Zinc monocysteine

Age-related macular degeneration (ARMD) is the leading cause of irreversible blindness in developed countries. There are currently no cures, but there are promising potential therapies that target the underlying disease mechanisms of dry ARMD. Stem cells, ciliary neurotrophic factor, rheopheresis, ozonated autohemotherapy and prostaglandins show promise in stabilizing or improving visual acuity. Age-Related Eye Disease Study vitamins may reduce progression to severe ARMD. Adjuvant therapy like low vision rehabilitation and implantable miniature telescopes may help patients adjust to the sequelae of their disease, and herbal supplementation with saffron, zinc monocysteine and phototrop may be helpful. Therapies that are currently in clinical trials include brimonidine, doxycycline, anti-amyloid antibodies (GSK933776 and RN6G), RPE65 inhibitor (ACU-4429), complement inhibitors (ARC1905, FCFD4514S), hydroxychloroquine, intravitreal fluocinolone acetate and vasodilators like sildenafil, moxaverine and MC-1101. Therapies that have not been shown to be effective include POT-4, eculizumab, tandospirone, anecortave acetate, the antioxidant OT-551, sirolimus and vitamin E.

To test the hypothesis that daily use of zinc-monocysteine (ZMC) supplement will be well tolerated and result in improved macular function in persons with dry age-related macular degeneration (AMD).

Eligible, consenting subjects were randomized to either ZMC 25 mg or placebo twice daily for 6 months. Both ZMC and placebo groups enrolled 40 participants, with best corrected visual acuity 20/25 to 20/70, macular drusen, and pigment changes. Masked personnel determined baseline, 3- and 6-month best-corrected visual acuity, contrast sensitivity, and light flash recovery time. Differences between ZMC and placebo were analyzed by a one-sided unpaired t-test of the paired differences between baseline and 3- and 6-month timepoints for right and left eyes separately.

By 6 months the ZMC group showed improved visual acuity (p < 0.0001) and contrast sensitivity (p < 0.0001). Macular light flash recovery time shortened in the ZMC group at 3 months by 2.1 sec (left eye, p = 0.0001) to 3.6 sec (right eye, p < 0.0001), and at 6 months by 7.2 sec (left eye, p < 0.0001) to 7.4 sec (right eye, p < 0.0001). This variable had no improvement in the placebo group. ZMC had a gastrointestinal irritation rate of under 2%.

ZMC 25 mg twice daily was well tolerated and was associated with improved macular function in comparison to a placebo in persons with dry AMD.