-
What is your favourite conventional emulsifier?
-
@Pharma, the name was Lanette N. As I said it is a great ingredient for pharmaceutical oriented products. I used to make this myself before, but in an industry it is more easy to use a ready made mix. In pharmaceutical industries, the main point of choosing an expuent is its function, and as you said, this is a functional one. We don’t have to sound smart, but efficient. 😉
Regarding the feel. I’d say that it is good enough. It really depends on the purpose of the product and where it is going to be applied. -
Apologies for the offtopic guys, but since we have several pharmacists in one place, I have a question. I read on one DIY supplier’s website (who is actively promoting Easynov) that W/O emulsions are the way to go for the simple reason that they somehow improve delivery of actives. My quick search didn’t give me anything particularly reliable on that topic. I understand that not all actives can be delivered deeper in skin and most of them shouldn’t be. But since most of pharmaceutical ointments are w/o, I wonder whether this statement has any scientific back up?
-
@ngarayeva001
Do you mean pharmaceutical creams? Ointments are W/O or anhydrous per its name (ointment or ‘salve’), or at least that’s the correct name usage here in NL. The Lanette cream I shared was O/W. I think there are about just as many O/W as W/O. It just depends on the indication, skin pathology, environment (is it a dry or wet environment, hairy or non hairy etc etc). That’s only my quick explanation as I am short in time. -
re: deeper in skin
Maybe they name W/O because these are occlusive and thus the used pharm. active has longer exposure time on skin.
Urea has been used to penetrate nails in some cases I believe (fungal or psoriasis related, not sure)
DMSO in extreme cases of extravasation of some chemos, but it’s not common in dermatics.
I think it’s mostly marketing propaganda (“penetrates in deeper skin layers”)
I can only think of a few medicinal reasons wanting actives in deeper skin layers and those aren’t cosmetic by far. And shouldn’t be! -
As @Doreen mentioned, occlusion is the reason why.Although, this line of thoughts is not always true and depends for example on the solubility of the actives in the base as well as in skin. This is because the preparation serves as reservoir which needs to create a concentration gradient to push the active into the skin. Completely undissolved active doesn’t do anything and a super well solubilised one prefers staying in the product rather than passing into adjacent skin. Hence, best skin penetration is (again a rule of thumbs) achieved when using an occlusive preparation (a cling film works wonders, too) in which an oil soluble and/or non-ionic active is dispersed. As mentioned, said active should be slightly/poorly soluble in the used preparation too. For example a salicylic acid suspension/partial solution in vaseline/petroleum gives great skin penetration (systemic effect!) whereas salicylic acid dissolved in a polar oil or alcohol or, even worse, salicyate acid/salt in an aqueous preparation will only result in superficial penetration (good enough for exfoliation) or a film of “inactive” salicylic salt on top of the skin, respectively (okay if salicylic acid is used as antifungal preservative).Occlusion and penetration enhancers make skin “loose/porous” (urea is probably the standard showing that effect), the former also avoids drying out of the preparation (e.g. no useless salicylic acid crystals forming on the skin) whilst the latter may help keeping actives dissolved during their passage trough skin (DMSO is a prime example).@em88: You’re right, Lanette N. Lanette SX is the version with SLES. ‘t was late and a long day at work. -
@Pharma, that note on salicylic acid is priceless! Appreciate it!
-
@ngarayeva001 You’re welcome!
-
@Pharma
What do you mean with ‘great skin penetration, systemic effect!’
How can a topical salicylic acid dispersion ever have systemic effect as target?
Several intoxications and even deaths have happened due to salicylic acid intoxication due to topical use. These occurances usually happened in patients with damaged skin and needed application on relatively large body parts, like with ichthyosis. But cases in healthy patients have been mentioned as well, usually not leading to death, but still quite serious.
I even remember a salicylate intoxication (also topical) of a forum member here. Maybe if you search, the discussion might still appear. I won’t mention this member’s name if he/she doesn’t begin about it his or herself.
Physicians, especially GP’s, don’t always recognize a salicylate intoxication (especially not if the pathway was transdermal), so numbers aren’t always correct. Plus many cases are mild and linked to other diseases. The recognition amongst GP’s I know from a clinical pharmacist I have worked with, who of course dealt a lot with intoxicated cases.
(So I know from a good source that I’m not overreacting with my warnings here and there.)I’m a bit amazed, as I am sure that you know all of this and probably a lot more than I do. Or did I misunderstand the seamingly positively sounding ‘great effect!’ sentence?
I know this forum is also viewed a lot (and sometimes taken part of) by usually girls who feel a desire to seriously overdo salicylic acid dispersions, either in aqeous or fatty medium for home made peels, that’s why I also feel a need to give a warning.A DIY webshop here in NL even sells aspirin tablets for this reason. “Grind about eight to ten tablets in a few spoons of honey or vaseline.”
Google on DIY blogs or Youtube for ‘home made aspirin mask’.
You’ll be horrified by the naivety. Concentrations don’t seem important, nor the time of exposure. When used on feet and upper arms, I see some using ‘extra’ occlusion by using socks or even plastic. And leaving it overnight. *shudders*(As a side note. I think Aspirin (or generic) tablets are mostly used in those DIY blogs instead of salicylic acid, or SA containing products e.g. Curcylic 40, because (at least here) it’s much easier to get. And oh well, it might give a bit of an analgetic effect too. (As far as I remember well from school, only the acetic anhydride reaction yielding its analgetic effect, and both forms being anti-inflammatory?)
Edit about the part that’s striked through: That particular DIY site has removed not only the ‘how to make a home made aspirin mask’ blog, but also has stopped selling aspirin tablets alltogether I see just now. I don’t know the reason but I could think of one!
-
@Pharma
My sincere apologies if I did misunderstand that part!!
It’s terribly late and I should go to bed rather than participate on forums with my sleepy head. :sleeping:Had to mention as I couldn’t delete my previous message anymore.
-
I wonder if aspirin even works for this purpose. I heard that many times, but as far as I understand aspirin is acetyl-salicylic acid which is a different molecule.
-
@ngarayeva001 - I have not seen any scientific evidence that aspirin works for this.
-
ngarayeva001 said:
I wonder if aspirin even works for this purpose. I heard that many times, but as far as I understand aspirin is acetyl-salicylic acid which is a different molecule.it could potentially work if the O-acetyl group were to be hydrolysed by esterase enzymes in the skin, but the rate of action would be much slower than with salicylic acid (see also: retinol vs. retinyl palmitate)
@Doreen also salicylic acid in bulk is nasty stuff; there’s a good reason it’s limited to 2% in leave-on products and 3% in rinse-off products -
@Doreen (I’m going to read the rest later, just an answer to the first, important passage): Sorry, exceptionally bad phrasing on my behalf! Yea, I was even thinking about intoxications when I wrote it and I know that even healthy people died from topical salicylate ODs
.What I meant was “very effective skin penetration (so effective that it can have unwanted systemic effects)”. Sorry again for the bad phrasing! -
Just curious whether salicylic acid penetrates and works when it isn’t properly solubilized? Because if not then the risk that someone inexperienced overuses it is minimal. I have a little bit of formulating experience but I cannot solubilize even 2%. Yes it solubilizes in PG. and then recrystalises again (in a toner).
-
ngarayeva001 said:I wonder if aspirin even works for this purpose. I heard that many times, but as far as I understand aspirin is acetyl-salicylic acid which is a different molecule.
It is indeed different, it is salicylic acid that has reacted with acetic anhydride. I have worked with acetylsalicylic acid in bulk (powder form). After a while you when you open the container you get a whiff of acetic acid smell when it has decomposed into rest products, i.a. salicylic acid).
@Perry (and ngarayeva001), it does work. Maybe not in scientifically correct researches, but the huge doses and the abnormally long exposure time (see Bill Toge’s explanation) probably make it work. I have seen video’s and pictures before and after, it looks like a typical ‘too much wart ointment left on too long’ (whitish skin that can be peeled off by layers).
I have also personally witnessed how acetylsalicylic acid reacts with stomach tissue, after a while it had the same corrosive effect.@Bill_Toge
Thanks for the explanation!
You’re totally right with the maximum levels. But sadly so many try homemade concoctions and completely overdo it.@Pharma
It’s ok. I understand.ngarayeva001 said:Just curious whether salicylic acid penetrates and works when it isn’t properly solubilized? Because if not then the risk that someone inexperienced overuses it is minimal. I have a little bit of formulating experience but I cannot solubilize even 2%. Yes it solubilizes in PG. and then recrystalises again (in a toner).Like Pharma explained, SA does work when dispersed instead of dissolved.
And because of its lipophilic character (which is quite unique for an acid) it can even (partially) dissolve in a fatty medium and it has a better affinity with skin being lipophilic (lipid membranes/sebum).
So a non-occlusive aqueous medium could potentially be less risky (even when fully dissolved).I thought I shared my formula (+ descriptions) with 2% salicylic acid toner with you a while ago?
If you also follow those (SA in polyol phase, both phases heated to 70C and polyol phase slowly adding to water phase at 70C and not waiting too long with raising the pH to at least 3.2 in the cool down) you should be fine. I’ve been making this toner for years now and I love it!
Remember that a formula alone doesn’t necessarily say a lot, it’s the description, the ‘protocol’ how to use it, that can make it fail or work.
But you’re totally right that it can be tricky. Once I tried another extract (hibiscus) along with the licorice salt I always use, and it turned into a gel. I thought only inorganic acids would turn that licorice salt into a gel, but Bill explained it could happen with organic acids as well. But the strange thing was that I used this licorice salt all the time with salicylic acid without problems.
If you still find it too troublesome/cumbersome, you can try Curcylic 40 at 5% (cocamidopropyl dimethylamine + 40% salicylic acid), it’s very easy to use. Trulux sells it too. -
@Doreen Okay then!BTW hibiscus extract is usually acidic . Salicylic acid is a weird thing because of the phenolic group just a carbon atom further away than the acid. This stabilises the acid; hence increased oil solubility and reduced interactions with other products. Regarding ammonium/potassium glycyrrhizate: it is pH sensitive and at low pH turns from a common “salt” into an emulsifier. That it gells is new to me (thanks for that tip!) but not astonishing given it’s related to sterols.
-
@Pharma
You’re totally right. And because hibiscus is acidic, I suspected that to be the culprit. I already was prepared for having to use more NaOH than usual to raise the pH in the cool down. I read in a leaflet of a manufacturer of dipotassium glycyrrhizate that it could form a gel when combined with inorganic acids, but since I thought I didn’t use any inorganic acids in that salicylic acid toner I was a bit baffled.
Because as I wrote in my previous reply: I used dipotassium glycyrrhizate every time in that 2% salicylic acid toner without a problem! No gelforming at all! So that’s when I thought, hey maybe that hibiscus extract that I use now as new addition may contain some inorganic acids? No idea, I’m not a bota … how do you call them, botanist? :smiley:
@Bill_Toge also gave good explanations about how licorice salts can behave with acids, inorganic or organic. But it’s still a mystery because I never had it turning into a gel before in acidic formulations with salicylic acid.N.B. Paula’s Choice uses that licorice salt too in one (or more) of her (liquid) exfoliating toners (pH of 3.2 even!) Probably in a lower concentration though. In my toner I use it at 0.3% (and have used it at 0.4%) without any problems at a pH between 3.7-3.9. Weird.
I’m totally with @ngarayeva001 that it’s tricky. I tried Euxyl PE9010 to preserve it a while ago and it precipitated. -
ngarayeva001 said:
can emulsify a lot
of oil (I tried up to 40% and it’s stable so far).Could you please advise me how many percent of emulsifier you use it for blended oil up to 40%
Thank you. -
Try 6-7%. If you add more it will be soaping.
Log in to reply.