Nicotine Replacement Therapy
- Rationale for development
- Historical background
- Misunderstandings about NRT
- NRT and weight gain after stopping smoking
- Pregnancy and lactation
Tobacco dependence is perpetuated by regular doses of nicotine, which produces stimulation, pleasure and other rewards. Regular smoking results in tolerance to these effects, and the presence of nicotine in the brain becomes necessary to maintain normal function. When tobacco use ceases, the sudden lack of nicotine causes the associated craving and tobacco withdrawal symptoms. NRT substitutes some of the nicotine obtained from smoking, thereby controlling craving and withdrawal symptoms.
In the late 1960s, Dr Ove Fernö was studying why smokers found it so difficult to give up. One of his friends, Dr Claes Lundgren, had noticed that submariners who were not allowed to smoke could cope by switching to chewing tobacco. Fernö was convinced that the key to the problem was abstinence from nicotine, and postulated that tobacco craving and withdrawal symptoms could be controlled by providing smokers with nicotine from an alternative source. However, pure nicotine is not easy to deliver – nicotine is an unstable compound. Various nicotine delivery forms were tested, and a chewing gum formulation in which nicotine was bound to a resin (to prevent the drug from being released too quickly) was launched as the first NRT product - Nicorette® Gum - in the global market in 1978. Continued development resulted in the introduction of the Nicorette® Patch in 1992, Nicorette® Nasal Spray (1994), Nicorette® Inhalator (1996) and Nicorette® sublingual tablet (1998). The name Nicorette® derives from nicotine delivered in the ‘right’ (= rätt, in Swedish) way.
Many smokers remain unclear about some of the important differences between NRT and cigarettes, including safety, dependence potential and nicotine content.
Health risks of nicotine
One of the most common misperceptions is about the effect of nicotine on health. Although nicotine addiction sustains tobacco use, it is the other components in tobacco smoke that cause lung cancer, chronic bronchitis and emphysema. In other words, people smoke for nicotine but die from tar, carbon monoxide and other harmful gases taken in along with nicotine. Nicotine addiction per se does not cause the harm associated with smoking, but tobacco is an extremely contaminated way of obtaining the drug. Nicotine has not been shown to cause cancer. Nicotine does exert some cardiovascular effects, but cigarette smoke also contains numerous other cardiovascular toxins. Further, nicotine’s cardiovascular effects do not seem to occur with gradual delivery of nicotine via NRT.
Potential for addiction
One frequent question is: “If nicotine is addictive, and cigarette smoking is addictive, won’t smokers get addicted to NRT?” It is important to understand that the addictiveness of nicotine largely depends on the dose and the speed of delivery to the brain. Smoking is a uniquely effective form of delivering nicotine to the brain because it is absorbed from the lungs and takes only 10–20 seconds to pass from the cigarette to the brain. Compared to cigarettes, NRT provides lower doses of nicotine, which are delivered more slowly, and NRT has low potential for abuse.
Transferred dependence may occur, and long-term use of NRT has been reported in a small proportion of abstinent smokers. Some smokers require prolonged treatment with NRT in order to prevent relapse to smoking, but long-term use of NRT is less harmful than continued smoking.
Dosage and duration of treatment
Many smokers underdose with NRT for various reasons: they may be afraid of becoming dependent on NRT, or falsely believe that nicotine causes tobacco-related disease. Others deny that they are addicted to tobacco and fail to understand that medical treatment is required in order to quit smoking.
Whatever the reason, it is important that an adequate dosage of NRT is used to control craving and other withdrawal symptoms in order to prevent relapse to smoking. Similarly, the duration of treatment must be long enough to control symptoms that may persist for several weeks following quitting. Some smokers may require prolonged NRT to stay quit.
Anxiety about weight gain is an important impediment to stopping smoking. Many smokers, particularly women, are concerned about their weight and fear that stopping smoking will result in weight gain. Many also believe that the only way to prevent putting on weight after quitting is to start smoking again. However, NRT (particularly nicotine gum) appears to be effective in delaying weight gain following smoking cessation - the more gum that a subject uses, the less weight gained.
Concerns about weight gain may prevent smokers from trying to give up. However, although most smokers who stop smoking will gain weight, the majority will put on less than 4.5 kg. It is also important to remember that the weight gain associated with stopping smoking represents a negligible threat to health compared to continued smoking.
Pregnant smokers should be advised and encouraged to stop smoking completely without pharmacologic treatment. However, many pregnant women continue to smoke. Cigarette smoking during pregnancy substantially increases the risk of spontaneous abortion, prematurity, low birth-weight and perinatal mortality. Although nicotine may have some potentially harmful effect on the foetus, NRT is less hazardous than continued smoking, which exposes the woman and foetus to numerous dangerous toxins. It has been concluded that the benefits of NRT outweigh the risks of continued smoking. However, NRT should only be offered to pregnant women if they are unable to stop smoking without treatment. Pregnant women should only use NRT if advised to do so by their physician, as part of a supervised programme to stop smoking. As nicotine passes into the breast milk, NRT products should be avoided by nursing mothers.