Test 1 Flashcards
This can be given to treat muscle rigidity from opioids
NDMRs
What should you do if you see a localized reaction at the site of morphine injection?
DON’T PANIC
Morphine causes histamine release, so this is a common reaction
These meds can be used to relieve sphincter of oddi spasm
Glucagon, nubain, and NTG
Opioids are weak (acids/bases)
Bases
Vd is related to
Lipid solubility and protein binding
A large Vd will equate to a long or short DOA?
Long
Do opioids produce amnesia?
NO
How do opioids produce bradycardia?
Vagal stimulation and inhibition of the SA node
The bradycardia and ventilatory depression caused by opioids are
dose dependent
Where do agonists/antogonists work?
They are Mu antagonists and full or partial kappa agonists
Do benzos provide enough muscle relaxation for surgery?
NO. Give the normal amount of muscle relaxant you would normally give.
Should you decrease the amount of muscle relaxant you give for a case if you have given a benzo?
NO
Do benzos or barbiturates induce enzymes?
Only barbiturates
Benzos have a (large/small) margin of error
Large
Which do we typically give for pre-medication and MAC sedation? Benzos vs. barbs
Benzos. These have essentially replaced barbs for these purposes.
How do benzos act at the GABA receptor?
They FACILITATE the actions of GABA at the receptor (increases it’s affinity and potency)
Where are GABAa receptors found?
On POST-synaptic neurons in the CNS
There are barely any GABA receptors outside the CNS
Why is there a ceiling effect with benzos?
Because all it can do is assist GABA to open the Cl- channels. After that, it can’t do anything else to achieve any effects.
If given in subtherapeutic doses, this type of medication can cause a person to enter Stage 2 (excitatory) Anesthesia, and result in bronchospasm or laryngospasm
Barbiturates
What does it mean if a drug has a short effect site equilibration time?
It means that the effects on the brain occur promptly after IV administration
The reversal for dexmedetomidine is
Atipamezole
The two preservatives used in propofol are
EDTA and sodium metabisulfite
How is the pharmacologic activity of barbiturates terminated?
Side chain oxidation at carbon 5, converting it to carboxylic acid
These medications are prepared as racemic mixtures
1) Ketamine (R and S, the S has more analgesic potency, undergoes faster metabolism, and has less incidence of emergence delirium)
2) Barbiturates (L and D, the L enantiomer has 2x the potency of D)
Effect of barbiturates on pain
Small doses can lower the pain threshold
If your patient’s seizure disorder has been treated with a barbiturate, such as phenobarbital, you can expect that they will metabolize your drugs about ___x as rapidly
2 (this is especially evident in muscle relaxants)
Do patients develop tolerance to barbs?
Yes, they induce their own metabolism and cause tolerance!
How is diazepam prepared?
In benzyl alcohol and propylene glycol. pH of 6.6-6.9.
Flumazenil is a _______ derivative
Imidazobenzodiazepine derivative
What’s unique about NMDA receptors?
They are both ligand and voltage-gated
The clearance of this medication is dependent of hepatic blood flow
Ketamine
How common are emergence reactions with ketamine?
10-30%
Why should ketamine be avoided with MAOIs and TCAs?
Because ketamine prevents the re-uptake of NE
MOA of propofol
Binds to the B1 subunit of GABA and inhibits NMDA
What converts fospropofol into propofol?
Endothelial cell alkaline phosphatases
What effect does sulfuration of barbituric acid have?
Makes it more lipid soluble
What is the structure of benzodiazepines?
A benzene ring fused with a seven-membered diazepine ring
The effects of benzos binding with GABA-A is thought to cause these effects
Sedation, anxiolysis, anticonvusant, and muscle relaxant. (everything but amnesia)
Where can GABA-A receptors be found?
Almost exclusively on post-synaptic membranes in the CNS
Which medication class causes a flattening of the CO2 response curve?
Benzodiazepines
Effect of midazolam on the CV system.
None at small doses. At induction doses, there is a drop in SVR and BP, but CO is unchanged.
Effect of diazepam on the CV system
Decrease in SVR, BP, and CO by 20%
Ativan has this as a solvent
Propylene glycol
How does flumazenil work?
It’s a competative benzodiazepine antagonist
Benefits of flumazenil
Reverses the sedation and respiratory depression. Also, it’s post-op use is not associated with any anxiety provoking or neuroendocrine response (increased BP, HR, , etc), as opposed to narcan.
A suboptimal dose of this medication can cause a patient to enter Stage 2 Anesthesia
TPL
Effect of TPL on pain
Small doses can decrease the pain threshold. It can act as an “anti-analgesic”
(TPL/Methohexital) can cause myoclonus and hiccups
Methohexital (the methyl radical causes convulsant activity)
Allergy to TPL
Rare (1:30,000), but if it happens, it causes SEVERE anaphylaxis.
If hepatic enzymes are induced, you can expect these medications to be metabolized faster
Oral anticoagulants, vitamine K, corticosteroids, TCAs, and phenytoin.
TPL should not be mixed with these meds
Overall, avoid mixing with opioids, catecholamines, and NDMBs, because these are all acidic in solution
Vecuronium
Atracurium
Pancuronium
Sufentanil
LR
Alfentanil
Midazolam
IBW calculation
Men:
105 + 6lbs for every inch over 5 feet
Women
100 + 5lbs for every inch over 5 feet
Relationship of pKa of the opioids and their ionization
Lower the pKa, the more non-ionized. Alfentanil has the lowest pKa of the bunch, 6.5, and has the highest % non-ionized (90%), and thus the fastest rate of onset.
This pain medication is contraindicated if
Meperidine (Demerol)
Unlike most opioids, this one can cause tachycardia and myocardial depression
Meperidine (Demerol). This is because structurally, it resembles atropine.
Effects of accumulation of normeperidine
Confusions, hallucinations, myoclonus, seizures
How does meperidine act to reduce post-op shivering?
Works on kappa and alpha-2 receptors
Compared with morphine, fentanyl has a (longer/shorter) onset and DOA
Shorter
Why is does ketamine has sympathomimetic effects
1) NMDA activity in the nucleus tractus solitarius***
2) Antagonist at muscarinic receptors
3) Inhibits the reuptake of NE
This medication is cerebroprotective and resembles vitamin E in structure
Propofol
This is a common premed we give that can inhibit the CYP450 system
Cimetidine
These medications are myocardial depressants
- Ketamine
- Propofol
- Meperidine
These medications have propylene glycol as a solvent
Diazepam, lorazepam, and etomidate.
These medications flatten the CO2 response curve
Benos
Barbs
Etomidate Propofol
These medications shift the CO2 response curve down/to the right
Opioids
These medications are water soluble
- Midazolam
- Dexmedetomidine
- Fospropofol
- Ketamine (both water and fat soluble)
