Nicotine: Dearly Poison or Wonder Drug?
by John Dunworth
What is nicotine?
How much nicotine is in a cigarette?
How does nicotine work?
What effect does nicotine have?
Why is hard to stop smoking?
Is nicotine a carcinogen?
What happens to the nicotine in my body?
Is nicotine all bad?
Poison or wonder drug?
Alkaloid, stimulant, relaxant, medicine, deadly poison – nicotine has been called many things. Scientist John Dunworth takes a look – and finds that it’s not all bad…
Nicotine is an alkaloide, a nitrogen containing organic chemical, which occurs naturally in nicotiana tabacum , the tobacco plant. This is a member of the nightshade family of plants which includes potatoes, tomatoes and red peppers. It is a substance made by the plant as a defence mechanism to protect it against herbivores, which is why it can be used as an insecticide.
It is also a stimulant, as is another alkaloide, caffeine. Named after one time French ambassador to Portugal, Jean Nicote de Villemain, it was first of interest for its medicinal properties. Nicote found it eased his headaches and sent some to the Queen of France to alleviate her migraines, apparently with such success that she renamed it “Herba Regina” – the Queen’s Herb.
A high nicotine electronic cigarette, by contrast, contains only 1.8 mg of nicotine and the smoker absorbs about a half to one third of the nicotine of a “normal” cigarette, according to research carried out by Health New Zealand, although users of newer models report stronger nicotine hits. Obviously, the zero nicotine option cartridge contains no nicotine and so none is absorbed.
When a cigarette is smoked (or an e-cigarette is vaped) and inhaled, nicotine passes via the alveoli in the lungs directly into the bloodstream. On entering the bloodstream, it stimulates the adrenal gland to release the hormone adrenaline (the so-called “fight or flight” hormone) which in turn stimulates the central nervous system to increase blood flow and pressure and respiration rate.
Glucose is released into the blood while insulin output is suppressed, causing high blood sugar levels. Also, it is taken by the blood stream to the brain where it increases the levels of the neurotransmitter, dopamine (as do cocaine, heroin and marijuana) which is associated with reward and pleasure. These effects take place within a few seconds of inhaling.
Nicotine is addictive – some people claim it is on a par with heroin, although this has been challenged recently. Continued nicotine use causes long term changes to the brain which cause the addiction. As nicotine use gives pleasurable sensations, stopping means that these are withdrawn and leads to craving for more. Typical withdrawal symptoms include powerful cravings for tobacco, irritability, difficulty in concentrating, sleep disturbance and increased appetite.
Adolescents may be more vulnerable to these brain changes and people who start smoking at this age are more likely to develop chronic addiction. It is also possible that exposure to second hand smoke in adolescence can cause these lasting changes to the brain’s reward and motivation circuits. Some researchers also claim that these effects may take place in an embryo if a mother smokes while pregnant, leading to a lower ability to resist addiction when older.
Researchers have found that there are nicotine receptors in the brain. When these are not saturated by nicotine, the smoker feels cravings. It only takes one puff of a cigarette to occupy 25% of these receptors, 75% by the third puff and 85% after a full cigarette. Although this reduces craving, it does not provide complete relief until 95% of the receptors are occupied after smoking 3 cigarettes. However, nicotine dependent people still continue to smoke after this point. Although nicotine replacement therapies probably saturate the receptors, according to some studies the long term success rate of NRT therapy can be as low as 1.8%!
Despite this, nicotine does not seem to be the only element in cigarette addiction. Some studies suggest that it is the actual act of smoking which is difficult to quit as well as the addiction to nicotine, leading some e-cigarette companies to offer zero nicotine electronic cigarette kits to their customers. Meanwhile, the successful Alan Carr method works in part by convincing smokers that their withdrawal symptoms are largely imaginary.
Although nicotine is toxic if ingested in large doses and is addictive, it is not a carcinogen (it does not cause cancer). As is well known, it is some of the other constituents of tobacco smoke that cause cancer.
The liver breaks down most of the nicotine to coteine. (Coteine levels in the blood are used in health examinations to determine how many cigarettes a patient smokes). The elimination half life (the time taken to reduce the nicotine level to half of what it was) is about 2 hours. However, most smokers have had another cigarette during this time and so the level continues to rise, only falling when smoking stops, such as overnight. In smokers smoking say a pack a day, there would still be significant levels in the blood after 8 hours without a cigarette.
Nicotine is also secreted into the saliva, and so enters the stomach and can be reabsorbed from the small bowel and thus recirculated into the blood stream. In pregnant women it freely enters the placenta and has been found in amniotic fluid and the umbilical cord and so enters the foetus. It also passes into breast milk and the breast fluid of non-lactating women and is found in cervical mucous secretions.
Perhaps surprisingly, no. The development of nicotine replacement therapies has allowed researchers a safe way to administer nicotine and their work has shown that nicotine has many beneficial effects. It is well known that the incidence of smoking in patients with mental illness is high and this is likely due to the previously mentioned feelings of euphoria produced by nicotine. The incidence of smoking among people with non-clinical depression is also high and possibly makes it harder for these people to stop smoking. In fact one article claims that half of all smokers in the USA have psychiatric problems.
It could possibly be used, even in small doses, as a treatment for some forms of tuberculosis that do not respond to current treatments and to treat acute spinal chord injuries. It may reduce cramping and other symptoms of colitis and might be used in prevention of classical Kaposi’s sarcoma with KS herpes virus infection.
It should be noted that there are no approved nicotine based drugs available yet for any of these treatments but, assuming funding is available, it only seems a matter of time before there are.
So, poison or wonder drug? Both potentially. As a pure substance nicotine is deadly poisonous in large enough doses. Taken as vapour in the small quantities and concentrations delivered by a cigarette or an E-cigarette or absorbed through the skin as in patches, it is safe but highly addictive. The future potential of nicotine as a clinical drug seems secure and extremely promising.
It is important to remember that the other components in cigarette smoke are deadly and that no one would ever recommend a cigarette as a delivery device for the beneficial properties of nicotine – except perhaps Big Tobacco!
The opinions expressed here are those of the author and do not necessarily reflect the views of ECigaretteDirect.
Image of a boy with an ice-cream and cigarette by Tingley.