A recently published randomized, double- blind, placebo-controlled study of 36 patients with stable international normalized ratios (INRs) demonstrated a clinically significant interaction between warfarin and high-dose acetaminophen (2-4 g/day).
Patients were randomized to receive placebo, 2 g of acetaminophen per day, or 4 g of acetaminophen per day. A stable INR was defined as 2 consecutive INRs at least 3 weeks apart that were in the therapeutic range.
Of the 24 patients assigned to an acetaminophen group, 13 had elevated INRs over the course of the 4-week study period. Two patients had elevated INRs in the placebo group.
INRs returned to normal in 83% of patients when acetaminophen was discontinued.
One study linked multiple pregnancies to an increased risk of developing atrial fibrillation later in life, and another investigated the association between premature delivery and cardiovascular disease.
Clinical features with downloadable PDFs