Salycilic acid shampoo

BelassiBelassi Member, PCF student
I'm thinking of designing a 2% SA shampoo. What solubiliser though? Is SA soluble in surfactants (eg CAPB, ALS)? Add sodium citrate? If so, how much?
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Comments

  • From another thread about AS, Betaine was found to increase the solubility of salicylic acid to 5 %
  • em88em88 Member
    edited March 2018
    SA is soluble in surfactants (at last based on my tests SLES+CAPB)
    The problem you may face as well is, if SA is added as powder in the shampoo, it will increase the viscosity and foam will appear. 
    Have you planned any pH range for the shampoo? I increased the pH to 5-5.5. 
  • Bill_TogeBill_Toge Member, Professional Chemist
    salicylic acid is soluble in surfactant solutions - you'll have to heat it up to dissolve it, though, and it does take its time dissolving
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • BelassiBelassi Member, PCF student
    Good, thanks for the info. I use hot process normally - the actives content in Plantaren APB is high, and makes it difficult to dilute in cold process. I was thinking of a pH of 4.5
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • There are different solubilizers for Salicylic Acid even for only water based formulas. The key factor is whether it will dissolve completely or it will separate after some hours. After dissolving it, you may leave it stagnant for some hours. If it separates/precipitates, you may need to change the technique or solubilizer (type or percentage) You may dissolve it in Glycereth-18 Ethylhexanoate (and) Glycereth-18. The Ratio here is Salicylic Acid : Hest G - 18 -O is 20 : 80 or 2:8 in case of using 2% Salicylic Acid, as shown in the following link, . Actually, you may combine two formulas together. Dissolving Salicylic Acid, then, making the shampoo. Re: https://www.ulprospector.com/documents/1113931.pdf?bs=605&b=186849&st=1&sl=58775328&crit=a2V5d29yZDpbU0FMSUNZTElDIEFDSUQgRk9STVVMQVRJT05d&k=SALICYLIC|ACID|FORMULATION&r=na&ind=personalcare https://www.ulprospector.com/documents/1182822.pdf?bs=605&b=238242&st=1&r=na&ind=personalcare For dissolving Salicylic Acid in Surfactants, I passed by a supporting formula for it: http://www.stepan.com/uploadedFiles/Literature_and_Downloads/Formulations/Cleansers_(liquid_soaps,_facial_and_bath_products)/StepanFormulation1072.pdf Also, Salicylic Acid can be dissolved in Ethyl Alcohol (SDA 40) or Denatured Alcohol in different Ratios. But the issues here is flammability (it shouldn't be heated) and the odor. Strong Fragrance should be added.
  • BelassiBelassi Member, PCF student
    edited March 2018
    I don't have access to specialist chemicals so unless I can do it with commonly available items I can't make it.
    I just tried an experimental batch with 2.5% SA in it. Can't tell at the moment if it will be clear because I have to wait for the bubbles to clear, but it looks hopeful.
    The thing is, I measured the pH as 3.2; adding more citric acid failed to change the pH so I stopped adding citric because I assume it's just buffering and changing the acid into a salicylate.
    Is a pH of 3.2 acceptable?
    EDIT: 
    I just realised what I did!!!!  Usually I have to add citric acid but this time I should have added NaOH to adjust the pH. Oh well. I will try that a bit later ... commercial brands seem to include sodium citrate so there will be some of that in it for sure.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • BelassiBelassi Member, PCF student
    edited March 2018
    Test formula:
    Plantaren APB 20%
    CAPB 5%
    Salicylic acid 2.5%
    pH adjustment q/s
    EDTA 0.2%
    Sodium benzoate 0.4%
    Lavender EO 0.2%
    Peppermint EO 0.1%
    Sage EO 0.1%
    Tea Tree EO 0.1%
    Water Q/S 100%

    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • BelassiBelassi Member, PCF student
    Adjusted the pH to 4.0 using NaOH. Acceptable?
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  • BelassiBelassi Member, PCF student
    + 1 hour: It cleared just fine, but did throw a very small amount of precipitate. I guess that I should be able to fix that by increasing the percentage of surfactant or decreasing the percentage of SA; this was a 2.5% trial, so 2% should fix it with a bit of luck.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • DASDAS Member
    Just a thought, instead of changing your base formula try to solublise it with a glycol.

    Might be silly, but they way I see it your goal is to incorporate SA into a formula, not building a system around the SA.
  • Chemist77Chemist77 Member, PCF student
    @Belassi I am not sure if this might be of any help but I have noticed in my lab that sodium cocoamphoacetate has been a very good surfactant for some of the worst insolubles in my formulations. Case in point chlorhexidine gluconate which just was a very stubborn component and always kept falling out of the solution. It was completely tamed by this amphoteric, still unsure if this could help you in anyway.
    Good luck though on your trials and we shall wait for your updates.
  • Bill_TogeBill_Toge Member, Professional Chemist
    salicylic acid works best between pH 3 and 4 - if the pH is lower than 3, your product would be classified as a skin and eye irritant

    also, adding citric acid has little if any effect because there is already a large amount of a much stronger acid present
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • em88em88 Member
    https://www.makingcosmetics.com/Salicylic-Acid-Solution_p_1123.html
    Have a look at this link. You can make something similar.
  • BelassiBelassi Member, PCF student
    Thanks, but that is a USA supplier, it would be too expensive to import.
    Anyway, this formula is successful. The small cloud has cleared overnight, it is perfectly clear. I tried it this morning and the sensorials are excellent; although now, the viscosity is too low. I will check the pH and adjust if necessary. I see that commercial ones use sodium citrate, presumably as a buffer. I can't buy that here but I can synthesise either potassium or sodium citrate easily enough.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • BelassiBelassi Member, PCF student
    Update: Yes the pH had drifted a bit. After readjusting it the viscosity improved. I think I will continue the design but I will reduce the SA content to 2%.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • em88em88 Member
    I told you that after adding AS, foam will be formed. 
    The link I provided was to have an idea and even make something similar. 

  • BelassiBelassi Member, PCF student
    Foam? I hope so! If I am making a shampoo I expect foam. Actually the test shampoo cleared more quickly than the others.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • em88em88 Member
    If foam is created during the process of making the shampoo, in my opinion is a problem. 
    1. you can't see if you are getting the result you want in terms of appearance (if everything is dissolved)
    2. you can't check the viscosity
    3. Time is wasted for the foam to disappear
    It is possible to incorporate SA in the shampoo and avoid foam 100% :)
  • I don't know if it's already mentioned, but I use trimethylglycine (betaine) as a solubilizing aid for both salicylic acid and allantoin. Also a  big plus: betaine is great for the skin. I haven't used it in combination with surfactants yet.
    I use 1.5-2% of betaine with 2% salicylic acid and I haven't had any precipitation problems anymore (I also no longer use sodium citrate).
    I've also used 1.5% betaine with 1.5% allantoin, it works great!
  • For Salicylic Acid Separation, try to monitor Stability Results: If the product is OTC or if it has API like Salicylic Acid, you may run Stability Studies .  Usually The Stability Studies are Long Term (3 years in case of OTC - 25C),  Accelerated (3 - 6 Months - 40C), Intermediate (1.5 Year - 30C), Refrigerated (3-6 months - 6C), Freezer (3-6 Months - below 0C), and UV (3-6 Months-One sample covered by foil and the other without foil with exposing the one without foil to sunlight).  With me, I didn't experience any separation with SLS, SLES, Chembetaine, and Alcohol.  But you can run Stability Studies to make sure of that.  Also, if you have access to inside or outside lab to test the product for Regression Analysis on Monthly Basis to see whether the Concentration of Salicylic Acid is declining by time.  If it's declining, it could be an indication of several factors: e.g Separation, Cross-Reaction, or other factors.  Also, if you get haziness at leat through 3 - 6 Months in the Accelerated Results or precipitation in the Refrigerated or Frozen Results, you may change the solubilizer, technique, or concentration of the solubilizer.
  • For Stability Studies, the min. submission for the Long Term should be 1 year and for retesting, it can extend up to 3 years.  Also, for refrigeration and freezer, it can extend up to 1 year.  If you can make the freezing down to -25C, it can be better.  These are just Guidelines but it may vary from manufacturing to another in Personal care and OTC products
  • @Belassi
    Maybe this is an interesting document. It's about trimethylglycine (betain) which I mentioned, for solubilizing salicylic acid and allantoin.

  • BelassiBelassi Member, PCF student
    Interesting, thanks; but no use for me since I cannot buy that here.
    However the formula I used has been perfectly stable so far, I have no problems with it.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • Regarding my post on March 19, for OTC which includes API, they should be Pharmaceuticals, therefore, I refer to the FDA Stability Studies for Pharmaceuticals:

    https://www.fda.gov/downloads/drugs/guidances/ucm073369.pdf

    But, it's non - binding recommendation
  • Ketoconazole 2%
    Salicylic acid 2%
    this shampoo is running good in india for dandruff.

    Any idea?

  • em88em88 Member
    In india everything is possible.
    There is still a problem with that formulation. In order to keep ketoconazole stable you will have to have pH around 7, this means SA has to be neutralized totally. 
  • @em88 ; ketoconazole shampoo is stable as per you mentioned pH 7.
    we got tested after two year.
    but with SA is challenging.
  • em88em88 Member
    @amitvedakar here is a nice paper regarding the stability of ketoconazole https://pdfs.semanticscholar.org/7afb/7edf582cb706c85382a1c28fdbeec646ec48.pdf
    The main problem with ketoconazole shampoos is dissolving it, but after dissolving it the next problem is stability. Ketoconazole is not stable in water solution. Within some time the impurities will increase very quickly. 
    I was wondering how did you manage to keep ketoconazole stable. Maybe we can talk in private and share some info together so we can optimize our formulations. :)

    Regarding the SA shampoo, the first problem I faced was the possibility to dissolve SA before adding it in the shampoo base and in the same time avoiding foam. I did this, now the process is smooth. No foam is created which means the bottle filling procedure comes immediately after the preparation. :) 
  • @em88 we dissolve it in con hcl. after dissolution we dilute it.
    maintain final product at pH 6 to 7.
    we purchased SA & ketoconazole combination prodct from the mkt which has 6.5 pH.  
  • GuntherGunther Member
    @Belassi
    I'd start with Sodium Salicylate, either by reacting bare salicylic acid with dilute NaOH, or by buying premade SS.

    SS is way more soluble than Salicylic Acid.

    You'd need to lower shampoo pH to match SA pka 2.97, to get 50% SA / 50% SS
    So you'd get more than 50% soluble SS at normal shampoo pH levels
    Compare that to 0% SS if starting with SA from the beginning.


    Many commercial shampoos have SS
    https://int.eucerin.com/our-research/ingredients/s/sodium salicylate


  • At PH  6.5 to 7. Ketoconazole is stable. but Will SA work at this pH.
    What pH should be maintained of  SA shampoo to work SA.
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