Acetaminophen is a widely used
analgesic, and recent studies have shown that it has some benefits in the ischemic heart. The purpose of this study was to test the effects of
acetaminophen on
infarct size, regional myocardial blood flow and the "
no-reflow" phenomenon in a rabbit model of coronary artery occlusion (CAO) and reperfusion. Rabbits were assigned to one of four groups: (1)
acetaminophen, 75 mg/kg in 75%
ethanol, 30 min before CAO, (2) vehicle at 30 min before CAO, (3)
acetaminophen at 18 min after CAO (12 min before reperfusion), or (4) vehicle at 18 min of CAO ( n = 10 each group). All rabbits received 30 min of CAO followed by 3 hr reperfusion. The extent of
ischemia was similar in all groups comprising 24-27% of the left ventricle.
Infarct size (% ischemic zone) was 51 +/- 5, 56 +/- 3 in groups 1 and 2 ( p = ns), 43 +/- 3 and 40 +/- 4 in groups 3 and 4 ( p = ns). Thus
acetaminophen did not affect the development of
necrosis. Heart rate and blood pressure were unchanged by
acetaminophen treatment. Regional myocardial blood flow was similar in all groups during occlusion and at the end of reperfusion.
Acetaminophen had no effect on the size of the anatomic zone of no-reflow that developed by 3 hours of reperfusion. We conclude that
acetaminophen has a neutral effect in this experimental model of
ischemia/reperfusion and appears to be safe in the course of experimental
myocardial infarction.