Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Ester doai
Reexamination Certificate
1998-01-29
2001-02-27
Fay, Zohreh (Department: 1614)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Ester doai
C514S561000, C514S562000, C514S912000
Reexamination Certificate
active
06194457
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid composition for treatment of the eyes. The liquid eye drop composition may-be used to treat irritations of the eye, dryness of the eye, and/or the onset or progression of cataracts.
2. Discussion of Related Art
The ocular lens of the eye is a relatively pliable and normally transparent tissue held in suspension between the aqueous and vitreous humors. The tissue has a fibrous type structure. The lens functions as a converging lens, in conjunction with the cornea, pupil, aqueous humor and vitreous humor. The pliability and transparency of the lens are necessary for the proper functioning of the lens in image formation and visual perception.
The lens of the eye is constantly exposed to light and ambient oxygen, and is thus very susceptible to oxidation, particularly light-induced lipid peroxidation. The lens has a complex biochemical system, well understood in the art, relying upon proteins, particularly proteins containing sulfhydryl groups, to maintain the system and in turn the transparency of the lens.
Light entering the eye permits the generation of free radicals within the lens, in particular the superoxide radical O
2
−
, which in turn can degenerate into other free radicals such as hydrogen peroxide and hydroxide radicals. These free radicals act to oxidize the proteins of the lens. Oxidation of the proteins is known to be a major factor leading to the onset of cataracts, which is a loss of transparency of the lens. See, for example, Varma, “Scientific Basis for Medical Therapy of Cataracts by Antioxidants”, Am. S. Clin. Nutr., vol. 53, pps. 335S-345S (1991).
Accordingly, the lens of the eye has an antioxidant defense system to respond to an oxidative stress and maintain the integrity of the lens. Various studies have shown that the antioxidant defense system includes the enzymes glutathione peroxidase, catalase and superoxide dismutase, and the antioxidants vitamin A (ascorbic acid), vitamin E (&agr;-tocopherol) and &bgr;-carotene. See, for example, Kamei, “Glutathione Levels of the Human Crystalline Lens in Aging”, Biol. Pharm. Bull., vol. 16, no. 9, pps. 870-875 (1993); Fletcher et al., “Glutathione and Aging: Ideas and Evidence”, The Lancet, vol. 344, pps. 1379-1380 (1994); and Jacques et al., “Antioxidant Status in Persons With and Without Senile Cataracts”, Arch. Opthalmol., vol. 106, pps. 337-340 (1988).
The role of each of the above materials in protecting the lens against degradation by oxidation has also been widely studied. Most studies have focused upon dietary supplementation of the materials to preserve the antioxidant defense system of the lens during aging, thus preventing or slowing the onset of cataracts. See, for example, Robertson et al., “Vitamin E Intake and Risk of Cataracts in Humans”, Annals New York Academy of Sciences, pps. 372-382; “Protective Role of Vitamin E in Cataract Development”, Vitamin E Research Information Service (1990); Devamanoharan et al., “Prevention of Selenite Cataract by Vitamin C”, Exp. Eye Res., vol. 52, pps. 563-568 (1991); and Jacques et al., “Epidemiologic Evidence of a Role for the Antioxidant Vitamins and Cartenoids in Cataract Prevention”, Am. J. Clin. Nutr., vol. 53, pps. 352S-355S (1991). See also U.S. Pat. No. 5,075,116 to LaHaye et al.
Studies have also confirmed that the materials vitamin A, vitamin E and glutathione have a close interaction in regenerating one another following oxidation of one or more of these molecules. See, for example, Stoyanovsky et al., “Endogenous Ascorbate Regenerates Vitamin E in the Retina Directly and in Combination With Exogenous Dihydrolipoic Acid”, Current Eye Research (1994); and Winkler et al., “The Redox Couple Between Glutathione and Ascorbic Acid: A Chemical and Physiological Perspective”, Free Radical Biology & Medicine, vol. 17, no. 4, pps. 333-349 (1994).
A role has also been reported for zinc and copper in maintenance of retinal metabolism. See Hirayama, “Histochemical Localization of Zinc and Copper in Rat Ocular Tissues”, Acta Histochem., vol. 89, pps. 107-111 (1990). Zinc has been cited as a cofactor for several antioxidant systems present in the retinal pigment epithelium. See Newsome et al., “Zinc Uptake by Primate Retinal Pigment Epithelium and Choroid”, Current Eye Research, vol. 11, no. 3, pps. 213-217 (1992).
Although extensive reporting has been done on the significance of dietary supplementation of various lens antioxidant system materials in maintaining the integrity of the defense system in times of oxidative stress and throughout aging, there is little discussion related to eye drop formulations that combat oxidation in the lens. One exception is Cataract Breakthrough, The Booklet, by Dr. Alex Duarte, discussing research in which the three amino acids cysteine, glycine and glutamic acid, the amino acids that make up and synthesize glutathione, were introduced to the lens through eye drops. Dr. Duarte recommends a cataract prevention treatment involving these eye drops in conjunction with dietary supplementation of all antioxidant defense materials.
SUMMARY OF THE INVENTION
It is an object of the present invention to develop a liquid eye treatment composition, that is an eye drop composition, that may be used in combating oxidation within the lens of the eye. It is a further object of the invention to develop an eye drop composition that may further be used to relieve irritations from the eye and eliminate dryness of the eye.
These and other objects are achieved with a liquid eye treatment composition containing a specific combination of lens antioxidant defense materials and buffering agents. The eye drop composition, when added to the eye, not only is capable of alleviating irritations and/or dryness, but is also capable of preventing the onset of cataracts from aging, or delaying or halting the progression of cataracts in patients already having cataracts. The composition of the invention achieves such results without the need for dietary supplementation of other antioxidant materials.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The eye treatment composition of the invention must contain each of the antioxidant materials vitamin A, vitamin E and reduced glutathione.
By “reduced glutathione” is meant a mixture of the three amino acids glutamic acid, cysteine and glycine which comprise and synthesize glutathione. The reduced glutathione preferably comprises these amino acids in substantially equimolar amounts, although glutamic acid and glycine may be included in greater amounts to account for reported lower percentage penetrations of these amino acids through the cornea compared to cysteine. Once within the fibrous structure of the lens, these amino acids interact to synthesize glutathione, which is known to act as an antioxidant in the lens.
The amount of reduced glutathione in the composition is from, for example, 0.1 to 10% by weight, preferably from 0.5 to 5% by weight, more preferably from about 1 to about 3% by weight of the composition. The amount of vitamin A in the composition is from, for example, 0.01 to 5% by weight, preferably from 0.05 to 2% by weight, more preferably less than about 0.1% by weight of the composition. The amount of vitamin E in the composition is from, for example, 0.01 to 10% by weight, preferably from 0.05 to 5% by weight, more preferably from about 0.1 to about 1% by weight of the composition.
As discussed above, each of the antioxidant materials cooperate with one another in the lens antioxidant defense system. The cooperation enables cyclical regeneration of the antioxidants, avoiding rapid elimination of the antioxidants from the eye which would require continues replenishment (that is, continuous eye drop application) if such were to occur.
The eye drop composition of the invention also preferably includes buffering agents to adjust the acidity or alkalinity of the composition. In order for the eye drop composition to be accepted by the eye without causing irritation, it is important that the composition be an isotonic solu
Absher Kenneth J.
Braswell A. Glenn
Duarte Alex
Fay Zohreh
McKenna & Cuneo, L.L.P.
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