(FORTUNE Magazine) – It's somewhat disconcerting that Nancy K. Bryan knows more about how men regard their penises than any woman--no, any person--I've ever met. She's sitting across from me, dressed in what looks like something from Talbot's, classy and corporate with gold buttons down the front. Her legs are crossed, lips pursed. Her hair is neatly cut just above her shoulders. I'm trying to reconcile this image with the words flowing from her mouth, and for a few minutes, I'm not quite paying attention. Then her voice fades in. "Men want a quality erection," she says, making a fist in the air. "That means sufficient hardness for a duration long enough to have satisfying sex."

I can do this. I'm an adult. A professional. I can take part in this discussion without snickering or squirming in my chair like a sixth-grader. Yet if Bryan were able to read my thoughts, she'd accuse me of being part of the problem. Outside of locker-room humor and barstool braggadocio, most men have a difficult time talking about sex. And it's worse when the topic turns to impotence.

Bryan wants to change that. As Bayer Corp.'s vice president of marketing for men's health products, she is trying to incite a kind of social revolution among men by getting them to open up about their sexual health. That may sound like a tall order, but it's the only way she'll be able to achieve her company's ambitious goal of unseating Viagra as the world's premier impotence drug by 2005. Her team has joined forces with peers at GlaxoSmithKline (GSK) and in the next few months will begin co-marketing a new impotence drug called Levitra, which the two companies already sell in Europe and which is likely to receive FDA approval for U.S. sales soon.

Although Viagra is the most widely recognized new drug brand of the past decade, Bayer and GSK are banking on the fact that in today's pharmaceutical industry there's no such thing as first-mover advantage. With the help of extensive clinical trials, head-to-head lab studies of competing drugs, and Information Age market surveys, nowhere is Peter Drucker's famous theory about "creative imitators" ruling markets more apt. Bryan aims to do to Viagra what Tylenol and ibuprofen did to Bayer's icon of old, aspirin. It won't be easy, of course. Not only will GSK and Bayer be going up against Pfizer, the world's largest drug company and arguably the industry's best marketer, but they will also be facing another impotence drug due to appear soon: Eli Lilly's Cialis. Challenging Viagra doesn't daunt Bonnie Rosello, the GSK U.S. marketing vice president who is Bryan's counterpart on the Levitra team: "My view about an icon," she says, "is that it serves as a useful benchmark for new entrants--nothing more."

Bayer and GSK have a lot riding on Levitra. Bayer discovered and developed it, then enlisted GSK to help with selling. Bayer, with $4.5 billion in drug sales last year, is one of Europe's few remaining drug powerhouses. Yet it is only the 18th-largest drug company in the world, and in an industry in which the cost of ushering in a single drug nearly quintupled to $800 million in the past decade, even important players like Bayer are struggling. A blockbuster sex drug might not only entice investors but also attract a buyer--top management has made it no secret that Bayer would like to find a taker for its drug business.

GSK is also struggling, but for the opposite reason. With sales of $32 billion and income of $7.1 billion last year, it is the world's No. 2 drug company, and like Pfizer it is the product of a series of recent mergers. GSK executives must prove to investors that the merged entity can produce drugs more efficiently than its predecessor companies and create strong revenue growth.

Bayer and GSK also need to prove that they can work together. The last time they tried to co-market a product, Bayer's cholesterol-lowering drug Baycol, the result was disaster. Baycol was expected to become a multibillion-dollar medicine. But in 2002, after Bayer recruited GSK to help peddle it, Baycol was implicated in 50 deaths and finally yanked from the market. In the U.S., nearly 6,000 Baycol users have filed suit against Bayer. The legal clouds have helped depress Bayer's U.S. share price 39% in the past year, to a recent $20.

Viagra celebrated a milestone anniversary recently. Just five years ago, in 1998, the little blue pill spawned the market for "erectile dysfunction" drugs with the biggest launch ever in the industry. Pfizer's sales and marketing prowess, coupled with media frenzy and endless Jay Leno punch lines, made Viagra so popular that, a mere year after its introduction, the name was added to the Oxford English Dictionary. Pfizer even got stoic former Senator Bob Dole to plug the product in TV commercials.

The marketing onslaught has never let up. In 2000, Pfizer sponsored free erectile-dysfunction (ED) screenings at Nascar events. The next year the company financed a "Cool Blue September" national concert tour, featuring disco-era band Earth, Wind & Fire. Last year Viagra became an official sponsor of Major League Baseball. In all, Pfizer spends an annual $185 million to promote Viagra, according to market researcher Verispan in Newtown, Pa. That includes direct-to-consumer advertising, meetings and events for doctors, advertising in medical journals, and the cost of sales visits to doctors, offices, and hospitals. More than 20 million men (and some women) around the world have tried it; more than a billion of the tablets, which retail for $6 or more a pop, have been sold. In 2002 the "Pfizer riser" had its biggest year ever, garnering $1.7 billion in sales.

The big numbers, however, obscure a little-known fact: Viagra is an underachiever. From its notoriety you might think it the drug industry's No. 1 bestseller. It's not; Viagra doesn't even make the top ten. Just before its introduction, financial analysts predicted that Viagra would quickly reach $4.5 billion in annual sales. Even that ambitious forecast seemed conservative--a landmark 1999 study deduced that 152 million men worldwide suffer from some degree of ED. But in Viagra's five years on the market, only 13% of men thought to have ED have gone to their doctors seeking it. Therein lies one of Nancy Bryan's greatest sources of hope.

Bryan believes she knows how to get men to ask for help with their erectile dysfunction--and to ask for Levitra. Her insights into the male psyche are culled from a compendium of Bayer/GSK-commissioned clinical studies and market surveys. She quotes from them chapter and verse like a televangelist. She can tell you, for instance, that promoting Levitra in Spain will be more difficult than in the U.S., since only 10% of Spanish men admit to having ED, vs. 22% of Americans. According to a Bayer/GSK survey of some 28,000 men in the U.S., Britain, France, Italy, Germany, Spain, Mexico, and Brazil, roughly a third of men who say they have ED agreed with this statement: "This problem has been devastating for me in some ways." Amazingly, though, only a small fraction have consulted their doctors. The main reason? They say they're embarrassed.

For Bryan, then, the calculus is simple: Cure the coyness; grow the market. "It's going to be important to communicate to men that it's okay," she says. "ED is just a natural consequence of aging. Kind of like when you reach the age of 40 and you start to need eyeglasses."

To be sure, Nancy Bryan is no disinterested angel of mercy. There's manipulation in her message. While her main focus is to erase the shame and stigma of ED, selling any erectile medicine involves promoting the disease as well as the cure. Five years ago researchers were still heatedly debating to what extent diminished potency was anything more than a natural part of aging. Thanks in part to the marketing of Viagra, the idea of ED is now entrenched--but not entrenched enough, say the marketers at Bayer and GSK. Citing industry-funded studies that suggest that 50% of men over 40 have difficulty achieving and/or maintaining an erection, they are full of stratagems for framing ED in the broadest possible terms as a quality-of-life issue that Levitra can fix.

So what is the best way to get to a man with ED? TO hear Nancy Bryan tell it, it's through his wife or partner. Since Levitra hasn't been approved in the U.S., the Bayer and GSK marketers are forbidden by FDA rules to detail their promotional plans. But it's pretty obvious that women will be a key target. Says Bryan: "When it comes to sexual satisfaction, women are clearly involved. They are part of the decision-making process in couples, so they play an important role for us." Levitra's European marketing campaign, which began last March in Britain and Continental Europe, focuses heavily on recruiting women. A web promotion for Levitra in the British Isles (www.levitra.co.uk) includes a seven-part primer for women, the first section of which is titled "Honey, it's not you!" It explains that although Hippocrates, the father of medicine, once described the causes of impotence as being "preoccupied with work or having an unattractive wife," modern medicine has found that 85% of ED cases are associated with medical conditions like diabetes, heart problems, or high blood pressure. A section titled "I need your help. Can we talk?" coaches women on how to broach the touchy subject. Levitra's German website (www.levitra.de) sympathizes about fears a woman may feel when faced with a partner's ED. ("Does he still love me?" "Is there another woman?")

Drug companies leave nothing to chance when it comes to enticing patients and doctors. The names of drugs, the color and shape of the pills, and the imagery used to sell products are heavily researched and tested, a little like the drugs themselves. In January 2002 the Bayer and GSK marketing groups met face to face for the first time at the Millennium Hotel in New York City. The purpose of the confab was to figure out "how to beat the blues," says Bryan, referring to Viagra's sky-blue tablets. GSK had commissioned a very expensive consumer research firm to compile patient opinions of Viagra. The firm discovered, perhaps conveniently for its client, that consumers didn't "resonate with the imagery" of Viagra, says Bryan. "They find the blue color too cool. They equate it with being sick." A goal became apparent: Come up with an enticing color for Levitra as well as an appealing logo. "We wanted something that would stand out, like the Nike swoosh or the Target bull's-eye," Bryan explains. The teams brainstormed, but to no avail. So Bryan, Rosello, and others decided to farm out the logo and pill-color quandary to a New York City ad agency. Months later, after extensive testing, Wishbone/ITP presented Bayer and GSK with Levitra's color: orange. Explains Bryan: "Orange is vibrant and energetic." And the logo? An orange and purple flame. But what is perhaps most inviting about a Levitra pill didn't come from the researchers at all: Its round shape and familiar Bayer logo give it an unmistakable, and reassuring, resemblance to Bayer aspirin.

Physicians are another key target for Levitra. When a patient comes in for his annual checkup, he's typically poked and prodded and screened for high cholesterol, high blood pressure, and glucose. Nowhere in the routine does the doctor ask about sexual function. GSK and Bayer salespeople are planning an all-out assault on doctors to get them to "normalize" ED by asking guys over 40, "So, how's your sex life?"

A way to win doctors' support is to impress them with clinical data. In anticipation of Levitra's U.S. launch, Bayer and GSK have gone to great lengths to do that, releasing more than a dozen studies meant to demonstrate the drug's safety and effectiveness. At the annual meeting of the American Urological Association in Chicago this spring, the companies unleashed what they consider the strongest evidence yet: a study of hard-to-treat men, including some who had had their prostate removed. Patients kept a diary of their experiences with Levitra and later answered standardized questions like "Were you satisfied with the hardness of your erection?" and "Did your erection last long enough for you to have successful intercourse?" The results suggest that Levitra "improved patient satisfaction with erection hardness, orgasmic function, and overall sexual experience" when compared with a placebo.

GSK and Bayer's blitz of statistics might seem merely self-serving were it not for the real men behind the numbers. Akhtar Qureshi, a 62-year-old accountant from Kendall City, Fla., has been married for 33 years; until about nine years ago, by his own account, he had sex with his wife at least two or three times a week. Gradually Qureshi, who is diabetic, noticed his erections becoming less rigid, and his sex life tapered off. His wife, very much a product of her Muslim upbringing in Pakistan, never uttered a word about the change. "I felt empty, as if I was no longer a man," says Qureshi. He went to doctors, who offered Viagra, but Qureshi says the drug gave him headaches and blurred vision. So he did nothing until winter 2000, when he saw an ad in the Miami Herald seeking men with ED problems for a clinical study.

Underwritten by GSK, the study was a double-blind experiment to test Levitra in an "at home" setting. Volunteers were given a four-week supply of either 20-milligram Levitra tablets or a placebo, and sent home. They were asked to take a pill, begin sexual activity, then, using a stopwatch, record the earliest time they perceived an erection adequate for intercourse. For seven months Qureshi patiently timed his responses to the pills he was given and filed weekly reports detailing his love life. "In the beginning, it was strange," he admits. By the luck of the draw, Qureshi had received Levitra, not the placebo, and the stuff worked. With Levitra coursing through his veins, he says he felt "confident I could finish the job."

The results of that study were part of what GSK showed the urologists. It said that a majority of Levitra takers became erect within 16 minutes. The message to doctors: Levitra could have a big advantage over Viagra, which needs up to an hour to take effect.

GSK and Bayer are also trying to capitalize on what they see as Viagra's medicinal weaknesses. Levitra, Viagra, and Lilly's Cialis all use the same "method of action"--they are all "PDE-5 inhibitors," which block an enzyme in the penis, relaxing key muscles and allowing the organ to become engorged with blood. But they vary slightly in their effect. Viagra's biggest failing is that for roughly 30% of men who try the drug, it doesn't work at all. For Levitra, independent studies place the number of "failures" at around 14%. Levitra is also six to nine times more potent than Viagra, which means that a smaller dose can bring decent results. Also, Viagra users are encouraged to take the pill on an empty stomach, because fats in the digestive tract can diminish the drug's effect. That limitation can be a real nuisance, jokes Lehman Brothers financial analyst Tony Butler: "Are you going to take your wife to Lutece and have broth for dinner just because you might want to have sex later?"

To exploit the differences between Levitra and Viagra, the marketers at GSK and Bayer have had to learn their customers' every whim and fancy. Men in the U.S., it turns out, aren't so big on foreplay. A clinical study of Levitra revealed that the average time between taking the pill and the first attempt at vaginal insertion was about four minutes. (By contrast, the average Argentinean waited 22 minutes.) So the fact that Levitra works more quickly than Viagra could be a major selling point.

Levitra's pluses have earned it crucial endorsements, another vital element in building buzz. Dr. Irwin Goldstein, a urology professor at Boston University's School of Medicine and author of more than 150 peer-reviewed studies on male sexual dysfunction, is one of the world's most cited authorities. He is also what drug marketers call a "thought leader," an expert who, like the cool kid in high school, helps define what's in and what's out. Fast talking and tweedy, Goldstein advocates frank sexual chat. At the AUA conference in Chicago, he was overheard quizzing two female photographers about the quality and frequency of their orgasms--and advising how to make them better. As I interview him, he casually informs me that since my 62-year-old father suffers from adult-onset diabetes and high blood pressure, I myself may someday need an erectile drug. Do I really need to hear this?

Goldstein helped put Viagra on the map--he raved about it before its 1998 release to anyone who would quote him, including Playboy. Now he's doing the same for Levitra. He says that he is most impressed by the drug's biochemical makeup, and that he sees "great potential" for Levitra as the prescription of choice because it requires lower doses than Viagra.

Goldstein may not be entirely impartial, but that's modern medicine: Disinterested experts are hard to come by when many of the leading medical minds also are conducting clinical trials for manufacturers and striving to expand the influence of their field. Goldstein, who has taken part in several major trials for Viagra, Levitra, and Cialis, insists he can be impartial because his earnings from the trials are channeled to Boston University Medical Center, not his bank account. Dr. Myron Murdock, another of Levitra's thought leaders, is a urologist who has helped oversee clinical trials for Viagra and each of its new rivals. "With a lack of food-intake issues and faster onset, Levitra fits into the sexual lifestyle of most men," he says.

Levitra's marketers aim to avoid what they see as Viagra's marketing missteps. In 1998 it seemed a coup when Pfizer convinced Bob Dole to be a spokesman for Viagra. In the commercials, the 70-something Kansan was stately and candid about his experiences with ED. The problem, some industry watchers now say, is that the ads pigeonholed ED as an ailment of old men. (Though the incidence of ED does increase with age, researchers say that millions of middle-aged guys also have it.) Pfizer has strived mightily to shift consumers' perception with ads featuring younger men, notably Texas Rangers first-baseman Rafael Palmeiro, who is 38.

Bayer and GSK plan to sidestep the age bias partly by betting less on celebrity spokespeople. Says David Pernock, vice president of sales and marketing at GSK: "We're going for mainstream America, regular guys in their 40s and 50s. Spokespeople will be part of the mix in our ads, but we don't want to make them the focal point because it's hard to find someone who represents all sufferers." GSK won't disclose the particulars of its upcoming TV campaign. Rosello hints that, to challenge Viagra, Levitra will have to find ways to highlight its specific advantages, such as how it will help ED sufferers achieve harder erections and have more satisfying sex.

Marketing Levitra won't be so different from the challenge of rolling out GSK's antidepressant Paxil in the early 1990s, says Rosello. Prozac ruled that market, just as Viagra rules ED today. When GSK introduced Paxil in 1993, rather than simply push it as a Prozac alternative, Rosello and her group differentiated it as a remedy for anxiety, which can accompany depression, and emphasized its specific benefits. "We made people aware that their symptoms--restlessness, fatigue, difficulty concentrating, muscle tension, and disturbed sleep--were actually caused by a condition, one that few patients understood at the time," she says. Paxil quickly gained market share and now accounts for about 25% of the roughly 20,000 antidepressant prescriptions written each year.

Pfizer is not taking the coming competition lightly. Last October the company filed legal challenges against Bayer, GSK, and Eli Lilly, claiming that their new PDE-5 inhibitors copy Viagra's method of action and therefore infringe on Pfizer's patent. The suits, still in the discovery phase, may not succeed--Pfizer lost similar cases against Levitra and Cialis in Britain and Europe. Whatever happens in the courtroom, it's easy to see why the marketing team at Pfizer might feel a little sore. They did the hard work of pioneering in ED. Janice Lipsky, head of Pfizer's U.S. marketing team for Viagra, remembers the dark ages before Viagra's introduction. As late as the mid-1990s no one discussed impotence; few people had ever even heard the term ED. Pfizer's marketers had to start from square one. Their first order of business was figuring out just how important sex is to men over 40. For Lipsky, a social psychologist, it was a fascinating time. "I remember an epiphany I had," she says, describing a survey Pfizer commissioned regarding Americans' attitudes and sexual behavior. "It's a prevailing assumption that we're a highly sexual, open nation, but people aren't having sex as often as you might think!" The average for men over 40: four times a month. Lipsky traveled across the country attending focus groups where men talked about sex and impotence. There she realized that perhaps the biggest obstacle Pfizer faced in putting its spin on erectile dysfunction was centuries of received wisdom. Men assumed, for example, that impotence means the complete inability to achieve an erection all the time. Says Lipsky: "That was the first myth we needed to dispel, explaining to men that if you're not functioning 20% of the time, that's still a condition, just a mild form. You don't want people not going to the doctor because it's not happening all the time."

What seemed at the time to be the marketers' biggest coup literally fell in their laps. Sometime in 1998, Bob Dole mentioned in passing during a televised interview that he had taken part in the clinical trials for Viagra. The marketers had been unaware of the ex-Senator's presence in the labs. Pfizer quickly approached Dole to conduct an ED public-education campaign. Those early ads helped some, but they didn't move the masses. Now Lipsky has her eye on the majority of sufferers, who are still mum about their ED. "We know how many men suffer from this condition, and we know we can help them. That's why I'm still here."

Which leads to the multibillion-dollar question: If the surveys are right, if 152 million men in eight Western nations truly suffer from ED, what will it take to unlock the market? As you'll recall, when Viagra debuted, Wall Street analysts predicted ED drug sales could hit the $4.5-billion-a-year mark by this year--a forecast that turned out to be wildly optimistic. With the arrival of Levitra and Cialis, they now say that in four or five years the market will grow to $5 billion, not much more than it was supposed to be already.

Indeed, many analysts think that, rather than boost sales, the newcomers may only succeed in sparking a price war. "Viagra is about $6 to $7 per pill. In 12 months, if the new drugs aren't snagging enough market share, I can see them undercutting Pfizer," says Morningstar equity analyst Todd Lebor. "I wouldn't expect any of these newcomers to make money on their ED drugs in the first 12 to 18 months. Not one dime. They'll cycle everything back into marketing and promotion." Standard & Poor's pharmaceuticals analyst Herman Saftlas thinks Viagra will stave off the challengers: "Viagra will retain the dominant position because of Pfizer's marketing muscle and the product's name recognition."

If only those Wall Street guys could escape their spreadsheets and engage in a little more pillow talk, maybe they'd see things the way Nancy Bryan does. She's confident that her marketing message will persuade the 100 million-plus silent sufferers of ED to up and get help.

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