N-acetylcarnosine (NAC) drops for age-related cataract

Cataract is the leading cause of world blindness.

The only available treatment for cataract is surgery. Surgery requires highly-trained individuals with expensive operating facilities. Where these are not available, patients go untreated. A form of treatment that did not involve surgery would be a useful alternative for people with symptomatic cataract who are unable or unwilling to undergo surgery. If an eye drop existed that could reverse or even prevent progression of cataract, then this would be a useful additional treatment option.

Cataract tends to result from oxidative stress. The protein, L-carnosine, is known to have an antioxidant effect on the cataractous lens, so biochemically there is sound logic for exploring L-carnosine as an agent to reverse or even prevent progression of cataract.

When applied as an eye drop, L-carnosine cannot penetrate the eye. However, when applied to the surface of the eye, N-acetylcarnosine (NAC) penetrates the cornea into the front chamber of the eye (near to where the cataract is), where it is metabolised into L-carnosine. Hence, it is possible that use of NAC eye drops may reverse or even prevent progression of cataract, thereby improving vision and quality of life (1).

Efficacy of N-acetylcarnosine in the treatment of cataracts

26 patients (41 eyes) were allocated to topical NAC 1% eyedrops twice daily. The control group consisted of 13 patients (21 eyes) who received placebo eyedrops and 10 patients (14 eyes) who did not receive eyedrops.

All patients were evaluated at entry and followed up every 2 months for a 6-month period (trial 1), or at 6-month intervals for a 2-year period (trial 2), for best-corrected visual acuity and glare testing. In addition, cataract was measured using stereocinematographic slit-images and retro-illumination examination of the lens. Digital analysis of lens images displayed light scattering and absorbing centres in two- and three-dimensional scales.

Tolerability of NAC eyedrops was good in almost all patients, with no reports of ocular or systemic adverse effects.

CONCLUSION: Topical NAC shows potential for the treatment and prevention of cataracts.(2)

References:

1: Dubois VD, Bastawrous A. N-acetylcarnosine (NAC) drops for age-related cataract. Cochrane Database Syst Rev. 2017 Feb 28;2:CD009493. doi: 10.1002/14651858.CD009493.pub2. Review. PubMed PMID: 28245346; PubMed Central PMCID: PMC6464029.

2: Babizhayev MA, Deyev AI, Yermakova VN, Semiletov YA, Davydova NG, Doroshenko VS, Zhukotskii AV, Goldman IM. Efficacy of N-acetylcarnosine in the treatment of cataracts. Drugs R D. 2002;3(2):87-103. PubMed PMID: 12001824.