Nicotine AddictionThursday, February 14, 2008 18:31
Nicotine Addiction by Carl R. Sullivan, MD
Carl R. Sullivan, MD was a guest on the Health in 30 Radio Show on May 16, 2008. Click here to listen to Dr. Sullivan talk about nicotine addiction.
45 million Americans are addicted to nicotine. There are far more people in this country hooked on nicotine than alcohol, heroin and cocaine combined. Nicotine may be the most powerfully addicting drug known to man and it has been estimated that 90% of people who start smoking will become dependent on nicotine. By some estimates the average smoker inhales several thousand chemicals into their lungs each time they take a puff. Some of these agents are known to cause cancer(s), damage normal lungs leading to bronchitis and emphysema and precipitate cardiovascular disease including heart attacks, high blood pressure and strokes. However, the component of tobacco smoke that keeps the smoker coming back for hit after hit after hit is nicotine. And while nicotine itself has some effect on the heart and circulation, its primary effect is on the brain.
Nicotine addiction is a brain disease. It is not a heart or lung disease any more than alcoholism is a liver disease. Let me try and explain a little about what happens in the smoker’s brain. All humans have specific places in our brains called receptors that bind natural chemicals called neurotransmitters. These neurotransmitters allow the brain to function normally so that we can move our bodies, speak, make plans, remember past events, experience fear and pleasure etc. One of the many neurotransmitters is called acetylcholine and it is found very commonly in many areas of the brain. This chemical is somewhat involved in the sense of reward and pleasure that we all experience. Through research, scientists were able to discover that nicotine (which does not naturally occur in humans) attaches to some of the same receptor sites in the brain that acetylcholine does and competes with acetylcholine for these receptor sites. In a way, it is like nicotine hijacks some of the receptors for its own use. Practically, what the smoker feels is an artificially enhanced sense of pleasure that is then also transmitted into their memory. Over time (but usually starting within a week or two of smoking initiation!) the brain adapts to this new chemical, nicotine, by creating more receptors. This changes the normal balance of chemicals in the brain and what occurs is that soon the brain only feels “normal” if there is nicotine present on the receptors. When there is not enough nicotine in the brain (and nicotine has a “half-life” of only about two hours) the smoker will begin to feel uneasy and need another hit of nicotine to feel normal. This pattern is monotonously repeated throughout the nicotine addict’s day. In that way it is no different than someone who is hooked on heroin needing to use several times a day.
Everyone knows that cigarettes are bad for you. Even the most addicted smoker knows it. And at least 70% of smokers would like to quit but they can’t. Many more would like to quit “if it were easy”. But the truth is that it is not easy. In 1964, when the first Surgeon General’s Report came out, 48% of American smoked cigarettes. In 2004 it was down to 21%. This is certainly a remarkable change and indicates that many smokers have been successful at stopping over the past 40 years. In the past it appears that most of these smokers did it “on their own” with minimal help. However, for the past ten years or so the percentage of Americans still smoking has not changed very much. There has been much speculation about why this has occurred but one thought is that many of the people still hooked on cigarettes are more highly nicotine dependent and just trying to go “cold turkey” is insufficient. The good news is that we have several useful tools to help smokers become tobacco free.
There are several clinically useful pharmaceutical products that have been developed over the last twenty years to help smokers stop using tobacco. (In all fairness there are several non-pharmacologic treatments that have shown some efficacy including the use of a telephone “Quit Line”; Cognitive Behavioral Therapy to manage concerns about weight gain, alcohol usage, depression; Brief therapies that focus on enhancing motivation to stop; self guided manuals etc. In general these are not widely available and/or are poorly reimbursed.). The products approved by the FDA for smoking cessation include:
1. Nicotine Gum
2. Nicotine Patch
3. Nicotine Nasal Spray
4. Nicotine Inhaler
5. Nicotine Lozenge
6. Buproprion (Zyban®)
7. Varenicline (Chantix®)
Let me describe briefly how each of these is to be used. (For a more complete description you can talk with your physician or pharmacist.)
Nicotine Gum – This product was first developed in Sweden and put on the market in 1984. It is available Over the Counter (OTC) in 2 mg and 4mg doses. In general the nicotine gum is to be used throughout the day and an average smoker will use between 12-20 pieces/day. It should be chewed 3 or 4 times and then “parked” between the cheek and gum where the user will experience a tingling sensation. When the tingling stops the user chews it a few times and then parks it again. After repeating this several times there will be no tingling sensation when the gum is parked and it can be discarded. The gum should NOT be chewed like regular chewing gum. The gum is used for several weeks with a gradual tapering in numbers of pieces chewed.
Nicotine Patch – This product came on the market in 1991 and has been OTC since 1996. There are different patch strengths available. In general a smoker puts the patch on each morning and then replaces it with a new patch the following day. Usually start with the highest mg patch (21mg or 16mg) for at least 6 weeks before beginning to taper from the patch over the next four weeks.
Nicotine Nasal Spray – Probably the most effective of the nicotine replacement products but also one of the least used. The product is available only by prescription and looks like a typical decongestant spray. The smoker will put one squirt in each nostril every 1 – 2 hours to start with and then gradually wean off. It is unclear why this product is not more widely used though it is speculated that smokers have some awkwardness about using it frequently in social situations.
Nicotine Inhaler – This small plastic device has been on the market since 1997 and is only available by prescription. The Inhaler contains a cartridge with nicotine and a small amount of menthol in it (to soothe the effect of nicotine on the throat). When used to stop smoking, the user will draw air through the mouthpiece and hold it in their mouth. The nicotine is mostly absorbed in the mouth (as opposed to cigarette smoke where the nicotine is absorbed in the lungs). In general a smoker will need 6-12 cartridges/day and they can get up to 80 puffs from each cartridge. Again it is recommended that this product be used for at least 10 weeks.
Nicotine Lozenge – Available OTC in 2mg and 4mg doses. Normally a smoker would use 1-2 lozenges every 1-2 hours to begin with. There is a gradual lengthening of the time between lozenges over several weeks.
Buproprion (Zyban®) – This was the first non-nicotine based pharmaceutical product approved for the treatment of smoking cessation and came on the market in 1997. It is only available by prescription and usually is taken as 150mg twice daily in the active treatment phase. Originally buproprion was used in the treatment of depression. However, it was discovered that it in some patients it relieved their desire for nicotine. Patients using buproprion are typically started on the medicine while they are still smoking. As the medicine is increased over the first week the patient will pick a “quit date” usually about a week after starting the medicine. It is recommended that this medicine be taken for 12 weeks.
Varenicline (Chantix®) – Varenicline is the newest approved treatment agent for assisting in smoking cessation. It came on the market in 2006 as a prescription medication. Like buproprion it is a non-nicotine based medicine. However, it is unique in that varenicline binds to the same receptors in the brain as nicotine does. Because it has a half life that is greater than 24 hours (as opposed to nicotine’s half life of 2 hours) it has a prolonged effect on the receptors. In a way it is kind of like a partial nicotine drug. Just like buproprion, smokers are encouraged to smoke for the first week while on varenicline before attempting to quit. This medicine has been shown to be very helpful and in a head to head comparison with buproprion, varenicline had a better smoking cessation rate at 12 weeks ( 30% vs 44%). The major side effect of varenicline is nausea which for most people will resolve in about 2 weeks. There are some post-marketing reports of depression and suicidal behavior in patients on varenicline though it is unclear if this is a real side effect or part of the pattern seen in some people who stop smoking. In 5000 patients enrolled in studies of varenicline before it was approved by the FDA, severe psychiatric disturbance was not seen more frequently than in patients who got a placebo.
One final note….most average smoker makes many attempts at stopping before they are successful. The important thing is to keep trying. There is no question that nicotine addiction is a serious problem and often times it takes serious treatment for patients to be stop for good.