CNS Stimulants Flashcards
1
Q
What can all stimulants cause in sufficient doses?
A
Convulsions/Seizures
2
Q
- What is the mechanism of action of Caffeine?
- There are pre- and post- synaptic receptors. What do each do?
A
- Competitive antagonist of adenosine receptors causing dis-inhibition of CNS
- Postsynaptic cause inhibitory postsynaptic potential. (Hyperpolarization)
Pre-synaptic receptors inhibit glutamate release.
3
Q
What two effects does caffeine have at higher doses?
A
- Inhibits cAMP phosphodiesterase: results in increased cAMP
- Induces release of calcium from intracellular stores
(Responsible for beneficial effects in asthma)
4
Q
What are 5 unique peripheral effects of caffeine?
A
- Positive inotropic and chronotropic effects
- Dilates coronary and systemic blood vessels. Constricts cerebral blood vessels.
- Produces diuresis
- Increases gastric secretions
- Modest bronchodilation
5
Q
How much coffee per day can create physical dependence?
A
2 cups per day
6
Q
What are the three sympathomimetic stimulants for this course?
A
- Cocaine
- Amphetamines
- Methylphenidate
7
Q
- Cocaine has what kind of pH/pKa profile?
- What are the two major forms?
A
- It is a weak base and therefore unionized in the unprotonated form (B)
- It is used as a Hydrochloride salt and a free base.
8
Q
Why is the free base form of cocaine more desireable?
A
It is volatile and can be smoked
9
Q
- How well is Cocaine absorbed?
- Where is it metabolized?
- What is the plasma half-life?
A
- It is well absorbed through any mucous membrane
- It is metabolized in plasma and liver
- Short half life (50 min). Shorter in CNS (10-30 min)
10
Q
What is the mechanism of action for Cocaine?
A
- Potent inhibitor of reuptake of NE, D, 5-HT
- It binds to the transporter itself.
- Reinforcing effects due to increased dopamine in synapse.
- Increases activity of tyrosine and tryptophan hydroxylases
11
Q
- What are the primary concerns with Cocaine overdose?
- What happens from cocaine use during pregnancy?
A
- Seizures, MI, Arrhythmias
- Similar to Fetal Alcohol but more significant. Low birth weight, learning and emotional problems, attachment disorder.
12
Q
What increases the abuse potential and psychological dependence of Cocaine?
A
Dosage forms that deliver drug rapidly to the CNS
13
Q
- What are Amphetamine and methamphetamine similar to?
- What is their acid/base status?
- What are they metabolized to?
- What is their relative half-life?
A
- Norepinephrine
- They are weak bases
- Metabolized to benzoic acid and excreted unchanged
- Relatively long half-life (much longer than cocaine)
14
Q
What is the mechanism of action for amphetamine and methamphetamine?
A
- Release of NE, DA, 5-HT from neurons
- Block reuptake of NE, DA and 5-HT
- Partial agonist of alpha receptors
- MAO inhibitor at high doses
15
Q
- What is the active form of Amphetamine?
- How is methylphenidate associated with amphetamine/methamphetamine?
- What has the highest abuse potential of the group?
- What is a prodrug of dextroamphetamine?
A
- Dextroamphetamine
- Methylphenidate is not technically an amphetamine but structurally and mechanistically similar.
- Methamphetamine because it gets into the brain better.
- Lisdextroamfetamine