Researchers in London expressed concern over a new family of drugs based on cathinone, the active ingredient in the plant khat, the BBC reported Oct. 7.

A controlled substance in the U.K., khat is commonly used as a stimulant in East Africa. Other "legal high" pills, based on a group of drugs called piperazines, will be designated as controlled substances in the U.K. early next year. The emergence of cathinone-based pills with their chemical structure altered suggests to some experts that manufacturers are trying to find ways around the new law.

The drugs are "being sold as a safer alternative to ecstasy," said John Ramsey director of TIC TAC Communications based at St George's Hospital in south London. "Presumably [users] think they're safe, and they're probably not," Ramsey said.

Some users of the cathinone-based drugs experience side-effects similar to drugs like ecstasy, amphetamine, cocaine and ketamine, including rapid heart rate, raised blood pressure, high temperatures, and seizures.