"I think they are actually trying to be more -- I speak for my own character, but I think it's somebody who is trying to be more, put something on for people he thinks he should be. And ultimately he meets somebody who makes him realize that who he is, is enough," Gyllenhaal said about his character.

"I think Maggie is doing the same thing for different reasons," Oscar-nominated actress Hathaway said. "I think Maggie, my character is trying to avoid being herself because it's easier to present a front to the world that doesn't mean that much to her than actually risk her heart. And I think that's another theme of the movie, is how much courage it takes to risk your heart."

Maggie struggles with early-onset Parkinson's disease. The disorder affects one's central nervous system, often impairing speech and motor skills. Maggie is a fine arts painter who encounters more and more difficulties to continue her work, and Hathaway said that she spoke with many Parkinson's patients in preparation for her role.

"What I learned about stage one Parkinson's, or early-onset Parkinson's disease, which my character has is that there are good days and bad days, and that there is so much anxiety that goes into the experience of being sick," Hathaway told Reuters. "And even on the good days it's not like you are having a good day, and you can forget about it. You are still processing your diagnosis and my character is living in fear of the future. And part of the journey that she goes on is learning to accept her diagnosis."

Maggie's illness is part of the reason for her careless attitude towards men and sex. Her relationship with Jamie starts as casual sex as well, but ultimately evolves into something deeper. The movie is packed with erotic scenes, and director Edward Zwick said it serves a purpose.

"All love begins with physical attraction. And to say that that's not true is to deny our fallibility as people. We are animal in that way," Zwick said.

"And I think that these people give themselves over to that as a way of avoiding love, as much as it is of going into love. And I thought that it would subvert the genre. I thought it would turn it on its head a little bit," he explained.

Zwick has helmed a variety of movies exploring a broad range of subject matter, including "About Last Night" (1986), "Legends of the Fall" (1994), "Courage Under Fire" (1996), "Blood Diamond" (2006), and "Defiance" (2008).

Gyllenhaal's character "Jamie" is a Viagra salesman who would do anything to succeed in the cutthroat world of pharmaceutical sales. To get access to doctors he brings flowers to nurses and flirt with the accountants. Nothing in the movie is over the top or made up, the actor said.

"All of that happened in the movie, particularly in 1996, and a lot of them have actually have been outlawed now -- all of the things that happened in there do happen and did happen," said the actor who memorized multiple pdf files describing effects and side-effects of medicines to sound convincingly in the film.

"Love & Other Drugs" will be released in theaters across North America the day before Thanksgiving, on Wednesday November 24, 2010.