N-acetylcarnosine

What it is

N-acetylcarnosine is carnosine with an acetyl group on the amino end. Formula C11H16N4O4, molar mass 268.27, CAS 56353-15-2. The acetyl group makes it more resistant to carnosinase (Wikipedia: Acetylcarnosine). It occurs naturally in heart and muscle.

In the eye

Mark Babizhayev proposed it as a prodrug of carnosine for the eye in 1996 and published trials of a 1 per cent drop in cataract from 2001 (Babizhayev 2002). The Can-C brand is linked to his company, Innovative Vision Products.

Independent reviewers have not confirmed those results. A 2007 review noted low statistical power and high dropout. The Royal College of Ophthalmologists stated in 2008 that the evidence did not support the claimed potential in cataract reversal. The 2017 Cochrane review found “no convincing evidence that NAC reverses cataract, nor prevents progression of cataract” and excluded the Babizhayev studies because the reviewers could not confirm that their methods were appropriate for clinical trials (Dubois and Bastawrous 2017).

In animals

N-acetylcarnosine drops are sold for dogs and cats with cataract. No controlled trial in dogs or cats is held in this database. A rat study of topical carnosine in a diabetic cataract model is listed at Yan 2008. The veterinary evidence blog SkeptVet reviewed the pet products in 2012 (SkeptVet).

Status

In Australia, the TGA Permissible Ingredients Determination allows carnosine only as an excipient in topical skin products and states that it is “not to be included in medicines intended for use in the eye” (Determination (No. 2) 2026, item 1206). No separate entry for N-acetylcarnosine was found in the parts of the Determination checked for this site. In the United States the drops are marketed as a supplement, not a drug. See Eye drops and Status.