Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y2 Pharmacology and Therapeutics > Drugs of Abuse: Cocaine and Nicotine > Flashcards

Drugs of Abuse: Cocaine and Nicotine Flashcards

1
Q

Describe the methods of cocaine administration

A

Paste (80%) and cocaine HCL (dissolved in acidic solution) - IV, oral, intranasal

Crack (precipitate with alkaline solution) and freebase (dissolved in non-polar solvent) - inhalation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is the bioavailability after admin via smoking, nasal and orally so low compared to when given via IV

A

pKa = 8.7
Oral cocaine ionized in GIT - unlikely to diffuse across plasma membranes
Inhaled cocaine unable to cross the membrane of the lungs
Slower absorption, prolonged action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the half life of cocaine

A

20-90 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the metabolic pharmacokinetics of cocaine

A

75-90% - liver cholinesterases produces prodecgonine methyl, ester benzoylecgonine (inactive)

Plasma cholinesterases mean cocaine can be metabolised in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does cocaine pharmacokinetics contribute to the addictive potential of the drug?

A

Rapid onset of action gives a reward of massive euphoria

Quick clearance from the system due to metabolism in the liver and blood, driving drug-seeking behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the pharmacodynamic effects of cocaine

A 
Local anaesthetic
Reuptake inhibition 
Euphoria
Myocardial infarction (CVS)
Hyperthermia (CNS)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain why cocaine has a local anaesthetic effect

A

Blocks the sodium channel and stops sodium influx
Disrupts action potentials, especially in nerves
Cocaine’s effect as a local anaesthetic are more effective when cocaine enters the sodium channel from the inside of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain why cocaine causes reuptake inhibition

A

Cocaine blocks noradrenaline reuptake transporters
More neurotransmitter remains in the synapse
Enhances NA, dopaminergic effects etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Does cocaine influence dopamine affinity/efficacy for the dopamine receptor?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain why cocaine causes euphoria

A

Ventral tegmental area -> nucleus accumbens for dopamine release
Cocaine inhibits the dopamine transporter, causing dopamine to accumulate in the synapse resulting in longer activation of the D1R receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the other effects of cocaine

A

Mild dose - positive reinforcing effects e.g. confidence, talkative, high energy

Chronic usage/high dose - negative/stereotypic e.g. irritability, hostility, extreme exhaustion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain how cocaine can lead to a myocardial infarction

A

Cocaine stimulates the sympathetic nervous system by inhibiting catecholamine reuptake
Sensitivity of adrenergic nerve endings to norepinephrine increases
Increased myocardial demand and atherosclerosis, decreased myocardial supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the opposing cardiovascular effects of cocaine

A

Acts as a class I anti-arrhythmitic by blocking sodium and potassium channels BUT this is dominated by the stimulation of the sympathetic nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the effects of sympathetic stimulation due to cocaine

A

Release of endothelium-1 + Inhibition of NO production -> vasoconstriction

Activation of platelets -> platelet aggregation -> thrombosis

Increase in HR, Contractility and BP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Draw a diagram that summarises the CVS pharmacodynamics of cocaine

A

-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain how cocaine causes hyperthermia

A

Increase in agitation, locomotor activity and involuntary muscle contraction
Leads to an increased body temperature

17
Q

How does cocaine influence sweat production and cutaneous vasodilation?

A

Elevates threshold for sweating/cutaneous vasodilation three fold

18
Q

What proportion of cigarettes are volatile and what substances does this include

A 
95%
Nitrogen
Carbon monoxide/dioxide 
Benzene
Hydrogen cyanide
19
Q

What proportion of cigarettes are particulates and what substances does this include

A

5%
Alkaloids (nicotine)
Tar

20
Q

Describe the dosing for nicotine spray, gum, patches and cigarettes

A

Nicotine spray - 1mg
Nicotine gum - 2-4mg
Cigarettes - 9-17mg
Nicotine patch - 15-22mg

21
Q

What is the pKa of nicotine and how does it affect pharmacokinetics

A

pKa = 7.9
Cigarette smoke is acidic - no buccal absorption
Absorption in alveoli is independent of pH

22
Q

Describe the time taken for absorption of nicotine via cigarettes, sprays, gums and patches

A

Cigarette - very quick to peak in 10 minutes
Spray - same peak time as cigarettes but much lpwer
Gum - slower increase, peak at 30 mins
Patch - very slow increase, remains at similar levels throughout use

23
Q

Describe the metabolic pharmacokinetics of nicotine

A

Hepatic CYP2A6 converts to inactive metabolite conitine

70-80%

24
Q

What is the half life of nicotine

A

1-4 hours

25
Q

What is the effect of nicotine on the sympathetic nervous system

A

Binds to cholinergic receptors

Drives both sympathetic and parasympathetic function - involved in autonomic function

26
Q

Explain how nicotine causes euphoria

A

Nicotine directly stimulates the dopaminergic neurone at the ventral tegmental area to cause increased dopamine release at the nucleus accumbens

27
Q

What are the cardiovascular effects of nicotine

A

Myocardial ischaemia, infarction -> arrhythmias and sudden death

28
Q

Explain how cocaine causes myocardial infarction

A

Causes increase in free fatty acids and LDL -> atherosclerosis
Increase SNS activity leads to platelet activation, coronary vasoconstriction and increase in heart rate, contractility and BP
Reduction in myocardial supply but increase in demand

29
Q

What effect does nicotine have on metabolism and appetite

A

Increases metabolic rate and prevents weight gain

Reduces appetite

30
Q

What effect does nicotine have on Parkinson’s and Alzheimers

A

Parkinson’s Disease; increase brain CYPs → neurotoxins

Alzheimer’s Disease: decrease beta-amyloid toxicity
decrease amyloid precursor protein (APP)

31
Q

Describe the effect of caffeine on nerves

A

Binds to A1 receptors on both the pre- and post-ganglionic bulbs

32
Q

Explain why cocaine’s local anaesthetic effect is more effective intracellularly

A
  1. Cocaine diffuses across the nerve to the inside of the cell and access the channel from beneath
  2. Due to its pKa it is more unionised extracellularly which can diffuse across the plasma membrane
  3. Once in the nerve cell, it becomes more ionised and can access the inside of the sodium channel
  4. When cocaine is charged it is a lot better at interacting with its target (sodium channel)
33
Q

What is the bioavailability for nicotine spray, gum, cigarettes and patches

A

Nicotine spray - 20-50%
Nicotine gum - 50-70%
Cigarettes - 20%
Nicotine patch - 70%

Y2 Pharmacology and Therapeutics (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions