FOR ALL OF HIS LIFE, BOB BOWMAN HAD A HEALTHY RELATIONSHIP WITH sex. It was good to him, before and after his divorce, a pleasure he took for granted. Bowman, 63, is on the dapper side, casually forthright. In his art-filled Los Angeles bungalow, he eases into intimate confidence. Three and a half years ago, he says, he underwent surgery for prostate cancer. The operation saved his life, but left him with a common residual effect. He was impotent. This seemed unfair, both to him and to his girlfriend. He visited a Los Angeles urologist named Harin Padma-Nathan to see what could be done. The answer: a lot. In early 1995, Bob Bowman found himself on the chemical cutting edge of the next sexual revolution.

Until recently, the only options would have involved body-shop mechanics, either a surgical implant or a pump of the sort advertised in the back of men’s magazines. But by 1995, new research, which ironically studied the erectile tis- sues removed to make way for implants, had yielded insights into how this most basic of human functions worked. And with these insights came drugs–quickly. First Bowman tried a smooth-muscle relaxant called alprostadil, which was developed for newborn babies with circulatory problems. Before sex, he injected himself at the side of his penis: his erections were immediate, and could last for hours. He next tried a treatment called MUSE that the FDA hadn’t yet approved (it since has): a tiny suppository inserted down the urethra via a thin plastic wand. For Bowman, ““it didn’t work.''

Then, 18 months ago, Bowman entered clinical trials for a drug that could change everything: a pill called sildenafil (trade name: Viagra) that, combined with some stimulus, promised to return afflicted men to proud full function. No needles, no pellet down the shaft. It worked. He can make love again, and better than he had in years. ““It’s as easy to take as aspirin,’’ he says. For a man who looked forward to a future of hypodermics or deprivation, the results are a modest miracle. His life under covers, he says now, ““is like I’m 30 years old.''

For millions of American men, this could be the future of male sexuality: better loving through chemistry. The National Institutes of Health estimate that between 10 million and 20 million men suffer from some degree of impotence; some experts believe even these figures are too low. Twenty million, says Dr. Leroy Nyberg Jr., director of urology programs at the NIH, is probably just ““the tip of the iceberg.’’ (Impotence is defined as an inability to get and sustain an erection; it does not address fertility, libido or orgasm.) The causes are everywhere, from hypertension to bicycle seats. Traditionally, men have been unwilling to discuss the problem or seek treatment for it. But now, as the 38 million men of the baby boom march toward their softening years, this well-kept secret may finally be coming aboveboard. ““With our anatomies breaking down, this is a way of becoming, of acting, younger,’’ says Alfred Pariser, a prostatectomy patient taking Viagra in the same trial as Bowman. ““If women can get face-lifts, why shouldn’t men do this?''

For the drug companies, treatments for impotence have the makings of a bonanza. ““It’s the one thing men will spend their money on,’’ says Dr. John Bancroft, director of the Kinsey Institute for Research in Sex, Gender and Reproduction. ““Anything that will improve their erections is big business. Sad, but there you go.’’ In 1995, wholesale revenues from erection drugs were $6.4 million; already this year they’ve topped $117 million. MUSE–the pellet treatment–hit the market in January; despite its unappetizing protocol, it has already been prescribed to 665,000 men.

These drugs are just the first wave. Three companies are now developing pills, which have the potential to open the market wide. Others are working on creams, even long-term gene therapy, which has been effective in rats. ““The whole time line has been revolutionary,’’ says Padma-Nathan. ““A few years ago I would not have thought pill therapy was possible.’’ And each new drug, with its attendant publicity, brings more men into the game. Some urologists expect the number of men seeking treatment to double in the coming years.

The biggest hope–and media hype–is for Viagra, which Pfizer submitted for FDA approval on Sept. 29; it may be out as early as next year. (Under federal regulations, Pfizer cannot discuss the drug while it is under review.) In clinical trials of 4,500 subjects, it has been between 48 percent and 81 percent effective, depending on the cause, with minor side effects. More than a decade in the making, Viagra was originally developed to treat high blood pressure. It didn’t work, but researchers noticed that their subjects didn’t want to give back their test samples. Unlike the injectables, Viagra doesn’t just produce an automatic response; but if your mind gets turned on, it should allow your body to follow. It can last even after ejaculation.

Wall Street can’t wait. Pfizer’s stock has risen 74 percent this year, in part on the promise of Viagra. Jami Rubin, a drug analyst for the investment-banking firm Schroder & Co., predicts that Viagra may be a billion-dollar drug that will expand the whole industry. ““It’s painless, discreet and it works,’’ she says. ““It’ll create its own category.’’ Dr. Tom Lue, a urologist at the University of California, San Francisco, who has prescribed the drug in trials, tells another anecdote to describe the demand for the drug. At one clinic, he says, people broke in and stole the medication. ““People are looking for a fountain of youth,’’ he says, ““including sexual function. There’s no question that this one is going to make a lot of people feel like a teenager again–including yourself and myself.’’ Is he buying Pfizer stock? ““No, it’s too high.''

Others, though, are less sold on Viagra. Some doctors insist that the future belongs to local medications, not a pill that circulates through the entire body. And for all Viagra’s publicity, Pfizer’s research has not yet been through peer review. ““They’ve presented the data in the most positive light,’’ says one top researcher, who is working on an alternative treatment. ““I think [Viagra] is going to have some effect. But I don’t think it’s going to live up to expectations.''

At Dr. Irwin Goldstein’s urology clinic in the Boston University Medical Center, the new chemicals are already reshaping the way we think of impotence. Goldstein, 47, is one of the pioneers of the erection business; his clinic sees 700 new patients a year. A voluble former engineering student, he runs through the office, posing questions of fluid dynamics. ““Is he up?’’ ““Is he down?’’ A patient turns to Goldstein and says: ““You saved my life.’’ In the 1960s the sex researchers Masters and Johnson declared that nearly all impotence was psychological. Now, Goldstein says, urologists believe the causes are most often physiological. ““Really,’’ he proclaims, ““it’s all hydraulics.''

This is the brave new erotic world, filled with chemical promise–but also with the potential for unforeseen social consequences. Like the birth-control pill, which fueled the sexual revolution, the new drugs work in the realm of culture as well as pharmacology. They reduce complex human endeavors to biology, then monkey with the biology. Bernard Asbell, author of ““The Pill: A Biography of the Drug That Changed the World,’’ draws a historical parallel. Both drugs, he says, ““draw us into ethical and moral choices that we’re not prepared to make.’’ What is the meaning of an erection if it is chemically enhanced? And what are the consequences of a market-driven quest for the perfect penis?

Goldstein’s proclamation that impotence is a problem of mechanics can be appealing. It takes all blame and guilt out of the equation. But many find it too simplistic. Even when the root cause is purely physical–a sports injury, a lifetime of smokes–by the time couples get around to treatment, says Dr. Stanley Althof, a clinical psychologist who works closely with urologists in Cleveland, ““most people have [gone through] 18 months to two years of not making love. Their psychological well-being is impaired. We can give an erection. The problem is getting the couple to use it.’’ Impotence has sparked a turf war between shrinks and urologists. Dr. Bernie Zilbergeld, an Oakland, Calif., sex therapist and author of ““The New Male Sexuality,’’ describes the war’s stakes bluntly: ““We both want more patients.''

THE LOSERS IN THIS EITHER/OR battle can be the patients and their partners. Zilbergeld says the drugs can be extremely helpful, but only if guys aren’t using them to get around other problems. In couples with deeper difficulties, he says, even the shots, effective in the doctor’s office, have sometimes failed at home. Alternatively, ““some women have not wanted the shots because they want to feel they can turn him on.’’ Yet even Zilbergeld cannot help admiring the successes he’s seen, which would have been impossible just a few years ago. ““One problem we sex therapists are having is–[the drugs] sound attractive to us, too. Why not just get the pill and get on with it?''

For many men, sex means much more than the occasional marital act. It is a focus of identity. When men present themselves to a sex therapist, says sociologist Michael Kimmel, author of ““Manhood in America,’’ they ““almost never say, “I’m not feeling enough pleasure.’ They all say, “I don’t feel like I’m enough of a man.’ For them, the sexual element is about gender; it’s not about pleasure.’’ Kimmel thinks an underlying problem is that some men are threatened by women’s growing sexual prerogative, and don’t want to admit that fear. Instead of reaching for a medication, maybe some guys would be better off treating their preoccupation with sexual performance; maybe some couples would be happier learning to cuddle their way into the late years, accepting each other’s changing bodies. ““If you treat [impotence] medically, and these guys can stay hard longer, then they might feel like men,’’ Kimmel says. ““But that doesn’t answer the larger cultural questions.''

The drugs, meanwhile, take on a cultural life of their own. It costs a fortune to develop a new pharmaceutical–the price tag for a product like Viagra runs to about $400 million before it even gets to market–but it has the ability to create its own demand. After Prozac or the diet pill Redux came out, says medical historian Dr. David Rothman, doctors and patients alike changed the way they defined depression and obesity: sickness becomes whatever we think the chemical can treat. ““Because the category of impotence is so elastic,’’ Rothman says, ““the potential for creep is enormous.’’ Most men suffer dysfunction at some time or another: with drugs available, who’s to say where impotence begins, or what level of sexual perfection truly qualifies as ““healthy’’? If we can be bionic, it is no longer so swell to be merely mortal.

Like silicon breast implants, developed for women with real disfigurements, the erection drugs may stimulate broader insecurities that only they can relieve, growing their market in the process. Erection drugs are unusual in our pharmacopeia: instead of easing pain, they facilitate pleasure. A sweet pill to swallow, but, says Rothman, one ripe for abuse. ““And if you’re going to want to get this drug, you’re going to get it. Physicians do not say no.''

““Bill,’’ who asked not to be identified, is someone who wanted the drug. Single and 32, he had never had any problems in the sack. But he was tempted by a friend’s injection medication. ““He told me, “If you use the stuff, you’ll last longer and it will make you much bigger’.’’ He did; it did. ““You just keep going all night,’’ he says. ““The performance is unbelievable. Once you get it you have to have it.’’ (He is speaking figuratively–the drugs are not addictive.) But then about two months ago, his erection wouldn’t go down: not the next morning, not the next evening. After more than 24 hours in this state, he called his doctor’s answering service. The receptionist hung up on him. ““She was thinking, this guy’s a pervert.’’ At Goldstein’s clinic, he was finally given an erection antidote, and learned how dangerous his condition was. Priapism of more than six hours, an infrequent side effect of the injection and pellet drugs (though not the pills), can cause permanent damage. Bill was left impotent. ““I feel less than a man,’’ he says. His scenario is rare, but with the advent of pills, more recreational use is inevitable.

This is the trajectory of a modern drug: it creates the context in which we live our lives. Bob Bowman and Bill are both living in that context: one immeasura- bly better for it, one diminished by its light. Bowman and his girlfriend say they have found well-being in ““moderation.’’ If he had to go back to the needle he’d do it. Bill is now semi-impotent; to have sex, he needs to use the same drug that caused the injury in the first place. The two men are avatars of the same future, two of the 20 million, brought together by chemistry. Their brave new world is full of potential, for love as well as waste. But it is surely coming, and before long. We’ve yet to find a drug we can say no to. An erection drug will not be the one.

IN OUR TABLE OF DRUGS TO TREAT impotence (““In Pursuit of Upward Mobility,’’ LIFESTYLE, Nov. 17), we mistakenly wrote that Vasomax is ““under FDA review’’–FDA approval hasn’t yet been requested–and we overstated its efficacy. Also, Caverject is more effective than we reported. It helps in over 80 percent of cases. NEWSWEEK regrets the errors.

Oral Medication Description Pros and Cons VIAGRA (sildenafil) Relaxes smooth-muscle Can cause headaches Under FDA review cells, the first step and Diarrhea. May help in achieving an most with partial erection. impotence. Duration Taken an hour before sex. Stimulation needed to get an erection. Oral Medication Description Pros and Cons SPONTANE Process is unclear, Studies indicate it (apomorphine) in but drug affects part helps mostly mild final trials by of brain that triggers cases-70% in one manufacturer erections. study. Duration Works only in response to physical stimulation. Oral Medication Description Pros and Cons VASOMAX Blocks adrenaline, Helped 60% to 80% of (Phentolamine) relaxing, smooth- those tested. Fewer under FDA review muscle tissue and side effects than dilating arteries. Viagra. Duration Taken 20 to 40 minutes Before sex. Requires stimulation for erection. Suppository Description Pros and Cons MUSE (alprostadil) Applicator inserted Can be used twice a approved 1997 into tip of the penis day. Not recommended delivers alprostadil with pregnant in gel form. partners. Duration Applied 5 to 10 minutes Before sex. Erection can last an hour. Injection therapy Description Pros and Cons CAVERJECT Injected in base of Effective in over 50% (alprostadil) penis. Relaxes smooth- of cases. May be approved 1995 muscle cells and opens painful and can’t be arteries. Used every day. Duration Injected 20 minutes before sex. Erections can last an hour or more. Injection therapy Description Pros and Cons EDEX (alprostadil) A slightly different Cheaper than Caverject Approved 1997 formulation of the and injected with a chemical in Caverject. smaller needle. Duration Injected 10 minutes to 2 Hours before sex. Erections can last over 1 hr. Devices Description Pros and Cons VACUUM PUMP A pump removes air Clumsy, but has few Approved 1982 from around sheathed side effects. Penis, pulling blood Ejaculation may into it. be difficult. Duration Just before sex. Erection Lasts till elastic ring at base of penis is taken off. Surgery Description Pros and Cons VASCULAR Directly repairing Effective only when began 1973 arteries to boost problem results from blood supply to the a simple vascular penis. injury. Duration Restores the ability to Have a normal erection. Surgery Description Pros and Cons PENILE IMPLANTS Malleable or inflata Newer implants are Began 1966 -ble, Containing are reliable but pump and reservoir of destroy erectile saline solution. tissue. A last resort. Duration Bent or pumped into Position. Erection lasts until unbent or drained.