Download Drug Information Question: ASA Supp Post CABG

Drug Information Question
What information is available about the efficacy of rectal aspirin versus oral aspirin given within 6 hours
of Coronary Artery Bypass Graft (CABG) surgery or its efficacy in other areas of cardiology?
PubMed and GOOGLE were searched using terms and phrases such as: rectal aspirin post CABG, aspirin
and CABG, rectal aspirin versus oral aspirin, rectal aspirin absorption
Although there was no information found regarding the use of rectal aspirin after CABG surgery,
information regarding rectal aspirin use was found in Acute Coronary Syndrome (ACS).
Oral aspirin is recommended in ACS patients to inhibit platelets and is given in most emergency
departments as a 162-325mg chewed oral dose. (1, 2) About 80-100% of the oral dose is absorbed and
the acetylsalicylic acid is converted to its active metabolite, salicylic acid, both in the stomach and during
first pass metabolism in the liver. (2)
Some patients with ACS are nauseated or vomit and are unable to receive oral aspirin. In this case a
rectal dose of 600mg is often given. (2) In this study, 24 healthy volunteers aged 19 to 57 (physicians &
medical students) were given a 162mg oral dose of aspirin and a 600mg rectal dose one week apart. (1)
Serum salicylic acid levels were drawn before each dose, and then 30, 60 and 90 minutes after each
dose. (1) All participants had no salicylic acid in their blood prior to the first dose. (1)There was no
difference in the salicylic acid levels at 30 minutes or 60 minutes but between 60 and 90 minutes the
drug levels were higher when the 600mg aspirin suppository was given (approximately 12ug/ml orally
versus 25ug/ml rectally). (1) Although this study found that there is a higher serum concentration of
salicylic acid with the rectal dose at 90 minutes this study did not prove that there was a clinical benefit
to giving the dose of aspirin rectally. (1, 2)
Although this study was not done in patients post CABG, the evidence suggests that the serum levels of
salicylic acid after rectal administration are as good as or better than the oral route that is known to be
an effective antiplatelet agent. (1) Until further research is conducted oral aspirin should be given when
possible, but rectal aspirin could be considered an alternative for patients not receiving oral
medications. (1, 2)
References
1.Maalouf R, Mosley M, Kallail J et al. A comparison of salicylic acid levels in normal subjects after rectal
versus oral dosing. ACAD EMERG MED Dec 2008; 16(2):157 – 161.
2. Society for Academic Emergency Medicine. Emergent aspirin use in cardiovascular disease in the
emergency department: oral dosing versus rectal suppositories. ACAD EMERG MED Feb 2009; 16(2):162164.