Cannabis 'munchies' inspire diet drug

Smoking cannabis increases appetite

Scientists believe the hunger-inducing effects of cannabis can be used to tackle obesity.

Smoking cannabis often triggers an urge to eat - what smokers sometimes refer to as "the munchies".

But researchers at French pharmaceutical company Sanofi-Synthelabo believe this chemical effect can be manipulated to curb hunger.

They are currently testing a drug which uses the scientific knowledge about cannabis to suppress appetite.

Early results from clinical trials on the experimental drug Rimonabant in the United States and Europe have been promising.

Patients taking the drug lost up to four kilos over a 16 week period.

Early theory

Doctors originally thought that cannabis affected the brain in a fairly random manner and that one of those random effects was hunger.

However, studies in the late 1980s showed that cannabis has a direct impact on appetite.

It triggers a surge in the brain's own cannabis-like chemicals.

These chemicals, called cannabinoids, play a role in regulating appetite.

Scientists at Sanofi-Synthelabo then discovered a way of blocking off receptors in the brain to stop these cannabinoids from sending "hungry" messages.

They have since developed a drug to perform this function. Successful results in animals have led to trials in humans.

The company is now half way through a phase III clinical trial involving more than 6,000 patients.

Human trials

This includes one study in the US where 2,800 patients comparing the performance of Rimonabant with a dummy pill to see if it helps to reduce weight and prevent weight gain.

A similar trial involving 1,400 patients in Europe is also underway. Both studies are due to end in August 2003.

Dr Lewis Aronne, director of the comprehensive weight control programme at the Weill Cornell Medical Center in New York, said early results were promising. His clinic is one of those involved in the trials.

He said weight loss among patients was "in the same ballpark as medicines we've seen before".

However, he added more research was needed to determine the long-term effects of the drug.

If the clinical trials are successful, the pharmaceutical company could seek approval for the new drug in 2004.