If you ever get a blood transfusion, that supposedly pure blood is likely to contain something more: caffeine, cough medicine and an anti-anxiety drug, a new study suggests.
Oregon State University (OSU) researchers analyzed 18 batches of human blood serum pooled from multiple donors, and every batch tested positive for caffeine.
In addition, 13 batches contained the anti-anxiety drug alprazolam (Xanax), and eight contained the over-the-counter cough suppressant dextromethorphan.
"From a 'contamination' standpoint, caffeine is not a big worry for patients, though it may be a commentary on current society," said study author Luying Chen, a doctoral student in pharmaceutical sciences at OSU.
"But the other drugs being in there could be an issue for patients, as well as posing a problem for those of us doing this type of research because it's hard to get clean blood samples," she added in a university news release.
The study was recently published online in the Journal of Pharmaceutical and Biomedical Analysis.
Along with showing how much Americans love caffeine, the findings highlight the potential for contaminated blood transfusions and suggest that blood used in research isn't necessarily pure.
The researchers made their findings as they were validating a new method to study how different drugs interact in the body.
Study author Richard van Breemen said that without "doing a comprehensive survey of vendors and blood banks, we can only speculate on how widespread the problem is." He's director of OSU's Linus Pauling Institute, in Corvallis.
"Another thing to consider is that we found drugs that we just happened to be looking for in doing the drug interaction assay validation -- how many others are in there too that we weren't looking for?" van Breemen added.
The batches of blood analyzed in the study came from various biomedical suppliers who get blood bank inventory that's nearing its expiration date.
The U.S. National Heart, Lung, and Blood Institute has more on blood transfusion.