How baker’s yeast Is helping scientists understand drug interactions

Frederick Roth, Canada Excellence Research Chair in Integrative Biology at the University of Toronto, has recently explained how baker’s yeast is providing scientists with a better understanding of drug interactions in humans.

Scientists have been limited in the scope of drug studies they have been able to undertake in humans (due to ethical and cost-related issues), which means drug interactions in patients are not extensively studied, even in the process of reviewing new drugs for approval.

When two or more medications are taken at the same time, their effectiveness can be suppressed or enhanced; similarly, one drug can magnify the toxicity of another. These types of interactions are a significant cause of illness and hospitalization.

This limitation has caused researchers to turn to simpler model organisms for their studies, thus enabling systematic study of drug interactions at relatively low cost. Roth and his colleagues have been testing drugs on the simple yeast Saccharomyces cerevisiae, also known as brewer's or baker's yeast.

Roth, who is also a senior investigator at the Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital in Toronto, explained how the common ancestry between humans and yeast makes this yeast ideal for studying drug interactions.

“Many aspects of yeast and human genomes have remained the same since they diverged from a common ancestor around one billion years ago,” he said. “When a specific combination of drugs has a surprising effect on yeast growth there is no guarantee that it will do the same thing to human cells. But it does give us a general idea of how often drugs are able to enhance or suppress each other's effectiveness.”

Roth’s research has shown in almost one-fifth of the combinations, one drug reduces the effectiveness of another. They also found some drugs have a greater tendency to suppress others, while other drugs are more frequently suppressed.

The team published a related study in 2011, showing that the compounds increased each other's effectiveness in about one-third of drug pairs tested. "If drug interactions are happening at anything approaching these rates in humans, we should be very concerned," Roth said.