PhilGeis
Forum Replies Created
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I encourage folks to design a system that should work (theoretically effective against Gram -/+ and fungi) and then confirm it works vs these in challenge testing both as made and after ageing. Passing a classic USP 51 (as EP or ISO) is not a guarantee. Prrservatives help in manufcturing but are primarily intended (as specified by FDA and EU cosmetic directive) to protect consumers in use and USP is not validated fpr that.
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There is a reason every cosmetic product on the market includes preservatives.
Why would you assume your product is uniquely “self-preserving.” -
Andraous said:I am doing a chalenge test before using any preservative
Why?
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Coke cola? A single-use product in a pressurized, herrmetically-sealed vessel at a prohibitive pH? Coke is clearly irrelevant.
Benzoic acid (Na benzoate) as preservative has a substantial Gram negative gap. One need merely look at COSMETIC products now on the market to see its limited use - and virtually always as a secondary preservative.
Please - preservation is a serious effort. Infections from contaminated cosmetics have resulted in blindness and even death. If you don’t know the subject well, please do not offer casual suggestions.
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Sodium benzoate by itself is not adequate. A simple check of cosmetic labels (not just for micellar water) shows virtually none using that option. Pseudomonads eat benzoate.
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Try to other biugunaide 1st - polyaminopropyl biguanide.
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From the big company cosmetic experience, I’ll offer that it’s both acquisition and development - rarely acquisition only to block others. Cosmeticss are so dynamic that first to market with a unique product/claim/compelling ad is much more of a win than slowing others - even if possible.
As consumers are more convinced of extravagant claims when combined with extravagant precetag, technology cost is often not a barrier. But advertising (even to puffery) is a factor in convincing without great technology. -
Another biguanide - polyaminopropyl biguanide.
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Think EU cosm directive allows 0.1% with stipulation - “Not to be used in applications that may lead to exposure of the end-user’s lungs by inhalation.”
Are there other nonpermissive directives? -
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.