5 - CNS Stimulants Flashcards
Name six CNS stimulants
Ritalin
Amphetamine
Cocaine
Nicotine
MDMA
Caffeine
What are phenylethylamines?
- Natural stimulant produced in brain & spinal cord
- Neurotransmitter
- Base structure for amphetamines
- Low addiction potential
What are the effects on the brain when taking amphetamines?
- Increase dopamine release
- Increase psychomotor activity
- Chronic use decreases dopamine neurons & their sensitivity
- Results in tolerance & dependence, withdrawal
Where are amphetamines detected and for how long?
Urine, up to 48 hours
Name the effects of amphetamines at 2.5-20mg, 20-50mg and >50mg
2.5-20mg = Increased HR, decreased BP
20-50mg = Decreased appetite, increased wakefulness
>50mg = Aggression/violence, paranoid delusions
How do methamphetamines act in the body?
- 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
Name the identifying structure of cocaine. What does this make cocaine?
Describe shape
- Tropane ring
- Makes cocaine a tropane alkaloid
Origami N
How much of cocaine is absorbed via oral administration?
- 75% metabolised due to first pass effect
- 25% reaches brain
How much of cocaine is absorbed via intranasal administration?
20-30% absorbed
How much of cocaine is absorbed via inhalation? How long for it to take effect & how long does it last?
- 6-32% reaches blood plasma
- Effect within seconds, lasts 5-10 mins
How much of cocaine is absorbed via intravenous administration?
All immediately
What are cocaine’s metabolites?
- Benzoylecgonine - in urine up to 3 days, 15-22 for chronic user
- Norcocaine - small amounts
What is the t1/2 of cocaine and where is it metabolised?
- t1/2 = 30-90 mins
- Almost completely by liver
What is the synaptic effect of cocaine?
- Blocks dopamine transporter -> dopamine accumulates in synaptic cleft
- Blocks Na+ channels, interferes w/ action potentials so can be used as an anaesthetic
What are the withdrawal symptoms of cocaine?
Hunger
Fatigue
Depression
Panic attacks
Dysphoric syndrome - intense boredom & craving for cocaine
What are the negative effects of cocaine?
Increased risk of stroke
Decreased attention
Insatiable hunger
Throat soreness
Chest pain
Asthma
Increased risk of infarction
What is cocaethylene and where is it formed?
Ethanol + cocaine, liver
What is the t1/2 of cocaethylene and why does it drastically differ from cocaine?
- t1/2 3-5x that of cocaine
- Ethanol inhibits metabolism of cocaine, harder to halve and eliminate
What are the long-term effects of cocaethylene?
Seizure
Liver damage
Compromised immune system
Increased cardiac toxicity compared to cocaine
