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pharmacology exam 2 > Benzos > Flashcards

Benzos Flashcards

1
Q

What would the effects of Midazolam, Diazepam, and Lorazepam be if your patient was also taking cimetidine, antifungals, calcium channel blockers, or erythromycin?

A

These drugs inhibit CYP450 enzyme system that metabolizes these drugs - so you could end up with unexpected sedation.

Lorazepam would be least effected because it has no active metabolites

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2
Q

Does Midazolam have active metabolites?

A

Yes - 1-hydroxymidazolam (half the activity) and 4-hydroxymidazolam (not present in detectable amounts)

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3
Q

Midazolam elimination half time? How does this compare to diazepam?

A

1.9 hours (much shorter than diazepam)

can be 2x in elderly r/t decreased hepatic blood flow

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4
Q

What is the duration of action of Midazolam? What drug properties cause this?

A

15 - 80 minutes. The drug is lipophilic and has rapid re-distribution, so duration of action is short.

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5
Q

How would the volume of distribution of Midazolam be affected in the elderly/obese? What would that mean for the drug effects?

A

Increased - CNS effects would be shorter. Elimination half-time is prolonged after bypass

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6
Q

How would renal failure affect the elimination of Midazolam?

A

It wouldn’t! It is metabolized and conjugated in the liver, so the kidneys aren’t doing much of the work

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7
Q

How would renal failure affect the drug effects of Midazolam?

A

It would decrease the amount of albumin, therefore increasing the amount of free drug, therefore having greater chance for toxicity

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8
Q

Is Midazolam an appropriate drug for a patient in pain?

A

No - no analgesic properties

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9
Q

What property of Midazolam is responsible for its rapid metabolism?

A

Its imidazole ring! It’s water soluble

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10
Q

Does Midazolam cause pain on injection?

A

Nope! It is water-soluble and doesn’t require a preservative

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11
Q

What would happen if Midazolam was mixed with LR, opioids, or anticholinergics?

A

Nothing - it can be mixed with other drugs without a lot of interactions

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12
Q

Does Midazolam undergo a phase I or phase II metabolism?

A

The drug is oxidized (phase I) but its metabolites are conjugated (phase II)

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13
Q

In a patient you are intubating who has a brain injury and increased ICP, would Midazolam be the drug of choice? Why or why not?

A

No! It does not prevent increase in ICP with laryngoscopy/change sympathetic response with laryngoscopy (HR, BP, and ICP all increase)

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14
Q

Would a long-term infusion of Midazolam be appropriate for an infant? Why or why not?

A

No! Encephalopathy in infants results from withdrawal after long term infusions

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15
Q

You give 0.1 mg/kg of Midazolam. Will their hypoxic drive to breathe be affected?

A

Nope! Dose dependent decrease in ventilation by decreasing hypoxic drive in doses > 0.15mg/kg

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16
Q

You administered Midazolam to your patient. Will they have their airway reflexes?

A

No. Depresses the swallowing reflex and upper airway activity

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17
Q

Which drug does Midazolam have synergistic respiratory effects with?

A

Fentanyl

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18
Q

You administered Midazolam 0.2mg/kg IV. What will the cardiac effects be?

A

Decrease in BP, increase in HR (at 0.2mg/kg IV)

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19
Q

What is the pre-op medication dose for Midazolam IV? What are the effects? What is the onset? What is the half-time to peak effect?

A

0.02-0.04mg/kg
anxiolytics, amnesia, sedation
onset is 30-60 seconds
half-time to peak effect is 5 minutes

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20
Q

You give your patient 0.4-0.8mg/kg oral Midazolam 15 minutes prior to induction. Is this appropriate?

A

No. Correct oral dose, but should be given 30 minutes prior to induction. Pediatric patients will get the high end or slightly above this dose.

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21
Q

What is the induction dose for Midazolam?

A

0.1-0.2 mg/kg over 30 seconds

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22
Q

What drug would facilitate induction with Midazolam In what dose?

A

Fentanyl! 50-100 mcg

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23
Q

You have done an induction with Midazolam at 0.1-0.2 mg/kg IV. You also administered propofol or thiopental. What is the effect?

A

Exaggerated drug effects

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24
Q

You are administering an opioid, propofol, or an inhaled agent. Is Midazolam an appropriate adjunct?

A

Yes. It is used to supplement these drugs in the maintenance of anesthesia

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25
Q

Your patient wakes up with severe post-op N&V. You gave Midazolam during the case. Is this the reason?

A

No. Rarely associated with N&V

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26
Q

What is the appropriate loading dose and drip for Versed for post-op sedation?

A

loading dose is 0.5-4mg

gtt is 1-7 mg/hr

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27
Q

Your patient has paradoxical vocal cord motion (upper airway obstruction with stridor). Which drug may be helpful and in which dose?

A

Midazolam at 0.5-1mg

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28
Q

Your patient has significant GERD and takes antacids regularly. How will this affect your Midazolam?

A

Changes the pH, decreases absorption

The drug is used to the acidic pH of the gut and the imidazole ring is designed for it to produce its effects under this physiologic pH; if the pH changes to more basic, then the shape of the imidazole ring will change which will affect absorption

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29
Q

You administer Midazolam with an opioid. What is the respiratory effect?

A

Synergistic - respiratory depression. Make sure they are on oxygen and a pulse ox

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30
Q

Contraindications of Midazolam?

A

Acute porphyrias

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31
Q

Why do benzos have a high margin of safety?

A

They are allosteric

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32
Q

Do benzos produce an isoelectric EEG?

A

No - they decrease alpha activity, but increase beta activity

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33
Q

Your patient’s airway reflexes have been impaired. Would this be due to a benzo or barb?

A

Benzo - depress swallowing reflex and upper airway activity

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34
Q

What effect do benzos have on the HPA axis?

A

Suppression

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35
Q

You have a patient that is thrombocytopenic. Is a benzo appropriate?

A

May not be - they inhibit platelet aggregation

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36
Q

What is the receptor that benzos act on?

A

pentameric GABA

2 alpha subunits, 2 beta subunits, 1 gamma subunit

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37
Q

Sedation effects come from which GABA subunits?

A

Alpha 1 and alpha 5

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38
Q

What are the 5 principle pharmacologic effects of benzos?

A

Anticonvulsant, anterograde amnestic, anxiolytic, skeletal muscle relaxant, sedative/hypnotic

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39
Q

Of the 3 A’s, which do Midazolam produce?

A

Amnesia

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40
Q

What is the big benefit of Midazolam over other benzos

A

Is water soluble with an imidazole ring

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41
Q

Does Midazolam undergo first pass when given orally?

A

Yes - only 50% reaches systemic circulation

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42
Q

Is Diazepam lipid soluble, water soluble, or both?

A

Lipid soluble

43
Q

Does Diazepam cause pain on injection?

A

Yes - it is lipid soluble so it requires propylene glycol and sodium benzoate agents to get in the blood

44
Q

What does the lipid emulsion of Diazepam do?

A

It decreases pain on injection, but also slightly decreases bioavailability

45
Q

You are doing a C-section case. Is it appropriate to use Diazepam? Why or why not?

A

No! It crosses the placenta and fetal concentrations can be greater or equal to those of the mother

46
Q

How will cirrhosis or renal insufficiency affect Diazepam or Midazolam?

A

All of the benzos are highly protein bound. Decreased protein binding = increased free drug

47
Q

How is Diazepam metabolized? Is this phase I or phase II?

A

It is oxidized in the liver via N-methylation (phase I)
secondary conjugation to water-soluble glucuronide
(phase II)

48
Q

What are the metabolites of Diazepam?

A

Desmethyl diazepam
Oxazepam
Temazepam

49
Q

What contributes to the longer half life of Diazepam?

A

The Desmethyl diazepam metabolite. It is metabolized more slowly, contributing to longer half life

50
Q

How long could the half life of Diazepam be?

A

48-96 hours!

51
Q

Your patient who got Diazepam in the OR drove home 7 hours later and got in a car accident. Why do you think this is?

A

The metabolite can have return to drowsiness at 6-8 hours!

52
Q

Your patient is 70 years old. How long do you expect the half life of Diazepam to be?

A

70 hours! Near-linear relationship between half-life and age related to changes in Vd (more adipose tissue, reduced liver function, decrease in proteins)

53
Q

If you have Midazolam and Diazepam and someone tells you the half life of the drug is about 2 hours - which drug are they referring to?

A

Midazolam - 1.9 hours; much shorter than half-life of Diazepam due to metabolite

54
Q

You give your patient a sedative dose of Diazepam. What is the expected effect on ventilation?

A

Minimal depressive effects at sedative doses

55
Q

At what dose do you start seeing increase in PaCO2 with Diazepam?

A

0.2 mg/kg

56
Q

What are the CV effects of Diazepam?

A

No direct action on SNS

minimal decreases in BP, CO, SVR (similar to natural sleep)

57
Q

What are the cardiac effects of Diazepam with Nitrous Oxide

A

Not associated with cardiac changes! None!

58
Q

What are the cardiac effects of Diazepam when used with Fentanyl?

A

Decrease BP and SVR

59
Q

What are the 4 main uses of Diazepam?

A

Pre-op medication, delirium tremens, skeletal muscle relaxation (tetany, lumbar disc disease), anticonvulsant

60
Q

Anticonvulsant dose for Diazepam?

A

0.1mg/kg as anticonvulsant dose

61
Q

Rank Lorazepam, Midazolam, and Diazepam in terms of potency.

A

Lorazepam > Midazolam > Diazepam

62
Q

Compare the onset of action (IV) between Lorazepam, Midazolam, and Diazepam.

A

Midazolam and Diazepam have similar onsets (30-60 seconds), but Lorazepam has a slower onset than both (1-2 minutes)

63
Q

Compare elimination half-time of Lorazepam, Midazolam, and Diazepam.

A

Diazepam (r/t metabolite 48-96 hours) > Lorazepam (14hours) > Midazolam (1.9 hours)

64
Q

What are the 5 possible uses for Lorazepam?

A 
Induction (not typical)
IV sedation during regional
anticonvulsant 
post-op sedation
anxiety
65
Q

Compare peak effect time of Midazolam and Lorazepam.

A

Peak effect time of Midazolam is 5 minutes. Ativan is 20-30 minutes.

66
Q

Compare duration of action of Midazolam and Lorazepam. What drug characteristic is responsible for this?

A

Duration of action of Midazolam is 15-80 minutes. Duration of action of Lorazepam is 6-10 hours. Midazolam is lipophilic, gets rapidly re-distributed.
Lorazepam has a lower lipid solubility/slower entrance to CNS.

67
Q

How long does it take after administering Lorazepam PO to see maximal plasma concentrations. How long does the therapeutic range last?

A

2-4 hours

Therapeutic range persists for 24-48 hours

68
Q

What is the duration of action of Lorazepam?

A

6-10 hours due to lower lipid solubility/slower entrance to CNS

69
Q

How long will anterograde amnesia likely last for Lorazepam?

A

up to 6 hours with minimal sedation

70
Q

Does Lorazepam have metabolites?

A

Inactive. Why the half-life if shorter than Diazepam

71
Q

Which benzo is least likely to be affected by age or liver disease?

A

Lorazepam (no active metabolites)

72
Q

Which benzo is least likely to be affected by drugs that inhibit CYP450?

A

Lorazepam

73
Q

Which benzo is most effective in limiting emergence reactions associated with Ketamine?

A

Lorazepam

74
Q

Of the three main benzos, which does not cause pain on administration? why?

A

Midazolam - imidazole ring that makes it water soluble so it doesn’t need an additive

75
Q

Which of the three main benzos would be best for post-op anxiety in PACU?

A

Lorazepam because it lasts longer

76
Q

How would obesity affect the elimination half times of your benzos?

A

Higher Vd = higher elimination half time

77
Q

What is a key characteristic of Remimazolam that makes it favorable?

A

Its metabolism if not dependent on organs (carboxylic ester moiety) = rapid degradation = fast recovery

78
Q

What is the primary use of oxazepam?

A

Sleep aid (but not insomnia because of slow onset time; short total sleep time)

79
Q

Oxazepam is a metabolite of which benzo?

A

Diazepam

80
Q

Is Oxazepam likely influenced by hepatic dysfunction or inhibitors of CYP450?

A

No

81
Q

What is the mechanism by which Alprazolam (Xanax) reduces anxiety?

A

Inhibits adrenocorticotropic hormone (ACTH) that becomes cortisol (stress hormone)

82
Q

What is the main use of Clonazepam?

A

Control of seizures, especially myoclonic and infantile spasms

MyoCLONus; CLONazepam

83
Q

What is the use of Flurazepam?

A

Used primarily for insomnia (but decreases REM), may also be used for myoclonic/infantile spasms

84
Q

Does Flurazepam have an active metabolite? What would be the effect?

A

Yes - Salkylflurazepam. Pharmacologically active with prolonged elimination half-time resulting in daytime sedation

85
Q

What is Tempazepam used for? What is its benefit over other drugs with this same use?

A

Insomnia. It has weak active and inactive metabolites so it doesn’t result in residual drowsiness even after extended use

86
Q

What is the shortest acting benzo?

A

Triazolam

87
Q

What does Triazolam treat?

A

Insomnia (falling asleep) hangover unlikely, but rebound insomnia may occur when discontinued

88
Q

What is Ro?

A

Investigational benzo with full agonist activity at GABA receptor. Similar DOA/onset, increased plasma clearance, decreased recovery time

89
Q

Disadvantages to Oxazepam?

A

Low PO absorption & short total sleep time

90
Q

What kind of drug is Flumazenil

A

Selective benzodiazepine competitive antagonist

91
Q

What is the structural difference between benzos and flumazenil?

A

flumazenil has a carbonyl instead of a phenyl

92
Q

What is the dosing for flumazenil? How long does it take for effects of the benzo to be reversed?

A

Initial dose 0.2mg IV, typically reverses in 2 minutes

93
Q

How often can you give additional doses of Flumazenil? What is the additional dose?

A

Every 1 minute, 0.1 mg IV

94
Q

At what dose should sedative effects of benzos completely be abolished by flumazenil?

A

0.3-0.6 mg IV

95
Q

At what dose of flumazenil will complete reversal of benzos occur?

A

0.5-1mg IV

96
Q

What is the duration of action of flumazenil?

A

30-60 minutes

97
Q

What benzo would most likely need repeat dosing of Flumazenil? Why?

A

Lorazepam (duration of action longer than the duration of action of flumazenil)

98
Q

Low dose infusion dose of Flumazenil?

A

0.1-0.4mg/h to maintain reversal

99
Q

If the cause of over-sedation was a TCA/antidepressant and you give Flumazenil, what will be the result?

A

May precipitate seizures

100
Q

Will flumazenil cause hypertension?

A

No. Not associated with acute anxiety, HTN, tachy, or increased neuroendocrine response

101
Q

What will you need to do to your MAC when giving Flumazenil?

A

Nothing - does not alter requirements for MAC

102
Q

What are the benzo-non benzos?

A

Zaleplon (sonata), Zolpidem (Ambien), Eszopliclone (Lunesta)

103
Q

What is the mechanism of action of bento-non benzos?

A

Bind on GABA at same sites as benzos, but are selective for GABA subunits, getting desired effects on sleeping with minimal side effects

pharmacology exam 2 (3 decks)

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