Please critique a formulation (personal product): need to get rid of warming sensation

Hello!
 
Here is a formula that we are testing:

Aqua (Water) 93.10

Ultrez 10 (carbomer) 0.30

Biolin (Inulin Alpha-glucan oligosaccharide) 5.00

Natcide (Parfum --->used as a preservative) 0.70

Witch hazel 0.30

Sodium Hydroxide (10% Solution)

The product purpose is to be used as a gel that aids for wiping for folks with hemorrhoids. Testers report slight warming sensation for several seconds after using it. My questions: I think it's Sodium Hydroxide. What do you think? What can we use instead? 

Best,

Comments

  • DoreenDoreen Member
    edited April 2018
    What is the pH of the product?

    Maybe the astringent effect of the witch hazel, although the % is very low, or the Naticide?
  • DASDAS Member
    What's the purpose, neutralize the carbomer?. Use triethanolamine 0,5%. But it would be better a carbomer that will work at lower pH.

    https://www.lubrizol.com/Personal-Care/Products/Product-Finder/Products-Data/367

    I don't know if it can be used, is it a cosmetic or a drug?. 

  • PerryPerry Administrator, Professional Chemist
    You can verify what is causing the stinging by doing a partial knockout experiment.

    Aqua (Water) 93.10
    Ultrez 10 (carbomer) 0.30
    Natcide (Parfum --->used as a preservative) 0.70

    Make 3 batches where in each one you leave out one of the ingredients below. Replace the missing volume with water.  Then test it and see which formula doesn't have stinging. If you leave an ingredient out and there is no stinging, you know that was the culprit.

    Biolin (Inulin Alpha-glucan oligosaccharide) 5.00
    Witch hazel 0.30
    Sodium Hydroxide (10% Solution)

  • AVisotskyAVisotsky Member
    edited April 2018
    Thank you guys for taking a look.
    Answers:
    The purpose is to neutralize the carbomer
    It's an OTC drug
    pH is between 4.5-5.5
    Perry, great point :) Just tried Naticide/witch hazel combo and no tingling. 
    So I guess Sodium Hydroxide it is. Waiting for a sample with triethanolamine. 
    Carbopol smart 3000 is a great idea!


     
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