4 - Legal Drugs of Abuse

Question 1

Name the conditions required for substance use to be determined as abuse

Answer 1

One of these must be met:
- Continued use despite social/interpersonal issues
- Repeated use causing failure in responsibilities
- Repeated use causing physically hazardous situations
- Use resulting in legal problems

Question 2

Name three legal substances that are abused and their effect

Answer 2

Caffeine, nicotine, alcohol

All increase dopamine in the brain

Question 3

What type of drug is caffeine?

Answer 3

Stimulant

Question 4

Name the physiological effects of caffeine

Answer 4

• Stimulates CNS
• Relaxes smooth muscle
• Can be a diuretic (increase urine production)

Question 5

As a drug, what is the benefit of caffeine being water-soluble?

Answer 5

Readily crosses blood-brain barrier

Question 6

When is caffeine used?

Answer 6

Recreationally and medicinally to reduce fatigue/increase alertness, energy and productivity

Question 7

How does caffeine work?

Answer 7

• Agonist at adenosine receptors (A1 & A2A), blocks adenosine from binding
• Adenosine prompts GABA release which blocks impulses between nerve cells in brain - caffeine inhibits this
• Increases epinephrine (adrenaline) levels -> increased endurance

Question 8

What are the physical effects of caffeine?

Answer 8

• Increased alertness
• Increased metabolic rate
• Increased anxiety
• Increase BP
• Diuretic
• Decreased risk of CV disease & diabetes

Question 9

What is the LD50 and t1/2 of caffeine?

Answer 9

LD50 = 150-200mg/kg
t1/2 = 3-4 hours

Question 10

What are the active metabolites of caffeine, their effects and their t1/2?

Answer 10

Paraxanthine - t1/2 = 4-6 hrs Increased alertness
Theobromine - t1/2 = 5-6 hrs Lowered BP
Theophylline - t1/2 = 5-8 hrs Bronchodilator (asthma)

Question 11

What is the long lasting synaptic effect of caffeine use?

Answer 11

Increased adenosine sensitivity
Increased adenosine receptor density

• Feel more tired when not taking caffeine - physical dependence

Question 12

What are the withdrawal symptoms of caffeine?

Answer 12

Depression
Fatigue
Irritability
Headaches

Question 13

What type of drug is nicotine?

Answer 13

Stimulant, but it relaxes a person due to increased dopamine

Question 14

Why does nicotine readily cross the blood-brain barrier?

Answer 14

It’s a lipophilic free base

Question 15

Where is nicotine absorbed?

Answer 15

Intestines only because it is basic (only absorbed in alkaline environments)

Question 16

Define biphasic action

Answer 16

When a drug can act as both an agonist and antagonist (inc. decr. acetylcholine transmission)

Question 17

Nicotine has biphasic action. Explain

Answer 17

Agonist - low doses, mimics NT
Antagonist - high doses, blocks NT

Question 18

What effects does nicotine have on the nervous systems?

Answer 18

CNS & PaNS (parasympathetic) - increased HR, BP, respiration

CNS - increased adrenaline, information processing, mental performance, memory

PeNS (peripheral) - increased HR, BP, acid production in stomach

Question 19

Why is inhalation the most addictive form of nicotine administration?

Answer 19

cmax reached within 10s
Effects go away within few mins -> frequent smoking

Question 20

Define first order elimination

Answer 20

Amount of drug eliminated is directly proportional to remaining concentration within the body

Question 21

What is the t1/2 and LD50 of nicotine?

Answer 21

t1/2 - 2 hrs
LD50 - 30-60mg (difficult to occur via inhalation)

Question 22

Where and how is nicotine metabolised?

Answer 22

Lungs
Kidneys - P450 enzymes
Liver - aldehyde oxidase

Question 23

What is nicotine’s metabolites?

Answer 23

Nicotine iminium -> cotinine -> trans-3-hydroxy cotinine

Question 24

What are the long-term health effects of nicotine use?

Answer 24

Increased risk of CV disease
Cancer
Chronic obstructive pulmonary disease (COPD)
Emphysema

Question 25

What are the symptoms of nicotine withdrawal?

Answer 25

Constipation
Headache
Irritability

Question 26

What is a unit of alcohol?

Answer 26

1 unit = 10ml

Question 27

What are the effects of alcohol per the unit ranges listed?
1-2, 4-6, 8-9, 10-12, 12+

Answer 27

1-2 - increased HR, more social & talkative

4-6 - impaired judgement & decision making, light-headedness, decreased reaction time & co-ordination

8-9 - decreased reaction time & vision, slur, hangover

10-12 - drowsy, increased risk of accident due to decreased co-ordination

12+ - alcohol poisoning, vomiting, coma, death

Question 28

Ethanol enters tissues proportional to water content, what does this mean?

Answer 28

High concentration in blood & brain, low concentration in muscles/fat

Question 29

How much alcohol is absorbed in the small intestine?

Answer 29

80%

Question 30

How and where is alcohol metabolised?

Answer 30

95% metabolised by alcohol dehydrogenase & P450 enzymes

85% - liver
15% - stomach

Question 31

What is the process of alcohol metabolisation?

Answer 31

Ethanol + alcohol dehydrogenase -> acetaldehyde
Acetaldehyde + aldehyde dehydrogenase -> acetic acid

Question 32

How does alcohol affect the brain?

Answer 32

Ethanol inhibits NMDA glutamate & GABA receptors

Question 33

What is BAC dependent on?

Answer 33

• Amount of ethanol consumed
• What time consumed
• Metabolic rate
• Health & drinking habits of perrson