Pharm Quiz 2 Flashcards
MOA of Barbiturates?
Barbiturates mostly enhance GABA mediated inhibitory neurotransmitters.
How does GABA react at GABAa receptor?
They increase the ion channel flow of chloride
How does Chloride influx affect the neurotransmitter?
Chloride makes the cell more negative which increases the threshold that must be overcome in order for an action potential to occur/be transferred.
GABA Receptors
GABA binds to a GABAa receptor which causes an ion channel to open. Chloride rushes in and causes the cell to become more negative, therefore increasing the threshold that needs to be overcome for an action potential to occur.
Alpha 2 Receptors
Considered a negative feedback loop.
Alpha 2 receptors mostly in CNS, they recognize that there is enough norepi/epi so it stops more production of these two.
Precedex will bind to these alpha 2 receptors and ‘falsely’ make the CNS think that there is enough norepi/epi.
Precedex acts as a false norepi because the alpha 2 receptor believes it is norepi and the body stops sending norepi.
NMDA Receptors
Excitatory receptor.
Ion channel.
Glutamate binds in, opens ion channel, and POSITIVE ions (Ca++) are sent through. This is excitatory effect.
We will want to use antagonists to block this excitatory effect
Baroreceptors
Throughout the body that are small groupings of cells that sense pressure changes and this sends a message to release or stop releasing certain hormones.
Some medications will blunt these baroreceptors.
Chemoreceptors
Pick up O2 and CO2 changes in the body.
They can tell the CNS to “take a breath”.
Some medications will blunt these sensors so that the body will not respond normally to changes in O2 and CO2
Are IV Induction medications lipophillic or hydrophillic?
Lipophillic
Vessel Rich Group
Brain, heart, i.e. highly perfused/vascular organs.
Only 10% of body mass.
Receive 75% of cardiac output
Vessel Poor/Semi-poor Group
Muscle/Fat semi poor group Ligaments vessel poor. Combined, they have.. 90% of body mass, but only 25% of Cardiac output
Why does a medication after one dose have to be re-dosed (or cont gtt started) before 9 minutes? Elimination, redistribution, or metabolism.
Redistribution
Compartment 1
Blood vessels and blood volume
Compartment 2
All the highly perfused/highly vascular organs:
Brain, liver, kidneys, gut, etc.
Compartment 3
Fat and vessel-poor group
Same compartment, but different phases.
What class of IV Induction drugs are some of the oldest drugs used?
Barbiturates
A drug that is protein binding. What happens if serum albumin level is low? High?
Low-
will be more “free” drug, so should require less drug
High/normal-
will be less “free” drug, so will require more/average drug
What are two factors that increase unbound fraction of barbiturates?
- Decreased plasma protein concentration.
2. Competition of other drugs for receptor sites (Aspirin, warfarin, naproxen.