Botanical-drug interaction study overshadowed by caffeine-tainted blood samples
A US-based team, which used 18 batches of supposedly pure human blood from multiple donors, said all the samples tested positive for caffeine with some also containing traces of cough medicine and an anti-anxiety drug.
“From a ‘contamination’ standpoint, caffeine is not a big worry for patients, though it may be a commentary on current society,” said Luying Chen, a Ph.D. student at the University.
“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.”
The team from Oregon State University (OSU) went on to say that while caffeine was detected in all lots, the anti-anxiety drug alprazolam was detected in 13 lots, while 8 lots contained the cough medicine ingredient dextromethorphan.
“Concentrations of these compounds in commercially available human serum for research were as high as 250 ng/mL for caffeine, 0.04 ng/mL for dextromethorphan, and 0.1 ng/mL for the anti-anxiety drug alprazolam,” the study details.
Study’s main objective
The presence of these contaminants did not detract from the research’s prime objective as Chen and Richard van Breemen, the director of OSU’s Linus Pauling Institute, revealed the method that effectively evaluated possible interactions between botanical dietary supplements and drug metabolism.
The method involved rapid protein precipitation and ultra-high pressure liquid chromatography, which was being used to support clinical studies.
In the clinical studies, participants take a drug cocktail along with a botanical supplement – hops, liquorice or red clover – to see if the supplement caused any of the drugs to be metabolised differently than they otherwise would.
“Botanicals basically contain natural products with drug-like activities,” van Breemen said. “Just as a drug may alter the drug-metabolizing enzymes, so can natural products.
“It can become a real problem when someone takes a botanical supplement and is also on prescription drugs – how do those two interact?
“It's not straightforward or necessarily predictable, thus the need for methods to look for these interactions. The odd thing in this case was finding all the tainted blood.”
The two researchers revealed that individual donors, who had to abstain from caffeinated foods and beverages, had to be enlisted so the research could be completed.
‘A fast, sensitive method’
Results pointed to “a fast, sensitive and specific method that was developed and validated for quantitation in human serum of probe substrates from a drug cocktail including caffeine, tolbutamide, dextromethorphan, and alprazolam”.
“This method uses rapid protein precipitation for sample preparation, fast ultra-high performance liquid chromatography (UHPLC) separations, and displays excellent peak shape and signal over noise (S/N) at the lower limit of quantitation (LLOQ).
“This method is being used to support Phase I clinical studies evaluating whether botanical dietary supplements can cause pharmacokinetic interactions with these cytochrome P450 (CYP) substrates.
“Notably, validation of this method revealed that most commercially available pooled human serum is contaminated with caffeine and alprazolam and, to a lesser extent, dextromethorphan,” the study concludes.
Source: Journal of Pharmaceutical and Biomedical Analysis
Published online: doi.org/10.1016/j.jpba.2019.112983
“Validation of a sensitive UHPLC-MS/MS method for cytochrome P450 probe substrates caffeine, tolbutamide, dextromethorphan, and alprazolam in human serum reveals drug contamination of serum used for research.”
Authors: Luying Chen, Richard B.van Breemen
