The National Cancer Institute is exploring whether smokers can be weaned from cigarettes by getting them to inhale mild doses of the nicotine that addicated them to smoking.

The hope is that milder doses of nocotine will still satisfy smokers, without their inhaling the harmful carbon monoxide and tars of cigarette smoke. The hope is also that a way will be found to reduce the smokers' need for nocotine until it disappears altogether.

Tests have begun on beagles to see if inhaled nicotine has any unforeseen harmful effects on the dogs. If not, the tests will be extended to humans.

Preliminary results suggest that nicotine is the only drug of promise in getting smokers to quit and that an aerosol spray of nicotine is the only means of delivering it in a satisfactory way.

"We tried first with nicotine chewing gums but they don't work," said Dr. Gio Gori, depty director of the division of cancer cause and prevention at the cancer institute. "The smoker gets his nicotine in punches with every inhalation, which is what we have to mimic if we are going to get smokers away from cigarettes."

Researchers no longer doubt that nicotine addicts smokers to cigarettes. So addictive is nocotine that beagles, put on "smoking machines" where they inhale cigarette smoke, are hooked, in one month. Gori said, "They suffer withdrawal if they don't get put on the machine three times a day."

An alkaloid whose chemistry is similar to other drugs, nicotine can be a stimulant in small doses, a depressant in larger doses and a poison in stiff doses. Nicotine can slow breathing, halt muscle movement, cause convulsions and stop the heart.

"We don't want to substitute one danger for another, so now wet're seeing what ill effects nicotine may have in small doses," Gori said. "We want to find out if it's possible to wean people away from cigarettes and then wean them away from nicotine itself."

The cancer institute has turned do nicotine after failing in the last eight years to find other ways of breaking smokers' habits.

Prevetntion clinics were developed, but the "cure rate" for smokers who volunteered for the clinics has never been higher than 20 per cent. Clay has been mixed with tobacco to reduce the burn time of a cigarette. Tobacco has been "blown up" with air to produce less smoke and tar. Porous filters have allowed its temperature. None works, mostly because they take the nicotine and flavor out of cigarettes.

Tranquilizers and drugs like antabuse and lobeline proved ineffective. Other drugs were tried but they were more dangerous than cigarettes.

"The only drug that turns out to be promising is nicotine itself, which makes sense," Gori said. "If people smoke because they are addicted to nicotine, it's conceivable that if you gave them the nicotine their craving for cigarettes would diminish."

Nicotine pills and chewing gum didn't work because smokers weren't inhaling the nicotine and they weren't getting enough of it. That's when the NCI developed an aerosol bomb that delivers a spray of nicotine inhaled by the smoker.

"We're going to study the safety of this technique for at least the next two years," Gori said."There is not too much danger with this bomb blast because if a user sprayed himself too often he'd lose consciousness and wouldn't be able to spray anymore. So there's a built-in safety factor here."

Gori said the cancer institute is also going ahead with plans to develop a "less hazardous" cigarette. In the past, this has meant designing a cigarette that has a litte tar and nicotine as possible. But, "instead of smoke, these cigarettes emit something close to hot air, which smokers don't like," Gori said. "We are now in the process of finding ways of safety putting nicotine and some flavors back in the cigarette."

The milder cigarettes on the market today have meant that some smokers are inhaling less tar and nicotine from each cigarette, Gori said, but it has also meant they're smoking more cigarettes to satisfy their habits. Gori said a smoker today puffs 11,000 cigarettes a year, 1,000 more than what people smoked six or seven years ago.