Hollywood hunk Bradley Cooper has stepped up to leading man status with his role as a struggling writer in thriller Limitless. The actor talks about the film’s unique premise of a drug that makes you superhuman, dealing with his new-found fame and 'stalking’ Robert De Niro.

With his chiselled good looks, intelligence and cracking sense of humour, Bradley Cooper seems to have it all.

His easy-going charisma makes women want to be with him and men crave a pint in his company.

But despite his charms, Cooper has still taken more than 10 years to secure his first bona fide leading man role.

He owes this honour in part to cult comedy The Hangover, which took him and co-stars Ed Helms and Zach Galifianakis from virtual unknowns to global movie heroes when it was released in 2009.

The film-makers behind his first solo outing, Limitless, decided to take a punt after seeing how the buddy movie performed.

The buzz around Cooper is about to get really loud, with The Hangover Part II hitting screens in May, but he’s not letting it go to his head.

“There is a scenario in which Limitless doesn’t do well, Hangover Part II is a huge success and it’s like, 'you can make buddy comedies the rest of your career’. Everything is tricky,” he said.

“If Limitless is not well received, it may be tougher for me to have a studio say 'we can rest the main character on this actor’s shoulders and feel he can be compelling enough to watch for two-plus hours’.”

In Limitless, Cooper is Eddie Morra, a New York writer with chronic writer’s block, his flat’s a mess and his girlfriend is not impressed. So when he’s offered a drug that will unlock his full brain capacity and allow him to become the perfect version of himself, he willingly swallows it.

“The script jumped off the page. When I read it, I couldn’t believe that this movie wasn’t even made and if it’s not, then how come I’m even having an audition for it?” he said, still incredulous he landed the part.

The pill allows Eddie to recall everything he’s ever seen, read or heard and makes him super-efficient. He knocks off his novel in four days, picks up languages with ease, then starts to plot what else he can achieve.

It’s not long before he’s wowed Wall Street by earning millions on the markets and impressed mega-mogul Carl Van Loon, played by Robert De Niro.

But the drug has powerful side-effects and attracts some unsavoury characters.

Working with screen icon De Niro was something of a dream come true for 36-year-old Cooper, who grew up watching him on screen.

“My connection to De Niro predates the movie – at least in my mind,” he says, laughing, aware he sounds like a stalker. “Before I met him, I thought, 'God his hands are just like my grandfather’s’ and I didn’t even know he was Irish and Italian, like my family.”

When Cooper was studying at the Actors Studio Drama School in New York in 1998, De Niro came for a question and answer session and an awestruck Cooper plucked up the courage to ask him a question.

“I was so embarrassed, I stayed standing up a beat too long, even when the next person was asking their question,” he said, grinning at the memory.

Cooper’s career began not long after, with a small part in Sex And The City. He went on to star in TV shows Nip/Tuck, Alias and Law & Order and had his first big movie role as Rachel McAdams’ other half in 2005’s Wedding Crashers.

But when The Hangover premiered in London some four years later, he and his co-stars still weren’t very well known. However, the film about three guys dealing with the aftermath of a Las Vegas bachelor party won fans all over the world and even picked up a Golden Globe award, propelling its stars into the stratosphere.