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Pharmacology > Benzos > Flashcards

Benzos Flashcards

1
Q

Benzodiazepine

5 pharmacological effects

A
  1. anxiolytics
  2. sedation
  3. anterograde amnesia
    [[cant remember anything after drug is given]]
  4. anticonvulsant actions
  5. muscle relaxation
    [[spinal level; not adequate for surgery muscle relaxation]]
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2
Q

What is the first drug you’ll give in the OR?

A

Benzodiazepine
-midazolam [[versed]]

  • diazepam [[valium]]
  • lorazepam [[ativan]]
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3
Q

Benzo structure

A
  • benzene ring

- fused with 7 member diazepine ring

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4
Q

Benzo mechanism of action

A

-facilitate there action of GABA on GABAa
[[gets the membrane ready and available for GABA]]
^GABA major inhibitory NT in brain

  • increases affinity of GABAa
  • DOES NOT activate GABAa receptor

BRS explanation;

Benzos bind to regulatory site; benzo receptor on the GABAa receptor

  • allosterically increase the affinity of GABAa receptor for GABA with an increase in the frequency of GABA- stimulated chloride conductance
  • causing hyperpolarization and inhibition

***benzos have NO ACTION in the ABSENCE of GABA

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5
Q

Benzo general facts

A

-does not produce skeletal muscle relaxation ENOUGH for surgery
[[enough for back pain or neck pain]]

  • it also does not alter the dose of muscle relaxant required for surgery
  • less of a potential for tolerance or abuse compared to OPIOIDS and BARBS
  • greater margin of safety in OD
  • DO NOT induce hepatic enzymes

-Benzos have a specific antagonist
[[Flumazenil aka Romazicon]]

**BENZOS have essentially replaced BARBS for premeds and MAC sedation
[[versed is the drug of choice]]

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6
Q

What enhances the affinity of GABA at a GABA a receptor

A

Benzos
Barbs
alcohol

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7
Q

How does GABAa receptor work

A
  • benzo binds to its receptor site on GABAa and facilities the opening of GABA -activated [[GABA a]] chloride channels
  • GABA binds to its receptor site on GABAa and activates the channel

-channel open increased chloride conductance
[[hyperpolarize/ inhibitory]]

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8
Q

Benzo is a what to GABA

A

allosteric agonoist

Benzes allosterically increase the affinity of GABA at GABAa receptors

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9
Q

what kinds of NT is GABA

A

inhibitory

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10
Q

What type of channel is GABAa

A

inhibitory, ligand gated, cya loop; pentomer [[5 subunits]]

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11
Q

Differences between the types of Benzos are

A

potency

lipid solubility

pharmacokinetic

**generally they are all;
HIGHLY lipid soluble
HIGHLY protein bound [[albumin]]

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12
Q

Midazolam

[[Versed]]

A

**has an active metabolite
[[1 hydroxymidazolam]]

water soluble preparation
^not painful when administered
[[can mix in a saline bag]]

imidazole ring

2-3x MORE potent than diazepam [[valium]]

90-98% protein bound
[[highly protein bound]]

0.9-5.6 min to effect site
[[time it takes too hit brain depends on BBB]]

extensive Fist Pass Effect
[[PO dose larger]]

Rapid redistribution
[[highly lipid soluble; short duration]]

E 1/2 t; 1- 6.5 hours
[[slower metabolism;’ elderly and Asians]]

*Renal failure does not effect
Vd, E1/2 t or clearance

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13
Q

What effects BBB

A

AGE
older person more sensitve

ALCOHOLIC
less sensitive

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14
Q

Metabolism of Versed

A

extensive HEPATIC metabolism

hydrolysis to water soluble compound
[[1 and 4 hydroxymidazolam]]

1- hydroxymidazolam
[[active metabolite]]

conjugated and excreted by urine

Renal failure DOES NOT affect
Vd, E 1/2 t or clearance

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15
Q

CNS effects of Versed and Valium

A
  • decreases cerebral blood flow (CBF)
  • decreases cerebral metabolic 02 requirement (CMR02)

-DOES NOT produce isoelectric EEG
[[no flat line on EEG]]

  • preserved cerebrovascular response to CO
  • DOES NOT help attenuate [[reduce]] the ICP response to laryngoscope

-ANTICONVULSANT
[[antiseizure]]

-AMNESTIC
[[won’t remember anything after med is given]]

**valium has same effects

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16
Q

Respiratory effects of Versed and Valium

A

-dose dependent DECREASE in ventilation

-in the presence of opioid
INCTREASED;
HYPOXEMIA HYPOventilation

-decreased upper airway activity [[coughing, gag, swallowing]]

-depresses swallowing reflex
[[help with secretion; suction]]

**versed has same effects

17
Q

CV effects of Versed

A

-Decreased SVR at INDUCTION dose
[[normal dose no change]]

induction dose decreases SVR; decreased BP

CO; no change in healthy heart

*does not attenuate [[reduce]] HR and BP with intubation
^just like with ICP

[[Valium has minimal CV effects]]

18
Q

VERSED DOSES

A

ORAP Premedication and Pedi;
0.25 - 0.5mg/kg PO
[[large post; first pass effect]]

max PO dose for pedi;
20mg

IV sedation;
1 - 2.5mg
max 5mg

INDUCTION DOSE
0.1 - 0.2mg/kg over 30-60 sec
[[remember onset can be 0.9-5.6 min]]

*maintenance can be incremental or infusion

19
Q

Diazepam

[[Valium]]

A

**Active metabolite
[[Desmethyldiazepam]]

preparation; organic solvent [[propylene glycol; benzyl alcohol]]
^PAINFUL on IV and IM injection

Viscous -pH 6.6 - 6.9

Highly Protein Bound
Highly Lipid Soluble
[[longer duration than versed; and 2-3x LESS potent]]

PO dose rapidly absorbed from GI tract
PO valium > PO versed
[[ no first pass effect ]]

20
Q

Metabolism of Valium

A

[[versed –>hydrolysis]]

Oxidation; n-demethylation–>
desmethyldiazepam active metabolite

hepatic micro enzymes; oxazepam
temazepam
^NOT active metabolites

E1/2 t; 21-37 hours
[[increases with age]]
LONG acting >24 hrs

active metabolite
desmethyldiazepam;
48-96 hours [[not as active as valium]]

21
Q

Benzos duration of action

A

short acting; versed
<5 hr

intermediate acting; Ativan
5-24 hrs

long acting; valium
>24 hrs

22
Q

CV effects of Valium

A

minimal changes in SVR, BP, CO

*if HR and BP come down its r/t reduced anxiety

23
Q

VALIUM DOSES

A

ORAL/ Premedication;

10 - 15mg
[[NO first pass effect; rapidly absorbed by GI tract]]

premedication IV; 0.2 mg/kg

INDUCTION IV;
0.5 - 1.0 mg/kg

ANTICONVULSANT;
0.1 mg/ kg
^lowest IV dose

24
Q

Lorazepam

[[Ativan]]

A

**most potent amnesties of all the Benzos **
5- 10x potency of Diazepam
[[versed 2-3x more potent than diazepam]]

Propylene glycol as solvent
[[HURTS on injection]]

NO active metabolites

metabolism less effected by alterations in hepatic function, age and other drugs

E1/2 t;
10-20 hours
[[intermediate DOA 5-24 hrs]]

**SLOW onset; peak is 2 hrs
[[useless in OR]]

25
Q

Flumazenil

[[Romazicon]]

A

**REVERSAL agent for Benzos

very safe antagonist

structure similar to Benzos;
imidazobenzodiazepine derivative

very specific, competitive antagonist

High affinity for benzo receptor
[[will knock benzodiazepines off GABAa receptor site]]

Short duration of action;
30-60 min

can be used in differential dx of coma
[[opioid vs benzo OD]]

DOES NOT cause sedation or respiratory depression

DOES NOT cause acute anxiety and neuroendocrine stress response
[[won’t wake up anxious like with narcan]]

metabolized by liver
excreted by kidneys

26
Q

Flumazenil DOSE

[[Romazicon]]

A

INITIAL IV;

  1. 2 mg IV
    * *wait 2 minutes

0.1 mg IV subsequent doses at 60 sec intervals

MAX 3mg total in 24 hours

infusion;
0.1 - 0.4 mg/hr
[[0.5 - 1.0 mcg/kg/ min]]

27
Q

If patient is on Cimetidine avoid which barbiturate

A

VALIUM
[[diazepam]]

valium undergoes oxidation

cimetidine inhibits CYP450 system; impacting the metabolism of valium
[[prolonged effect]]

[[versed; hydrolysis]]

Pharmacology (7 decks)

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