Sodium PCA

The full Regimen Lab Skincare Encyclopedia Entry for Sodium PCA is in development. Check back in a few weeks for an update!

What is Sodium PCA?

PCA is the cosmetic ingredient term used for the cyclic organic compound known as 2-pyrrolidone-5-carboxylic acid. The sodium salt is a naturally occurring humectant in the stratum corneum at levels about 12% of the Natural Moisturizing Factor (1) corresponding to about 2% by weight in the stratum corneum (2). The sodium salts of PCA are among the most powerful humectants.

What are its benefits to the skin and how is it used it the cosmeceutical industry?

Sodium PCA is a humectant that has high water absorbing properties and binds moisture to cells, and hold several times its weight in water.  It is also considered to be hygroscopic, which means that it has the ability to absorb moisture from the air. 

Among its many functions is that it delivers moisture to the hair and skin, and is often seen as an emollient or humectant in hair conditioners and moisturizers. It is also used as an ingredient in shampoos, hair sprays, permanent waves, skin fresheners and other hair and skin care products. 

Clinical Studies 

A study wherein treatment with  a  cream  containing  5%  sodium-PCA  also  increased  the  water-holding  capacity  of isolated  corneum  compared  with  the  cream  base  (3).  The  same  cream  was  also  more effective than a control product containing no humectant, and equally effective as a similar established  product  with  urea  as  humectant,  in  reducing  the  skin  dryness  and  flakiness. 

1 Jacobi O. Moisture regulation of the skin. Drug Cosmet Ind 1959; 84:732–812.

2 Laden K, Spitzer R. Identification of a natural moisturizing agent in skin. J Soc Cosmet Chem

1967; 18:351–360.

3 Middleton JD, Roberts ME. Effect of a skin cream containing the sodium salt of pyrrolidone

carboxylic acid on dry and flaky skin. J Soc Cosmet Chem 1978; 29:201–205.

4 Ajinomoto Co., Inc. 1994b. Supplementary safety evaluations on animals. Technical Bulletin AJD-8002.

5 Usines Chimiques D’lvry-la-Bataille (UCIB). 1987. Comedogenic capacity ofpyrolidone carboxylate sol aquesuse 50%.

*more related studies: https://journals.sagepub.com/doi/pdf/10.1177/109158189901800206