How nicotine works
“More than 4,000 compounds are found in cigarettes, and though it is the nicotine that causes addiction, these compounds do the bulk of the damage to the body.”
Drugs are compounds that are used to treat, cure, or manage diseases. Drugs can be made in the lab, derived from proteins or made from chemicals derived from natural sources. To be useful, drugs must enter the body, travel to the site of disease and be present in the body long enough to be effective. Unfortunately, drugs are not given road maps to negotiate their way through the body. Defence mechanisms within our bodies include special cells in the lungs, bloodstream and skin, the acid of the stomach and the liver, which filters foreign substances from the blood.
Delivery systems can help drugs evade those traps. There are many different kinds of delivery systems because there are many different kinds of drugs. The role of the delivery system is to keep the drug in the body long enough and in high enough concentrations to be effective in treating disease. Cigarettes are designed to quickly deliver the naturally occurring alkaloid nicotine to the body. A typical smoker will take 10 puffs on a cigarette. If that person smokes 1-1 1/2 packs of cigarettes a day, they are getting 300 “hits,” sending approximately 1 mg per cigarette of nicotine daily to the brain.
Many compounds are added to cigarettes to increase nicotine’s effect once inside the body. These are commonly referred to as additives or flavourings, which mask the serious effects some of these compounds have on the body. More than 4,000 compounds are found in cigarettes, and though it is the nicotine that causes addiction, these compounds do the bulk of the damage to the body.
Some Additives and Their Effects
Some of these ingredients, like ammonia, a common household cleaner, are used to increase the amount of nicotine that enters the body. Ammonia increases the pH of cigarette smoke. This increase in pH changes the form of nicotine from a nicotine salt to a free nicotine.
Compared to the nicotine salt, this free nicotine easily enters cigarette smoke. In fact, it has been shown that ammonia treatment can result in a 100-fold increase in the ability of nicotine to enter into the smoke. This can result in an up to 40% higher nicotine delivery. All cigarettes treated with ammonia, whether light, menthol, filtered, or low tar, deliver more nicotine more quickly to the smoker.
Different forms of the organic acid, levulinic acid, are added to cigarettes to mask the harsh taste of the nicotine and increase the binding of nicotine to brain receptors, which increases the “kick” of nicotine. Most drugs act by binding to cell receptors. This binding activates the cell to some action. The more nicotine that binds, the greater the effect nicotine will have on the brain. Some additives are used to disguise the bitter taste of the tobacco so that smokers will enjoy the experience. Glycyrrhizin, derived from liquorice, and cocoa are typically thought of only as compounds to flavour cigarettes. Not well known by most people is the fact that these compounds either are bronchodilators or contain other substances (cocoa contains the alkaloid bronchodilator theobromine) which dilate, or open up, the lung membranes.
Dilating lung membranes with bronchodilators will increase the amount of nicotine that enters the body. Alkaloids, which are compounds of plant origin, often have pharmacologic properties, which make them valuable as drugs, but which are poisonous if used incorrectly. Some examples of alkaloids with pharmacological properties are morphine, codeine, cocaine, caffeine and LSD.
Tar, Invisible Gases and Nitrosamines
Collectively, these compounds are referred to as tar. Tar is the visible smoke produced by burning tobacco. Tar transports many of the chemicals contained in cigarette smoke directly into the body, as well as the poisonous gases nitrogen oxide and carbon monoxide. It has long been known that tobacco smoke is carcinogenic, or cancer-causing–in fact, it is the smoke that is the most dangerous element of smoking.
Minute particles of tar travel into the tiniest branches of the lungs–the alveoli–where they stick. The body works to eliminate these particles from the lungs by coughing, but over time and with continuous smoking, the tar collapses the alveoli, reducing the ability of the lungs to transport the necessary gases, oxygen and carbon dioxide, through the body.
Burning tobacco generates more than 150 billion tar particles per cubic inch. According to chemists at R. J. Reynolds Tobacco Company, cigarette smoke is 10,000 times more concentrated than the automobile pollution at rush hour on a freeway. The lungs of smokers, puffing a daily ration of 20 to 60 low to high tar cigarettes, collect an annual deposit of 1 – 1 1/2 pounds of the gooey black material.
Visible smoke contributes only 5-8 percent of the total output of a cigarette. The remaining percentage is the invisible gas phase of cigarette smoke and contains, nitrogen, oxygen, the toxic gases carbon monoxide, formaldehyde, acrolein, hydrogen cyanide and nitrogen oxides. These gases are poisonous, and in many cases, interfere with the body’s ability to transport oxygen. Among the worst offenders are the nitrosamines. Strictly regulated by federal agencies in food substances, their concentration in bacon and beer must not exceed 5 to 10 parts per billion. A typical person ingests about one microgram a day while a typical smoker takes in 17 times as much per pack of cigarettes.
The tobacco-specific nitrosamines found in cigarette smoke are formed from natural components of the tobacco plant during the curing of the tobacco. Like many carcinogenic compounds, they can act as tumor promoters or tumor initiators by acting directly on the genetic makeup of individual cells of the body. This genetic damage is very difficult for the cell to repair and is associated with the development of cancer. Cigarette smoke is also a source of chemicals called polycyclic aromatic hydrocarbons, which specifically cause gene mutations in the p53 tumor suppressor. In its normal state, this gene protects against cancer. This mutation is present in about 60 percent of all cases of lung cancer.