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This is a one off so it’s just to have some extra safety, it’s for the US.

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Thanks Mark, here it is a question of a pH 4 simple 4% Glycolic Acid gel, shouldn’t have the potential to do much harm, but the client wanted it without preservatives so there’s that (similar formulas have passed USP51 in the past).

Do you have a sample development contract or release form? Didn’t find much googlign.

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Make that product liability only.

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Trouble with sodium lactate is that you need 10% to get to pH 4 in a 5% Glycolic Acid solution.

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@zwapp not considering all of the ones I listed together, but separately! I prefer to keep formulas as simple as possible.

Emulium Mellifera  is used in a lot of Asian sunscreens? Good to know, only issue it that it’s only available in large quantities. I have a sample here, might try it!

Thanks for the Arlacel 2121 tip. I’m going with silane coated ZnO and possibly Butyloctyl Salicylate re sunscreen. Hard to turn into a superfluid, but you can get close enough as long as you don’t need vhigh SPF.

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“Preservative free. Self-preserved by alcohol.” or “Preservative free; free of synthetic preservatives. Preserved by natural ingredients.”

There: Have your cake and eat it too.  AFAIK what (a minority) of people are concerned with are synthetic preservatives. I don’t see how either of the above would be “asking to be sued” please elaborate.

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@zwapp I think your intuition is wrong and it’s more likely that it’s protected than not, depends the kinetics of degradation and skin penetration. Here’s one study showing how retinol is very well protected in a sunscreen formula exposed to daylight https://www.ncbi.nlm.nih.gov/pubmed/18405792 and this doesn’t even account for skin penetration.
You might not need any protecting factors if it penetrates the skin quickly and deeply enough.

“photoisomerization yield is reported as a function of 260 nm excitation time. 330 min continuous excitation led to ~60% isomerization yield.” https://www.ncbi.nlm.nih.gov/pubmed/21494846 seems to slow to be of much concern in a topical. I also noticed there’s a patent describing UV protection of tres.

At the end of the day you’d have to measure it.

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I don’t see why you cant use both: “Preservative Free. Self-preserved by alcohol” or whatever else. 
What people are concerned with are synthetic preservatives.

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@MarkBroussard I’m using a similar combination already to help stabilize it, but the addition of .1% Sodium Ascrorbate is interesting.
Otherwise if you can do a OWO emulsion that can double shelf-life.

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Or a stabilization system that’s not too obvious?

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@DRBOB@VERDIENT.BIZ The lowest hanging fruit here is to add ~1% Lauric Acid and have that tested.

If that doesn’t work try adding 1% Glyceryl Caprylate Caprate instead. Increasing the amount of caprylic/capric acid could also work.

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@Microformulation makes sense, so they would create a stabilized Rx version of Retinol that wouldn’t affect the legality of Retinol used in other products. Or if not going the NDA route find a way to market it as a cosmetic with patent protected stabilized Retinol, analogous to Ferulic Acid stabilized Vitamin C serums?

Must be a challenge to get a 1 year shelf-life and keep retinol degradation under 10% of the label claim; air and UV proof packaging and an anhydrous formula packed with Tocopherol(s) and other fat soluble retinol protective antioxidants (e.g. BHT) could perhaps do it.

I’ve have the same issue, I want to optimize for long term stability and present a simple degradation curve to my customers so they know what they can expect when the product is stored out of sunlight at room temperature, even if it degrades more than 10% in a year. Some people might want to use it past the EXP date too, this way they’ll at least know how much bang remains.

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I have always had this point of view.

Devil is in the details, synthetics can be safer than naturals and vice versa. But if you can use fewer additional ingredients that only function to preserve a product then that’s good design and possibly good for long term safety as long as the preservation is robust.

I’m all with you on retaining integrity in your marketing, which I think you can do whilst ticking off some marketing boxes. Most people don’t care either, and just want something that either makes their skin feel nice or in the case of skin diseases makes the disease go away ASAP.

Details such as lab name can be subtly shared for those who are looking if the lab is fine with it, really a question of good graphic design where you have your information hierarchy sorted out. Not something that would go on the front packaging. At the very least I’d say it’s challenge tested; people are wisening up about the risks of naive preservative free formulas.

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@Microformulation so would they get a NDA for the patentable? stabilization system retinol combo or make one leading to a monograph? Or to a prescription drug? Could a company block inclusion of retinol in non Rx formulas because they found a way to stabilize it or simple spent the money to prove it has drug like effects, would the FDA even be OK with that? It’d take hundreds of products off the market.

@Belassi thanks, interesting stuff. If only ascorbic acid didn’t break out people with acne more often than not, found any way around that?

@DRBOB@VERDIENT.BIZ Good example, because retinyl palmitate again has a higher side-effect to efficacy ratio than retinol.
See the paper “Unoccluded Retinol Penetrates Human Skin In Vivo More Effectively Than Unoccluded Retinyl Palmitate or Retinoic Acid” and then there’s concern about phototoxicity which might be unique to the palimate form or just more pressing due to less effective skin penetration and hence higher potential for UV exposure “Photo-induced DNA damage and photocytotoxicity of retinyl palmitate and its photodecomposition products”.

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@Microformulation I get what you’re saying, but you can call it preservative free and still explain that it contains (natural) ingredients acting preservatives that are not classified as (synthetic) preservatives right under that claim, you could also include the lab name and log # of the challenge test. To me that’s the best way to go about it.

Talked to Lincoln and waiting for their docs, their MOQ is 40 lb BTW.

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somewhere I learned that going from mildly acid (pH ~ 6.0) to more acidic {pH | 3.0 <= pH <= 4.5} does indeed result in those benefits over time.

Sounds about right, the popular AHA lotions are pH 4 - 4.4.

I second what @Microformulation says.  C12-15 alkyl benzoate isn’t only for solubilizing stuff, though it’s good for that.  It confers a glide like no other ester.  It reduces greasy skin feel in high-fat emulsions.  I use it in some silicone-free formulations to reduce soaping effect.  It’s used in sunscreens a lot (but personally I would never make sunscreens because I don’t want to pay for testing or get into anything that’s a regulated drug).  It adds to the mildness of products.  It provides modest occlusion.  In my limited hobbyist world, I find C12-15 alkyl benzoate very versatile.

Interesting, I’m working on a sunscreen, I’ve used cyclomethicone for increased slip and otherwise primarily caprylic/capric triglycerides as emollients. Would be interesting to see what C12-15 does in comparison to both. Thanks for the paper and the testing tips, Sclerotium Gum has been good to me

EMULSIFIERS 

Montanov 68 I’ve used once, was less stable than Olivem 1000 in my sunscreen application, but could be a better choice for an AHA lotion! This is something I’m curious about, which emulsifier has better TEWL reduction properties? My instinct would say Monatov 68 as Olivem retains oleic acid chains and we know oleic acid increases TEWL https://www.google.com/patents/EP2237765B1?cl=en

I’m not very worried about PEGs, but if you can find better non PEG options that makes the choice easy, I luckily don’t have to worry about pinching pennies at the moment and can choose rather freely, although It’d be nice to avoid 25 kg MOQs.

Other emulsifiers I have considered testing

Polyglyceryl-6 Distearate (and) Jojoba Esters (and) Polyglyceryl-3 Beeswax (and) Cetyl Alcohol

Potassium Cetyl Phosphate Polyglyceryl-6 Distearate (and) Sucrose Stearate (custom mix) BTMS from lotioncrafter, because people LOVE the skin feel. Not sure about pH compatibility haven’t even tried.

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somewhere I learned that going from mildly acid (pH ~ 6.0) to more acidic {pH | 3.0 <= pH <= 4.5} does indeed result in those benefits over time.

Sounds about right, the popular AHA lotions are pH 4 - 4.4.

I second what @Microformulation says.  C12-15 alkyl benzoate isn’t only for solubilizing stuff, though it’s good for that.  It confers a glide like no other ester.  It reduces greasy skin feel in high-fat emulsions.  I use it in some silicone-free formulations to reduce soaping effect.  It’s used in sunscreens a lot (but personally I would never make sunscreens because I don’t want to pay for testing or get into anything that’s a regulated drug).  It adds to the mildness of products.  It provides modest occlusion.  In my limited hobbyist world, I find C12-15 alkyl benzoate very versatile.

Interesting, I’m working on a sunscreen, I’ve used cyclomethicone for increased slip and otherwise primarily cap

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@zwapp interesting to note that Paula uses Resveratrol in her sunscreen, maybe not well thought through or perhaps the SPF protects it? Looks like they’re using the 1% trick so hard to say how much there’s in it but definitely less than 1%.

@Microformulation why would someone sponsor a NDA for retinol or resveratrol? I’m all for it, but I’ve heard it’s beaucoup pesos and time to get an application through. How many bucks are we talking?
Tretinoin works, but Retinol has a better dose adjusted efficacy to side-effect profile long term so I actually see Tretinoin as an inferior compound.

@Belassi have you measured the effect of pine bark on vit c oxidation? Is it demonstrated in literature? Where can I order your cream? Send me a pm if it’s available to the US!

@DRBOB@VERDIENT.BIZ Perhaps they would NDA retinol to reduce competition as OTC manufacturing is more expensive? Otherwise I’d think a company that size would look for patentable analogs like with T-resveratrol analogs which they could exclusively market the heck out of, bit risky though if it’s not actually superior to the real thing, but that hasn’t stopped drug companies in the past.

My 5 cents on resveratrol: 10% alcohol seems to do OK at solubilizing 1% and it’s most stable at pH > 4. Does not play well with Benzoyl Peroxide which coincidentally has a near identical chemical structure. Could be a great option for long term acne prevention as a nurturing BP alternative.

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@Bill_Toge Formula is basically a silane coated zinc oxide sunscreen with caprylic/capric triglycerides emulsified by olivem 1000, stabilized by xanthan gum and glyceryl stearate. Currently using no preservatives, will be packaged in airtight bottle, pH 7. 

@Microformulation thanks will do, I’ll let ya’ll know what they say.

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Also I’m wondering why they’re not disclosing what lab performed the trials, aren’t they required to?

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Thanks Mark!

Yes, I meant.. “MAS”, so they’ll give a kind of cooling light clay mask feel? Perhaps with some desired pH increase. I’m familiar and have used it in a liquid clay mask formula. Are there any good alu free alternatives when it comes to skin feel? 

C12-15: Is there anything in particular in the formulas above that needs solubilizing though? I don’t see it as often in non AHA moisturizers.

Do you have any studies on combinations of AHAs showing synergistic effects? Would be really interested to check those out

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Thanks @zwapp for the formula and detailed rundown!

Yes, aware of active acid level. But I doubt there is any significant difference in skin effects due to pH difference of e.g. 3.5 to 4 with regards to “cohesion of stratum corneum, enhanced epidermal barrier, antimicrobial defense, proteinases-regulating desquamation for optimal cell turnover unassisted by acid exfoliants” if you have any studies that suggest otherwise please share, I think a lot of these effects might be conferred by the AHA molecules in the skin in a not-so pH dependent way.

My question re: alkyl benzoate is how it compares to other similar emollients and why it seems to be the preferred choice in this type of formula. Do you have any take on that?

Also, why is MAP so prevalent in these?

Good tip re: GDL, FYI Scleroitum Gum works well in low pH formulas, but can be a bit slimy feeling.

What alternative PEG free emulsification systems would ya’ll recommend?

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In this case the sum of the parts > the parts alone judging from my own experience (it’s better to have both in one to treat backne), from dermatologists recommending the product (AHA’s alone or in gels are not very suitable for consumer use) and from customer reviews.

The thing is, AHA’s don’t need low pH to affect ceramide and collagen synthesis, so you don’t want or need the product to be an extreme exfoliant like you’d get with pure AHA.For the avg consumer daily use scenario it’s an extremely useful combination. It could also serve as a base for acid stable actives.

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Here’s another full formula from Vanderbilt, I have some questions

1. Why are they all using Magnesium Alu Silicate? Better skin feel than only using gums?
2. Why C12-15 Alkyl Benzoate and not e.g. Squalane or (more) Caprylic/Capric Trigylcerides?
3. Why Ammonium Hydroxide instead of Triethanolamine as pH adjuster? Are there more “natural” alternatives? NaOH, Urea etc?
4. Would a BTMS based emulsification system likely work here? 

Intensive AHA Moisturizing Lotion No. 476 

A 

VEEGUM® Ultra Magnesium Aluminum Silicate 1.50

VANZAN® NF Xanthan Gum 0.50

Water 73.34

B
Glycerin 3.00

Butylene Glycol 2.00

C

Cetyl Alcohol 1.00

Glyceryl Monostearate SE 3.00

Caprylic/Capric Triglyceride (Neobee® M-51) 5.00

C12-15 Octanoate (FinesterTM EH-252) 1.00

Dimethicone (XIAMETER® PMX-200 Silicone Fluid 350cs3) 1.00

Steareth-2 (Brij® S24) 0.83

Steareth-21 (Brij® S7214) 0.83

D

Glycolic Acid, 70 % 7.00

Triethanolamine 3.20

Citric Acid (to pH 3.8 ± 0.2) q.s.

E
Preservative, Fragrance q.s.

METHOD
While heating the water to 75°C, slowly add the VEEGUM Ultra and VANZAN NF sequentially or as a dry blend to the water agitated at maximum available shear. Mix until fully hydrated. Add the remaining water phase ingredients from Part B, mixing until uniform. Maintain the water phase at 75°C. Blend the Part C oil phase ingredients and heat to 75°C. Add the oil phase to the water phase with good agitation; mix until uniform. Cool while mixing. Add the Part D and Part E ingredients when the emulsion is <40oC. Adjust as necessary to pH 3.8 ± 0.2. 

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@johnb it’s an exfoliating moisturizer, many use them as facial moisturizers to get smoother skin and get the benefits of AHA’s (stimulated collagen and ceramide synthesis). I used the second one myself as a teenager to help backne. Some people also use them for keratosis pilaris.

@Bill_Toge in this case I’m just asking how you could simplify it, whilst maintaining or improving sensorials. A good starting point would be, what’s the base formula that gets you 90% of the performance of the formulas above.

@MarkBroussard Lactic acid is also exfoliating, but maybe ~30% less than glycolic? At the end of the day I don’t think you’ll get dramatically different effects with either one, although lactic can have the drawback of ant-piss scent depending on source. 
“2003 randomized clinical efficacy of superficial peeling with 85 percent lactic acid versus 70 percent glycolic acid”

@Soapily I would not use olive oil in any moisturizer, too much oleic acid and disruption of the skin barrier.
“2002 Impact of topical oils on the skin barrier: possible implications for neonatal health in developing countries.”