Inhibitif: An Ingredient Analysis

Have you seen these billboards? They are everywhere...



At the moment, Canadians are being bombarded with a glossy marketing campaign for Inhibitif, a topically applied product that is supposed to reduce the apparent growth of hair, with results comparable to lasering. A few days ago, I was asked about it, and seeing as I had been wondering what it could be all about, I decided to take a closer look.

A review of the website did not reveal much, except that supposedly the product is "breakthrough". According to the “How does it work?” page (link HERE),
“INHIBITIF’s technology is based on a multiple-action approach on the selective inhibitory activity of its formulations on the IGF‑1‑receptor tyrosine-kinase activity.”
This claim immediately piqued my curiosity: anything that affects a cell signalling receptor (particularly one so important as the IGF-1 receptor) is a serious matter and bears closer examination.

There are four products in the Inhibitif range, the Advanced Hair-Free Body Serum, the Hair-Free Body Serum (Natural), Hair-Free Face Serum, and Hair-Free Deodorant.

I focused first on the Advanced Hair-Free Body Serum, as it sounded like their 'flagship' product. I looked at the ingredient list on the website but at first glance, it was not apparent which ones are the active ingredients. It took some time for me to realize that the active ingredients are not in the ingredient list on the website page, they are listed separately on the label of the bottle in the product photo. The print is extremely tiny and out of focus, so it is easy to overlook. I had to zoom into the product label to get the listing of the active ingredients.

According to the label shown on the website, the Advanced Hair Free Body Serum contains: 0.41% lauryl isoquinolinium bromide, 0.20% dihydromyricetin, 0.25% Pseudoalteromonas ferment, 7.00% maize propanediol (these numbers may be incorrect as the print becomes more blurry the more the image is zoomed in).

Unlike the website page, the label on the box for the Advanced Hair Free Body Serum provides the complete ingredient list.

Inhibitif Advanced Hair-Free Serum product package.
Looking at the product ingredient lists was not getting me any closer to answering the question, what are the ingredients that are inhibiting hair growth? Using Google, I was able to find this page entitled “The Contents” on the company website. Strangely, this page is hidden from view: there is no way to access it from the top menu of the home page, and the only way to find it is through a search engine.

The Contents page lists "dihydromycerin" and lauryl isoquinolinium bromide as the two compounds responsible for its ability to inhibit hair growth. (Note: the product label gives the correct name for the first ingredient which is actually dihydromyricetin.) The other compounds, Pseudoalteromonas ferment and aloe, are likely only present to condition the skin and make it feel softer. Propanediol is an organic solvent, forming part of the base of the formulation, and it may enhance absorption of the product into the skin.

Only the Advanced Hair-Free Serum contains both dihydromyricetin and lauryl isoquinolinium bromide. The remaining three products, the Hair-Free Serum (Natural), the Face Serum, and the Deodorant, contain only dihydromyricetin as the active ingredient.

Let’s take a closer look at these two ingredients.

Dihydromyricetin is a type of flavonoid compound isolated from certain plant species [1]. It is a common component in plant extracts used in traditional Chinese medicine; it is known to be anti-inflammatory, with potential for treating cancer [2, 3]. Dihydromyricetin has gained some attention recently as being a possible hangover cure [4].

Dihydromyricetin (ampelopsin; CAS No. 27200-12-0; see Note 5)

According to Inhibitif’s Contents page, dihydromyricetin “targets the stimuli that boost follicular growth”. However, a search of the scientific literature failed to locate a single document that shows that dihydromyrecetin has any inhibitory effect on hair follicle growth [see Note 1]. There was one document that showed that an extract containing a number of different polyphenol compounds, including dihydromyricetin, appeared to stimulate proliferation of mouse hair epithelial cells [5].

In the U.S., there is a competing product on the market, Dermadoctor Gorilla Warfare Hair Minimizing Facial Moisturizer, that contains dihydromyricetin as the active ingredient responsible for the hair minimizing effect. The description for Dermadoctor Gorilla Warfare states that dihydromyricetin is “anticipated to cause selective inhibition of tyrosine kinase activity of the IGF-1 receptor and prevents follicular growth during the anagen phase”. This is a similar claim to the one made on Inhibitif’s website.

IGF-1 stands for Insulin-Like Growth Factor 1, a hormone produced by the liver, whose receptor is the IGF-1 Receptor (also abbreviated as IGF-1R). The IGF-1 receptor is a transmembrane protein that spans the cell membrane. Binding of IGF-1 to the IGF-1 receptor activates it and triggers a conformational change to the portion of the receptor that resides within the cell, thus communicating a signal coming from outside of the cell to the inside the cell. Activation of the IGF-1 receptor triggers a cascade of signaling events within the cell that ultimately activates transcription factors that regulate gene expression.

Schematic diagram of IGF-1 receptor (source link)
IGF-1 plays an important role in signaling growth and proliferation, and IGF-1 receptors are found in various tissues throughout the body, including skin and hair tissue. IGF-1 receptors are actively expressed by hair follicles while they are in the growing “anagen” phase, and are believed to play an important role in maintaining hair follicles in this growth phase [6].

In theory, inhibition of the IGF-1 receptor in hair follicles may lead to inhibition of hair growth. However, I could not find any scientific evidence showing that dihydromyricetin inhibits or even interacts with the IGF-1 receptor. A recent review of IGF-1 receptor inhibitors makes no mention of dihydromyricetin; those compounds which are known inhibitors of the IGF-1 receptor bear no resemblance to dihydromyricetin [7]. The complete lack of published scientific evidence to back this claim casts a real shade of doubt over whether dihydromyricetin has any effect on hair growth. And, even if dihydromyricetin is capable of inhibiting IGF-1 receptors, would one really want to? The hair follicle resides within the dermis, meaning that any active compound that is reaching the hair follicle is also reaching the blood vessels found in the dermis and therefore being circulated to the rest of the body. Given that IGF-1 receptors play a central role in regulating the growth cycles of various tissues throughout the body, there may be unknown and possibly dangerous consequences to inhibiting this receptor. This is a particular concern if the inhibiting compound is not specific and is capable of inhibiting the insulin receptor, which shares much structural similarity to the IGF-1 receptor [7].

Lauryl isoquinolinium bromide is an N-alkylated derivative of isoquinoline; it is a quaternary ammonium, carrying a permanent positive charge on the nitrogen atom, and the counter ion is bromide anion.
Lauryl isoquinolinium bromide (2-dodecyl isoquinolinium bromide; CAS No. 93-23-2)

An intensive search of published scientific literature failed to locate any articles providing evidence that lauryl isoquinolinium bromide affects hair growth. However, I managed to find two patent applications describing topical depilating products, both of which cite lauryl isoquinolinium bromide as the active ingredient [8, 9] (see Note 3).

U.S. Patent Application No. 2010/0263135 described a process wherein a patient’s skin was waxed, and the skin subjected to electroporation, with a device that provides an electrical current to "open the pores", and a solution of lauryl isoquinolium bromide was applied to the treated skin [9]. The concept was to use electroporation to enhance penetration of the active ingredient below the epidermis and into the dermis, which is where hair follicles reside. The inventor claimed that this caused “permanent epilation”, comparable to permanent epilation resulting from laser treatments. This may be taken to mean that the hair follicles are destroyed by the application of lauryl isoquinolinium bromide.

There are at least two other similar hair inhibiting products on the market which contain lauryl isoquinolinium bromide as the active ingredient: in the U.S., Nu Skin Dividends Aftershave Balm, and in Europe, Decelerine. The product information sheet for Decelerine is a little more informative than Inhibitif’s website, but still fails to answer the question of how lauryl isoquinolium bromide works [10]. However, it does include photographs showing of the effect of Decelerine on hair growth.

Decelerine product information sheet, page 8 (source link)
Alkyl isoquinolinium bromides, including the lauryl derivative, were formerly used in OTC products for treating topical acne, and dandruff/seborrheic dermatitis/psoriasis, but since the U.S. FDA moved to restrict their use for lack of safety data, they are no longer to be found in such products [11]. The primary industrial applications for lauryl isoquinolium bromide are as an agricultural chemical, a fungicide, a bacteriocide, and a wood preservative [12]. The MSDS for lauryl isoquinolinium bromide indicates that, when applied in pure form, it is acutely toxic if absorbed or ingested, and a skin and eye irritant [13]. 

Lauryl isoquinolium bromide is obtained by alkylation, with a lauryl group, of the nitrogen residue in isoquinoline, a polycyclic aromatic organic compound that was first isolated from coal tar (see Note 4).

Isoquinoline (CAS No. 119-65-3)
As a general rule, polycyclic aromatic organic compounds are of concern as they may have the ability to interact with and interfere with biological processes involving important molecules such as nucleic acids and hormones. As with many other polycyclic aromatic compounds, isoquinoline is acutely toxic if ingested or absorbed through the skin, and it is harmful to aquatic life [14]. Isoquinoline and many of its derivatives have some level of biological activity, including toxicity [15]. Although isoquinoline has not been found to be mutagenic or carcinogenic in cancer assays [16], the effects of long term exposure to isoquinoline on human health are not known. Lauryl isoquinolinium bromide is a simple alkyl derivative of isoquinoline, and will likely share many of the same properties with regards to biological and ecological effect, as the primary biological activity is due to the presence of the isoquinoline group.

Compounds that affect hair growth generally fall into three classes [17]:

  1. cytotoxic compounds that kill cells, particularly those that are actively proliferating;
  2. antiandrogens; and
  3. drugs that act on potassium channels.
The information in the patent applications and the product sheet for Decelerine, and the fact that isoquinoline and many of its derivatives are known to be toxic, suggest that lauryl isoquinolinium bromide is cytotoxic to hair follicles that are in the anagen (growing) phase, i.e. when cells within the follicle are actively dividing and proliferating.

Inhibitif instructs users of Advanced Hair-Free Serum to “apply evenly on shaved or waxed body areas twice per day for 2 months” and “reduce application to once every other day to maintain results.” With societal pressure on women to be completely hair-free, female users would likely apply this all over the legs, under the arms, and possibly over other parts of the body. Given that the active ingredient is penetrating into the dermis, where the hair follicles reside, it is likely some of it is being absorbed into the bloodstream and circulated to the rest of the body. If lauryl isoquinolinium bromide is being applied to large areas of the body for an extended period of time, my concern is that the quantity of lauryl isoquinolinium bromide that is being absorbed into the body is not going to be insignificant.

Last few words...

Inhibitif’s products are by no means a ‘breakthrough’. Similar hair-growth reducing products have been on the market for a while, but it appears that the majority of these products been marketed solely to men, for the purposes of reducing facial hair. It is only gaining attention now that these products are being aggressively marketed to women for reducing both body and facial hair.

Three of the Inhibitif products contain only dihydromyricetin, a compound for which there is no evidence that it can inhibit hair growth. Only the Advanced Hair-Free Serum contains an ingredient that appears to be capable of reducing hair growth, but the evidence suggests that this ingredient may be toxic not only to hair follicles but to other parts of the body. The product must be applied over an extended period of time so the active ingredient can be absorbed into the dermis to affect hair follicles, but this also means that the active ingredient is likely entering the bloodstream as well. As isoquinoline and many of its derivatives are known to be toxic, this raises concerns over the potential risks associated with long term exposure to topically applied products containing lauryl isoquinolinium bromide.

With users applying large quantities of this product on the skin, some lauryl isoquinolinium bromide will inevitably end up in sewage effluent. It is not known whether this compound can be degraded or if it will accumulate in the environment. Given that lauryl isoquinolinium bromide is fungicidal and bacteriocidal, and isoquinoline is known to be toxic to aquatic wildlife, the effect of releasing this compound into the environment cannot be dismissed.

***

Notes:

1. All searches conducted on National Centre for Biotechnology Information databases, and the databases of the U.S. Patent and Trademark Office (USPTO), European Patent Office (EPO), and World Intellectual Property Office (WIPO).

2. The Patent Cooperation Treaty (PCT) is an international patent law treaty that provides a unified procedure for filing patent applications to protect inventions in each of its contracting states. The WIPO oversees the filing of international patent applications (also referred to as PCT applications). Upon filing a PCT application, the International Search Authority of the WIPO will issue a search report and an opinion on the patentability of the invention. Filing a PCT application with WIPO does not result in the grant of the patent; the applicant must select member states to enter the application into, and submit a request to enter the application into the national patent office of the chosen member states before the expiration of a set deadline.

3. A patent application must be examined and granted by a national patent office before it may be enforced; this process is known as patent prosecution. Many patent applications never make it through the examination process and are abandoned by the applicant. The patent laws of most (if not all) countries provide numerous mechanisms and grace periods to maintain an application and keep it ‘alive’ during prosecution, but once a final grace period has passed without a response from the applicant, then the application is ‘dead’ and all of the subject matter encompassed by the application passes into the public domain, i.e. it can be used by any member of the public.

4. Coal tar is a by-product of the industrial process of converting coal to coal gas. It is a dark coloured liquid that contains thousands of unidentified organic compounds, many of which are polycyclic aromatic compounds. Coal tar is used as the active ingredient in OTC medicated products for treating chronic skin conditions including dandruff, psoriasis, and seborrheic dermatitis, as well as treatment for killing hair lice. However, it is often a treatment of last resort due to the risks associated with long-term exposure; formulations containing more than 5% coal tar are considered to be a Group 1 Carcinogen by the International Agency for Research on Cancer (IARC).

5. CAS Numbers are the registry numbers assigned to chemical compounds by the Chemical Abstracts Service, a division of the American Chemical Society. CAS maintains a Registry, which is a comprehensive index of all known chemical compounds, and a database of scientific literature that is searchable by the CAS Number.



References:

1. NCBI PubChem Compound Summary for Dihydromyricetin (CID 161557): http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=161557


2. Qi, S. et al. “Ampelopsin reduces endotoxic inflammation via repressing ROS-mediated PI3K/Akt/NF-kB signaling pathways.” Int. Immunopharmacol. 2012 Jan;12(1):278-87.


3. Zhang, B. “Ampelopsin sodium exhibits antitumor effects aggainst bladder carcinoma in orthotopic xenograft models.” Anticancer Drugs. 2012 Jul;23(6):590-6.


4. Shen, Y. “Dihydromyricetin as a novel anti-alcohol intoxication medication.” J. Neurosci. 2012 Jan 4; 32(1):390-401.


5. Towatari, K. et al. “Polyphenols from the heartwood of Cercidiphyllum japonicum and their effects on proliferation of mouse hair epithelial cells.” Planta Med. 2002 Nov;68(11):995-8.


6. (a) Rudman, S., et al. “The Role of IGF-1 in human skin and its appendages: morphogen as well as mitogen?” J. Invest. Dermatol. 1997 Dec; 109(6):770-7; (b) Bernard, B. A. “Hair biology: an update.” Int. J. Cosmetic Science. 2002;24, 13-16.


7. Arcaro, A. “Targeting the insulin-like growth factor-1 receptor in human cancer.” Front. Pharmacol. 2013 Mar 22;4:30.


8. International Patent Application PCT/AU2007/001380 (WO 2008/034178). “Topical Depilating Composition”. Filed Sept. 19, 2007. Expired patent application; never entered the national phase in any member state.


9. U.S. Patent Application No. 2010/0263135. “Process for Permanent Body Epilation.” (dead application); stems from International Patent Application PCT/EP2008/065326 (WO 2009/086973). Filed Nov. 11, 2008. According to U.S. Patent & Trademark Office records, this application was abandoned for lack of response, after the patent examiner issued a report stating that the claims were obvious in view of the PCT application [8], as well as the above-noted Nu Skin hair-reducing product for men, DividendsTM Aftershave Balm.) Corresponding European Patent Application No. 2227217 was granted on April 15, 2013, but has been deemed withdrawn as of Oct. 2, 2013 for lack of payment of the grant fee.


10. DecelerineTM product information sheet, March 2008. Lipotec, Inc. http://www.dermoday.com/dosyalar/1234888016.pdf


11. U.S. Code of Federal Regulations Title 21: Food and Drugs, Volume 5, Section 310.545. Ingredients listed in this section were introduced for public use before regulations came into place that require submission of safety and effectiveness data, and as such, lack data establishing safety and effectiveness for the specified use. Manufacturers of products containing the listed ingredients are required to submit evidence of safety and effectiveness for the specified use; lack of compliance would result in FDA regulatory action.



12. NCBI PubChem Substance Summary for Lauryl isoquinolinium bromide (SID 134972839)
http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=134972839&loc=es_rss

13. Lauryl isoquinolinium bromide: Material Safety Data Sheet. http://www.chemcas.com/v2/msds_t/cas76/93-23-2.asp

[Note: toxicity tests are carried out with application of lauryl isoquinolinium bromide at 100% concentration.]

14. Isoquinoline Material Safety Data Sheet, PDF available from LookChem.com
http://www.lookchem.com/msds/2011-06%2f1%2f282162(119-65-3).pdf
[Note: toxicity tests are carried out with application of isoquinoline at 100% concentration.]

15. (a) Vearrier, D. "Quinolizidine and Isoquinoline Poisoning." Medscape.Com. http://emedicine.medscape.com/article/816548-overview#showall ; (b) Nagatsu, T. “Isoquinoline neurotoxins in the brain and Parkinson’s disease”. Neuroscience Research. 1997. 29(2), 99-111; (c) McNaught, K. St.P. et al. “Toxicity to PC12 cells of isoquinoline derivatives related to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.” Neuroscience Lett. 8 March 1996. 206(1), 37-40.


16. NCBI PubChem Compound Summary for Isoquinoline (CID 8405)

http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=8405&loc=ec_rcs

17. Jankovic, S.M., Jankovic, S.V. “The control of hair growth”. Dermatol. Online J. 1998 Oct;4(1):2.


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30 comments

  1. I don't think we have this on the market in Australia yet, but I suppose it's only a matter of time. I am not at all a fan of anything that is absorbed into the blood stream - all that information on the use of nano particle technology in Invisible Zinc products scared me off completely. Think I'll leave this one on the shelf. It actually surprises me that products like this, which can have a cellular effect are allowed to be sold to the public seemingly so easily. Great post Louise xx

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    1. Hi Heidi, thanks for your comment. According to the Inhibitif website, this is being marketed in Australia by a chain called Priceline.

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    2. Oh dear - Priceline are huge and everywhere.... I suspect we'll see a big push on this during our Summer months then.

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    3. Just reading above, with myself having a science background, i looked into this further, and i did actually find a study on the ingredient' dihydromyricetin ' which is presented as an active molecule under the ingredient 'Telocapil' which is why studies were not easily found onthe net as its under a different name, here is the link to a study showing it actually does inhibit hair growth , and it seems the Natural Inhibitif sold in australia has a higher level of this showing it would slow and delay the hair regrowth.. here is the link to one of the studies'
      .http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCwQFjAA&url=http%3A%2F%2Fwww.provitalgroup.com%2Fdownload.php%3Ff%3Dpublic_suom_files_suom_productfiles_suom_Telocapil%2520brochure.pdf&ei=faZbUoTIKc2kigekpIFY&usg=AFQjCNFzUnKSDU02DFG7Mgh2wLkyHVBINg&bvm=bv.53899372,d.aGc&cad=rja

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    4. Hi Tina, thanks for your comment. I came across the same link to the product brochure for Telocapil during my research for this article but I did not include it as it did not present much additional evidence beyond the claim made by Dermadoctor Gorilla Warfare. I am not saying that the photos are not genuine evidence, but notice that there is no actual evidence showing that dihydromyricetin is interacting with the IGF-1 receptor: there are no binding assays, nor are there any references to published scientific articles that prove their claims. Product brochures by companies selling a product are not going to be objective: their goal is to sell a product. My first preference is to review the scientific literature, i.e. articles published in peer-reviewed scientific journals: this helps to eliminate bias. After that, my next preference is to review the patent literature, because most patent applicants would not go to the trouble of submitting an application unless they really felt their invention worked.

      It's possible that dihydromyricetin may be slowing hair growth via the same mechanism as its potential anti-tumor activity (the idea being the same, the inhibition of cell proliferation). From the studies I have read, dihydromyricetin's potential anti-tumor activity is via a different biochemical pathway that does not include the IGF-1 receptor. However, I can't draw any firm conclusions until I see real objective, scientific evidence of a mode of action.

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  2. Great review as always Louise, thanks for the info on this product.

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  3. Hello Louise,
    Thank you for the your thorough research. I did see an for this product and wondered about it. I think I will pass on it.
    I am fascinated by your indepth knowledge on this subject and so many other areas too such as: fashion and writing ability.
    The leaves are starting to glow. Have a wonderful weekend
    Helen xx

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  4. Hi Louise, thanks again for yet another very informative post. As Heidi mentions abode! I don't think this has infiltrated Australia yet, but I'm sure it will.
    I will be avoiding it, and will advise others to do so too.
    Loved your article in the magazine, too!

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  5. Ouch! Fungicide, wood preservative!! It won't be going anywhere near my body. Thanks so much for this in depth explanation.
    Have a terrific weekend!

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    1. Hi AWSL, thanks for your comment. I would actually like people to focus on the fact that lauryl isoquinolinium bromide is an polycyclic aromatic compound, a group of compounds that immediately raise a red flag due to their propensity to have biological effects, not that is has industrial applications outside of skin care. It has so far has escaped scrutiny because it hasn't been in used in skin care products for a long time (probably since it was included in the list of hundreds of compounds that the FDA flagged as lacking in adequate safety & effectiveness data, which was back in the early 1990s). It was originally found in OTC skin care products for treating acne, dandruff, psoriasis and seborrheic dermatitis. Its use as a fungicide and wood preservative is likely at very high concentrations (likely near or at 100% concentration) and should not be compared to the concentrations being used in skin care products. My concern is that there is no data on the risks to human health associated with long term, low level exposure to this compound.

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  6. They have something similar in France for legs and underarms but I was too lazy to slap on another product...gee whiz now that you list it out like that who knew?? It should come with a warning!! Thanks for the heads up.

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  7. Great post, Louise! I had not heard of this product, but it might have been one to interest me, so I'm very glad I read your review. I think I will stick to shaving/waxing...

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  8. Oh My God - thanks Louise - I will give this a wide berth! It is scary to me the stuff that folks are making and marketing today!

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  9. Thank you for this clear and well-organized presentation, Louise. I'm reminded of my high school Chemistry teachers anti-makeup lectures - "Just because the government made them stop using thallium doesn't mean you're safe!"

    My mom had terrible psoriasis, and she was outraged when the only product that had ever cleared up the lesions was taken off the market. The active ingredient was Lead.

    I'm fanatical about skin care, vain, too, but I don't want my products to be cooked up by the Borgias.

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  10. Thanks for the detailed info Louise. I haven't seen the billboards around Calgary but maybe I'm just not paying attention. I am always on the lookout for a permanent hair removal solution that will work for those of us with fine, very light hair. Lasers do not work and electrolysis can scar so I have to consider other options. These don't sound like good alternatives. I'm stuck with the razor for now I suppose.

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  11. I haven't seen and probably won't be paying attention even if those billboards are everywhere. It doesn't make sense to me to try and force a change in nature this way.

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  12. Nice to see a scientific look at the dangers of ingredients in a product without any "chemophobia". You should share this post with the David Suzuki foundation as they put out many similar articles. Their social media followers would likely find it interesting.

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  13. Thank you for doing the research. And twice thank you for making it publically available. I have been teaching technical writing for a while and I have to say, the simplicity and clarity with which you write does you credit.

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  14. Hello,
    I was sold on the product after seeing the cute blue and white cartoon on a Toronto TV station. There isn't much on the product to inform oneself not even the box. I have used it but it was not what I expected. The orange liquid feels like mouth wash when applied. Minty fresh coolness except the smell reminds me of Dettol (yuck). Adding to the experience the orange tints your skin, clothes, hands and my white sink! After the shave it held off growth for a day or two. I only used it once a day because of the mess that goes along with application.
    I found this research because of my curiosity about the mystery chemicals that I have been applying on my body that smelled like an old heavy duty cleaner. How does this get approved and sold on our health store shelves? Thank you for the science that would had taken me days to figure out on my own!

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    1. Hi there, thank you for your comment. Neither of these compounds are considered drugs, and neither are on Health Canada's Cosmetic Ingredient Hotlist, and therefore do not need to be approved or regulated. Many chemical ingredients have been "grandfathered" for use, in the sense that they have been around for a very long time and continue to be in use, but have never been subjected to long-term safety testing - this is the case with the alkyl isoquinolinium bromides, which used to be used in acne and dandruff/psoriasis/dermatitis treatment products before the U.S. FDA moved to restrict their use. Canada is still running behind the U.S. in this regard.

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  15. A letter from a reader received Feb. 11, 2014:

    Hello Louise

    I tried to post this to your site, but couldn’t so am emailing you instead.

    I was very glad to see your thorough review of this product. I tried it, and was initially impressed with the results. I contacted the manufacturers to find out if it was suitable for my 11 year old daughter to use. They advised me that she should not use the advanced serum, but rather the one without the alkyl isoquinolinium bromide. This raised suspicions and I asked why - to which they answered it was because her body was still developing. (Please note there are no age related advisories on the Advanced Serum packaging.)

    I then asked them if it was safe for me to use and for proof of studies done to demonstrate safety. They advised me "We comply with the regulatory body in the respective countries we sell into including the retailers."

    I wrote to the body whom I believe controls these products in Canada (Health Canada) requesting some evidence of product safety and they claim to be looking into it. I wrote to them in September 2013 and haven't had a response to date, despite a few follow ups. I also wrote to Boots in the UK, where I bought the product, to request the Product Data Safety Sheet, and they could not supply that.

    One piece of information I have found is that the alkyl isoquinolinium bromides are not permitted for use in Japan at concentrations higher than 0.05%. In the Inhibitif Advanced Serum, the compound appears at a concentration nearly 10x higher (the label lists it as >0.41%).

    Like you I am extremely concerned with the dangers involved in applying an essentially untested product on a regular and ongoing basis to the skin. It also makes you wonder about the safety of the thousands of other cosmetics available on the market. How safe are they to use on a regular basis? What testing is being done and who is protecting the interests of the consumer?

    Its really good to come across a site like yours which questions the marketing hype and researches the ingredients thoroughly. Keep up the good work!

    Best regards,
    [name withheld for privacy reasons]

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  16. Thank you so much for this post!
    I was considering trying Inhibitif, but wondered if what was in it was safe.
    After reading your clear and thorough investigation I have no more doubts.
    I will tell all my friends about it.
    By the way, a good website to research safety of cosmetics is www.ewg.org/skindeep

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    Replies
    1. Hi Maira, thanks for your comment. I am aware of the EWG website but I do not refer to it as it is not a completely objective source of scientific information, and it does not present chemical compounds in the context of their most common usage. My references are from the scientific literature (i.e. science textbooks and published, peer-reviewed journals) and I also refer to the patent literature if necessary.

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  17. Hi Louise,

    Would you say it's UNSAFE to use the hair free FACE serum as well? Which is I recall correctly doesn't contain that long-named substance?

    Hope you can reply. Thank you.

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    1. Hi Kita, thanks for your comment. Please re-read the section above on dihydromyricetin, and then if you have any further questions, email me directly.

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  18. I'm a PCOS sufferer of Middle Eastern ethnicity so I get a double whammy of hair growth! Here in the UK, my doctor used to prescribe a cream called Vaniqa which reduces the rate of facial hair growth, the cream is now too expensive for the National Health Service to prescribe so I was interested in Inhibitif as an over-the-counter alternative. Vaniqa worked well for me in a short timeframe so I was particularly curious to check out the ingredients in Inhibitif and see whether they had any similarities. A long time ago I was also prescribed another hair-reducing medicine (can't remember the name) which was primarily prescribed to men with prostate cancer, so when I read Dihydromyricetin is a potential cancer treatment I wondered whether this could be the same drug.

    I would be curious to hear whether anyone else with PCOS or hirsutism has tried this product and what the outcome was? The ingredient which makes Vaniqa effective is eflornithine and there are currently no other medicines available in the UK that contain this as the active ingredient. Obviously this is a controlled drug but I've found nothing like it since I last managed to get hold of it so just curious really.

    Thank you Louise for this post and your research! - Sara


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    1. As far as I can tell from the published research, dihydromyricetin (ampelopsin) is only in the very early stages of research as an anti-cancer therapy. There is some preliminary animal studies that show it has promise, but so far, there have been no human clinical trials.

      I have heard of Vaniqa (eflornithine); it is one of the few drugs known that actually do help reduce rate of hair growth. Is it possible to get a drug plan to help you cover the cost of it? Unfortunately, I have not heard from anyone with PCOS or hirsutism who has tried this product.

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  19. Hi, can you advise please, does inhibitif contain any ingredients that may cause skin lightening? I've been using for 10 weeks and I think in some areas my skin is lighter

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    Replies
    1. Hi Dee, apologies for the delay in responding. As far as I can tell, Inhibitif does not contain any ingredients that are known to cause skin lightening (specifically, tyrosinase inhibitors). If hair growth is being inhibited and you have dark hair, then your hair follicles may not be as noticeable, thus making skin appear lighter overall; hair follicles contain melanin pigment which is more noticeable for those with dark hair.

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  20. Hi, can you please advise, does inhibiting contain any ingredients that may cause skin lightening? I've been using for 10weeks and in some areas my skin appears slightly lighter

    ReplyDelete

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