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Pmcol 305 > Nicotine > Flashcards

Nicotine Flashcards

1
Q

forms of tobacco product (8)

A

cigarettes
e-cigarettes
cigars
cigarillos
shisha
smokeless
patches
gum

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2
Q

electronic cigarettes

A

vapourize e-juice containing nicotine (glycerin or PG-based)
no tar “cleaner smoke is healthier”
flavours + additive → severe adverse effects
diacetyl + vitamin E acetate

vapour damages immune system (same as cigarettes)
5-8x more nicotine per puff than cigarettes

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3
Q

diacetyl

A

butter flavour of e-cigarettes
obliterates lung tissue → bronchiolitis obliterans
‘popcorn’ lung in factory workers = holes in lungs

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4
Q

vitamin E acetate

A

antioxidant
severe allergic reactions by inhalation

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5
Q

hookah

A

water cools smoke → less irritating, fewer particulates
- but, increase time of exposure to chemicals
uses shisha

hot air vapourizes chemicals - 11x more CO
elevated CO in blood → increased hr
increased risk of lung disease, oral/lung cancer

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6
Q

shisha

A

most processed, flavoured, tobacco form

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7
Q

smoke

A

an aerosol = particulates + gases

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8
Q

particulates in smoke

A

nicotine
water
tar
PAHs
benzo[a]pyrene
metals

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9
Q

gases in smoke

A

nicotine, CO, CO2, NO, nitrosamines, ammonia, nitrites, sulfur, alcohols, ketones, aldehydes, hydrocarbons

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10
Q

first-hand smoke

A

inhalation of smoke directly from burning tobacco

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11
Q

second hand smoke

A

smoke that has already been inhaled by others

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12
Q

third hand smoke

A

fumes from fingers, clothes, fabric

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13
Q

nicotine

A

alkaloid
uncharged = free base

causes addiction
competitive acetylcholine receptor agonist

protects plants from pests → pesticide

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14
Q

administration

A

inhalation (11-20% bioavailability)
oral - smokeless forms (50-80% bioavailability)

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15
Q

inhalation

A

controlling pH in cigarettes optimizes absorption (free base)
burning generates up to 4000 new chemicals
pyrolysis → lower bioavailability

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16
Q

free base

A

both nitrogens are neutral (no hydrogens)
weak base
easily reduced by plants
pH > 6

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17
Q

monoprotonated

A

one nitrogen is protonated = +1 charge
3 < pH < 9

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18
Q

diprotonated

A

both nitrogens are protonated = +2 charge
pH < 6

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19
Q

1 cigarette

A

~ 8mg nicotine
delivers 0.5-2 mg
occupies 80% of binding sites (nAChRs)

60 mg is lethal

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20
Q

pharmacokinetics + addiction

A

1-2 puffs/min - 2 sec long
1-2 ug nicotine/kg body weight is delivered to the brain
= one pack/day is optimal for brain stimulation

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21
Q

oral - smokeless forms

A

3-4x greater nicotine absorption
slower rate of absorption

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22
Q

distribution

A

blood pH is 7.4 = 70% monoprotonated, 30% unprotonated
<5% is bound to plasma protein

brain, liver, kidney, spleen, lung

least to adipose (less blood supply)

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23
Q

metabolism

A

nicotine → cotinine
in liver
aldehyde oxidases: CYP2A6 + CYP2B6
monooxygenases process small amount

half life = 2hr

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24
Q

CYP2A6 mutation

A

slows metabolism = greater [nicotine] for longer time → off target effects
results in lower tobacco use
aversive

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25
Q

excretion

A

kidneys

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26
Q

nicotine concentration vs time

A

plasma [nicotine] peaks in the evening
receptors re-sensitize over night
= first daily cigarette is most pleasant

27
Q

acute effects

A

sympathomimetic

affects heart rate, bp, GI movement, motor commands, focus, + mood

28
Q

mechanism of action

A

affects ACh, DA, GABA, Glu
binds + depolarizes cells via nAChRs

29
Q

biphasic mechanism

A

at high doses
high affinity → inactivation of receptor

30
Q

acetaldehyde

A

from burning
may inhibit monoamine oxidases and boost NT levels

31
Q

nAChRs in CNS

A

cortex, basal forebrain, hippocampus, basal ganglia, thalamus, cerebellum, brainstem

presynaptic nAChRs depolarize terminals → prolonged DA, glu, GABA release

32
Q

mechanism of reinforcement

A

presynaptic receptors on GABA, DA, + glu neurons
= more GABA released → disinhibition of DA neuron
= more DA release
= more glu released → increased firing of DA

more dopamine =
pleasure, reward, addiction

33
Q

acute adverse effects

A

stimulation of vomiting centre - common in first time users (area postrema - dorsal brainstem)

headaches, nausea, disrupted ANS functioning
alternating tachy- and brachycardia
severe intoxication → seizures, hypotension, respiratory depression

34
Q

nAChRs

A

heteropentameric receptors
9 a + 3 b subunits

conduct cation influx to depolarize neurons - Na+, Ca2+

35
Q

presynaptic nAChRs

A

increase NT release

36
Q

postsynaptic nAChRs

A

depolarize cell

37
Q

high affinity

A

continuous exposure to agonist (nicotine) inactivates receptor

38
Q

receptor subunit composition

A

affects reinforcement + reward

determine inactivation rates

39
Q

a6

A

modulate locomotor responses

40
Q

a7

A

facilitate glutamate release
not inactivated

41
Q

b2

A

subunit knockout in mice prevents DA release
self-administration stops
= important in reward

42
Q

a4b2

A

antagonists block reward

most important for DA reinforcement
main functional nAChRs on VTA DA-ergic soma
activation drives DA release and reinforcement

govern GABA release - inactivate quickly and for a long time

43
Q

a6b2

A

mainly on DA-ergic terminals in NAc
do not release DA after systematic nicotine administration

44
Q

single dose of nicotine injected into NAc

A

elevates DA levels for 80 minutes
3x baseline

45
Q

first use

A

unpleasant
targets brain regions/circuits for dizziness, nausea, sweat

46
Q

tolerance

A

little or no decrease in heart effects, tremor, peripheral vasoconstriction
= no change in physical effects

47
Q

metabolic tolerance

A

increased enzyme activity

48
Q

cellular tolerance

A

receptor inactivation
affects reward

nAChR expression increases in PFC - a4b2
enhances sensitivity to nicotine effects

49
Q

behavioural tolerance

A

mindset stages experience
ritual of smoking

50
Q

withdrawal

A

physiological: headache, drowsiness, insomnia, increased appetite + weight gain, GI upset
psychological: craving, mood changes, irritability, anxiety, restlessness, depression, difficulty concentrating, poor judgement + psychomotor performance

51
Q

dependence

A

addicted if have to smoke within 30 min of waking
occurs within days of habit
physical + psychological

quick metabolism → withdrawal → seek more
cue-driven habit

52
Q

long term adverse effects

A

cancer (lung, liver, colorectal)

accelerate skin aging due to peripheral vasoconstriction
sexual dysfunction - impaired NO signaling
type 2 diabetes → stressed vasculature is insensitive to insulin

53
Q

cancer

A

benzo(a)pyrene initiates cancer = intercalating agent
nicotine enhances growth/metastasis (not initiation)
- inhibits apoptotic signaling by binding a7 nAChRs on mitochondria → allows cells with damaged DNA to replicate

54
Q

nicotine → in vitro

A

enhances cancer cell growth

experiment - mice given cancer
treated with nicotine/saline for 2 weeks
removed tumours
continued treatment
→ nicotine treated mice regrew tumours

55
Q

long term adverse effects - tobacco

A

cataracts, macular degeneration
tooth decay, periodontitis, IBS, Chrohn’s
infection
rheumatoid arthritis, osteoporosis
cardiovascular disease - CHD, MI, ischemic stroke
COPD → emphysema, chronic bronchitis

56
Q

COPD

A

inflammation of airways covered in tar + ash deposits
cilia function is impaired by PAH + ketones in smoke

57
Q

smokers’ cough

A

when quitting
indication of recovery of cilial function

58
Q

pregnancy

A

constriction of umbilical arteries → reduced oxygen
increased addiction risk
higher risk of stillbirth, premature or miscarriage, low birth weight
cleft palate + lip - higher risk

59
Q

smoking cessation

A

alternate form of nicotine to ease withdrawal and cravings
reduce use instead of complete elimination
3 day hump (withdrawal) → clearance from bloodstream

harder to quit smokeless forms - higher doses

60
Q

pharmacological cessation aids

A

bupropion
varenicline

61
Q

bupropion

A

antidepressant
nAChR antagonist - blocks channel even when nicotine is present (competitive)
DAT + NET inhibition → decrease sympathomimetic
helps reduce cravings

62
Q

varenicline

A

partial nAChR agonist
reduces reward and cravings

63
Q
A

Pmcol 305 (18 decks)

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