Session 4: Clinical Impact
Nicotine and Withdrawal
Nicotine is a quick-acting drug, travelling from the lungs to the brain in
seven seconds (with nicotine from pipe, cigar, and chewing tobacco, absorbed
through the mucous membranes of the mouth). It has a half-life of about two hours.
The mechanism of action for nicotine is gradually becoming understood. The drug
mimics the action of the neurotransmitter acetylcholine by acting on nicotinic
acetylcholine receptors, concentrated heavily in just a few regions of the brain.
Although nicotine stimulates the Central Nervous System, the drug is
nevertheless described as having as relaxant effect.
Nicotine is also known to act on the dopamine ‘reward pathway’, the mesolimbic
dopaminergic nerve tract of the brain, enhanced and disrupted by nearly all the
major drugs of addiction, including cocaine, heroin, amphetamines, and alcohol,
Glassman and Koob (1996) have demonstrated decreased levels of monoamine
oxidase in smokers, with MOA-B at 40% below normal levels. Moreover, the level
has been shown to return to normal in former smokers. MAO-A is involved in serotonin
oxidisation of serotonin, the neurotransmitter involved in behaviour and mood; whilst
MAO-B is involved in dopamine oxidisation, the neurotransmitter involved in the
of Parkinson’s Disease found in smokers, a disease characterised by a decrease
of dopamine and loss of dopamine neurons). Neuronal brain alteration persists
for months after nicotine cessation.
the largest single cause. The combined cost of each pack to society and the
individual smoker and family is nearly $40 (Sloan, Osterman & Picone, 2004).
is now placed on nicotine treatments. Current approaches can be divided into
techniques of nicotine replacement therapies (NRT’s - patches, gum, spray),
self-support groups; aversion therapy), pharmacological intervention (antagonist;
anxiolytic and/or antidepressant), and alternative/complementary therapies
(acupuncture, staple, and laser treatments; herbalism, hypnosis).
Withdrawal symptoms usually start within a few hours of the last cigarette and peak
48 to 72 hours later when most of the nicotine and its by-products are out of the body.
However, symptoms, and especially craving and mood swings can last for weeks.