Tobacco Trouble ?

For centuries this substance, obtained from the plant Nicotiana tabacum has entertained (or rather haunted) the human race. After Colombus's introduction of this habit into the new world, a tobacco epidemic has gripped the entire world. The addictive ingredient in tobacco is mostly nicotine, while its adverse effects on human bodies are largely attributable to its tar content. When smoked, about 4,000 different molecules are released and this includes the radioactive substance Polonium 210.

Not only the active smoker inhales it but also the 'sidestream smoke' it generates, makes passive smoking a reality. Nicotine is then rapidly absorbed from the lungs. The vast capillary networks surrounding the pulmonary alveoli aid its absorption directly into the blood stream. The onset of its action is very quick, since it takes only a few seconds to pass across the blood brain barrier. The blood-brain barrier acts as a frontier of defense in the brain, against many molecules thus protecting the brain.

Nicotine then liberates a long list of neurotransmitters including, noradrenaline, adrenaline (they make the heart race, pump more blood into the circulation, makes you alert, increases the blood glucose level and many related actions responsible for 'fight or flight reaction'), beta endorphin (a pleasure chemical in the brain, which binds to the opioid/morphine receptors), dopamine (a substance released from the 'reward center' of the brain ) and many others. These substances make smokers feel alert, cool and all the effects a smoker feels. These are the same chemicals that cause the serious cravings when one tries to kick the habit.

Nicotine, in addition, stimulates nicotinic cholinergic receptors in small doses, but depresses them in larger amounts. Tobacco causes a plethora of diseases. Cardiovascular diseases including peripheral arterial diseases; pulmonary diseases like emphysema, chronic bronchitis and cancers are just a few of them. It also decreases the sperm count, and even causes impotency (due to its vasoconstricting action).

But not all of us know that it guards against some diseases too. The frequency of ulcerative colitis, Alzheimer's disease, Parkinson's disease, and even breast cancers (in women harboring the BRCA gene =BReast CAncer) are statistically less in smokers than in non smokers. But the risks far outweigh the benefits it offers. Hence, kicking the habit is a more sensible option than to carry on smoking.

Quitting Tobacco: An Easy Way For The Blind To Go!

Its really hard to quit smoking. So much so, that its quitting has been compared to that of cocaine or even heroin. First and foremost, a resolute and firm mental preparation is required. Once a decision has been made, it can be set forth into action. However, there are certain drugs which make quitting easier. For example, nicotine may be supplemented as a gum, nasal spray or as a dermal patch, so that a small amount of it will be released and weaning off may be easier (guess you remember, fight fire with fire).

Apart from that, clonidine, bupropion, varenicline (Chantix) and many other drugs have been tried. Bupropion (Wellbutrin, Zyban) is a dopamine and norepinephrine reuptake inhibitor (DNRI). Dopamine, the reward chemical, and norepinephrine are secreted by nerve terminals in the brain. They then exert their effects, till they are metabolized or they are recalled back (reuptake) to the originating cells. Thus, actions cease once they are uptaken by the secreting cells themselves. Bupropion, by preventing their (dopamine and nor-epinephrine) reuptake, lets them remain in the synapse for alonger time, thereby making the person feel the high, even while they are not on tobacco. Varenicline, on the other hand, acts as a partial agonist at nACh (nicotinic acetyl cholinergic) receptors. A partial agonist is one substance (ligand) that can bind with a receptor and can elicit an action, though milder. Thus when varenicline is given, it stimulates the same nACh receptor that nicotine of tobacco smoke used to bind and stimulate. Thus, the craze for the crazy puff is gone. But, no matter what therapy you are on, as long as you are resolute, you can win, and nothing else matters!!

Recently, a vaccine is being developed that would bind nicotine and thus will not allow nicotine to bind to the nicotinic receptors. This is expected to wean away smokers since they will no longer be able to get the 'kick'. Normally a vaccine is given to boost immunity to pathogens. Here however its properties will be exploited for another noble purpose.

N.B. Recently (July 1, 2009) the US Food and Drug Administration (FDA) has announced that bupropion and varenicline manufacturers must carry a 'boxed warning' in their labels, that use of these drugs has been associated with serious neuropsychiatric events. They can cause symptoms ranging from mood changes to suicidal tendencies, hostilities and agitation. Whether they were the effects of nicotine withdrwal or the effects of the drugs themselves were not clear.

However, the site concluded with the following advice: "Any adverse events associated with varenicline or bupropion should be communicated to the FDA's MedWatch reporting program by telephone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at http://www.fda.gov/medwatch, or by mail to 5600 Fishers Lane, Rockville, Maryland 20852-9787."

Last updated: 2nd July 2009