Anti-inflammatory drugs are taken for many conditions including asthma, rheumatoid arthritis and colitis. The most common class of these drugs, glucocorticoids, works very well, yet the side effects, such as muscle wasting and insulin resistance, can be so unpleasant that people stop taking them.

For many years, it has been suggested that if a more specific glucocorticoid could be developed then the side effects would be less severe, but this has not been possible because of the difficulties in predicting side effects.

In Genome Medicine, a new approach using metabolomics by Wynand Alkema, Thomas Hankemeier and colleagues from Leiden, Netherlands, is used to follow muscle wasting in healthy volunteers taking prednisolone, a type of glucocorticoid. They carried out a randomized, double blind, placebo controlled dose response experiment and found that even on the first day volunteers who took a high dose of prednisolone had early effects of muscle wasting. This was demonstrated by the presence of increased levels of certain amino acids and 3-methylhistidine in the urine and blood.

This study shows that using metabolomics to analyse urine samples is a non-invasive way to study side effects of drug treatment and that effects can be monitored even after a single dose. This approach is likely to be useful for the analysis of off-target effects in many medicines.

This research article is part of a series on pharmacogenomics that was recently launched in Genome Medicine.