• Tobacco and the lung

If there is such a thing as a clinician who has not encountered patients whose lives have been blighted or ended prematurely by addiction to tobacco smoking, he or she is unlikely to be a respiratory physician. Respiratory medicine is dominated by the health consequences of smoking, and the poverty that smoking exacerbates. Preventing smoking is fundamental to improving respiratory health. That is why all in respiratory medicine should welcome the advent of electronic cigarettes.

The principal addictive component of tobacco smoke is nicotine. The mechanisms of nicotine addiction are highly complex but include at least two important reward pathways: one mediated directly and immediately by stimulation of dopamine release in the shell of the nucleus accumbens, and one indirectly and after more sustained use through release of dopamine in the nucleus accumbens core in response to stimuli associated with nicotine administration.1 In animal models the latter might be a visual stimulus, such as a light that shines when nicotine is administered; in humans, they are likely to include the rasping sensation of smoke in the throat, the smell of tobacco, or possibly also other behaviours associated with drug delivery such as unwrapping and sharing cigarettes. With the establishment of tolerance of dopamine release, however, abstinence from smoking induces intense withdrawal symptoms and cravings to smoke that can be reduced by administering medicinal nicotine, and to a degree by other smoking stimuli. Conventional nicotine replacement therapy products typically provide the first but not the second. Electronic cigarettes, and other devices in development with the potential to provide nicotine by inhalation in a formulation that mimics smoking, do both.

Nicotine is not a carcinogen and has a range of cardiovascular and other effects on the human body2 similar in hazard to those of caffeine. Therefore, while many in …