The director Edward Zwick has faced many challenges in his career. For his Civil War drama, 'Glory,' he built an entire fort on a Savannah, Ga., beach and then laid siege to it. While shooting his domestic terrorism thriller, 'The Seige,' he shut down the Brooklyn Bridge for an entire day. But these pale, perhaps, before the latest challenge he has set for himself: persuading men to shell out for a romantic comedy. That's what people are calling 'Love and Other Drugs,' even if the label is a loose fit. Adapted from Jamie Reidy's best-selling memoir about the Viagra gold rush in the late 1990s, it stars Jake Gyllenhaal as a womanizing pharmaceutical representative who falls in lust, and then in love, with a beautiful young woman (Anne Hathaway) with Stage 1 Parkinson's disease. It would be a plunge deep into disease-of-the-week territory, if not for the raunch -- sex scenes, sex tapes, nudity, an orgy -- that Zwick has seasoned the film with and that may leave some in the audience wondering whether they are watching a film about Viagra, or on Viagra. 'One resists categorization at one's peril,' said Zwick, a voluble 58-year-old with curly brown hair, a neatly trimmed beard and a resonant bass voice, over breakfast at the Gramercy Park Hotel. But, he added, 'romantic comedy has come to mean a couple of moderately talented actors placed in implausible situations obliged to go through a set of paces that are all too familiar, the end result being neither romantic nor comedic.' Whatever you call it, 'Love and Other Drugs,' which opens on Wednesday, signals a change of direction for Zwick, best known for movies like 'The Last Samurai,' 'Legends of the Fall,' and 'Blood Diamond.' These are handsome epics that make big claims on both the moral high ground and the audience's emotions, and that tend to elicit words like solid, stirring and old-fashioned from critics. If 'Love and Other Drugs' has any precedent in Zwick's work, it is the film that kick-started his career, 'About Last Night,' the 1986 romantic comedy starring Rob Lowe, Demi Moore and an assortment of thigh-length sweaters to give even the most doctrinaire '80s revivalist pause. In all Zwick's movies 'the thing that has always interested me -- amidst the scale, the historical spectacle, or the social significance or the political resonance -- has been the relationships,' he said. 'In this case the challenge and the joy of it was to strip all that away. The investment is only in the personal.' He compared the endeavor to the salto mortale, the 19th-century Italian circus act in which acrobats flew through a ring of fire into what they hoped would be a pair of hands on the other side. 'I was asking them to make that leap,' Zwick said of his stars. 'We were either in this together, the three of us, or not.' Hathaway described herself as initially 'discomfited' by the script, with its mixture of emotion and ribaldry -- a sort of James L. Brooks for the Age of Apatow. 'I thought the script covered so much terrain, the love story was quite frank, and my character was electric,' she said. 'I was thrilled by the prospect of doing it, but also terrified by the ways I thought it could go wrong. The characters field such big emotions. This was a very big, capital L, capital S Love Story. Let me put it this way: I didn't have a call into my agent saying, 'Find me a part where I can take my clothes off.'' Sensitive to 'this age of screen savers and screen capture' as he called it, Zwick gave his stars veto power over sequences that made them feel uncomfortable, and screened a series of films -- including Michael Winterbottom's 'Nine Songs,' Julio Medem's 'Sex and Lucia,' Bernardo Bertolucci's 'Last Tango in Paris' -- soliciting their opinions about what they liked and didn't like, what worked and what didn't. 'Anything that didn't feel organic immediately got a big thumbs down from us,' Hathaway said. 'Any time the actors felt self-conscious, we were instantly taken out of the story. The film couldn't stop in order for the characters to make love.' Zwick speaks of the sex scenes in his new film as a kind of dramatic icebreaker: the ingredient necessary to 'break down the wall' with which contemporary audiences guards their emotions. 'A sex scene is gratuitous when it only exists for its own sake,' he said, adding, 'We thought if we were to look at these scenes as we would look at any other scene, to advance the plot, or drive conflict, or overcome an obstacle, then we could apply all that we already knew about scene work and craft to the scene.' By the end of the shoot they had 'become pretty intimate' Gyllenhaal said, referring to the three-way chemistry among himself, Hathaway and Zwick. It's similar, he noted, to what he finds in some of his favorite films: 'There's something about the chemistry between the two characters, but in the case of Billy Wilder, or James Brooks or Cameron Crowe, you feel the chemistry with the director too. It was all three of us in there.' Zwick's willingness to collaborate with his actors is nothing new. 'He sees it as his job to disappear so that you can do yours,' said Denzel Washington, who won an Oscar for his role in 1989's 'Glory,' and later worked with Zwick on 'Courage Under Fire' and 'The Siege.' Washington pointed to the scene in 'Glory' in which his character, an escaped slave, is whipped for insubordination: staring right into the camera, he sheds a tear. 'It was something that just happened in the moment but Ed seized the moment, reset the cameras, and did some extra shots. He adjusted to the situation on the fly. He has a very good flow with his crews and his actors. It's never us against them. You're all in it together.' Zwick has had his misfires, most notably 'Legends of the Fall,' a woozy piece of calendar-art classicism in which Brad Pitt attempts to outdo the Montana plains for mythological resonance. His last film, 2008's 'Defiance,' about Jewish resistance fighters in the Belorussian forest during World War II, did not do particularly well at the box office. The kind of big-canvas filmmaking Zwick has specialized in is something of an endangered species in today's recession-strapped Hollywood. 'As in real life the middle class is being squeezed,' he said. 'If I made 'Glory' today, I would have to do with a platoon, not a regiment.' 'Love and Other Drugs' was made for just $30 million, with Zwick and his stars taking a fraction of their usual pay. Thus far the experiment appears to have paid off, Zwick said, if audience tests are anything to go by. 'It plays equally well to men, women, men over 30, women under 30, all four quadrants, so called,' he said. 'Once they're there they have an identical experience of the movie. The question is: Will they come?' Asked if he would like to repeat the experience of making a film in a similar vein,' he answered before the question was finished. 'It's funny to have come full circle in this way, somewhat later in my career, and come to that recognition but the answer is yes. I had a great time. I remembered all the things I most love about making movies.' 