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Pulmonary system > Pharmacological approaches to smoking cessation > Flashcards

Pharmacological approaches to smoking cessation Flashcards

1. Describe the pharmacology of nicotine 2. Describe the various forms of nicotine replacement therapies 3. Describe the mechanisms of action of drugs used as smoking cessation therapies as well as their side effects and any safety issues associated with their use 4. Compare the efficacy and tolerability of all agents used in smoking cessation.

1
Q

Route of entry of nicotine

A

-inhaled and absorbed from alveoli
-also absorbed from skin and mucous membranes
(is very lipophilic so is readily absorbed)

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2
Q

How quickly does nicotine get to the brain

A

When inhaling it, get to the brain in about 10 seconds

*important for immediate reward

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3
Q

Half life of nicotine

A

1-2 hours

*why people can’t just smoke 1 cigarette a day

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4
Q

Metabolism of nicotine

A

CYP2A6

*may explain why some people can smoke more infrequently than those who are rapid metabolizers (chain smokers)

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5
Q

Major metabolite of nicotine + purpose

A

cotinine (is inactive)

  • can use as marker for nicotine use because it has a longer half life (15 hours)
  • can’t rely on smoker word to say that they quit - a good trial back up with samples from patient - evidence that they are smoking
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6
Q

Plasma continine levels required for addiction

A

50-70nm/mL (approx 5 cigarettes/day)

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7
Q

MOA nicotine

A
  • is a Nicotinic receptor agonist
  • increases dopamine release
  • dopamine stimulates reward pathways in the brain
  • can also cause release of acetylcholine, norepinephrine, serotonin, beta-endorphin, GABA
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8
Q

Net effect of nicotine (low dose, high dose)

A

Low doses: stimulant predominates

Higher doses: reward predominates

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9
Q

Effect chronic exposure of nicotine

A

Chronic exposure to nicotine leads to nicotinic receptor upregulation
-may be due to receptor desensitization

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10
Q

Withdrawal from Nicotine (symptoms and duration)

A

1) Lightheadedness < 2 week
5) Irritability or aggressiveness < 4 weeks
7) Restlessness < 10 weeks

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11
Q

Interventions for smoking cessation

A

1) Non-pharmacological
- cognitive behavioral therapy (CBT)
- acupuncture
- hypnosis
2) Phamacological
- nicotine replacement
- other drugs

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12
Q

Modalities of nicotine replacement

A

1) Gum
2) Patch
3) Inhaler
4) Spray

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13
Q

What do all replacement forms of nicotine have in common + why (2)

A
  • they all bypass the gut
  • don’t want to swallow nicotine because:
    1) Low oral bioavailability
    2) In higher doses, nicotine is a gastric irritant
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14
Q

Nicotine replacement gum available doses

A

-2mg or 4 mg of nicotine (cigarette is 1-3 mg)

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15
Q

How to use nicotine gum

A

1) Chewed briefly, the placed in cheek (buccal absorption)

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16
Q

Side effects of nicotine gum

A
  • local irritation

- gastrointestinal upset

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17
Q

Nicotine replacement lozenges - use

A

Very similar to gum (similar use and pharmacokinetics)

-the more you suck on it and swallow it the more your stomach will be upset

18
Q

Nicotine replacement patch

A

Transdermal delivery
Provides continuous 24 hours release of nicotine
- was easy to invent because nicotine is so lipophilic -just have membrane against the skin allowing nicotine to percolate through the skin (skin determines rate of deliver of the drug)the

19
Q

Negative of patch

A
  • will irritate the skin
  • can’t be titrated acutely - people often associate activities with smoking -cant put on a patch prior to these activities to receive enough nicotine to not crave smoking - is very gradual onset whereas the lozenge and gum are more rapidly acting
20
Q

Combination of nicotine replacement therapies

A

Can safely combine two nicotine replacement therapies (i.e. patch + gum/lozenge)

21
Q

Nicotine replacement inhalers -purpose

A

-look like cigarettes so replicate the behaviour of smoking

22
Q

Nicotine replacement inhalers - absorption

A
  • absorption occurs in oral cavity not in the lungs
  • because is a water vapor can’t travel as far as the lungs (and cannot absorb as rapidly into the bloodstream as smoke can)
23
Q

Side effects of nicotine replacement inhalers

A
  • cough

- local irritation (throat/mouth)

24
Q

Nicotine replacement-nasal spray advantages

A

-must faster absorption

25
Q

Side effects of nasal spray

A
  • local irritation (nose/throat)

- fastest absorption -might get people addicted to the nasal spray

26
Q

Nicotine replacement -sublingual spray

A

Spray under tongue
Pretty good absorption
Still causes irritation

27
Q

Varenicline (Champix) - MOA

A
  • is a partial agonist at nicotine receptors (alpha4beta2)
  • therefore will stimulate receptor but produces less than a full response (less release of dopamine - mimics rewarding feeling from smoking)
  • if taking Varenicline and relapse (start smoking) a lot receptors occupied by partial agonist so will not get as big of a high from smoking
28
Q

treatment duration Varenicline

A
  • twice daily x 12 weeks
  • target quit date should be at least 1 week after starting Varenicline (because need to get to steady state and deal with main side effect = nausea)
29
Q

Issue with Varenicline

A 
Psychiatric adverse effects
-depression
-agitation
-hostility
-behavioral changes
-suicidality * only thing that sets this list apart from nicotine withdrawal
BUT conflicting evidence
-problem with assessing psychiatric effects is that they are difficult to separate from effects of nicotine withdrawal
30
Q

Patients with cardiovascular disease and champix

A
  • was effective

- but small increase in risk of cardiovascular event

31
Q

Bupropion (Zyban) - MOA

A
  • developed as an antidepressant and still used for this
  • reuptake inhibitor - block reuptake pumps that remove NT from synapse
  • get more NT in synapse
  • more binding to receptors
  • greater activity of the neurotransmitter
  • inhibits reuptake of dopamine and noradrenaline in brain (helps to feel better during withdrawal) and may also act as nicotinic receptor antagonist (if relapse and go to smoke won’t get as much as a reward from smoking
32
Q

Buproprion treatment regimen

A
  • don’t quit until started buproprion and comfortable on it -target to quit usually 2nd week
  • twice daily x7-12 weeks
33
Q

Side effects of buproprion

A
  • insomnia
  • dry mouth
  • nausea
34
Q

Safety issues of bupropion

A

-all antidepressants may stimulate impulsive (suicidal) behaviour in youth

35
Q

Nortriptyline - MOA

A
  • inhibits reuptake of serotonin and noradrenaline

- minimal effects on dopamine reuptake

36
Q

Disadvantage of nortriptyline

A

-antichonlinergic side effects

37
Q

Evidence for use of nicotinic replacement therapies

A
  • comparing efficacy of various nicotine replacement therapies (NRT)
  • all NRT were statistically better than control (placebo)
  • no clear advantage of one NRT over another
  • cochrane review
38
Q

NRT versus other drugs -evidence

A
  • few trials directly compare NRT versus buproprion or varenicline
  • results suggest that bupropion may have similar efficacy to NRT
39
Q

Buproprion vs. varenicline

A

-more varenicline subjects were abstinents at 12 months vs. BUP
(not by very much though)
-but nauses might occur more frequently with varenicline versus bupropion

40
Q

Future direction of smoking cessation

A

Nicotine vaccines

  • formation of antibodies to nicotine
  • antibody-nicotine complex unable to cross the blood-brain barrier
  • in phase 3 not doing so well in animal studies
41
Q

Electronic cigarettes

A
  • deliver nicotine (and other substances) in vapour form

- intended to more closely resemble an actual cigarette

Pulmonary system (19 decks)

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