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N926 Pharmacology > Benzodiazepines > Flashcards

Benzodiazepines Flashcards

1
Q

Five principle pharmacologic effects of benzodiazipine

A
  • Anxiolytic
  • Sedative and hypnotic
  • Anterograde amnesia
  • Spinal cord muscle relaxant
  • Anticonvulsant activity
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2
Q

pH of midazolam

A

3.5

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3
Q

pK of midazolam

A

6.15

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4
Q

midazolam metabolism is slowed by:

A

CYP inhibitor

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5
Q

midazolam elimination is not altered by

A

Renal failure (eliminatin t1/2, clearance, Vd)

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6
Q

What are the two metabolites from midazolam?

A

1-hydroxymidazolam

4- hydroxymidazolam,

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7
Q

Which midazolam metabolites more of concern? Why?

A

1-hydroxymidazolam.

It has half of the effect of midazolam, needs to be further broken down.

midazoam was oxidized into 1-hydroxymidazolam during phase 1, conjugated during phase 2 for elimination

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8
Q

Which drugs will inhibit CYP450 activity for midazolam? What does it cause?

A

cimetidine, erythromycin,calcium channel blocker, antifungals

Causes unpexted CNS depression

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9
Q

What CNS effect does midazolam have?

Does ICP during intubation increase or decrease or?

neuroprotective?

what happens if long term gtt stopped?

A
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10
Q

Midazolam respiratory effect

Larger than what dose causes resp depression?

Airway effect>

A
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11
Q

midazolam CV effect

greater than what dose causes hotn?

How does it affect intubation response?

A
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12
Q

midazolam preop dosage and onset times

A
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13
Q

midazolam induction dose

A
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14
Q

midazolam side effects

A
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15
Q

midazolam contraindications

A
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16
Q

reaction b/w diazepam and water

A

Insoluble in water (propylene glycol, sodium benzonate)

• Painful on injection

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17
Q

How well is diazepam absorbed in GI?

A

Rapidly absorbed in GI

18
Q

Diazepam Vd

A

Large Vd reflecting extensive tissue uptake of lipid soluble drug

  • Patients with a large BMI will have larger Vd
  • Crosses the placenta – fetal concentrations > mother
19
Q

How well does diazepam bind to protein?

A

Extensively protein bound (albumin)

• Cirrhosis and renal insufficiency result in increased unbound diazepam with increased side effects

20
Q

Two metabolites of diazepam

A
  • Desmethyl Diazepam – metabolized more slowly than parent drug and half as potent – may cause return of drowsiness at 6-8 hours. Elimination half-life 48-96 hours?! Can accumulate in plasma with chronic use
  • Oxazepam

(• Temazepam)

21
Q

elimination half life of diazepam

A

>40hrs

22
Q

diazepam age and half-life relationship

A

near-linear

23
Q

diazepam PK in elderly altered by:

A

Slow drug absorption

Increased percentage of adipose tissue

Decreased plasma proteins

Decreased hepatic blood flow and metabolism

Decreased cardiac output

Prolonged circulation = slower onset, remains in CNS longer

24
Q

diazepam ventilation effect

A

In sedative doses, produces minimal depressive effects on ventilation:

  • Exaggerated when combined with opioids or alcohol
  • COPD may cause prolonged depression of ventilation
25
Q

diazepam hemodynamic effect

A

Even when administered for induction of anesthesia, minimal decreases in BP, CO, SVR are seen (similar to natural sleep)

  • Addition of nitrous oxide not associated with adverse cardiac changes
  • Concomitant use of fentanyl results in decreased BP and SVR
26
Q

diazepam clinical application

A

Preoperative medication

  • Largely replaced by midazolam in children
  • Management of delirium tremens
  • Skeletal muscle relaxation properties useful for:
  • Rare patient with tetany
  • Lumbar disc disease
27
Q

anticonvulsant use of diazepam

dose?

seizure caused by what?

A

0.1 mg/kg IV effective in abolishing seizure activity produced by lidocaine, delirium tremens and status epilepticus

28
Q

side effect and complication of diazepam

A

Overdose can be managed if CV and pulmonary systems are supported and other drugs such as ETOH are not present

29
Q

contraindicatio of diazepam

A

Most common adverse effects are:

  • Unexpected respiratory depression and over sedation
  • They should be avoided in patients with acute porphyrias
30
Q

Compare onset of lorazepam with midazolam and diazepam

Also tell me the IV onset, peak time

how long does antegrade amnesia last

when is maximum plasma concentration reached?

A

Slower onset of action than midazolam or diazepam
• Maximum plasma concentrations 2-4 hours after oral admin
• Antegrade amnesia may last up to 6 hours with minimal sedation (PO)

• Onset 1-2 minutes IV; peak effect 20-30 minutes

31
Q

How is lorazepam metabolized in liver?

Are there active metabolites?

A

conjugated with glucuronic acid in the liver

  • inactive metabolites
  • less likely to be influenced by alteration in liver fxn, age or drugs that inhibit cyp450 (e.g. cimetidine)
32
Q

duration of effect of Lorazepam

A

6-10 hrs

33
Q

half time of lorazepam

A

14 hrs

34
Q

How is lorazepam used clinically?

A

Postoperative sedation of intubated patients

  • Delayed emergence
  • Amnestic effects may last several days
  • May delay weaning from ventilator
35
Q

Reversal agent for benzodiazepines

A

Flumazinel

36
Q

What type of reversal agent is flumazenil?

A

Selective antagonist

37
Q

Dosage of flumazenil

A
  • Initial dose .2mg IV (typically reverses effects in 2 minutes)
  • Further doses of .1 mg IV given at 60 second intervals
  • .5-1.0 completely abolish the therapeutic effect of benzos
  • Unresponsive patients who do not respond to 5 mg of Flumazenil mostly likely have other issues
38
Q

What type of patients is not recommended to receive flumazenil?

A

Not recommended for patients being treated with antiepileptic medication for seizure control

39
Q

Can flumazenil reverse abruptly? Why?

A

No. Due to its weak intrinsic agonist effect

40
Q

Flumazenil is not associated with what?

A
  • acute anxiety
  • hypertension
  • tachycardia
  • increased neuroendocrine response (release of steroids etc.)
41
Q

Do you change MAC requirement d/t flumazenil? Why?

A

not alter anesthetic requirements of MAC. B/c gas and flumazenil work on different receptors

N926 Pharmacology (16 decks)

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