27 CNS Stimulation (concepts) Flashcards
what is caffeines mech of action?
what does this do to the presynaptic and to the post synaptic?
it blocks adenosine receptors.
Postsynaptic adenosine receptors produce IPSP’s
Presynaptic adenosine receptors inhibit glutamate release
**Caffeine blocks both of these inhibitory effects (disinhibition) resulting in CNS stimulation **
what does the inhibition of phosphodiesterase by caffeine do?
caffine also increases the release of calcium from intracellular stores. ER
Results in increased cAMP concentrations; property of these compounds that results in benefit for asthma
Therapeutic usefulness
of caffeine?
Used as an aid to stay awake
Treatment of headache
what are teh effects of caffeine as a CNS stimulant?
Effects include increased alertness and capacity for tasks requiring
sustained attention
Decreased fatigue and drowsiness
Can cause nervousness, restlessness and tremors
High doses can stimulate medullary respiratory, vasomotor and vagal centers
what does chronic use of caffein cause to happen?
it causes a tolerance to develope.
what are the sympathomimetic stimulants?
cocain
amphetamines
what are teh 2 major forms of cocaine?
- cocaine hydrochloride: water soluble
- cocaine free base: lipid soluble, volatile
free base is made by extracting cocaine base from an alkaline solution into ether
how is cocaine metabolized and what do you look for when you do drug testing?
Metabolized primarily by serum and liver esterases It can also be demethylated at the nitrogen
Very short half-life (50 min)
Testing for cocaine use: look for metabolites in urine
what is the mech of action of cocaine?
Cocaine is a potent inhibitor of the reuptake of norepinephrine, dopamine and serotonin
Cocaine receptor on transporter for dopamine, competes for binding of the endogenous ligand resulting in increased ligand in the synapse
Central reinforcing effects believed due to an action on dopamine synapses in the ventral striatum
Increases tyrosine and tryptophan hydroxylase (due to loss of end- product inhibition)
Local anesthetic; vasoconstrictor
what gives cocaine?
Produces euphoria, feelings of elation, well being and competency
- Due to ↑ DA in mesolimbic circuit
- High abuse potential - very reinforcing
what is a theraputic effect of cocaine?
Local anesthesia in upper respiratory track
what is the duration of action of amphetamines?
4-6 hours
longer than cocaine 50 mins.
what is teh metabolism of amphetamines?
what are they metabolized to?
1) Deamination to benzoic acid (predominant route)
2) Also excreted unchanged as amphetamine- base excretion increased in acid urine
what is the mechanism of action of amphetamine?
Releases norepinephrine, dopamine and serotonin
Blocks transmitter uptake into presynaptic terminals (like cocaine)
Direct partial agonist of alpha-adrenergic receptors
MAO inhibition (at high doses)
what is the mechanism of action of nicotine?
Agonist of nicotinic cholinergic receptors
- Neuromuscular junction - not as affected
- Autonomic ganglia
- Sympathetic ganglia activation results in release of epinephrine
- Parasympathetic ganglia activation is predominant; results in GI effects (nausea; increased motility)
c. CNS receptors
- Found in many brain regions
- Results in membrane depolarization (excitation)
