Term
| Can hypnosis and unconsciousness be achieved with benzos? |
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Definition
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Term
| Does liver disease affect the metabolism of benzos? |
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Definition
| Yes, it will prolong them because they undergo metabolism in the liver |
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Term
| What is the mechanism of action for benzodiazepines? |
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Definition
> Act on alpha and gamma subunits of the GABA receptor in CNS
> Enhance ability of GABA chloride ionophore to bind to its receptor (via allosteric change)
> Receptors found almost exclusively on post-synaptic regions in the CNS
> Receptor density greatest in cerebral cortex and areas associated with memory formations (hippocampus, frontal cortex) which is why they are associated with amnesia. |
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Term
| What is the important function of the amino acids at the top of the GABA receptor channel? |
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Definition
| They are positively charged that attract negatively charged chloride ions, but repel positively charged ions such as sodium. This is necessary because chloride channels are large enough to let Na+ through otherwise. |
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Term
| ______ effects of benzos reflect activation of alpha-1 subunits of GABA receptors, whereas ______ effects reflect activation of alpha-2 subunits of GABA. |
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Definition
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Term
| What is the primary inhibitory neurotransmitter in the spinal cord? And in the brain? |
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Definition
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Term
| What is the primary excitatory neurotransmitter in the spinal cord? And in the brain? |
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Definition
| aspartic acid (aspartate); glutamate |
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Term
| How do benzos affect the cardiovascular system? |
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Definition
| May have mild CV effects, which are normally seen as a minor decrease in SVR and BP. Heart rate changes are seen as a reflex to any BP changes. May increase if BP low and vice versa. |
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Term
| How do benzos affect the respiratory system? |
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Definition
| Transient apnea is a potential problem, especially with rapid IV infusion of diazepam |
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Term
| How do benzos affect the musculoskeletal system? |
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Definition
| They induce relaxation of spastic muscle activity via central inhibition- much like flexeril or Soma |
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Term
| T/F. Benzos do not have much pain relieving effects. |
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Definition
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Term
| What is the drug of choice for status epilepticus? |
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Definition
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Term
| T/F. Benzos antagonize NMBD's. |
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Definition
| FALSE. They synergize NMBD's. |
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Term
T/F.
A) benzos completely safe to give pregnant women because they do not cross the placenta.
B) Benzos allow for a decreased dose of other anesthetics because they potentiate them. |
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Definition
A) FALSE. Benzos cross placenta well and leads to fetal depression
B) TRUE |
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Term
A) T/F. Ethanol causes local dehydration of cell protoplasm.
B) How does ethanol affect cutaneous blood flow? |
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Definition
A) TRUE. It is an astringent and humectant
B) It increases it when applied topically |
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Term
A) What is the effect of ethanol injection near nerves?
B)T/F. Ethanol is a potent CNS stimulant. |
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Definition
A) It blocks conduction by decreasing Na+ and K+ conductance (requires high dose)
B) FALSE. It is a potent CNS depressant |
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Term
A) How does ethanol affect pain threshold and mood?
B) How does ethanol affect respiration? |
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Definition
A) it raises pain threshold and causes euphoria
B) It depresses sensing of CO2 from chemoreceptors in medulla and thus may affect hypercapneic drive |
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Term
| How does ethanol affect the CV system? |
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Definition
> causes cutaneous vasodilation via central mechanism- central temp control mechanisms depressed in high doses which causes a significant loss of body heat
> high plasma conc. causes cardiac depression by both central and direct mechanisms |
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Term
| How does ethanol affect the GI tract? |
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Definition
> increases gastric blood flow & secretion (makes you hungry)
> high conc. cause severe gastric irritation and erosion
> vomiting with large ingestions d/t local irritant effect |
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Term
| How does ethanol affect the liver? |
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Definition
| > increases synthesis of fat in the liver leading to "fatty liver" and eventually cirrhosis |
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Term
| Explain the metabolism of ethanol |
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Definition
1. ethanol is converted to acetaldehyde (ethanal) by the liver enzyme "alcohol dehydrogenase" which contains zinc and requires NAD as a cofactor
2. Another liver enzyme (aldehyde dehydrogenase) converts acetaldehyde to acetic acid, which can then be used as an energy source |
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Term
| Explain the metabolism of methanol |
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Definition
| metabolized by same enzymes as ethanol, but the resultant compounds are formaldehyde then formic acid |
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Term
| Why is methanol very dangerous? |
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Definition
> Formaldehyde damages retinal cells and leads to blindness with only 15mL of methanol
> formic acid can't be utilized by body and build-up leads to acidosis (can be fatal) |
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Term
| What is the treatment of methanol toxicity? |
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Definition
> Large doses of ethanol to "tie-up" metabolizing enzymes until methanol can be excreted in urine
> There is a newer agent called fomepizole (Antizol) that inhibits alcohol dehydrogenase so you don't get the dangerous metabolites formaldehyde and formic acid |
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Term
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Definition
> more potent sedative and amnestic than midazolam and diazepam
> undergoes glucuronide conjugation to form inactive metabolites that are excreted by the kidneys
> elimination 1/2 time: 15 hours
> lorazepam metabolically cleared slower than midazolam
> less influenced by alterations in hepatic function or drugs that inhibit P450 enzymes |
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Term
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Definition
> 2-3 x more potent than diazepam
> 2x greater affinity for benzo receptor than diazepam
> amnestic effects greater than sedative effects (like most other benzos)
> metabolized by CYP3A4 enzymes to 1-hydroxymidazolam which is half as potent as midazolam and has a half time of 6 hours. This is then rapidly conjugated to 1-hydroxymidazolam glucuronide which is cleared by the kidneys.
> hepatic clearance rate 5x greater than lorazepam and 10x greater than diazepam
>elimination 1/2 time: 3 hours |
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