non-barb IV induction agents Flashcards Preview

Summer Pharm (2016) ** > non-barb IV induction agents > Flashcards

Flashcards in non-barb IV induction agents Deck (78):
1

What is the generic propofol prepared in?

what does this imply

sodium metabisulfite

Caution/avoid in asthmatics because this preparation leads to bronchospasm

2

propofol CV effects

  • HUGE ↓ in BP (25-40%)
    • Greater than with sodium pentothal (STP)
  • Dose dependent myocardial depression & vasodilation result in:
    • ↓ in SV, ↓ CO & ↓ SVR
  • Heart rate unchanged (? baroreceptor inhibition)
    • Baroreceptors do not activate nor are inhibited

3

non-barb induction drug that inhibits CYP450

Precedex

4

Ketamine amnesia

Produces ‘dissociative anesthesia’

  1.  depression of neuronal function in association areas of the cerebral cortex & thalamus
  2. stimulation of the hippocampus (limbic systems)

produces a marked sensory loss and analgesia, and amnesia 

5

Etomidate is what drug class?

Carboxylated Imidazole derivative

Imidazole= C3H4N2

6

Etomidate

CNS effects

  • Rapid loss of consciousness after a single dose
  • Cerebral vasoconstriction leads to decreased CBF, ICP, CMRO2, IOP
  • Increases EEG activity in epileptogenic foci
  • increases myoclonic movements more than propofol and methohexital (disinhibiting extrapyramidal system)
  • Anticonvulsant properties, BUT can be associated with Grand Mal Seizures (caution in pt with hx of seizures)
  • High N/V

7

induction agent that supresses cortisol synthesis

etomidate (Amidate)

8

Precedex metabolism?

rapid metabolism

conjugation and CYP45 metabolism

Metabolites cleared in urine and bile

Inhibits CYP-450 (can interfere with opioid clearance)

9

Etomidate causes  _1_  

via inhibition of the coversion of _2_ to _3_

The enzymes inhibited are _4_ and _5_

This inhibition may provide an advantage of having _6_

  1. dose-dependent adrenocortical supression (adrenal cortex)
  2. cholesterol to
  3. cortisol
  4. 11 beta-hydroxylase
  5. 17-alpha-hydroxylase
  6. Stress free anesthesia

10

Ketamine pharmacokinetics

Vd, lipid solubility, onset, DOA, E½t

Large Vd (3 L/kg)

High lipid solubility

onset - 30 sec(rapid), short duration

max effect for 1 min, effect terminated by redistribution

DOA 5-10 min

E1/2t 2-3h

11

Which of these non-barb induction agents have analgesia effects?

(Ketamine, etomidate, propofol)

KETAMINE

12

Propofol metabolism

depends on hepatic blood flow ; clearance exceeds hepatic blood flow

CYP450; mainly by glucuronidation

metabolized to 2 inactive metabolites: glucuronide & sulfate & 1 weak metabolite 1-hydroxypropofol (1/3 potency)

excreted by urine

13

myoclonus side effect comparison 

thiopental, etomidate, methohexital, propofol

etomidate > methohexital (brevital) > propofol > thiopental (STP)

14

drugs that induce changes in the EEG

Thiopental (Pentothal)

Propofol

 

15

Amnestic dose of propofol 

30 mcg/kg/min

16

Ketamine class

Phencyclidine derivative (PCP)

Non-barb induction agent

17

What solvent is etomidate prepared in?

Propylene glycol solvent (anti-freeze)

these were the older drugs, newer drugs don't cause pain anymore (?)

18

With Etomidate physiologic activity will be ___________ in an acidotic patient

Less, but not much.

It is a basic solution with a pH of 8.2, however the pKa is 4.2 and it is 99% ionized at physiologic pH

19

What is the structure of propofol?

2,6-di-iso-propylphenol

Oil at room temp, insoluble in aqueous solution

very lipid soluble

20

What type of patients may have and exaggerated respone to hypotension with propofol?

  1. Hypovolemic
  2. Elderly
  3. those with poor LV function d/t CAD

Rapid hydration (bolus) prior to administration is recommended

21

How does ampofol formulation differ from diprovan/propofol preparation?

Low lipid formula: 5% soy, 0.6% egg lecithin

No preservative needed

More pain with injection

22

propofol other side effects

  • Pain on injection (premedicate with lidocaine)
  • Crosses placenta, rapidly removed from fetal circulation
    • Usually use just to induce

23

Which non-barb induction agent potentiates neuromuscular blockade?

Etomidate

Enhances NDMR activity

24

Ketamine is a racemic mixture of which enantiomers?

Equal parts R and S enantiomers

S enantiomer is

  • more potent analgesic
  • faster metabolism
  • lower incidence of emergence delirium

25

Does propofol depress the spinal cord?

NO

26

Potential side effects of propofol due to lipid emulsion

  1. risk of infection
  2. pain on injection
  3. hypertriglyceridemia
  4. potental for pulmonary embolism
  5. bradycardia (rare 1.4/100,000)

27

Etomidate doses:

induction, maintenance, sedation

Induction 0.2 - 0.3 mg/kg

Maintenance: 10 mcg/kg/min with N2O and opioid (but inc PONV)

Sedation: 5-8 mcg/kg/min 

28

propofol

onset, DOA, E½t, redistribution time, contex sensitive time ½t

onset ≈30 sec

DOA 5-10 min (then redistributed)

E½t 0.5-1.5 hrs

redistribution time 2-8 min

contex sensitive time ½t 40 min

29

Propofol induction dose?

Adult vs. toddler

GA maintenance dose?

Sedation infusion dose?

  • Induction 1 - 2.5 mg/kg, up to 3mg/kg
    • toddlers/Kids higher dose bc they have a larger central distribution and higher clearance rate
    • Elderly need lower dose due to smaller central distribution and lower clearance rate
  • GA 100-300 mcg/kg/min
  • Sedation 25-100 mcg/kg/min

30

Dexmedetomidine MOA

Central and peripheral alpha2 adrenergic receptor agonist 

  • producing sedation by
    • decreasing sympathetic nervous system activity
    • decreasing the level of arousal
  • regulates the cardiovascular system by
    • inhibiting norepinephrine release 
  • decreases sympathetic outflow from the CNS and augments cardiac vagal activity

31

propofol class

 

used in

a phenol derivative

2,6 di-iso-propylphenol

 

non-barb induction, general anesthesia, TIVA, maintenance

32

How is propofol supplied?

What implications does this have?

1.2% egg

10% soybean oil

2.25% glycerol base solution

  • worry about egg yolk allergy
  • painful on injection
  • the prep supports bacterial growth

33

Where does precedex produce hypnosis and anagesia?

Hypnosis in locus ceruleus

Analgesia in spinal cord

34

Does propofol potentiate muscle relaxants?

Nope

35

Ketamine MOA?

  • blocks the opening of the NMDA channel and prevents further ion influx → inhibits the excitatory response of glutamate → inhibits memory formation
    • When glutamate binds to the NMDA subtype of the glutamate receptor, the channel opens and allows Na+, Ca++ to enter the cell and K+ to exit
    • Flux of these ions depolarize the postsynaptic neuron and initiate an action potential.
  • depresses transmission of impulses in the medial medullary reticular formation
    • this is important for transmission of the affective-emotional components of nociception from the spinal cord to higher brain centers
  • binds with opioid (mu, delta, kappa) → subanesthetic doses  (0.2-0.5 mg/kg)
  • binds to monoaminergic receptors → antinociceptive (at descending levels)
  • binds to cholinergic receptors → acts as an antagonist (antimuscarinic effects)
  • inhibits neuronal Na+ channels → produces a modest local anesthetic action
  • inhibits Ca++ channels → cerebral vasodilatation

36

Precedex CNS effects?

Dec CBF (no change in ICP/ CMRO2)

Dec MAC of volatile agents and opioid requirements

Depress thermoregulation (depress shivering if hypothermic)

37

Precedex dose?

1 mcg/kg bolus over 10-15 min

followed by

0.2-1 mcg/kg/hr

38

propofol respiratory effects

  • Apnea after induction dose
    • Faster & larger doses will produce more apnea (if given slowly the risk is avoided)
  • ↓ TV, ↓ RR
  • ↓ ventilatory response to CO2 & hypoxia
    • PaCO2 rises → ↓ pH
  • Bronchodilation in COPD patients → propofol good these patients
    • Unless sodium metabisulfite (generic) is present which can lead to bronchospasms
  • Hypoxic pulmonary vasoconstriction (HPV) remains intact

39

Etomidate metabolism

Liver hydrolysis by hepatic enzymes or N-dealkylation & plasma esterases

to carboxylic acid

FAST biotransformation

excretion: 85% renal, 13% biliary excretion 2% unchanged

40

How is propofol metabolized?

  • clearance exceeds hepatic blood flow
  • Conjugated in liver to glucuronide and sulfate by CP450 to water soluble compounds
    • Liver function doesn't effect rate of metabolism
    • safe for liver and renal patients 
  • renal excretion
    • CRF doesn't affect clearance
    • less than 1% excreted unchanged
  • first pass effect
  • Mostly inactive metabolites
    • 4-hydroxy-propofol 1/3 potency

41

propofol onset

20-30 sec

"one arm-brain circulation"

42

What is in the preservative of diprivan?

Disodium edetate (EDTA)

43

Induction drug with the most N/V

Etomidate

44

What is the pH and solubility of etomidate like in solution? In the body?

In solution: pH 6.9, water soluble

In body: pH 8.2 (weak base), lipid soluble

45

Ketamine: respiratory effects?

Minimal, no CO2 response alteration

Bronchial smooth muscle relaxation

Increases PVR (avoid in pulmonary hypertension)

Increases salivation

46

Which drug has a greater decrease in BP propofol or TPL?

Propofol

47

Ketamine doses

premedication (sedative/analgesic), induction, maintenance?

Premed: 0.2-0.5 mg/kg

Induction 0.5-2 mg/kg IV

Maintenance: 1-2 mg/kg/hr

48

Dexmedetomidine pharmacokinetics

PB

E1/2 t

Vd

Highly PB - 90-94%%

E1/2t 2-3h 

Vd 3 L/kg

49

Which of these are chiral compounds:

Thiopental, etomidate, ketamine, propofol

All EXCEPT for propofol

50

Dexmedetomidine (precedex) is ____ soluble (water/lipid)

Water

51

Etomidate: CV effects

MINIMAL, lacks SNS effects

HR, BP, PAP, CO, SVR, PVR = unchanged

52

Ketamine: CV effects?

Sympathomimetic NMDA effect & inhibits reuptake of NE

inc BP, HR, CO

Inc myocardial work and O2 consumption

Myocardial DEPRESSANT, especially in sick people with decreased NE stores

53

Etomidate MOA

augumens the inhibitory tone of GABA at the GABAa receptor

Increases affinity of GABA to GABA-a receptor, which increases chloride conductance, hyperpolarizing/inhibiting the postsynaptic cell membrane (same as propofol)

binding at ß2=sedation, other properties

binding at ß3=anesthetic properties

54

Why must an opioid be given with Etomidate, Propofol and Barbiturates for the induction of anesthesia

They have NO analgesic properties, and the opioid is needed to blunt the SNS response to laryngoscopy

55

what factors influence propofol's pharmacokinetics?

  • weight (calculate dose to IBW)
  • co-existing diseases
  • age (ex: kids need more of the drug)
  • co-administration of other drugs

56

how does age affect propofol dosage

increase dosage with younger patients (they have the highest ED95)

decrease dosage with the elderly

57

Etomidate: Respiratory effects

Ventilatory response to CO2 depressed minimally

Decrease TV Increase RR

(except big fast dose can lead to apnea)

Hiccups, coughing

58

Precedex respiratory effects?

Minimal change in RR

Moderate dec in TV

No change in CO2 responsiveness (good for COPD pts)

Upper airway obstruction possible

59

Precedex CV effects?

Dec HR, SVR, BP

(bolus can cause a transient increase in BP and dec HR)

Potential for severe bradycardia, heart block, systole

Decreases catecholamine levels during GA

60

Dexmedetomidine antagonist

Antipamezole 

it is a specific and selective alpha-2 antagonist that will rapidly and effectively reverse sedative and CV effects of precedex

(also reserached as potential anti-parkinson's)

61

propofol CNS effects

  • ↓ CBF, ↓ ICP, ↓ CMRO2, ↓ CPP, ↓ IOP
    • cerebral protection 
  • cerebral protection from antioxidant effects (resembles Vitamin E) 
  • EEG burst supression
  • hiccuping
  • myoclonus
  • hallucinations
  • opisthotonos (weird eye positioning)
  • anti-emetic & anti-pruritic effects at (low, sub-hypnotic doses)

62

Etomidate pharmacokinetics

(lipid solubility, onset, peak, DOA, Vd, E1/2t, PB)

highly lipid soluble

onset ≈30-60 sec

peak 1 min

DOA 3-5 min (terminated by redistribution)

Vd 2.5-4.5 (large)

E1/2t 3-5h

High hepatic extraction ratio and clearance (caution in liver patients, prolonged effects)

Highly protein bound (75%)

63

Etomidate: Endocrine effects

Prevents conversion from cholesterol to cortisol by inhibiting 2 enzymes (major: 11-beta-hydroxylase, minor: 17-alpha-hydroxylase)

Adrenocortical suppression for 4-8 hrs reduces mineralocorticoid and corticosteroid production

64

Propofol pharmacokinetics

E1/2t? VD?

E1/2t 0.5-1.5h

LARGE VD 3.5-4.5 L/kg

65

Propofol is excreted renally, how is this effected in chronic renal failure

It does not effect clearance d/t inactive metabolites

66

Ketamine: CNS effects

Crosses BBB

Dissociative state

caused by depressed neuronal function in association areas of cortex and thalamus while stimulating limbic/hippocampus (caution with psych patients)

Amnesia (less than benzos),

nystagmus (rapid eye movement),

pupil dilation,

salivation, lacrimation,

myoclonic activity

Increases CBF, metabolic rate/ CMRO2, ICP, IOP

Emergence reactions: dreaming, out of body sensation, illusions, fear

67

Ketamine contraindications?

Inc ICP

Open eye injury

CAD (for sole anesthetic)

Vascular aneurysm

Uncontrolled HTN

pulmonary HTN

Psych diseases/PTSD

Pheochromocytoma

 

68

What is a limiting factor in using etomidate for induction of anesthesia

It depresses aderenocortical function

69

Propofol Vd

3.5-4.5 L/kg

70

Propofol MOA

  1. decreases the rate of dissociation of GABA from GABAa
    1. increases Cl- influx in the cell → hyperpolarization
    2. decreases neuronal excitability
  2. potentiates the binding of GABA to GABAa (ß1 subunit)
  3. inhibits glutamate action at the NMDA receptor

71

which drug causes hypnosis through locus ceruleus?

Precedex

72

Prompt awakening of propofol, ketamine and etomidate is due to 

Etomidate, Ketamine = redistribution

Propofol = high drug metabolism

73

Dexmedetomidine drug class?

Alpha-2 adrenergic agonist

74

Ketamine metabolism?

Hepatic enzymes to ACTIVE metabolite: norketamine (not a significant clinical effect) &

hydroxilated to hydroxynorketamine  & conjucated to water soluble

urinary excretion

Clearance affected by liver blood flow (equal to HBF)

75

propofol redistribution 1/2 time

2-8 minute

 

CNS actions are terminated by redistribution from the brain to other compartments

76

What is the reason aquavan (fospropofol) isn't used often?

Fospropofol is the prodrug of propofol

once it gets to the plasma, it hydrolyzes to propofol

It effects people differently and is therefore very unpredictable

has slower onset, higher Vd, and higher potency

77

Effects  of Propofol

  1. Sedation/hypnosis
  2. Anesthesia
  3. Amnesia
  4. Antiemetic
  5. Antipruritic
  6. Anticonvulsant
  7. Attenuation of bronchoconstriction

78

Propfol unlike thiopental, etomidate and ketamine is not a ___________ compound

Chiral