Scientists believe they are close to developing a pill to boost male stamina, which could become as popular as Viagra.

The drug, used to treat Parkinson's disease, has been found to raise a man's chances of sustaining multiple orgasms during sex.

In trials, the drug Cabergolin was prescribed to minimise the effects of the hormone prolactine, which is produced by men at the point of orgasm.

We interviewed these subjects and found they were able to have multiple orgasms in very rapid succession

Manfred Schedlowski, Medical psychologist

The hormone has the effect of reducing a man's desire for more sex by preventing new erections.  

Normally, the 60 test people, all healthy males, between the ages of 22 and 31, needed a break of 19 minutes between love making.

However, after taking Cabergolin, they were able to have several orgasms within a few minutes.

Medical psychologist Manfred Schedlowski, who was involved in the trials at Essen in Germany, said the drug raised the libido to enable the male to orgasm again more quickly.

He said: "We saw that prolactine rises after orgasm and then thought maybe prolactine is a negative feedback system.

"Subjects who took this drug had decreased prolactine levels, and reported their orgasm was better and there was a shorter refractory period.

New developments

"We interviewed these subjects and found they were able to have multiple orgasms in very rapid succession.

"This is sitting very nicely with our hypothesis that orgasms and sexual drive are steered by prolactine and dopamine in the brain."

Cabergolin has been on the market in Germany for several months and is used to treat Parkinson's disease and prevent women producing milk when they want to stop breast feeding.

The drug had no side effects on men during the tests, according to an article to be published in the International Journal of Impotence Research.

The researchers now plan to carry out trials to investigate whether Cabergolin will have the same effect on women.

The market for drugs like Viagra has swelled and is thought to be worth about £1bn.

It is thought Cabergolin could have similar potential...