Author:David M Grosser, MB BS FRACS
Lots of our patients when prescribed aspirin choose to use coated aspirin whether or not they have a history of peptic ulcer disease or aspirin intolerance. This is a trend supported generally by the primary practitioner.
This has been cause for some concern as aspirin is considered to fail in some patients and because of this, secondary support such as clopidogrel is used for patients after they have received a drug eluting coronary stent. This has been considered as a problem of aspirin resistance.
It appears that the reason for this resistance has been discovered in a significant study of 400 healthy adults aged 18 years to 55 years, platelet-inhibition response to the administration of a single 325-mg dose of immediate-release or enteric-coated aspirin was evaluated to assess the activity of cyclooxygenase-1.
: all of the individuals receiving immediate-release aspirin were responders, but up to 49% of those given enteric-coated aspirin were nonresponders.
:repeat exposure, with immediate-release aspirin; all nonresponders turned into responders.
One of the powerful conclusions of the study is that aspirin resistance may not actually exist. It would appear that enteric coating interferes with intestinal absorption to such an extent as to render the drug ineffective as far as platelet inhibition is concerned.
We need to question the idea of using enteric coating and have concern as to the alleged protection against risk of gastric bleeding provided
by these preparations. There is little evidence that protection exists so there may be no reason to consider use of enteric coating in most instances.
The study is simple and efficient and based on very specific functional assessment and although the tests were carried out in healthy volunteers there is no obvious reason it would be different in an alternative arrangement.
My advice to all my patients taking platelet inhibitors to prevent thrombosis with arterial disease, especially with angioplasty, stents and grafts is to use SOLUBLE uncoated aspirin.
Common Names locally for Coated Aspirin are CARTIA and ASTRIX. These products should be replaced with soluble aspirin.
1. Grosser T, Fries S, Lawson JA, Kapoor SC, Grant GR, Fitzgerald GA. Drug resistance and pseudoresistance: An unintended consequence of enteric coating aspirin. Circulation. 2013;127(3):377-385.
Results The rate of aspirin nonresponsiveness was 15.8%, 8.1%, and 52.8% for plain aspirin, PL2200, and EC aspirin, respectively (p < 0.001 for both comparisons vs. EC aspirin; p = 0.30 for comparison between plain aspirin and PL2200). Similarly, 56% of EC aspirin–treated subjects had serum TXB2 levels >3.1 ng/ml, compared with 18% and 11% of subjects after administration of plain aspirin and PL2200 (p < 0.0001). Compared with findings for plain aspirin and PL2200, this high rate of nonresponsiveness with EC aspirin was associated with lower exposure to acetylsalicylic acid (63% and 70% lower geometric mean maximum plasma concentration and 77% and 82% lower AUC0–t [area under the curve from time 0 to the last time measured]) and 66% and 72% lower maximal decrease of TXB2, with marked interindividual variability.
Conclusions A high proportion of patients treated with EC aspirin failed to achieve complete inhibition of TXB2 generation due to incomplete absorption. Reduced bioavailability may contribute to “aspirin resistance” in patients with diabetes. (Pharmacodynamic Evaluation of PL2200 Versus Enteric-Coated and Immediate Release Aspirin in Diabetic Patients; NCT01515657)
Journal of the American College of Cardiology
January 2017> DOI: 10.1016/j.jacc.2016.11.050
Enteric Coating and Aspirin Nonresponsiveness in Patients With Type 2 Diabetes Mellitus
Deepak L. Bhatt, Tilo Grosser, Jing-fei Dong, Douglas Logan, Walter Jeske, Dominick J. Angiolillo, Andrew L. Frelinger, Lanyu Lei, Juan Liang, Jason E. Moore, Byron Cryer, Upendra Marathi