A drug that can lower cholesterol levels and prevent the liver from being attacked by the hepatitis C virus has come a step closer following a successful trial on laboratory animals.

The drug works in an unusual way by interfering with the natural genetic mechanism in the cells of the liver that keeps cholesterol levels high and – coincidentally – allows the hepatitis virus to replicate within the organ. The study, which was carried out on African green monkeys, lowered cholesterol levels by up to 40 per cent over three months with the help of just three intra-venous injections given over five days at the start of the trial.

Each injection contained a watery solution of a short, single-stranded molecule of RNA – a close relative of DNA – which found its way to the liver and bonded with a similar type of RNA which is found within the organ's cells. This prevented the natural RNA from working normally, boosting the activity of certain genes, which lowered cholesterol and blocked the hepatitis C virus.

The study, published in Nature, was carried out by the Danish drug company Santaris. Scientists believe the findings support the idea of a new generation of drugs based on the ability to interfere with the natural functions of RNA.

Human trials of the new drug are expected to begin later this year.