Cocaine, Amphetamines, and ADHD Flashcards
How do Psychostimulants or CNS Stimulants work, in general?
They augment nt action (usually dopamine). They increase dopaminergic activity in the mesolimbic pathway (reward pathway).
What is the reward pathway called?
The Mesolimbic pathway.
What law outlawed cocaine and when?
The 1914 Harrison Narcotic Tax Act
What is cocaine’s mechanism of action?
Blocks the re-uptake of dopamine. (Blocks pre-synaptic transporter). It can also raise the levels of NE and serotonin at high levels.
What are the mechanisms of action for Amphetamines?
Amphetamine gets taken into cell by re-uptake transporter. Once in the cell, it interferes with VMAT, stopping the packing of nts back into vesicles, leading to a higher concentration of nts in the cytoplasm. Can cause nt transporter to work backwards and push dopamine into the synapse. Can increase NE and serotonin too.
What occurs when someone takes cocaine?
It mimics our stress response. Produce vasoconstriction, hypertension, tachycardia. Increased sense of energy (increased CNS arousal); anorexia, hypothermia. Euphoria.
How does Cocaine affect sodium channels?
It blocks sodium channels; can cause local anesthesia properties, cardiac toxicity (alterations in cardiac rhythm)
What is Cocaine salt as a Powder? Is it water-soluble?How can it be taken?
Water-soluble, may be administered orally, IV, or nasally.
Why can’t you smoke Powder Cocaine?
Because when it is heated, it chemically breaks down.
What is Cocaine in the base form? Is it water-soluble?How can it be taken? Why can it be smoked?
Insoluble in water, but soluble in alcohol, acetone. Heating the free-base converts cocaine to a stable vapor that may be inhaled.
Which has the faster onset of action: IV cocaine or smoking cocaine? Which has greater bio-availability?
Smoking cocaine. IV cocaine has 100% bio-availability.
Does cocaine cross the blood-brain barrier? Placenta?
Yes for both. It can concentrate in the brain longer than its half-life.
How long is the half-life of cocaine in plasma?
About 50 minutes.
Where is cocaine metabolized? What is it’s metabolite?
Enzymes in the plasma and liver. Major metabolite is Benzoylecgonine.
What happens when ethyl-alcohol and cocaine are used together?
They are co-metabolized into Cocaethylene, which acts like cocaine. Increases euphoric effect. Risk of dual-dependency. Increases the severity of withdrawal.
What is the half-life of Cocaethylene?
Half-life is 150 minutes.
What neural projections does the dopaminergic pathway consist of?
Neurons projecting from the VTA (ventral tegmental area) to the NA (nucleus accumbens) and prefrontal cortex. They are likely involved in sensing/processing reward.
What is the half-life of methamphetamine?
About 12 hours.
Where is cocaine metabolized?
60% metabolized slowly in liver; 40% excreted unchanged.
What is the prevalence of ADHD?
10%
How many patients with ADHD are treated with stimulants?
50%
What medication is used in 90% of pxs with ADHD who are using medications?
Methylpehnidate
What are the 3 dose forms of Methylphenidate?
- Ritalin 2. Concerta (XR). 3. Daytrana (patch-form).
How does Methylphenidate work?
Like cocaine, it inhibits pre-synaptic dopamine transporters.
Why does Methylphenidate have less abuse potential than cocaine?
It enters the brain slower. Detaches slower from the transporter preventing further increase in dopamine.
What are the 3 forms of Amphetamine available?
- Adderall. 2. Adderall XR. 3. Dextroamphetamine (Dexedrine).
What is Vyvanese?
Lis-dexamphetamine. Equal affinity for receptors, but believed to have less abuse potential.
