs water ingress - test it. -
You;d consider adding preservative esp if water contamination in use. Is that likely for your product?
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Links for methods.
Many compendial methods folks use (e.g. ISO, PCPC, ASTM) require purchase. If the price is tough to meet - to understand how such testing can be performed, you might look at methods that have been published on line.For preservative testing, see US Pharmacopeia 51
http://www.pharmacopeia.cn/v29240/usp29nf24s0_c51.html
or Europen Pharmacopoeia 5.1.3
https://www.drugfuture.com/Pharmacopoeia/EP7/DATA/50103E.PDFFor testing product quality (for microbes), see USP 61 (count) and 62 (specific microbes)
https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/generalChapter61.pdf
https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/generalChapter62.pdf