what are the four main steps of neuronal regulation of physiology
1) transmission of action potential down axon
2) release of neurotransmitter from axon
3) binding of neurotransmitter to post-synaptic cell
4) post-synaptic cell changes action
list the ways medications can interfere with neuronal regulation of physiology
- alter axonal conduction (local anesthetics blocking ACh)
- alter synaptic transmission
- receptor agonism or antagonism
define agonist drug
- causes same effect as it occurs in nature --> receptor activation
define antagonist drug
- drug reduces or causes opposite effect --> receptor deactivation / blockade
list the steps in synaptic transmission
1) NT synthesis and storage vesicles
2) release of NT into cleft
3) post-synaptic receptor binding (reversible)
4) inactivation of NT (reuptake, enzymatic degradation, diffusion)
list agonist drug effects
- drug increases synthesis of NT molecules
- drug increases number of NT molecules by destroying degrading enzymes
- drug increases relay of NT molecules from terminal buttons
- drug binds to auto receptors and blocks their inhibitory effect on neurotransmitter release
,-drug binds to postsynaptic receptors and either activates them or increases the effect on the
neurotransmitter molecules
- drug blocks the deactivation of neurotransmitter molecules by blocking degradation or
reuptake
list antagonist drug effects
- drug blocks the synthesis of neurotransmitter molecules
- drug causes the neurotransmitter molecules to leak from the vesicles and be destroyed by
degrading enzymes
- drug activates autoreceptors and inhibits neurotransmitter release
- drug is a receptor blocker; it binds to the postsynaptic receptors and blocks the effect of the
neurotransmitter
list the peripheral neurotransmitters
- acetylcholine
- catecholamines and monoamines (epinephrine and norepinephrine)
list some possible effects that drugs affecting the CNS can have
- affect movement (limit or cause involuntary)
- induce sleep or arousal, impact cognitive function
- treat anxiety, depression or other psychiatric conditions
- affect memory (positive and negatively)
- increase focus and attention
,what is the main problem for CNS drugs
- must cross blood brain barrier (BBB)
what is the function of the BBB
- effectively protects against passage of foreign substances into the brain
- prevents the entry of damaging and therapeutic substances
- barrier is achieved by structure and function of CNS capillaries (tight junctions and basement
membranes) --> impermeability
list general principles pertaining to crossing the BBB
- large molecules do not pass easily
- low lipid-soluble molecules do not pass BUT lipid soluble pass
- highly charged molecules do not pass easily
AKA we <3 small, non polar and lipid soluble drugs
how / when is the BBB affected and thereby allowing easier entry
- at birth b/c not fully formed
- post-radiation
- if infectious agents are present
- trauma, ischemia, inflammation
list the mechanism by which compounds are able to cross the BBB
- passive diffusion (for non-polar, lipid soluble drugs like morphine and ETOH)
- facilitated diffusion (glucose)
- active transport (carrier molecules used)
what is a transient ischemic attack (TIA)
- mini stroke, can occur without permanent damage
- could be due to bleeding in the brain, but more commonly due to blood clots
, list pharmacological interventions to decrease risk of future stroke post-TIA
- anti-platelet agents = aspirin (ASA) mono therapy; combo of aspirin and extended-release
dipyridamole; clopidogrel (Plavix) monotherapy
- works by ASA irreversibly acetylates COX-1 to prevent synthesis of TXA2, which is key to
platelet aggregation
what criteria must be considered for tPA administration
- time (3 hours), patient age and medical hx (BP, DWI-PWI) MRI
what is the affect of tPA
- produces local clot breakdown
list side effects of tPA
- hemorrhage, usually into region
- mild systemic bleeding (internal of GI or GU)
what should be monitored post tPA administration
- vascular system and neuro checks every 15 min for 2 hours, then every 30 min for 6 hours,
then every hour for 24 hours
- no other anticoags for 24 hours
- if you have decreased platelet aggregation, monitor due to increase risk of bleeding -->
consideration for PT intervention planning
discuss blood pressure control and management for patients post- ischemic stroke
recommendation = < 185/110
- preserve cerebral perfusion and minimize risk of bleed
list meds common post ischemic stroke responsible for BP control
(IV)
- labetalol (Trandate): alpha and beta blocker that blocks epinephrine)
- hydralazine (Apresoline): direct smooth muscle relaxation
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