Rival stands up to sexy super-drug

By GEOFFREY COWLEY

CHICAGO - When you think of erectile dysfunction, you think of - what else - Viagra.

Introduced less than two years ago, Viagra is the first and only impotence pill and tops $US1 billion ($2 billion) in annual sales worldwide.

About 4 million American men take it regularly, generating 200,000 prescriptions every week.

But it may soon have competition. An estimated 30 million US men - roughly half of those aged over 40 - suffer some erectile trouble. Drug companies are racing to expand the options for treatment, and TAP Pharmaceuticals, of Lake Forest, Illinois, is now close to the goal.

Last week, a federal advisory committee recommended approval of TAP's new erection drug, Uprima. If the Food and Drug Administration follows the panel's advice, as expected, the new pill could reach the market within three months.

Uprima comes in a lozenge that dissolves under the tongue, delivering medication directly to the bloodstream. As a result, it usually takes effect within 19 minutes, about three times faster than Viagra, which must pass through the digestive system.

Uprima does not cause the hazy vision that afflicts some Viagra users, and it may prove less dangerous when combined with heart medications containing nitrates.

But this drug may not be a ticket to better sex. Its side-effects can include nausea, vomiting and blackouts, and studies suggest it fails more than 40 per cent of the time.

Getting an erection is not as simple as it looks. The process starts when the aroused brain sends nerve impulses to the penis, triggering production of a chemical called cyclic GMP, which increases blood flow by relaxing the smooth muscle cells that surround the arteries.

As the penile tissues become engorged, their swelling crimps the veins required for drainage, causing the organ to swell and harden. Viagra (sildenafil) helps to sustain erections by slowing the breakdown of cyclic GMP within the penis.

Uprima (apomorphine) takes a different tack. By mimicking dopamine, one of the chemicals that nerve cells use to communicate with one another, it enables the brain to send stronger signals south.

Each drug seems to have its own advantages. In 27 Uprima trials involving 3000 impotent men, those taking 4mg lozenges succeeded in having sex 56 per cent of the time.

That does not match the 70 per cent success rate documented by Viagra users. The catch for them is that they have to plan their sexual encounters up to an hour in advance. Uprima allows more spontaneity.

Both drugs have serious sideeffects. Viagra's can include death if the user happens to combine it with nitrates.

But Viagra's most common side-effects - flushing, headaches and nasal congestion - may be easier to tolerate than those of Uprima. One in five Uprima users suffers nausea, one in seven has dizziness and one in 30 experiences sudden drops in blood pressure that can cause fainting.

During clinical trials, a 33-year-old man who took 4mg in his doctor's office fainted on the way home, driving his car into a fence.

That clearly worried the FDA's advisers. Though they voted to approve Uprima at doses of 2mg and 4mg, they thought the product should carry a warning that alcohol could exacerbate its side-effects.

And even as they recommended approval, some committee members predicted tragedies as men pass out at the top of stairs or while driving.

In the meantime, at least nine other impotence remedies - pills, gels, creams, even nasal sprays - are now in development. And the more distant future offers the hope of physicians treating impotence at the source, by restoring damaged nerves and blood vessels.

- INDEPENDENT