Drugs that could slow down the ageing process in humans seem possible in future with the researchers successfully achieving the feat on worms through medicines being used to treat epilepsy.

Researchers in the United States have tested some drugs, already approved for humans, and found that it could prolong the lifespan of worms, a report published in 'Nature' said.

Kerry Kornfeld along with his team at Washington University, Missouri, tested drugs on a tiny, short-lived worm called Caenorhabditis elegans.

Researchers have shown before that tweaking certain genes can prolong this worm's life.

They divided the worms into various groups and administered the food doped with 19 medicines that are prescribed for a range of problems.

They fed the worms with drugs used as steroids to diuretics to anti-inflammatory conditions, the report said.

"We went through a pharmaceutical textbook and picked a drug from each class," Kornfeld said.

The researchers found that some of the drugs had no effect whereas high doses of some even killed the worms.

The team, however, found that an anticonvulsant used to fight epilepsy and two other similar compounds lengthened worms' lives by as much as 50 per cent, the report said.

The anticonvulsants -- developed in the 1950s -- are known to act on the nervous system, but nobody knows how it exactly functions, it said.