Navigation Links
'Resistance' to low-dose aspirin therapy extremely rare
Date:12/5/2012

PHILADELPHIA Roughly one-fifth of Americans take low-dose aspirin every day for heart-healthy benefits. But, based on either urine or blood tests of how aspirin blocks the stickiness of platelets blood cells that clump together in the first stages of forming harmful clots up to one third of patients are deemed unlikely to benefit from daily use. Such patients are called "aspirin resistant." Clots are the main cause of most heart attacks and strokes.

In people who have suffered a heart attack, low-dose aspirin reduces the chances of a second event by about one fifth, making it perhaps one of the most cost-effective drugs currently prescribed. Although consumed widely by the worried well, the relative usefulness of low-dose aspirin in patients who have never had a heart attack is more controversial. According to previous primary prevention studies, low-dose aspirin reduces this group's very low risk of a first attack by about the same number of serious stomach bleeds it causes.

In a study of 400 healthy volunteers published online this week in Circulation, the journal of the American Heart Association, scientists from the Perelman School of Medicine at the University of Pennsylvania, went looking for people who are truly resistant to the benefits of aspirin, such as might result from a particular genetic makeup. They failed to find one case of aspirin resistance; rather, they found "pseudoresistance," due to the coating found on most brands of aspirin, often preferred by patients for the protection it is claimed to provide the stomach. What's more, a urine biomarker of platelet stickiness was not able to find which volunteers were even pseudoresistant.

The study was led by Tilo Grosser MD, research assistant professor of Pharmacology, Susanne Fries, MD, research assistant professor of Pharmacology, and Garret FitzGerald, MD, FRS, director of the Institute for Translational Medicine and Therapeutics.

"When we looked for aspirin resistance using the platelet test, it detected it in about one-third of our volunteers," said Grosser. "But, when we looked a second time at the incidence of aspirin resistance in the volunteers, the one-third that we measured who was now resistant was mostly different people. Nobody had a stable pattern of resistance that was specific to coated aspirin."

Presently a blood test using a specific device can be used in the doctor's office to diagnose "aspirin resistance." Alternatively, an FDA-approved urine test is available for an indirect marker of platelet stickiness. Either can be used to determine if a patient is likely to benefit from aspirin. However, neither approach was supported by the Penn study. The blood test picked up pseudoresistance, while the urine test failed even to segregate these individuals from those clearly responsive to aspirin.

To address the reason for this pseudoresistance, the researchers compared test results of coated aspirin with the same dose of regular uncoated aspirin in volunteer subgroups for coated versus immediate-release, uncoated aspirin. Resistance was absent in the group that took the uncoated aspirin.

The coating delayed absorption compared to immediate-release, uncoated aspirin. This led to a false impression of aspirin resistance in people taking coated aspirin. Platelets of such patients remained sensitive to aspirin when examined in a test tube, so they were not truly resistant to the action of aspirin.

Uncoated, immediate-release aspirin is generic and cheap - less than 1 cent per pill but most low-dose aspirin taken in the U.S. is the more expensive, coated, branded variety. Although supposedly easier on the stomach, coating of aspirin has never been shown to reduce the likelihood of serious stomach bleeds compared to the same dose of uncoated aspirin.

"These studies question the value of coated, low-dose aspirin," notes FitzGerald. "This product adds cost to treatment, without any clear benefit. Indeed, it may lead to the false diagnosis of aspirin resistance and the failure to provide patients with an effective therapy. Our results also call into question the value of using office tests to look for such resistance."


'/>"/>

Contact: Karen Kreeger
karen.kreeger@uphs.upenn.edu
215-349-5658
University of Pennsylvania School of Medicine
Source:Eurekalert  

Related medicine news :

1. New drug overcomes resistance in patients with rare sarcoma
2. Drug resistance biomarker could improve cancer treatment
3. Many Americans Still in the Dark About Antibiotic Resistance
4. Understanding antibiotic resistance using crystallography and computation
5. Recent findings may help to fight melanomas resistance to chemotherapy
6. Scripps Research Institute receives $20 million to shed light on HIV drug resistance
7. UCI researchers find cause of chemotherapy resistance in melanoma
8. Mutation breaks HIVs resistance to drugs
9. Protein linked to therapy resistance in breast cancer
10. New Strep Throat Guidelines Tackle Antibiotic Resistance
11. Environmental Gene-Swapping May Play Part in Antibiotic Resistance
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
'Resistance' to low-dose aspirin therapy extremely rare
(Date:1/21/2017)... ... 21, 2017 , ... Salveo for life, a company that distributes an effervescent ... United States as part of its presence to expand its market reach. , Using ... the productions of nasty toxins as a result of drinking alcohol, eliminating those toxins ...
(Date:1/21/2017)... ... 21, 2017 , ... Northern California Medical Associates (NCMA) is ... multi-specialty medical group. The dermatology practice provides general dermatologic treatment, outpatient surgery, clinical ... this excellent dermatology practice to our group’s medical services,” explains NCMA CEO, Ruth ...
(Date:1/20/2017)... ... ... A new partnership between Goodwill® and Roadie, Inc. aims to make it easier ... couches to dressers and bicycles. Roadie — the national on-the-way delivery network — will ... through February 28th. , “January is an exciting time when resolutions are made ...
(Date:1/20/2017)... ... , ... Lice Troopers, the lice removal company based in South Florida, has ... holiday season. , “It happens every year around this time,” says owner, Arie ... which is the head-to-head gateway that lice need to spread.” , As children return ...
(Date:1/20/2017)... ... January 20, 2017 , ... Vitamin Well ... VW+ 002. The drinks have been produced in collaboration with Zlatan Ibrahimovic and ... your workout. , After a successful launch in Sweden last year, the next ...
Breaking Medicine News(10 mins):
(Date:1/19/2017)... , Jan. 19, 2017 Conference Call and Webcast ... VNDA ) today announced it will release results for the fourth ... closes. ... will host a conference call at 4:30 PM ET on Wednesday, ... and full year 2016 financial results and other corporate activities. To ...
(Date:1/19/2017)... LONDON , January 19, 2017 Incretin ... Sympathomimetics and Others The global anti-obesity drugs ... the first half of the forecast period and CAGR of 38.7% ... expected to grow at a CAGR of 32.8% from 2016 to ... million in 2021, and $24,063 million in 2027. ...
(Date:1/19/2017)... BOCA RATON, Fla. , Jan. 19, 2017 ... ), a medical device company specializing in the ... conditions, such as keloids, with superficial radiation therapy, ... quarter and full year 2016 financial results on Thursday, ... The Company will hold a conference call ...
Breaking Medicine Technology: