Neuro / Psych SketchyPharm Flashcards
Which benzos do not require microsomal monooxygenases to work?
OTL = Outside The Liver (still technically conjugated in the liver but do not require the slow Phase I reactions) O = oxazepam T = temazepam L = lorazepam
Is Triazolam long or short acting?
Short-acting, high addictive potential like alprazolam, oxazepam, and midazolam
What effect do benzos have on REM sleep?
Like alcohol, they decrease REM sleep
Are the three Z’s good for sleep maintenance?
No - they have a rapid onset of action but also a short halflife, reducing tolerance but at the same time only making them good for inducing sleep (maybe with the exception of eszopiclone which has a slightly longer halflife)
What is the firstline treatment of neonatal seizures?
Phenobarbital
How is essential tremor treated?
Drugs: Nonselective beta blockers + primidone (think of the lady getting a perm and combed with a shaking hand)
Self-medication: Transient suppression by alcohol
(also mediates GABA, like primidone)
What are the mechanisms of etomidate and propofol? What are the adverse effects?
Both potentiate GABA-A (think of the cab in the back)
Propofol - profound respiratory depression / hypotension
-> not good for those who aren’t hemodynamically stable
Etomidate - stable in those with cardiovascular risk, but profound nausea / vomiting post-op.
In what “state” are patients in when they take ketamine?
Cataleptic state - it is a dissociative agent - causes nystagmic gaze with eyes open
-> NMDA antagonist
Hallucinogen and irrational behavior during recovery
What are the advantages of ketamine?
Good analgesia, amnesia, and hypnosis. Can be used to induce or sustain anesthesia in patients with CV problems
How does blood:gas partition coefficient relate to induction speed, recovery time, potency, and MAC?
Increased blood:gas partition coefficient = increased solubility in blood = slower rate of rise to reach mass = slower induction speed
Also, since more gas will be soluble in blood = takes longer to clear from blood = longer recovery time.
How does oil:gas partition coefficient relate to induction speed, recovery time, potency, and MAC?
Increased solubility in lipids = increased potency = lower minimum alveolar concentration required to induce (potency is inversely proportional to MAC)
Lipid solubility has no relation to induction speed / recovery time
What does MAC mean?
Minimal alveolar concentration (ED50) - the concentration of inhaled anesthetic required to prevent 50% of patients from moving in response to noxious stimuli (MACs are additive btw, so you can give two adjacents at 0.5 their MACs and produce 1.0 MACs worth of sedation).
What is the order of anesthetic equilibration within the tissues? How do these compartment sizes differ)
Highly perfused tissues equilibrate first -> brain, heart, kidney, liver (small compartment)
Medium blood flow second -> muscles (medium size)
Low blood flow last -> fat (largest size)
What are the organ systemic effects of inhalation anesthetics (IA) and which one is the exception? Think CV, respiratory, brain, kidney, and liver.
Nitrous oxide is the exception
CV - drop in blood pressure by various mechanism
Respiratory - decreased minute ventilation, hypercapnia
Brain - Increased blood flow (increases ICP)
Kidney - Decreased RBF / GFR
Liver - Decreased hepatic blood flow
What is the primary toxicity of concern with nitrous oxide?
By inactivating methionine synthase, it can halt DNA production, leading to bone marrow depression and even pernicious anemia (B12-dependent enzyme)
What is the unique risk incurred by usage of halothane?
Hepatotoxicity - “H” - it is metabolized in liver, and can lead to trifuoloracetylated proteins which are hepatotoxic and can cause hepatitis / necrosis
-> centrilobular necrosis (Zone 3)
Which IAs are most likely nephrotoxic and what is its mechanism?
Sevoflurane -> metabolism in liver leads to the formation of inorganic fluoride ions
Also NEPHrotoxic = METHoxyflurane
What inhaled anesthetic is most likely to cause seizures?
Enflurane = Epileptogenic (think of the shaking pinata)
What agent other than the inhaled anesthetics can cause malignant hyperthermia? What is the mechanism? Treatment?
Succinylcholine. Remember than N20 can’t cause this however.
Susceptible: Autosomal dominant mutation in RyR (voltage-sensitive Ca+2 channel). (think of RYAN)
-> excessive release in Ca+2 (due to mutation) results in excessive SERCA activity which generates excessive heat
Treatment: Dantrolene - RyR antagonist
Are local anesthetics analgesics?
No, they are not specific inhibitors of the pain pathway (i.e. opioid analgesics). They just nonspecifically inhibit the conduction of action potentials
What form of the local anesthetic (LA) is active and how does it work? That is, what is the mechanism of action?
Only the protonated form -> binds to the LA binding site on the OPEN sodium channel and stabilizes the inactive state of the channel
Extends refractory period by delaying return to closed / resting conformation (occurs in a progression from increased threshold to total action potential abolishment)
What lipid solubility profile for a LA is most clinically effective and why?
Moderate hydrophobicity
Too low - hydrophilic molecules cannot cross to interior of membrane
Too high - hydrophobic molecules will get stuck in the membrane and not want to enter the cellular cytoplasm
What does the pKa of the given local anesthetic determine? What is their relative pKa range?
The time of onset. All are weak bases overall -> protonated form is the charged form, with pkas between 8-9
Low pKa = LA is relatively acidic, will easier lose proton exist in deprotonated and uncharged form -> rapid crossing of membrane and rapid onset
High pKa = LA is relatively basic, will exist in protonated form which is charged -> slow crossing of membrane and slower onset
What are three examples of regional anesthesia procedures?
- Spinal anesthesia - injection into lumbar cistern for lower abdominal, pelvic, rectal, or orthopedic surgery
- Epidural anesthesia - Injection into epidural space -> for childbirth / labor
- Nerve block - injection around nerve truck for site distal to surgery -> i.e. brachial plexus for hand surgery