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40 Cards in this Set

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What are the effects of benzodiazepines?

Anti-anxiety


Sedative-hypnotic


Amnestic


Anticonvulsant


Spinal Cord mediated Muscle Relaxation

What receptor does a Benzodiazepine act on?

Benzos potentiate the activity of GABA which is an inhibitory neurotransmitter in the CNS leading to hyperpolarization of the cell membrane.

What is the volume of distribution, and protein binding for Benzos?

Large Volume of Distribution and highly protein bound.

How are Benzos effect terminated?

Redistribution




Also has active metabolites when broken down

Do benzos have a small or large theraputic index?

Large, the dose range is wide meaning a lot of medication can be given before reaching a toxic dose.

What are common side effects of Benzos?

Fatigue


Drowsiness


Decreased Motor Coordination


Impaired Cognitive Function


Anterograde Amnesia

What is the PO and IM bioavailability of Midazolam?

PO 50% and IM 80-90%


Has high protein binding 95-96%


Is water soluble in the syringe but becomes lipid soluble at biologic pH

How is the action of Versed terminated?

Redistribution


is Metabolized in the liver with a high hepatic extraction ratio. It is metabolized to 1-hydroxymidazolam (semi-active) and excreted by the kidney.

What are the systemic effects of Midazolam?

CV stable


Resp dose dependent changes in tidal volume


CNS dose dependent reductions in CBF, amnesia, and cerebral metabolic requirement of O2

What is the bioavailability of Diazepam

PO 100% IM 50-60%


Lipid soluble with large Vd (burns when IV)


Extensive protein binding




Has a low Hepatic Extraction Ratio


Metabolites are active Nor Diazepam, Oxazepam, and Temazepam

What are the systemic effects of Valium?

CV Minimal depression (similar to sleep)


Resp Some depression with detectable increase in CO2


CNS amnesia




Has anticonvulsant and muscle relaxant

Why does Lorazepam have a slower onset than other benzos?

It has a lower lipid solubility.


Has inactive metabolites (metabolized in the liver)




Is a more potent Amnesic (5-10 x diazepam)




Minimal depression of CV and ventilation

What are considerations of Flumazenil (Romazicon)?

May be associated with onset of seizures, confusion, and agitation




Has a shorter half life than benzos so could re-sedate.



What anticholinergic is the only one to cross the Blood Brain Barrier?

Scopolamine


causes CNS depression by combining with muscarinic cholinergic receptors in the brain preventing the neurotransmitter acetylcholine

What medication is utilized for patients with a family history or direct history of malignant hyperthermia?

Propofol

What is the mechanism of action of propofol?

It modulates the GABAA receptor by hyperpolarizing the membrane of the post synaptic neuron.

What are the actions of Diprivan?

It is a hypnotic without analgesic or amnestic properties.


Lipid soluble, in a soybean oil, glycerol, and egg products.


Isotonic with a pH 7.0-8.5


Rapid metabolized, extensively distributed.


Clearance from plasma exceeds Hepatic blood flow

What are the systemic effects of Propofol?

CV hypotension with decreases in CO & SVR


Decreases CBF and ICP Can reduce CPP


Antipruritic, antiemetic, and Anticonvulsant

What is the mechanism of action for Etomidate?

A modulator of GABAA receptors enhancing the affinity of the inhibitory neurotransmitter GABA.

What are the phamacokinetics of Etomidate?

pKa of 4.2 (weak Base)


Moderately lipid soluble


Large Vd


76% albumin bound


Redistribution accounts for awakening


Metabolized by hydrolysis in the liver and plasma

Why should you administer narcotics with Etomidate?

It is a IV hypnotic without analgesic activities.

What are the systemic effects of Etomidate?

CV minimal effect


Maintains CPP


May activate seizure foci on EEG


Causes adrenocortical suppression limiting response to stress (do not give to septic pts)


Nausea and Vomitting are common


Myoclonic muscle activity (pretreat with Narcs)

What are the properties of Barbiturates

Its a Hypnotic with no analgesic properties


Lipid Soluable with a rapid onset and LOC


It has a short duration of Action


It is an acid medication


The chemical structure decides the class and action

Which medication is now used instead of Barbiturates?

Propofol

How do barbiturates work?

They have a direct and an indirect action on the GABAA Receptors.


Directly it mimics GABA and attaches directly to the activating receptor


Indirectly it attaches to the receptor and increases the affinity for GABA (ligand).


Thus suppressing transmission of excitatory neurotransmitter (Glutamic acid)

How are barbiturates Metabolized

By Hepatocytes and other extrahepatic sites.


Has a low Hepatic Extraction Ratio, but is not dependent on hepatic enzyme activity for clearance (opposite of normal LHER) because the Liver has a high reserve capacity to oxidize Barbs


Metabolites are inactive (will not Resedate)

Systemic Effects of Barbiturates?

CV myocardial depression, vasodilitation, and transient hypotension.




Resp transient respiratory depression or apnea (can cause histamine release)




CNS decrease CBF, CMRO2, and ICP

What are two barbiturates?

Sodium Thiopental




Methohexital

What are the pharmacokinetics of Sodium Thiopental?

High lipid solubility


72-86% bound to albumen


Redistributes in 5min from brain to inactive tissue causing short duration of action.

What are some of the effects of Methohexital?

Lowers Seizure threshold (used in ECT)




Offers more rapid recovery than thiopental




Can cause Myoclonus and pain on injection




Hepatic Extraction Ratio is Larger than most


Barbs (perfusion dependent)

What is the action of Ketamine?

It is a dissociative anesthetic that can cause hallucinogenic effects.




Binds to NMDA receptor inhibiting Glutamate by inhibiting the presynaptic release of it.

What are the pharmacokinetics of Ketamine?

Highly lipid soluble (Crosses BBB)


Low protein binding


Large Vd


Rapid distribution from plasma to tissues


Metabolized by hepatic microsomal enzyme cytochrome P-450


High Hepatic Extraction Ratio

What are the systemic effects of Ketamine?

CV increased HR, BP, CO, MVO2 requirements




Resp no respiratory depression, decrease airway resistance (good for Asthma)




CNS potent cerebral vasodilator, Increases CMRO2, CBF, ICP, and intraoccular pressure

What are precautions for the use of Ketamine?

Increased IOP




Risk of emergence delirium (psych hx, elderly, children(nightmares)) side effect less with concomitant use of Benzos.




Inhalation agents prolong duration of action




Use cautiously with CAD

What is the class and mechanism of action for Dexmedetomidine?

Alpha2 adrenergic agonist




Reduces symathetic outflow (sympatholytic) by inhibiting the release of NE (presynapse) causing sedation


Postsynapse it inhibits symathetic activity decreasing BP and HR



How to remember which alphaadrenergic receptor works on what tissue?

Alpha 1 Brains


Alpha 2 Veins

Pharmacokinetics of Dexmedetomidine.

Affinity for alpha2 verses alpha1 (1620:1)




Rapid distribution half-life of 6 minutes




Elimination half-life of 2 hours




Biotransforms in the liver

Systemic effects of Dexmedetomidine?

CV Moderate BP and HR reductions




Profound decrease in catecholamine levels in the plasma




Use caution in pts with advanced heart block