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20 Cards in this Set
- Front
- Back
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What are the general properties of CNS stimulants?
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- Increase activity of CNS neurons
- Either enhance excitation or suppress inhibition - Can produce convulsions (at sufficient dose) |
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What are the clinical uses of CNS stimulants?
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- Limited
- Attention-Deficit Disorder - Attention-Deficit Hyperactivity Disorder - Narcolepsy |
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How much caffeine is in a cup of coffee?
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80-200 mg caffeine
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What receptors does caffeine act on? Effect?
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- Post-synaptic adenosine receptors --> prevents IPSP production and hyperpolarization
- Pre-synaptic adenosine receptors --> prevents inhibition of glutamate release (disinhibition) * Leads to CNS stimulation |
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What are the three actions of caffeine?
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- Antagonizes adenosine receptors (increases CNS stimulation)
- Inhibits phosphodiesterase (increases cAMP and mild bronchodilation) - Induces release of Ca2+ from ER |
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What are the effects of Caffeine on the CNS?
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- Increased alertness and attention during sustained tasks
- Decreased fatigue and drowsiness - Can cause nervousness, restlessness, and tremors - High doses stimulate medullary respiratory and cardiovascular centers (can cause tachycardia) |
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What are the effects of Caffeine on the PNS?
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- Positive ionotropic and chronotropic effects (direct effects on myocardium)
- Dilates coronary and systemic blood vessels - Constricts cerebral blood vessels (helpful for headache) - Diuretic - Increased gastric secretions - Modest bronchodilation (due to PDE inhibition) |
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Uses of Caffeine?
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- Stay awake
- Added to aspirin to treat headaches (Excedrin) |
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What are the symptoms of an "overdose" of caffeine?
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- Nervousness
- Insomnia - Excitement |
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What are the symptoms of "withdrawal" from caffeine?
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- Feelings of fatigue and sedation
- Headaches and nausea - Vomiting (rare) |
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What are the sympathomimetic stimulants? How do they work?
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- Cocaine
- Amphetamine - Methamphetamine - Methylphenidate |
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What are the chemical properties of cocaine?
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- Weak base
- Unionized in the unprotonated form (B) which predominates at alkaline pH - Free base is made by extracting the hydrochloride salt from an alkaline solution into either or another organic solvent - Free base is absorbed more quickly across membranes; more important it is more volatile and can be smoked |
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How is cocaine administered / absorbed?
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- Well absorbed through any mucous membrane
- Shortest time to peak effect and duration of action: IV and smoked - Slower: transmural or oral |
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How/where is cocaine metabolized? Half-life?
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- Serum and liver esterases
- Also can be demethylated at the nitrogen - Very short half-life (50 min) in plasma; CNS even shorter ~10-30 min |
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How can you screen for cocaine?
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Urine screens detect metabolites
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What is the mechanism of cocaine?
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- Potent inhibitor of reuptake of NE, dopamine, and serotonin by binding to transporter
- Reinforcing effects due to increased dopamine in synapse - Increased activity of tyrosine and tryptophan hydroxylases (loss of end-product inhibition) increases NT in synthesis |
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What are the mechanisms of action of cocaine?
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- Local anesthetic
- Peripheral sympathomimetic effects (due to inhibition of NE reuptake in PNS) --> vasoconstriction, tachycardia - Increased alertness and vigilance (due to inhibition of NE reuptake in CNS) - Euphoria, elation, feeling of well-being (due to inhibition of DA reuptake in mesolimbic circuit) |
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What are the effects of inhibited NE reuptake in PNS (caused by Cocaine)?
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Peripheral sympathomimetic effects --> vasoconstriction and tachycardia
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What are the effects of inhibited NE reuptake in CNS (caused by Cocaine)?
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Increased alertness and vigilance
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What are the effects of the inhibition of DA reuptake in the mesolimbic circuit (caused by Cocaine)?
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Euphoria, elation, feeling of well-being --> high abuse liability
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