Pharma
Forum Replies Created
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Removing hydrogen peroxide would remove one of the possible intermediates in one of the AA degradation pathways. However, there are some issues with that: For one, this won’t stop degradation and for another, you’d have to use a solvent which allows full activity of SOD (this usually means more water and some electrolytes).A thiol or sulfur based antioxidant would work. Also, use airless and lightproof containers, a good chelate and increase viscosity. -
A: They mention glycol ether (which the products I’ve seen do not contain) and B: the patent is over 15 years old… wouldn’t it be expired?Also, that patent doesn’t seem right from a scientific angle. Sure, many things in cosmetics aren’t as we think they should theoretically be because theory only goes that far.Apart from that: Why do most not use an antioxidant which regenerates oxidised ascorbic acid and/or captures oxygen or a ‘suicide’ inhibitor of pigment formation?
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Robert said:Regard Azelaic acid do you think suspended particles will be effective, I tried glycols to dissolve and then add it to the cream base but always same results grainy and sandy cream
Skinoren, a pharmaceutical product, contains micronized azelaic acid and they showed skin resorption… a not so great one, honestly… Anyway, micronized particles do slowly dissolve on skin, then penetrate skin leaving the solvent ’empty’ and ready to dissolve some more crystals and so on. To obtain such sink conditions, the trick is to have an okayish solubility in the carrier (cream/gel) but keep it lower than solubility in skin
. Alternatively, use a solvent which penetrates skin easily but that will require the use of an excess activce and result in lots of active ingredient remaining on skin (likely the case with Skinoren). -
Rockstargirl said:
…Waiting for replicator nano bots…You don’t have to wait, just go ‘free from preservatives’ and you’ll have a self-replicating cosmetic formulation which highly selectively activates certain cell types in your skin :smiley: !
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Just a side note: You’re not really anhydrous . Especially not in a blend of a glycol with a hygroscopic salt and an open beaker. Also, there’s plenty of oxygen available… maybe store in a closed bottle?Furthermore, colour isn’t linearly correlated with concentration, the amount of degradation product could be very small. On the other hand, the yellow colour might as well be all LAA being oxidised.The issue with combining ascorbic acid with a phenol or some other stuff is the creation of an ‘electron sink’: Whilst plain LAA might not react with oxygen even in solution (or not to a visible degree) it easily does start to react if you add for example ferulic acid. Under others, because ferulic acid reacts first and then LAA reduces it back, ferulic acid oxidises again, more LAA reduces it back and all the while oxygen enters the bottle and keeps the cycle running until nothing is left…
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jackleon80s said:Is there an emulsifier that is more suitable for petrolatum, that is one that will preserve most of its physical properties, and not turn it into a cream? Thanks againA: There are emulsifiers which are more suited for this or that kind of oil phase but it all depends on what you’re planning on mixing and creating therewith. Should you formulate with PEG-based emulsifiers and use the HLB system therefore: petrolatum has an exceptionally low HLB requirement for o/w emulsions = even more hydrophobic/lipophilic emulsifiers can give stable emulsions. This also means that it’s harder (in theory) to create stable w/o emulsions with it… but I guess that’s the point where you trash HLB and use other means.B: Yes and no. An emulsifier will not ‘preserve the physical properties’ of the inner phase but most can (but don’t have to) maintain the properties of the outer.C: An emulsifier is meant to turn two immiscible phases into an emulsion; an emulsion is often a cream. Whether or not that cream feels & looks like one of its ingredients depends on the type of emulsion more than the emulsifier.
No offense, but again, please get yourself a book or two about the basics of cosmetics and then ask questions if you don’t understand enough. -
@Perry I wouldn’t make cosmetics if it were so :blush:
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If the ingredient is better soluble in silicone oils than in sin, then you have a ‘problem’ (as long as you formulate cosmetics and not pharmaceuticals, it doesn’t really matter).
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What the heck… I’m speechless from all that stupidity (mostly because that lawyer, dumb as he/she might be, most likely earns 10 times as much as I do)!
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A small addition to that, just to avoid a possible misconception: Viscosity loss caused by some of the above mentioned wetting agents does only apply to emulsions containing classical emulsifiers but not polymer stabilised emulsions such as those made with Sepinov EMT. If viscosity goes down the drain there, it’s highly likely caused by another mechanism.
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Phytate is a polyelectrolyte, worse than citric acid (theoretical 12 negative charges!). GLDA and EDTA just carry up to four… still, if you’re encountering issues with salting out effects try using ingredients with a low amount of trace metals so you can safely use the bare minimum of a chelate. As alternatives, caprylyl hydroxymic acid might work (personally, I don’t trust that guy) and, theoretically, nordihydroguaiaretic acid might too. Depending on the ingredients and the overall preservative system, you might get away without using any chelates at all. Maybe @PhilGeis has some experience with atypical and/or nonionic/monoionic chelates?Regarding azelaic acid: if it isn’t micronised, then a suspension will easily feel sandy/grainy (and possibly irritating where there are too large crystals sitting and dissolving on the skin). Heating can speed up dissolution but you should only add as much azelaic acid as your system can dissolve at room temp (better even slightly below that), else it will always crystallise out once cooled down (because solubility of it increases with increasing temperature and vice versa). Also, recrystallisation will easily lead to even larger crystal needles than before.50°F? Are you an Inuit? Cause for all others, 50°F (=10°C) isn’t considered heating but cooling :smiley: !To my current knowledge and experience, azelaic acid can not be properly dissolved in anything acceptable at an effective concentration unless you want to go anhydrous and/or gooey/sticky. You’ll likely have to come to terms with a life full of compromises.As mentioned in another thread on salicylic acid, neutralising such an acid will render it water soluble but also utterly useless and ineffective (though you can still claim ‘contains XYZ%’).
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Don’t mix BTMS with glyceryl stearate SE if you don’t know what the ‘SE’ is (it’s often an anionic emulsifier which would be incompatible with cationics). A PEG-based emulsifier would work well, though.The choice between cetyl alcohol, glyceryl stearate (not SE), or both is up to your preferences regarding texture etc. At a low pH (where they turn nonionic), also lactylates and fatty acids can do. An oil thickening ingredient would be something I’d add if it were my product. Thinking of cetyl palmitate, a wax, or any other high melting point oil/fat/ester/hydrocarbon/etc.I have no idea why you want to add TEA or NaOH (especially at the mentioned 1.8%). Sure, if you have to raise pH because salicylic acid gives you a too low pH, there’s no issue with that… except that you’ll neutralise most of the SA and render it a useless electrolyte which might kill your emulsion. If SA isn’t dissolving well in water, now that’s a different issue (which in my opinion shouldn’t be solved by adding a base though that is, only at first glance, the easiest and fastes way to deal with it).If SA is in the oil phase, you might even omit pH adjustment completely and thereby get the full effect of SA without an uncomfortable feeling due to a low pH (especially if you don’t add any solvents to the water phase which might draw SA out of the oil and into the water phase). Sure, pH might be really low but the amount of SA causing that will be small and easily be compensated by pH active substances on your skin = not as irritating as the same % of lactic acid (water soluble AHA) at a pH possibly even 0.5 to 1 unit higher.Alternatively, you could substiture BTMS with stearamidopropyl dimethylamine (I think this blend might be patent protected, check if you’re trying to sell your creation). It’s an alkaline cationic emulsifier somewhat similar to BTMS but will react with some of the SA to form a composit acting as cationic emulsifier and water soluble salicylate at the same time (with SA keeping some of it’s activity compared to neutralisation with TEA or NaOH). However, you might want to combin that with more cetyl alcohol and/or glyceryl stearate and probably also with an approximately equal amount of an emulsifier having two alkyl chains such as distearoylethyl dimonium chloride (Varisoft EQ65) and/or a polyglyceryl diester (thinking of Emulium mellifera).Per @Dtdang‘s suggestion: A nonionic emulsifier with a large head group (PEG-100 stearate, polyglucosides, polyxylosides…) would be a wise co-emulsifier in your case. In general, nonionics should also work as main emulsifiers (many but not all are salt tolerant) whilst an anionic one will require some knowledge of its chemistry (not all work at low pH, go with sulfate/sulfonate/taurate/isethionate) and make for a great fortifying co-emulsifier in a nonionic base.
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Touché :smiley:
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@coco Azelaic acid is very poorly soluble in water and poorly soluble in many oils. Your product will likely turn out to be a suspension rather than a solution. On the upside, solid particles will not affect salt susceptible polymers.@HAL49 Citric acid is a triprotic acid = up to three negative charges = easier neutralisation of cationic emulsions, easier ‘cross-linking’ of positive charges, and higher salinity. These effects are also the reason why magnesium sulphate is used in w/o emulsions.
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@PhilGeis It’s a petrochemical and these are commonly considered synthetic. Technically, petroleum jelly isn’t chemically altered but a purified residue from crude oil distillation and hence might be considered as derived from natural resources. However, the definition of ‘natural compounds‘ as used in sciences such as chemistry, pharmacy, or biology does not apply to mineral oil and similar fossil compounds because these have been ‘synthesised’ through processes involving heat, pressure, and time rather than metabolism of living organisms. It also doesn’t matter here that the educts were, once upon a time, living creatures. ‘Synthetic’ may not be an appropriate term but ‘natural’ is even less so and for 99% of the people, the expression synthetic is a good enough term for a sufficiently well description (using the word ‘non-natural’ might be better but given the ambiguity and frequent misuse of the word ‘natural’ would make things even worse). Guess most people can live with the not super correct term ‘synthetic’ better than with ‘aliphatic hydrocarbons of fossil origin’ or ‘carbon footprint positive non-renewable resource’ (yea, I know, many of the renewables aren’t yet and might never be ‘carbon negative’, let alone sustainable… cosmetics will probably never be neither sustainable nor friendly to the environment and the choice might not be if we want to kill our planet but how and when).
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Citric acid and the base used to counter-act the low pH are electrolytes, especially when reacting with each other
. Citric acid is probably not your best choice, try lactic or hydrochloric acid and try not to play yo-yo with pH. -
Squinny said:…I haven’t opened the one I got from MySkinRecipes yet (but I bought 250ml which worked out to be $0.10 a ml - so once I open I’ll let you guys know if it smells or not - for the difference in price I dont care
…Looking forward to your observation. Got several products from MSR and they all seem totally fine. Guess I’ll reorder there sooner or later and if their TEC is good quality, I’ll likely restock with that.So far, all aluminium-free deodorants I’ve ever tried either failed or contained TEC (never made one myself, I use TEC mainly as solvent and to stabilise urea). -
Is it the smell of a non-castrated male, of wet fur, sweaty, or other? Depending where you live (indoors or warm country), it might have dense and insulating winter fur and therefore have too hot for the climate .Washing a cat or dog once a month isn’t an issue. Personally and after reading a bunch of pet shampoo labels, I feel more comfortable using baby shampoo for my dogs than 90% of the pet products.Using proper, good food and supplements (which is easier done with dogs than cats, I admit) can have a tremendous effect on scent.
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BHA? Do you mean butylated hydroxyanisole or beta-hydroxy acid?The INCI BHA refers to the former, an antioxidant which should not be used at that high concentration. If you mean the latter: Which acid exactly (probably salicylic acid)? Adding TEA will only abolish an acids effect (but have no effect on HEC).Also, if you were to make an acid peel, why did you decid to go with a cationic emulsion? Sounds somewhat counterintuitive and is highly likely to kill the emulsion if you don’t use further emulsion stabilising co-emulsifiers and other fortifying tricks (and/or make sure that the acid remains dissolved exclusively in the oil phase… which it won’t given the amount of propanediol).Also, what’s the final pH?
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This are very basic questions and I highly recommend that you first do some reading.
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Depends.Classic w/o emulsions tend to not require o/w co-emulsifiers but may. Atypical w/o emulsions might even be made entirely with mid to high HLB emulsifiers.
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Miassa said:Thank you for your answers
So how can i know if my emulsion is w/o or o/w ??You can try and calculate according to one of the systems or simply ‘measure’ the outcome. The most basic test is try and wash the cream of. A more advanced and visual one uses a water and an oil soluble colour. And you may also measure electrical resistivity.
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Betaine is an inner salt, one side is anionic and the other cationic. Like any acid (especially organic ones), their dissociation (turning from charge neutral to negative) depends on their pKa value and the solutions pH. The change is gradual and leads from an inner salt to a standard salt, not a ‘cationic’ the way you commonly think of. This means that betaine at lower pH behaves like an organic salt and charge antagonising effects are in the range of any other organic salt (= less pronounced than with table salt).
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Miassa said:…the sens of the emulsion follows the lowest hlb ??What do you mean by this?The type of emulsion is determined by all the emulsifiers and their ratios (as well as the oils used and the way you prepare the emulsion). The HLB system is also only applicable to a very narrow set of formulations. HLD would be more accurate but once you have lamellar structures, no system is currently able to accurately predict the outcome.
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Wellll… @Pharma hasn’t reliable experience with hair care and betaine/TMG.Yes, at lower pH it becomes cationic and should act somewhat as conditioning agent (given that it’s highly hydrophilic, very small, and super water soluble isn’t helpful at all). On the up-side, it can be used to replace salt as thickening agent.I like it a lot in leave-on skin care products and don’t get the skin feel a conditioning agent would cause by them. This doesn’t mean it’s impossible that it’s helping with detangling and combing.