Chapter 7 - Nicotine and Caffeine Flashcards
What is nicotine?
leaves of tobacco plants; Nicotiana tabacum is most commonly used (highest nicotine content); absorbed when smoked or chewed
Nicotine content of popular tobacco products
cigarettes (10mg, 1-2mg gets absorbed); cigars and pipes (amount varies, 5mg to 350mg)
What are some smokeless tobacco products?
chewing and dipping tobacco, snuff
What are E-cigarettes?
involves inhaling vaporized nicotine; vegetable glycerin added to make “smoke” visible, can cause lipid related lung injury; 0.3-4mg of nicotine in 15 puffs
despite a decrease in ____, there has been a significant increase in ____
smoking cigarettes; vaping
Tobacco use can cause…
cancer (lung, mouth); cardiovascular issues (heart attack, stroke); pulmonary disease (emphysema)
Secondhand smoke risks
cancer; heart disease
in kids: bronchitis, pneumonia, ear infections, SIDS
Thirdhand smoke risks
remnants of tobacco smoking on material in the smoker’s local environment (skin, hair, clothing, walls); risk to young kids
History of tobacco
concerns as early as 17th century; early 20th century research focused on adverse effects
Absorption (pharmacokinetics of smoking)
enters from mucous membranes (mouth, nose, throat) and lungs; tar sticks to mouth, nose, throat, and lungs– nicotine leaches from the tar
Flue Curing (of cigarettes)
treat leaves with vented heat; produces neutral pH of tobacco smoke (7); allows smoke to be inhaled (cigarettes)
The large surface area of the lungs provides a…
very effective route for nicotine to be absorbed into blood stream
Best pH for absorption in the mouth is ____
pH 8.2
-sometimes chemicals are added to e-cigs to increase their pH
Most products yield blood concentrations of ____
12 to 16 mg of nicotine per ml of blood
Approximate absorption time for tobacco products
smoking 7mins, oral products 20 mins, vaping 20-30 mins
Nicotine can readily cross the ____
blood brain barrier
Nicotine metabolization
mostly in liver by CYP-2A6 enzymes; produces active metabolite cotinine
Nicotine elimination
half life of about 2 hours; 30% faster in smokers (pharmacokinetic tolerence)
Nicotine is an agonist for the ____
nicotinic ACH receptor
– Ionotropic receptor
– When bound to receptor site, positive ions flow into the neuron: Ca2+, Na+, K+
– depolarizations
-Each nicotinic ionotropic receptor comprises a configuration of α & β subunits
What does it mean to have biphasic effects (nicotine)?
It first activates receptor by opening channel (agonist)
-Then, receptor enters desensitized state: the channels close and the receptor cannot be activated (functional antagonism)
-Occurs when nicotine is still bound to the receptor
-In time, desensitized state ends and receptors can be activated again
Upregulation of ACH receptors
brain compensates for the repeated closing of nicotinic receptor channels by upregulating nicotinic receptor numbers; end up with more nicotinic ACH receptors expressed on post
synaptic neurons
Peripheral NS (dist. of nicotinic receptors)
in ganglia of the ANS (symp and parasymp.); overall activation increases sympathetic NS; neuromuscular joints (voluntary muscle contractions)
Central NS (dist. of nicotinic receptors)
receptors are found in structures important for arousal and cognitive functioning (ex. hippocampus and cerebral cortex); motor functioning (basal ganglia); reward circuitry where they increase DA (VTA and NA)
What are some other NTs that nicotine effects?
ACH, glutamate, GABA; other constituents of tobacco smoke may enhance these effects
physiological effects of nicotine
HR and BP: first cig of the day incr HR and BP then becomes desensitized (acute tolerance); reduces appetite
movement (behavioural effects of nicotine)
depends on use (naive vs users); hand tremors in naive users; increased purposeless behaviours in chronic users
cognition (behavioural effects of nicotine)
NAIVE ONLY (tolerance effect)
improves attention, vigilance, information processing speeds (e.g. Stroop Test); improved memory (word recall)
subjective effects on naive users
negative subjective effects; nausea, disequilibrium, tension, jitteriness, confusion; acute tolerance to these effects
subjective effects on chronic users
positive subjective effects; feelings of vigor, arousal, reduced fatigue; habitual users likely to become addicted
Nicotine abstinence syndrome
includes craving, irritability, anxiety, hostility, concentration difficulties, impatience, insomnia
How do some people smoke but don’t get addicted?
can be psychosocial factors (coping skills, less stress, better social support); can be genetic factors (Differ in gene expression for α5, α3, β4 receptor subunits, which are found on chromosome 15)
Some ways that smokers quit
Cold turkey; Nicotine replacement (e.g., nicotine patches, gum); Varenicline (Chantix): a partial agonist of nicotinic ACH receptor
- less activation of nicotinic receptors (reduces
effectiveness of nicotine); Bupropion (antidepressant): increases DA which may
compensate for reduced DA in reward pathway with nicotine withdrawal
Research suggests that making it to ____ of nicotine abstinence is best predictor of success
two weeks
-the problem seems to be that most cessation
strategies do not work and smokers do not make it to two weeks
What is caffeine?
Mild psychostimulant of the xanthine family (includes theobromine and theophylline)
oral administration of caffeine
food, drink, pills
pharmacokinetics of caffeine
absorption across intestinal walls; peak concentrations at around 40mins; penetrates brain and placental blood barriers
caffeine is metabolized in the ____
liver
what is the half life of caffeine?
varies widely (3-10hrs); decreased by nicotine; increased by antidepressants
caffeine is what kind of agonist?
adenosine receptor agonist
-Adenosine: primary role in the control of
sleep
effects of caffeine
Increases heart rate, blood vessel constriction,
increases breathing rate, reduces appetite,
increases attention and alertness, and produces
positive mood
What causes caffeinism?
high doses; agitation, anxiety, insomnia, negative mood, rapid heart rate and high blood pressure
-recommended no more than 400 mg per day
(adults); 100 mg in adolescents
