Urine Samples could be Used to Predict Responses to Drugs, Say Researchers
News Aug 11, 2009
Researchers may be able to predict how people will respond to particular drugs by analyzing their urine samples, suggest scientists behind a new study published in the journal Proceedings of the National Academy of Sciences.
Not all drugs are effective in all patients and occasionally, susceptible individuals can have adverse reactions to them. In this study, researchers from Imperial College London and Pfizer Research and Development showed that it was possible to predict how different individuals would deal with one drug by looking at the levels of different products of metabolism, known as metabolites, in their urine before they took a dose of the drug.
The researchers say that this kind of 'metabolic profiling' could ultimately be a valuable tool for predicting how different individuals will react to drugs, enabling those developing drugs to match drug treatments to individuals' requirements and avoid adverse side effects. They argue that those developing new, personalized approaches to medicine will need to consider metabolic as well as genetic profiling when developing drugs, in order to produce a complete picture of different individuals' makeup.
Metabolic profiles reflect complex gene-environment interactions and the activities of gut bacteria - factors that can influence drug metabolism and toxicity.
Bacteria in the gut, or gut microbes, live symbiotically in human and animal bodies and there is growing recognition that they play an important part in influencing people's metabolic makeup. The study provides evidence that gut microbes can have a crucial role in determining a person's response to a particular drug.
The new study looked at 99 healthy male volunteers aged between 18 and 64, taking one dose of the commonly used painkiller acetaminophen, widely known as paracetamol in the UK. The researchers took urine samples from the men before they took the paracetamol dose and for six hours afterwards and analyzed the metabolites in the samples using 1H NMR spectroscopy.
The results revealed that a compound called para-cresol sulphate, which is derived from para-cresol produced by bacteria in the gut, was an indicator of how the men would metabolise the dose of paracetamol. Those with higher levels of para-cresol sulphate metabolized the drug in a different way from those with lower levels.
The scientists suggest that this is because the body uses compounds containing sulphur to process drugs like paracetamol effectively and para-cresol can deplete sulphur compounds in the body.
The body uses sulphur to process a variety of drugs, not just paracetamol, so the new findings about para-cresol could have significant implications for a whole group of drugs, say the researchers. Further work is now needed to explore areas such as the relationship between para-cresol and other drugs, and whether para-cresol has any relevance to instances of accidental paracetamol poisoning.
The researchers also suggest that where the bacteria in the gut are affecting the body's ability to process a particular drug, it might ultimately be possible to alter the makeup of these bacteria so that the body can process a variety of drugs more effectively and safely.
The ideal drug is one that only affects the exact cells and neurons it is designed to treat, without unwanted side effects. This concept is especially important when treating the delicate and complex human brain. Now, scientists have revealed a mechanism that could lead to this kind of long-sought specificity for treatments of strokes and seizures.READ MORE