CNS Stimulants Flashcards
How do methylxanthines promote wakefulness?
Antagonism of adenosine receptors pre- and post-synaptically (block IPSPs and promote Glu release)
Caffeine
What are its central effects?
What are its peripheral effects?
Caffeine
Via adenosine antagonism and inhibition of PDE-3 and calcium release: Increased alertness, decreased fatigue, restlessness and medullary stimulation.
Increase in inotropy/chronotropy, diuresis, increase in gastric secretion, bronchodilation, and constriction of cerebral blood vessels (dilation of others).
Caffeine
What are its clinical uses?
What are its withdrawal symptoms?
At what level of consumption is tolerance observed?
Caffeine
For wakefullness and as an adjunct in treating headache.
Fatigue/sedation, headaches, nausea. Rarely vomiting.
2 cups of coffee, which is about 200-250mg.
Why is cocaine sometimes formulated as “crack cocaine”?
Crack cocaine is a “freebase” formulation–it is uncharged, more volatile, and more easily absorbed.
Cocaine
What is its mechanism of action?
What are its clinical indications?
Cocaine
Blocks uptake of NE, 5-HT, and dopamine. This causes alertness and euphoria.
Sometimes used as a local anesthetic in upper respiratory tract due to its vasoconstrictive function.
Cocaine
Describe its kinetics.
What are its toxic effects?
Cocaine
It is rapidly absorbed through many muous membrane (often snorted or smoked). It is metabolized by plasma and liver and is very short-lived.
It is moderately neurotoxic: seizures and cardiovascular disturbance. It is addicting with mild withdrawal sypmtoms (dysphoria, fatigue). It is a teratogen.
Describe four formulations of amphetamines (or similar stimulants)
Dextroamphetamine (Adderall), Methylphenidate (Ritalin), Methamphetamine, Lisdextroamphetamine (prodrug).
Amphetamines
What is their mechanism of action?
What effects does this cause?
What are their clinical indications?
Amphetamines
Promote release of NE/5HT/Dopamine and blocks their reuptake. At high doses, agonizes alpha receptors and inhibits MAOI.
Arousal, elevated mood, respiratory stimulant, decreases appetite.
Narcolepsy and ADHD. Abused by athletes, soldiers, and students.
Amphetamines
What are their side effects?
Describe their acute toxicity.
Amphetamines
Insomnia, growth suppression secondary to weight loss, abdominal pain, increased temperature, and facial tics.
Overdose can cause restlessness, psyhosis, and permanent neurotoxicity.
Why is methamphetamine often abused?
(as opposed to other amphetamines)
The methyl moiety increases its CNS penetration. It can be synthesized from OTC supplies (pseudoephedrine).
So far as I know, there is no “blue” meth.
Nicotine
What is its mechanism of action?
What are the physiological effects?
Nicotine
it activates nicotinic cholinergic receptors.
Activation in muscles causes contraction–resultant desensitization causes relaxation. Autonomic ganglia are stimulated, and dopamine is released in the nucleus accumbens (reward).
Why are cigarettes thought to be more addictive than cocaine?
How does environment contribute to this addiction?
Although one drag on a cigarette provides less of a “hit” than a line of cocaine, the lifetime of a cigarette offers many opportunities for association.
The association is strong enough that it also affects contextual cues, like setting, time, and ritual.
Nicotine
Describe the mechanism of tolerance.
What are the symptoms of withdrawal?
How do most smokers “quit”?
Nicotine
Downregulation of nicotinic (and other) receptors.
Irritability, anxiety, depression, short attention span, and increased appetite.
Asides from dying? Nicotine replacements (eg gum, patches).
Bupropion
What class of drug is it?
What is its clinical indication?
Bupropion
It is an atypical antidepressant (mechanism unclear)
It is more often used to reduce nicotine cravings and withdrawal symptoms.
Varenicline
What is the mechanism of action?
What is its clinical indication?
What are its side effects?
Varenicline
Partial agonism of nicotinic receptors–activate it slightly, but also block nicotine binding.
It is used by smokers to reduce cravings and reduce the reward from smoking.
Nausea, insomnia, headaches, constipation. Suicidal thoughts?
