5 - CNS Stimulants

Question 1

Name six CNS stimulants

Answer 1

Ritalin
Amphetamine
Cocaine
Nicotine
MDMA
Caffeine

Question 2

What are phenylethylamines?

Answer 2

• Natural stimulant produced in brain & spinal cord
• Neurotransmitter
• Base structure for amphetamines
• Low addiction potential

Question 3

What are the effects on the brain when taking amphetamines?

Answer 3

• Increase dopamine release
• Increase psychomotor activity
• Chronic use decreases dopamine neurons & their sensitivity
• Results in tolerance & dependence, withdrawal

Question 4

Where are amphetamines detected and for how long?

Answer 4

Urine, up to 48 hours

Question 5

Name the effects of amphetamines at 2.5-20mg, 20-50mg and >50mg

Answer 5

2.5-20mg = Increased HR, decreased BP
20-50mg = Decreased appetite, increased wakefulness
>50mg = Aggression/violence, paranoid delusions

Question 6

How do methamphetamines act in the body?

Answer 6

• Enter neuron by passing through membrane
• Enters vesicles containing NT
• Released into synaptic cleft via NT release
• Block dopamine channels from reabsorbing dopamine
• Flood synaptic cleft with dopamine

Question 7

Name the identifying structure of cocaine. What does this make cocaine?

Describe shape

Answer 7

• Tropane ring
• Makes cocaine a tropane alkaloid

Origami N

Question 8

How much of cocaine is absorbed via oral administration?

Answer 8

• 75% metabolised due to first pass effect
• 25% reaches brain

Question 9

How much of cocaine is absorbed via intranasal administration?

Answer 9

20-30% absorbed

Question 10

How much of cocaine is absorbed via inhalation? How long for it to take effect & how long does it last?

Answer 10

• 6-32% reaches blood plasma
• Effect within seconds, lasts 5-10 mins

Question 11

How much of cocaine is absorbed via intravenous administration?

Answer 11

All immediately

Question 12

What are cocaine’s metabolites?

Answer 12

• Benzoylecgonine - in urine up to 3 days, 15-22 for chronic user
• Norcocaine - small amounts

Question 13

What is the t1/2 of cocaine and where is it metabolised?

Answer 13

• t1/2 = 30-90 mins
• Almost completely by liver

Question 14

What is the synaptic effect of cocaine?

Answer 14

• Blocks dopamine transporter -> dopamine accumulates in synaptic cleft
• Blocks Na+ channels, interferes w/ action potentials so can be used as an anaesthetic

Question 15

What are the withdrawal symptoms of cocaine?

Answer 15

Hunger
Fatigue
Depression
Panic attacks
Dysphoric syndrome - intense boredom & craving for cocaine

Question 16

What are the negative effects of cocaine?

Answer 16

Increased risk of stroke
Decreased attention
Insatiable hunger
Throat soreness
Chest pain
Asthma
Increased risk of infarction

Question 17

What is cocaethylene and where is it formed?

Answer 17

Ethanol + cocaine, liver

Question 18

What is the t1/2 of cocaethylene and why does it drastically differ from cocaine?

Answer 18

• t1/2 3-5x that of cocaine
• Ethanol inhibits metabolism of cocaine, harder to halve and eliminate

Question 19

What are the long-term effects of cocaethylene?

Answer 19

Seizure
Liver damage
Compromised immune system
Increased cardiac toxicity compared to cocaine