Scientists are reporting development of a new form of aspirin -- taken daily by about 60 million people in the United States alone to reduce the risk of heart attack and stroke -- that could extend aspirin's benefits to people who may not respond to the drug. Their advance toward coping with "aspirin resistance" appears in the journal ACS Nano (ACS Publications).
Shiqi Peng, Ming Zhao and colleagues note that aspirin lowers cardiovascular disease risk by keeping blood cells called platelets from clumping and forming clots. But some experts believe that aspirin doesn't work for millions of people, who may switch to more costly, potent prescription drugs with more serious side effects.
Scientists have tried to address aspirin resistance by combining it with other drugs. But Peng and Zhao say that the problem remains. Their research group decided to modify aspirin in an effort to make it work for more people, according to a September 4, 2013 news release, "A new form of aspirin to overcome 'aspirin resistance'."
Researchers linked aspirin to a carrier consisting of a fragment of protein that can transport aspirin directly to damaged parts of blood vessels where clots form
Experiments with laboratory rats, stand-ins for humans in such early tests, showed that the carrier delivered aspirin to areas of blood vessels where clots were forming. It released aspirin inside the developing clot and stopped the clot-formation process.
The authors acknowledge funding from the Engineering Research Center of Endogenous Prophylactic of the Ministry of Education of the People's Republic of China, PHR (IHLB), the National Natural Science Foundation and the Beijing Natural Science Foundation and Special Project of China.
The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 163,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio. Follow ACS on Twitter and/or Facebook.
Aspirin use and macular degeneration studied by Australian scientists
In an Australian study, Gerald Liew, Ph.D., of the University of Sydney, Australia, and colleagues examined whether regular aspirin use (defined as once or more per week in the past year) was associated with a higher risk of developing AMD by conducting a prospective analysis of data from an Australian study that included four examinations during a 15-year period. Of 2,389 participants, 257 individuals (10.8 percent) were regular aspirin users.
A recent Australian study suggests link between regular aspirin use, increased risk of age-related macular degeneration. Regular aspirin use appears to be associated with an increased risk of neovascular age-related macular degeneration (AMD), which is a leading cause of blindness in older people, and it appears to be independent of a history of cardiovascular disease and smoking, according to a report published Online First, January 21, 2013, by JAMA Internal Medicine, a JAMA Network publication, JAMA and Archives Journals.
Whereas one recent study suggested that regular aspirin use was associated with AMD, particularly the more visually devastating neovascular (wet) form of macular degeneration, other studies have reported inconsistent findings. Aspirin is one of the most widely used medications in the world and is commonly used in the prevention of cardiovascular disease, such as myocardial infarction (heart attack) and ischemic stroke. As for the recent Australian study on aspirin's link to wet macular degeneration, here's what the Australian study found: High levels of vitamin D in the bloodstream appear to be associated with a decreased risk of developing early age-related macular degeneration (AMD) among women younger than 75 years, according to recent studies.
Also, the University of California, Davis reprinted for patients an article by Deborah Braconnie online in Medical Xpress, referring readers to the study. See, "Associations between Aspirin Use and Aging Macula Disorder: The European Eye study." It's published in the journal, Opthalmology. See, Ophthalmology, October 5, 2011. Smoking also is a preventable risk factor for AMD, the authors write in the study background.
On the other hand, what helps macular degeneration? Check out the studies, "High Levels of Vitamin D Appear to Lower Risk of Age-Related Macular Degeneration in Young Women" and "Omega-3 Fatty Acid Intake Linked With Reduced Risk of Age-Related Macular Degeneration in Women."
Nutrients that may help abound in online articles. You also may want to check out the article, "How To Prevent The Fastest Growing Cause Of Legal Blindness." In that article by Bill Sardi, vitamin C supplementation is suggested. Magnesium, fish oil, garlic, and resveratrol are natural blood thinners (but not the alpha form of vitamin E) the article notes.
After the 15-year follow-up, 63 individuals (24.5 percent) developed incident neovascular AMD, according to the results.
"The cumulative incidence of neovascular AMD among nonregular aspirin users was 0.8 percent at five years, 1.6 percent at 10 years, and 3.7 percent at 15 years; among regular aspirin users, the cumulative incidence was 1.9 percent at five years, 7 percent at 10 years and 9.3 percent at 15 years, respectively," the authors note, according to the January 21, 2013 news release, Study suggests link between regular aspirin use, increased risk of age-related macular degeneration. "Regular aspirin use was significantly associated with an increased incidence of neovascular AMD."
The authors note that any decision concerning whether to stop aspirin therapy is "complex and needs to be individualized." "Currently, there is insufficient evidence to recommend changing clinical practice, except perhaps in patients with strong risk factors for neovascular AMD (for example, existing late AMD in the fellow eye) in whom it may be appropriate to raise the potentially small risk of incident neovascular AMD with long-term aspirin therapy," the authors conclude, according to the news release, "Study suggests link between regular aspirin use, increased risk of age-related macular degeneration."
You can check out the abstract of the original study. This study was supported by project grants from the National Health and Medical Research Council Australia. See the abstract of the study, "The Association of Aspirin Use With Age-Related Macular Degeneration," February 25, 2013. JAMA Internal Medicine. The abstract of the study noted in its conclusion that regular aspirin use is associated with increased risk of incident neovascular AMD, independent of a history of cardiovascular disease and smoking. The objective of that study was to determine whether regular aspirin use is associated with a higher risk for developing age-related macular degeneration (AMD) by using analyzed data from a 15-year prospective cohort.
Commentary: Relationship of Aspirin Use with Age-Related Macular Degeneration
In an invited commentary, Sanjay Kaul, M.D., and George A. Diamond, M.D., of Cedars-Sinai Medical Center, Los Angeles, write: "This study has important strengths and limitations. It provides evidence from the largest prospective cohort with more than five years of longitudinal evaluation reported to date using objective and standardized ascertainment of AMD."
"The key limitation is the nonrandomized design of the study with its potential for residual (unmeasured or unobserved) confounding that cannot be mitigated by multivariate logistic regression or propensity score analysis," the authors continue, according to the news release, "Study suggests link between regular aspirin use, increased risk of age-related macular degeneration." Also see the study, "Regular Aspirin Use 10 or More Years Ago Associated With Increased Risk of Type of Age-Related Macular Degeneration."
"From a purely science-of-medicine perspective, the strength of evidence is not sufficiently robust to be clinically directive. These findings are, at best, hypothesis-generating that should await validation in prospective randomized studies before guiding clinical practice or patient behavior," the authors conclude, according to the news release which also explains: "However, from an art-of-medicine perspective, based on the limited amount of available evidence, there are some courses of action available to the thoughtful clinician. In the absence of definitive evidence regarding whether limiting aspirin exposure mitigates AMD risk, one obvious course of action is to maintain the status quo."
The Commentary appears in the JAMA Internal Medicine, published online January 21, 2013. For more information, check out the news release, "Study suggests link between regular aspirin use, increased risk of age-related macular degeneration." Also see, "Aspirin Use Linked to Macular Degeneration." Also, you may wish to read the abstract of the study, "The Association of Aspirin Use With Age-Related Macular Degeneration," February 25, 213. JAMA Internal Medicine.