Drug firm is creating fast-acting, inhaled Viagra

The maker of the anti-impotence drug Viagra has started work on an inhalable version that should hit the spot - so to speak - much faster than the pill form.

The pharmaceuticals company Pfizer has already tested the new version of the drug on dogs and human volunteers, and formal pharmaceutical tests are believed to be planned. "We are always keen to look at new formulations of drugs," said a spokeswoman for Pfizer, which developed Viagra from the heart drug sildenafil. "But we are trying to establish if this has any advantage over the pill form."

According to New Scientist magazine, a patent filed about 18 months ago by the scientists at Pfizer's research laboratories in Sandwich, Kent describes a new form of sildenafil that can be absorbed in water, and so could be used either as a nasal spray or other liquid form.

Such delivery methods are commonly used for fast-acting drugs, as the inside of the nose contains plenty of blood vessels with thin skin covering, allowing chemicals to migrate rapidly into the bloodstream.

Dr David Delvin, who has private clinics in London and Brighton, prescribes Viagra to 150 men. He said yesterday "This would be quite a good idea - a lot of men have difficulty because of the long delay between the time that they take Viagra and the time when it starts working."

One of the problems with the pill form is that it takes at least an hour to take effect, meaning that sex has to be carefully timed. But the delay can be even longer if the man has a full stomach - which, as Dr Delvin pointed out, can be a problem after a romantic dinner.

It could be years before a nasal spray is available, though. Even though the pill form has passed all the requirements for approval, the spray would have to start again with the standard regime of three tiers of clinical tests before it is cleared for general use.