Drugs and Behavior ch 10: Nicotine and Tobacco

nicotiana rustica and nicotiana tobacum

two of 60 species off nicotiana, N. tobacum provides all of the tobacco used in the USA (cigarettes, cigars, snuff, chewing tobacco, and pipe tobacco). 

Nicotine

the main drug in tobacco, a psychomotor stimulant

tobacco use history

indigenous to south america, spain controlled market, flourished in virginia, england gets a piece of action, popular in Europe (1614 London about 7000 shops), attempts to suppress tobacco smoking failed because it was believed to have medicinal value. it peaked at beginning of 17th century.

most popular tobacco product

e-cigarettes — 27.5% of high school students use them

prevalence

• in 2016, 19% of people over 12 years were smokers

• more males than female

• 18-25 ages have the highest smoking rate

• as education level increases, the rate of smoking decreases

• unemployed people smoke more

• the earlier a person startes, the harder it is to quit

factors in smoking

• the adolescent brain is more sensitive in reinforcing effects of nicotine

• PET scans show greater effects of nicotine in people with hostile or aggressive personalities

• novelty-seeking adolescents are more receptive to tobacco ads

pharmacology of nicotine

mimics ACH, acting on ANS and CNS. it has biphasic effects: low doses stimulate ACH and high doses retard neural transmission

ACh receptor subtypes

muscarinic receptors (M1-M2) and nicotinic receptors

pharmacokinetics of nicotine

readily absorbed across all body membranes: nose, mouth, lungs, GI tract, skin. site of contact and length of time tobacco contacts membranes affect absorption. readily absorbed through the lungs less so through oral or nasal. acidity of delivery medium affects absorption. it distributes quickly (throughout body in 10-20 mins and smoked nicotine reaches brain in 7 seconds)

metabolism

by the liver, excreted in all body fluids but mostly urine

nicotine halflife

about 2.5 hours

nicotine BLO

the patch and chewing gum were not effective alternatives because the pharmacokinetics don’t match. it takes about 60 mins for the patch to hit its peak and 30 mins for the chewing gum

tolerance

develops quickly - within the first few cigs ever smoked and within the first few cigs of the day. it leads to the rapid onset of daily smoking of 20 cigs a day. metabolic tolerance also occurs

physical dependence (withdrawal symptoms)

• craving, irritability, anxiety

• difficulty concentrating, restlessness

• increased appetite and insomnia

occasional smoking

85% of adolescents who occasionally smoke more than 2 or 3 cigarettes develop nicotine dependence

weak primary reinforcer

nicotine is one. rats won’t readily take it. it has a unique ability to alter the reinforcing aspects of other non-drug stimuli in the environment

dual-reinforcing effects of nicotine

has weak primary reinforcing properties but increases the reinforcing properties of other non-drug stimuli in the environment (the taste of cig, burn in the lungs, social reinforcers around while they smoke)

acute effects

mimic ACH; enhances alertness, learning, and memory. increases heart rate, BP, and heart contraction. it relaxes skeletal muscles, decreases appetite for sweet food. negative reinforcement could drive smoking behavior

chronic use effects

increases risk of dying form all these life-threatening diseases.

• lung and oral cancers

• emphysema

• heart disease and stroke

• pregnancy complications

tobacco culprits

tar, nicotine carbon monoxide

tar

a sticky substance, adhering to cells in the lungs and airways leading to them. they alter the composition of cilia that normally sweep unwanted particles.

nicotine

a toxic, dependence-producing psychoactive drug, found exclusively in tobacco. it stimulates CNS receptors sensitive to acetylcholine and releases adrenaline. it inhibits activity in the GI tract.

carbon monoxide

an orderless, colorless, tasteless gas. it attaches itself to hemoglobin, preventing oxygen from being carried from the lungs to the rest of the body. there is a higher affinity than oxygen. in tobacco, it produces a subtle but effective asphyxiation of the body.

3/4

of the nicotine originating from cigarettes being smokes ends up in the atmosphere

health consequences of tobacco

cardiovascular disease (arteriosclerosis and atherosclerosis, coronary heart disease and stroke), respiratory disease (chronic bronchitis and emphysema), and cancer

tobacco use increases risk of

• lung cancer

• larynx cancer

• mouth cancer

• lip cancer

• bladder cancer

• pancreatic caner

• kidney or uterine cancer

cigar smoking

nicotine content in cigar smoke is absorbed directly through tissues lining the mouth.

5x higher risk of lung cancer

2x higher risk of mouth, throat, and esophagus cancer

45% higher risk of COPD

27% higher risk of coronary heart disease

forms of smokeless tobacco

chewing tobacco; loose-leaf, fine-cut, plug, twist, dry snuff

influences on relapse

• withdrawal

• stress

• social pressure

• alcohol use

• weight gain

treatment goals

• control nicotine withdrawal

• break habits of movements used in smoking

• learn coping skills

behavioral programs

• individual or group therapy

• effective compared to placebo

• high relapse rates

• contingency management

nicotine replacement therapies

gum, patch, nasal spray and inhalers (most similar pharmacokinetics), lozenge, vaporizer. they have a double chance of quitting, and are more effective when combined with behavioral programs. they are generally safe long-term.

bupropion

an antidepressant, not nicotine-based, and superior to placebo.

varenicline

a nicotinic partial agonist

harm reduction

smokeless tobacco products (vaporizers), lower carcinogen cigarettes, nicotine gums, patches, and lozenges

dangers of vaping

outbreak of lung injuries and deaths, increased odds of asthma and chronic obstructive pulmonary disease